Soil Health Risk Research Articles

Hazards of toxic metal(loid)s: Exploring the ecological and health risk in soil–crops systems with long-term sewage sludge application

Sewage sludge (SS) is commonly used as agricultural fertilizer worldwide. However, the toxic metal(loid)s in SS raises concerns about soil contamination and the potential risks to human health. This study, conducted since 2007 on the North China Plain, examines the impact of SS use on crops. An experiment was designed with five treatments: conventional fertilization (CK) and four levels of SS application (W1, W2, W3, and W4: 4.5, 9.0, 18.0, and 36.0 t ha−1, respectively). Soil concentrations of eight toxic metal(loid)s (Zn, Cu, Cr, Cd, Ni, Pb, As, and Hg) were analyzed to assess pollution risk using various indices. Health risks associated with maize and wheat grains were also evaluated. Additionally, the impact of long-term SS application on crop yield, soil quality, and human health within a wheat-maize rotation system was examined. SS application increased wheat and maize yields by 5.37 to 19.08 % and 6.97 to 17.94 %, respectively, across treatments W2 to W4. Despite the toxic metal(loid)s in the grains remaining within safe limits, their concentrations showed an upward trend, especially under the W4 treatment. Moreover, SS application significantly increased the soil Zn, Cu, Cr, Cd, Pb, and Hg levels (P < 0.05) without exceeding the national standards. The geo-accumulation index values revealed rising pollution levels for Zn, Cu, Cd, and Hg, which shifted from no contamination to moderate contamination and then to moderate-to-high contamination, yet the overall pollution level remained safe. Soil ecological risks increased from moderate to serious, with Hg posing the greatest risk, particularly under the W4 treatment. Long-term crop intake from the area significantly exposed children and adults to As, contributing 42.12 % and 34.62 % to hazard index (HI), respectively. The HI values for toxic metal(loid)s in these grains surpassed one in both age groups, suggesting health risks from long-term SS cultivated crops.

Data mining for assessing soil fertility

The study is devoted to the use of data mining to assess soil fertility, which is a modern and effective tool in agriculture and ecology. The method includes integrated approaches to data collection, processing and analysis aimed at determining soil fertility, its composition and potential for successful agricultural use. Using a variety of machine learning techniques and statistical models, researchers can predict crop yields, optimize fertilization and soil management strategies, and identify environmental and soil health risks. In particular, the use of the regression method makes it possible to build models that predict the values of fertile soil parameters based on available data. Using machine learning techniques such as Bayes' theorem and support vector machines (SVM), researchers can effectively estimate soil fertility, predict soil characteristics, and optimize agricultural practices. The results of the study demonstrate the high performance of the models in soil sample classification tasks, highlighting their potential for improving soil resource management and increasing crop yields. Such machine learning techniques provide powerful tools for agricultural workers and researchers, facilitating more precise and sustainable agriculture, which is essential for food security and ecosystem resilience.

Content, Distribution, Source Analysis, and Risk Assessment of PAHs in Arable Soils of Taiyuan

PAHs (polycyclic aromatic hydrocarbons) accumulated in arable soils have significant impacts on farmland quality and human health, which has attracted wide attention from scientists and the public. A total of 22 arable soil samples were collected from Taiyuan, an old industrial city, including three districts (industrial zones, hilly areas, and sewage irrigation area), and the contents of 21 PAHs were detected using the GC-MS method. The sources of PAHs in soils were analyzed using the diagnostic ratios (DRs) method and positive matrix factorization (PMF) model, and the soil health risks were analyzed using the incremental lifetime cancer risk (ILCR) model. The results indicated that the average concentrations of Σ21PAHs and Σ16PAHs in arable soils of Taiyuan were 934.6 ng·g-1 and 787.7 ng·g-1, respectively, which were lower than the soil pollution risk screening value of agricultural land stipulated in GB 15168-2018. 3-5 rings PAHs were the dominant components, accounting for~90% of the Σ21PAHs. Approximately 60% of sites in industrial zones, 13% in hilly areas, and 33% in the sewage irrigation area had high PAHs contents larger than 1000 ng·g-1. The spatial distribution of PAHs showed that more severe PAHs pollution in the soil occurred in industrial areas than that in the other two districts. The DRs suggested that the combustion of coals, bio-masses, and traffic emissions were the dominant sources for PAHs pollution in arable soils in Taiyuan. The simulation results of the PMF model indicated that the sources and contribution rates of PAHs in cultivated soils were coal and biomass burning sources (59%), traffic sources (22%), and coking sources (19%). The risk assessment confirmed that the arable soils in Taiyuan had high potential carcinogenic risks; thus, more attention should be paid to the PAHs pollutions in arable soils.

