2D transition metal dichalcogenide MoS2 monolayer quantum dots (MoS2-QD) and their doped boron (B@MoS2-QD), nitrogen (N@MoS2-QD), phosphorus (P@MoS2-QD), and silicon (Si@MoS2-QD) counterparts are proposed as selective sensors for NH3 gas.

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This study evaluates the sources and health risks associated with heavy metals in Ipata spare part market in Ilorin, Nigeria. Soil and water samples were collected within and outside the market for heavy metal (As, Pb, Mg, Mn, Cd, Cr, Cu, Zn, Fe and Ag) analysis using Atomic Absorption Spectrometry. The results indicate that all the heavy metals analyzed show higher concentration within the recycling market than the control location. The concentration of heavy metals at the market decreases with an increasing depth between 0 and 50 cm and appears to be stable below 50 cm of the soil depth. All the Hazard Indices (HI) estimated for the soil samples are less than one (< 1) which is the standard set by USEPA, whereas, the Hazard Index (HI) for the water samples within the station is greater than 1. The Incremental Lifetime Cancer Risk (ILCR) for soil samples ranged from level I to level V, while that of water samples ranged from level VI to Level VII based on Delphii method of classification. This shows that the main lifetime cancer risk occurs through the water exposure pathway. Similarly, according to the mean, P5% and P95% cumulative probability using the Monte Carlo simulation, the ILCR is above the acceptable range of 1.00E−6 and 1.00E−4. All the pollution indices reveal that the significant pollution at the park is more of anthropogenic than pedogenic and lithogenic. Therefore, the market is contributing immensely to environmental pollution which may lead to unforeseen danger to human health.

Natural radioactivity measurement and dose assessment are important aspects of radiation protection. The goal of this study is to validate the previous results obtained from the in-situ measurements in the study area in order to ascertain the level of radiation hazards to the populaces living around the mining site.A3 Â 3-inch lead-shielded NaI(Tl) detector was used to measure the activity concentrations of 40 K, 238 U and 232 Thin soil, water and guinea corn grain samples collected from a granite mining field in Asa, Kwara State, North-central Nigeria. The overall mean activity concentrations of 40 K, 238 U and 232 Th are 441.06, 11.51 and 15.42 Bqkg À1 for the soil samples, 20.67, 0.66, and 0.88 BqL À1 for the water samples and 214.31, 5.25 and 8.86 Bqkg À , 1 respectively for the grain samples. The bioaccumulation/transfer factors are 0.49, 0.46 and 0.58 for 40 K, 238 U and 232 Th respectively. The mean values of all the radiological hazard parameters are within the permissible limit recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation. Consequently, the risk of indoor and outdoor gamma radiation exposure is comparatively less for these Granite soils. Hence, the results in this study will reference future studies in terms of basic radiological data.

Magnetic susceptibility measurement was carried out on 26 top-soil samples randomly collected from the study area and 5 selected top-soil samples outside the station, using the Bartington MS meter linked to a computer operated using Multisus2 software. The Measurements was done at both low (0.47 kHz) and high (4.7 kHz) frequency susceptibilities which was further used to calculate the frequency dependent susceptibility (Χ FD ). The values for low frequency mass magnetic susceptibility ranges between 96.6×10 −5 m 3 kg −1 and 146×10 −5 m 3 kg −1 with an average value of 117.35×10 −5 m 3 kg −1 and standard deviation of 12.22×10 −5 m 3 kg −1 . The result reveal high magnetic susceptibility values at the station compared with the values observed outside the station which ranges between 53.0×10 −5 m 3 kg −1 and 72.3×10 −5 m 3 kg −1 with an average value of 63.2×10 −5 m 3 kg −1 and standard deviation of 7.01×10 −5 m 3 kg −1 . This significant magnetic enhancement indicates high concentration of ferrimagnetic minerals in the soil and thus evidence of pollution due to the activities at the station which implies that the magnetic enhancement is of anthropogenic source than pedogenic and lithogenic. Analysis of the heavy metals also reveals higher values at the station. The correlation analysis between the mass specific magnetic susceptibility and the heavy metals concentrations (i.e. Cu (R=0.92), Fe (R=0.88), Cr (R=0.85), Zn (R=0.83), Cd (R=0.79), Mg (R=0.72), Mn (R=0.60), Pb (R=0.67)) which was conducted to further investigate the relationship between the soil magnetic susceptibility values and elemental variations, demonstrated magnetic susceptibility can be used as a proxy method for assessing the pollution of these heavy metals.There is no funding received for this research work. ORCID iDsMuyiwa Michael Orosun https://orcid.org/0000-0002-0236-3345 Naheem Banji Salawu https:/ /orcid.org/0000-0001-5089-2359 Louis Hitler https://orcid.org/0000-0002-0286-2865 ReferencesAyoubi S and Adman V 2019 Iron mineralogy and magnetic susceptibility of soils developed on various rocks in western Iran Clay and Clay Minerals. 67 217-27 Ayoubi S and Karami M 2019 Pedotransfer functions for predicting heavy metals in natural soils using magnetic measures and soil properties J. Geochem. Explor. 197 212-9 Beget J E, Stone D B and Hawkins D B 1990 Paleoclimatic forcing of magnetic susceptibility variation in alaskan loess during the late quaternary Geology 18 40-3 Blundell A, Dearing J A, Boyle J F and Hannam J A 2009 Controlling factors for the spatial variability of soil magnetic susceptibility across England and Wales Earth Sci. Rev. 95 158-88 Brempong F, Mariam Q and Preko K 2016 The use of magnetic susceptibility measurements to determine pollution of agricultural soils in road proximity Afr. J. Environ. Sci. Technol. 10 263-71 Caggiano R, Coppola R, Di Leo S, Macchiato M and Ragosta M 2005 Comparison between in situ soil magnetic susceptibility measurements and heavy metal concentrations: the case of the...

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