Human Health and Soil Health Risks from Heavy Metals, Micro(nano)plastics, and Antibiotic Resistant Bacteria in Agricultural Soils

Humans are exposed to agricultural soils through inhalation, dermal contact, or the consumption of food. Human health may be at risk when soils are contaminated; while some soil contaminants such as heavy metals (HMs) have been extensively studied, others such as micro(nano)plastics (MNPs) or antibiotic-resistant bacteria (ARB) pose novel threats. This paper investigates the linkages between soil contamination and human health risk by reviewing the state of knowledge on HMs, MNPs, and ARB in agricultural soils. A keyword-based search in Web of Science, Scopus, and Google Scholar was conducted, complemented with a backward snowball search. We analysed main sources of contamination for agricultural soils, risks to human health differentiated by uptake pathway (ingestion, inhalation, dermal), and interactions of contaminants with microorganism, soil fauna, and plants. Results show that the emergence and spread of ARB and antibiotic resistant genes from agricultural soils and their contribution to antibiotic resistances of human pathogens is recognized as a significant threat. Likewise, a growing body of evidence indicates that MNPs are able to enter the food chain and to have potentially harmful effects on human health. For HM, knowledge of the effects on human health is well established. Multiple agricultural practices increase HM concentrations in soils, which may lead to adverse health effects from the ingestion of contaminated products or inhalation of contaminated soil particles. Severe knowledge gaps exist about the pathways of the contaminants, their behaviour in soil, and human uptake. Little is known about long-term exposure and impacts of MNPs, antibiotics and ARB on human health or about the possible combined effects of MNPs, ARB, and HMs. Missing monitoring systems inhibit a comprehensive assessment of human health risks. Our research demonstrates the need for human health risk assessment in the context of agricultural soils, in particular to be able to assess risks related to measures reinforcing the concept of the circular economy.

Spatial distribution characteristics of heavy metal(loid)s health risk in soil at scale on town level

In order to reveal the Spatial distribution characteristics of heavy metal(loid)s health risk in soil on the town-scale, 788 topsoil samples were collected from a town in the hinterland of Chengdu Plain, with 5 subordinate communities and 17 administrative villages as the research sub regions. The USEPA health risk assessment model was used to assess the health risks of heavy metal(loid)s Cd, Hg, As, Cu, Pb, Cr, Zn and Ni in the soil, the health risk analysis method system based on the geographic detector and the optimized rank-size theory model are used to clarify the spatial differentiation and risk level difference of health risk in the study area. The results showed that the average values of Cd, Hg, As, Pb, Cr, Cu, Ni and Zn in the soil of the study area were 0.221, 0.155, 9.76, 32.2, 91.9, 35.2, 37.1 and 108.8 mg/kg, respectively. The health risks of heavy metal(loid)s in soil to adults and children are generally within the acceptable range, but the maximum hazard index of children and the maximum non-carcinogenic risk value of Cr to children are 2.653303 and 1.213098 respectively, which were exceeding the acceptable range. The carcinogenic risk of Cr and As to adults and children and the carcinogenic risk of Cd to children are at 1 × 10–4 to 1 × 10–6, exceeding the 10–6 health threshold. The q-value range of heavy metal(loid)s health risk spatial differentiation of soil in the study area is 0.016–0.425. The spatial differentiation of non-carcinogenic risk of Hg, As, Ni, Pb, Cd and Cr and the spatial differentiation of carcinogenic risk of Cr and As are larger, which needs further attention. The strictly controlled area of heavy metal(loid)s health risk in the soil of the study area (R ≥ 1.1) is mainly concentrated in the central, western and northeast sub regions, and most sub regions belong to the safe utilization area (0.9 < R < 1.1). The health risk assessment of heavy metal(loid)s in soil on a town scale is of positive significance for enriching health risk research methods, measuring health risk levels at different scales, and formulating refined risk management and control strategies.

Heavy metal contamination assessment and probabilistic health risks in soil and maize near coal mines.

ObjectiveCoal mining activities have continuously introduced heavy metals into the soil–crop system, causing increasing damage to crops. This study integrated the analysis of the heavy metal contamination status and human health risk in soil and maize near coal mines to help formulate control strategies for soil quality, maize production, and safe consumption.MethodThis study was carried out on maize agricultural land near a coal mining plant. Heavy metal contamination was assessed by the geo-accumulation index (Igeo), enrichment factor (EF), and bioaccumulation factor (BCF). The Monte Carlo simulation was used to estimate the probabilistic health risk of heavy metals exposure in soil and maize. The relationship between the concentration of heavy metal in the soil and that in maize was further visualized by correlation analysis and random forest analysis.ResultsThe results revealed that the mean concentrations of soil Ni, Cu, As, Cd, Sn, Zn, Pb, and Hg were all above the local background level. Ni was the most severely polluted heavy metal in maize and had a concentration higher than the risk control standard for corn in China (NY 861-2004). The Igeo values of all heavy metals were low, and EF values showed enrichment in V, Cr, Ti, Ni, and As. The assessment of probabilistic health risk exposed by heavy metals in soil and maize indicated that 1.16 and 1.46% of residents exceeded the carcinogenic risk level due to heavy metal exposure from soil and maize, respectively. Children were the most sensitive to maize and soil heavy metal exposure in the contaminated area. Ingestion of heavy metals was associated with the highest health risk to residents, followed by dermal contact and inhalation. As and Cr in soil and Cr and Ni in maize had the greatest impact on human health risk. Furthermore, maize heavy metals were affected the most by soil Cr, Cd, and V.ConclusionThese results may provide useful information for human carcinogenic risk associated with soil and maize heavy metal exposure due to coal mining activities.

Assessment of heavy metals concentrations, soil-to-plant transfer factor and potential health risk in soil and rice samples from Ezillo rice fields in Ebonyi State, Nigeria

This study examined the level of heavy metals (Pb, Ni, Cd and Cr) concentrations in soil and rice samples from two paddy fields (field 1 and 2) located in Ezillo, Ebonyi State by means of flame atomic spectrophotometer. Topsoil soil samples at depths 0–4 cm and 4–8 cm were collected before planting (BP), after planting (AP) and during harvesting (DH) stages. The concentrations of the metals in soil from field 1 at depth 0–4 cm decreased in this order of Cr > Ni > Pb > Cd (BP), Ni > Cr > Pb > Cd (AP) and Cr > Ni > Cd > Pb (DH) while at depth 4–8 cm, the orders were Ni > Cr > Cd > Pb (BP), Cr > Ni > Pb > Cd (AP) and Ni > Cr > Pb > Cd (DH). In field 2, at depth 0–4 cm, the order Cr > Ni > Pb > Cd was found in all the farming stages while at depth 4–8 cm orders were Cr > Ni > Cd > Pb (BP), Cr > Ni > Pb > Cd (AP) and Ni > Cr > Pb > Cd (DH). In the rice samples, the orders were Cr > Ni > Pb > Cd in field 1 and Cr > Ni > Cd > Pb in field 2. The levels of the metals in both soil and rice samples were relatively low when compared with permissible limits of some regulatory agencies. The estimated average daily intake (ADI), hazard quotients (HQ) and total hazard index (THI) of the metals in both soil and rice indicate higher values in children than the adult group. The HQ and HI values were below the permissible safe limits of 1.0. This is an indication that the selected metals in the paddy soil and rice present no appreciable threat to food safety. Therefore, with respect to the investigated metals, the rice produced from these fields is safe for human consumption.

Comparative Assessment of Radiation Background Due to Natural and Artificial Radionuclides in Soil in Specific Areas on the Territories of State of Washington (USA) and Lithuania

Activity concentrations of 226Ra, 232Th, 40K, and 137Cs in soil samples collected at Mount Rainier National Park and Satsop Nuclear Power Plant zone in State of Washington (USA) and Curonian Spit National Park and Ignalina Nuclear Power Plant zone in Lithuania have been measured by gamma spectrometry. The results have been compared with the worldwide measured average values reported by the UNSCEAR. Higher activity concentrations of 137Cs were found in Curonian Spit National Park due to Chernobyl accident fallout. The radium equivalent activity (Raeq), the external hazard index (Hex), the internal hazard index (Hin), the absorbed dose rate (D), and the annual effective dose rate (AEDR) were also calculated and compared with the international recommended values. These calculated hazard indices used to estimate the potential radiological health risk in soil and the dose rate associated with it are below their permissible limit.

Fluorine enrichment of vegetables and soil around an abandoned aluminium plant and its risk to human health.

In the process of electrolytic aluminium production, a large amount of fluoride is deposited into the surrounding environment. The growth of crops within these areas creates a state of high stress in plants that can easily result in excessive fluorine enrichment in agricultural products, which in turn poses a health threat to humans via the food chain. However, it is not clear what the degree of influence is or how long the impacts of fluorides in soil and agricultural products last for. In this study, 122 vegetable species and 36 surface soil samples were collected within 10km of an aluminium plant that had been abandoned for five years. The single factor index and the geological accumulation index methods were used to evaluate the degree of fluorine pollution in vegetables and soil within the study area. The hazard index and the hazard quotient were used to assess vegetable and soil health risks, respectively. The results showed that the fluorine content of 89.26% of agricultural products exceeded the Chinese Maximum Levels of Contaminants in Foods and was higher than in other regions, indicating that the emissions of fluoride from the aluminium plant still had a significant effect on fluorine accumulation in vegetables. The total fluorine (Ft) content in the surrounding surface soil (average value 1328.32mgkg-1) was similar to the soil fluorine background in the nearby uncontaminated settlement area, but the soil water-soluble fluorine (Fw) was very high, indicating that the fluorine pollutants emitted from the aluminium plant had gradually been diluted by the high background of the original soil, but the solubility of these pollutants was higher (average 15.00mgkg-1) and would continue to threaten the safety of agricultural products in this region. Within 1km of the abandoned aluminium plant, the degree of fluorine enrichment in vegetables, and Ft and Fw in soil were significantly higher than other ranges, indicating that this was the main fluoride deposit area. Based on the HI and HQ evaluation, vegetables and ground dust around the aluminium plant still had high non-carcinogenic risks for children, even though it has been abandoned for more than five years.

Environmental stability and oral bioaccessibility of synthetic Pb-bearing phases to better evaluate soil health risks.

A large amount of contaminated sites is shown around the world which may induce a health risk due to the presence of contaminants such as metal (loïd)s bearing phases. Health risk assessment is based on contaminant bioaccessibility. However, it is needed to understand every contaminant behavior in physiological matrix to be a realistic way to assess and interpret these sanitary risks. Due to the complexity of contaminated soil matrix, the use of synthetic minerals seems to be the better tool to understand their behavior in physiological matrix. Then, this study aims to highlight the environmental stability and the behavior during bioaccessibility ingestion (UBM) of selected synthetic lead-bearing phases. For this purpose, three Pb phases (galena, beudantite, and anglesite) commonly found in contaminated environments (particularly mining sites) were synthesized and characterized (structurally and morphologically). The sequential BCR extractions have shown that most of the lead is in a stable and non-mobilizable form (up to 93%). The lead present in these phases represents very few risks of migrating into the environment during physicochemical condition changes. The results of the bioaccessibility revealed a relatively high stability of the pure bearing phases in the physiological matrix. Lead is stable for 97.0% to 99.2% during the gastric phase and 97.0% to 99.9% during the gastro-intestinal phase. Moreover, the synthetic mixtures of galena/beudantite and anglesite/beudantite have been realized considering the proportions commonly found in the mining contexts. This has shown a similar behavior compared to pure phases except in the case of the anglesite mixture inducing a clear cocktail effect (drastic increase of Pb amount from gastro-intestinal phases). At last, this study is a first and interesting step to assess the behavior of these bearing phases in heterogeneous and complex medium such as soil.

Assessment of Potentially Toxic Elements Pollution and Human Health Risk in Soil of Ilesha Gold Mining Site, Southwest Nigeria

ABSTRACT The paper presents results of research to determine the health risk of potentially toxic elements (PTEs) in soils of gold mining area in Ilesha, Southwestern Nigeria. Eighteen top soil samples were collected and analysed for PTEs using ICPMS. The pollution level in soils were assessed using pollution load index (PLI) and potential ecological risk index (PERI). The human health risk was assessed using hazard index (HI), non-carcinogenic risk index and carcinogenic risk index. All the PTEs were higher than crustal average values except Fe and follow the order Mn &amp;gt; Ba &amp;gt; Cr &amp;gt; Zn &amp;gt; Cu &amp;gt; Ni &amp;gt; Pb &amp;gt; Co &amp;gt;Fe &amp;gt; As &amp;gt; Cd. The soil samples can be classified as unpolluted to moderately polluted (0.18-1.23) and low risk (15.28-94.24) based on PLI and PERI respectively. The values of hazard Index (HI) calculated for child and adult population for all the pathways were &amp;lt;1 and pose no obvious non carcinogenic risk to the population except for ingestion pathway where 33% of the samples showed value &amp;gt;1 in child population. As, Co, Cd and Pb constituted high cancer risk in the study area with child at higher risk than adult. The Total Cancer Risk (TCR) in the study area based on all the pathways ranges between 0.19 -3.86 and 0.18-3.58 for child and adult respectively and the ingestion route seems to be the major contributor to excess lifetime cancer risk followed by the dermal pathway.

Radiological Assessment and Mechanical Separation of NORM Contaminated Soil from Iraqi Oil Fields

Naturally occurring radioactive materials (NORM) contaminated sites at Al-Rumaila Iraqi oil fields have been characterized as a part of soil remediation project. Activity of radium isotopes in contaminated soil have been determined using gamma spectrometer High Purity Germanium detector (HPGe) and found to be very high for Al-Markezia, Al-Qurainat degassing stations and storage area at Khadhir Almay region. The activity concentration of samples ranges from 6474.11±563.8 Bq/kg to 1232.5±60.9 Bq/kg with mean value of 3853.3 Bq/kg for 226Ra, 843.59±8.39 Bq/kg to 302.2±9.2 Bq/kg with mean value of 572.9 Bq/kg for 232Th and 294.31±18.56 Bq/kg to 156.64±18.1 Bq/kg with mean value of 225.5 for 40K. Six hazard indexs radium equivalent, representative level index, adsorbed dose rate in air, annual effective dose equivalent, external hazard index, and internal hazard indexes were calculated to estimate the potential radiological health risk in soil and dose rate associated with it and found to be high. Screening of contaminated soil was performed to evaluate the feasibility of particle size separation. The fractions obtained varied between 75 µm (200 mesh) to 300µm (48 mesh).The results show that the largest weight percent in fine particle size cut ( -75, -125+75, -250+125) µm is 73.9% and all radium isotopes are concentrated in 37.5µm particle size while small fluctuations are observed in the other particle size cuts.

Assessment of radioactive materials and heavy metals in the surface soil around uranium mining area of Tongliao, China

Natural and artificial radionuclides and heavy metals in the surface soil of the uranium mining area of Tongliao, China, were measured using gamma spectrometry, flame atomic absorption spectrophotometry, graphite furnace atomic absorption spectrophotometry and microwave dissolution atomic fluorescence spectrometry respectively. The estimated average activity concentrations of 238U, 232Th, 226Ra, 40K and 137Cs are 27.53±16.01, 15.89±5.20, 12.64±4.27, 746.84±38.24 and 4.23±4.76Bq/kg respectively. The estimated average absorbed dose rate in the air and annual effective dose rate are 46.58±5.26nGy/h and 57.13±6.45μSv, respectively. The radium equivalent activity, external and internal hazard indices were also calculated and their mean values are within the acceptable limits. The heavy metal concentrations of Pb, Cd, Cu, Zn, Hg and As from the surface soil were measured and their health risks were then determined. Although the content of Cd is much higher than the average background in China, its non-cancer and cancer risk indices are all within the acceptable ranges. These calculated hazard indices to estimate the potential radiological health risk in soil and the dose rate are well below their permissible limit. In addition the correlations between the radioactivity concentrations of the radionuclides and the heavy metals in soil were determined by the Pearson linear coefficient.

Measurement of Surface Dose Rate of Nuclear Radiation in Coastal Areas of Akwa Ibom State, Nigeria

In this study, the surface doses rate measurements were done in-situ using dose rate meters. The analysis of naturally occurring radionuclides (40K, 238U and 232Th) has been carried out in soil samples collected from Eastern Obolo, Ikot Abasi, and Ibeno local government areas of Akwa Ibom State, using gamma spectroscopy operated on a Canberra vertical high purity 2’’×2’’ NaI(Tl) model 802 detector. The activity concentration (Bq.kg-1) of the samples ranges from 34.65±2.56 to 214.12±4.34 with mean value 94.60±3.42 for 40K, 5.12±0.38 to 38.5±2.38 with mean value 15.16±1.83 for 238U and 0.03±0.77-30.59 with mean value 15.40±0.73 for 232Th. This study also examines some radiation hazard indices, the mean values obtained are 44.46 Bq.kg-1, 20.52 nGy.h-1, 0.02 mSv, 0.17 Bq.kg-1, 0.20 Bq.kg-1 for Radium Equivalent activity (Raeq), Absorbed Dose rate (D), Annual Effective Dose Rate (Eeff Dose), External Hazard index (Hex) and internal Hazard index (Hin) respectively. These calculated hazard indices to assess the potential radiological health risk in soil and the dose associated with it are well below their permissible limit. The soil and sediments from the study area provide no excessive exposures for inhabitants and can be use as construction material without posing any immediate radiological threat to the public. However, the public is cautioned against excess exposure to avoid future accumulative dose of these radiations.

Physiological Growth Indices of Maize Under Semi-Arid Irrigated Conditions as Influenced by Subsoil Compaction and Nitrogen Fertilization

The study was initiated to access the effect of subsoil compaction and nitrogen fertilization on various growth indices of maize, at research farm, Department of Soil Science, Punjab Agricultural University, Ludhiana. The split plot design was employed with three levels of subsoil compaction (main plot), three levels of N fertilization (subplot) and three replications. The dry matter accumulation, leaf area (LA) and growth indices were significantly lower under higher level of subsoil compaction. The crop growth rate (CGR) was significantly higher under C0 treatment at 30 DAS, 60 DAS and at harvest than that in C1 and C2 treatment. Higher root mass density was observed in the surface soil under C2 treatment, while a reverse trend was recorded at 15–30 and 30–60 cm soil depth, where higher root mass density was observed under C0 treatment than that in C1 and C2 treatment. Application of higher dose of N resulted in higher dry matter, LA index and growth indices than that in lower N application. A positive exponential relationship was observed between grain yield-CGR and biomass yield-CGR. The total N uptake was lower under C2 subsoil compaction level, while higher N rates improved N uptake. The N fertilization resulted in favourable nutrient regime and thereby improved maize growth, development and yield formation under higher subsoil compaction levels. Further studies could be done to access the environmental and soil health risks associated with higher N application under compacted subsoil conditions.

Natural Radioactivity in Soil Samples in Nineveh Province and the Associated Radiation Hazards

The natural radioactivity due to presence of 226 Ra, 232 Th and 40 K in soil of Nineveh zone, Nineveh province, Iraq were measured by using gamma-ray spectrometry based on high-purity germanium detector. The specific activity of soil samples ranged from 16.21 to 38.83 Bq/kg with an average of value of 32.52±6.48 Bq/kg, 8.53 to 28.37 Bq/kg with an average of 20.30±5.36 Bq/kg, 236.03 to 613.11 Bq/kg with an average of 378.93± 123.29Bq/kg, and 2.18 to 17.92 Bq/kg with an average of 8.17± 5.55 Bq/kg for 226 Ra, 232 Th, 40 K and 137 Cs respectively. The study also examine some radiation hazard indices such as Radium equivalent activity (Raeq), Absorbed gamma dose rate (D), External hazard index (Hex), Internal hazard index (Hin) and gamma index (Iγ). These calculated hazard indices to estimate the potential radiological health risk in soil. The radium equivalent activity average (Raeq) was less than the permitted value (370 Bq/kg). The average absorbed dose rate value also less than the permissible limit of 55 nGy/h. The external hazard index, internal hazard index and gamma index of soil samples were less than unity.

Evaluation of Naturally Occurring Radioactivity Materials (NORM) of Soil and Sediments in Oil and Gas Wells in Western Niger Delta Region of Nigeria

Oil mineral leases (30, 58 and 61) in Delta and River States are the major oil blocks in the oil and gas rich Niger Delta region of Nigeria that is characterized by environmental degradation from oil and gas activities. This research work presents an analytical approach on natural radioactivity assessment in soil and sediment in 15 oil fields of these OMLs. Concentrations of natural radionuclides (226Ra, 232Th and 40K) were determined using gamma spectroscopy. The mean activity concentration of 226Ra, 232Th and 40K for OML30 is 40.2 ± 5.1, 29.9 ± 4.2 and 361.5 ± 20.0 Bq kg−1, respectively; the corresponding values obtained for OML58 is 20.9 ± 2.8, 19.4 ± 2.5 and 260.0 ± 14.1 Bq kg−1, respectively. While the mean activity concentration of 226Ra, 232Th and 40K for OML61 is 29.3 ± 3.5, 21.6 ± 2.6 and 262.1 ± 14.6 Bq kg−1, respectively. These values obtained show enhanced NORMs, but are well within the world range and values reported in some regions and countries of the world, and are slightly above control values, values obtained in Southwestern region of Nigeria and some countries reported average values. The study also examined some radiation hazard indices, the mean values obtained are 86.6 ± 9.3 Bq kg−1, 0.6 Bq kg−1, 40.8 ηGy h−1, 0.05 μSv y−1, 0.2 and 0.3 for radium equivalent activity (Raeq), representative level index (Iγ), absorbed dose rates (D), annual effective dose rates (E ff dose), external hazard index (H ex) and internal hazard index (H in), respectively. These calculated hazard indices to estimate the potential radiological health risk in soil and sediment are well below their permissible limits. The soil and sediments from the study area provide no excessive exposures for the inhabitants and can be used as construction materials without posing any radiological threat or harm to the public users. However, oil-field workers and host community residents are cautioned against excess exposure to avoid future accumulative dose of these radiations from sludge and sediment of this area.

γ-Spectroscopy measurement of natural radioactivity and assessment of radiation hazard indices in soil samples from oil fields environment of Delta State, Nigeria

The analysis of naturally occurring radionuclides (226Ra, 232Th and 40K) has been carried out in soil samples collected from oil and gas field environment of Delta state, using gamma spectroscopy operated on a Canberra vertical high purity 2″×2″ NaI(TI) detector. The activity concentration of the samples ranges from 19.2 ± 5.6Bqkg−1 to 94.2 ± 7.7Bqkg−1 with mean value of 41.0 ± 5.0Bqkg−1 for 226Ra, 17.1 ± 3.0Bqkg−1 to 47.5 ± 5.3Bqkg−1 with mean value of 29.7 ± 4Bqkg−1 for 232Th and 107.0 ± 10.2Bqkg−1 to 712.4 ± 38.9Bqkg−1 with a mean value of 412.5 ± 20.0Bqkg−1 for 40K. These values obtained are well within the world range and values reported elsewhere in other countries, but are little above some countries reported average values and some part of Nigeria. The study also examined some radiation hazard indices, the mean values obtained are, 98.5 ± 12.3Bq.kg−1, 0.8Bqkg−1, 54.6ηGyh−1, 0.07μSvy−1, 0.3 and 0.4 for Radium equivalent activity (Raeq), Representative level index (Iγ), Absorbed Dose rates (D), Annual Effective Dose Rates (Eff Dose), External Hazard Index (Hex) and Internal Hazard Index (Hin) respectively. These calculated hazard indices to estimate the potential radiological health risk in soil and the dose rate associated with it are well below their permissible limit. The soil and sediments from the study area provide no excessive exposures for inhabitants and can be use as construction materials without posing any immediate radiological threat to the public. However, oil workers in the fields and host communities are cautioned against excess exposure to avoid future accumulative dose of these radiations from sludge and sediment of this area.