To manage the positive and negative aspects of application of nanomaterials to natural systems, it is necessary to know the distribution and fate of these materials in such systems. In this regard, the nanoparticle background concentration is one of the factors affecting the transfer process. In this study, in order to investigate the effect of background concentration on the transport of titanium dioxide nanoparticles, transport of TiO2 nanoparticles was first investigated in undisturbed soil columns under different flow rates. The flow rates were equal to the saturated hydraulic conductivity (Ks), 0. 9 Ks, 0. 7 Ks, and 0. 5 Ks (unsaturated flow) applied by peristaltic pump (BT100-1F) to the different soil columns. Then, in order to investigate the effect of the first experiment (background concentration after the first experiment) on subsequent experiments, in a column after the saturation flow test and measuring the outflow and determining the concentration of TiO2 nanoparticles as a function of time, flow rates at unit volume of 540, 420, and 300 μ L/min, respectively, are 0. 9, 0. 7 and 0. 5 times the saturated hydraulic conductivity, respectively. Parameters explaining the transport of nanoparticles using measured data of breakthrough curves based on one-site sorption model and one kinetic site sorption model were estimated. At 540 μ L/min, the amount of TiO2 nanoparticles in outflow from the column was lower relative to the absence of the background concentration due to the increase in the concentration of nanoparticles and, therefore, the possibility of more collisions and formation of larger aggregates that caused trapping (straining) them in the pores of the soil. By decreasing the flow rate from 540 to 420 and then 300 μ L/min, there was no background concentration in the soil column due to the increase of the nanoparticles in the soil column and the lack of sorption site for more nanoparticles were introduced into the outlet from the column. Therefore, due to the effect of TiO2 NPs background concentration on the transfer of these particles in the soil, it is necessary to determine their background concentration in the contaminated soil and water where TiO2 NPs are used for remediation of contamination. Also, effect of background concentration on the transfer process depending on the influent flow rate should be considered. In the one kinetic sorption site model, taking into account the detachment coefficient of TiO2 nanoparticles, the results of estimation the nanoparticles transport through soil column were significantly improved (R2>0. 89, ME, and RMSE were also much lower than the one site sorption model at all flow rates).

One of the main problems in soil pollution evaluation is the lack of regional standards. The objectives of this study were (i) to estimate the background concentration of some heavy metals for environmental assessment and, (ii) to locate heavy metal polluted soils in part of central Mazandaran Province. The study region with 5500 km2 area is important in terms of agricultural activities and population density. Using nested-systematic method, 256 composite soil samples were taken from the depth of 0-10 cm, including 148, 60, and 48 soil samples in agricultural land, urban area, and natural lands (forest and rangeland), respectively. After preparation and extraction of soil samples with 5 N nitric acid, the total concentration of Cu, Zn, Ni, Pb, and Cd was measured by an atomic absorption spectrometer. Natural background concentration (NBC) of Cu, Zn, Ni, Pb, and Cd was estimated to be 28.3, 40.2, 45.7, 34.2, and 0.23 mg kg-1, respectively. Interpolated distribution map of contamination factors (CF) and pollution load index (PLI) of heavy metals were prepared using NBC. The overlap of CF and PLI maps with geology and land use maps was indicated that the concentration of Pb, Zn, and Cu has been affected by human activities such as traffic, whereas Cd and Ni contents are controlled by natural factors such as parent material, and agricultural activities, mostly. Based on the classes of CF, most samples are moderately contaminated with heavy metals.

Background: Indoor levels of 222Rn in some residential areas in Ramsar are as high as 31, 000 Bq/m3, resulting in mean internal exposures up to 71 mSv/y. The main goal of this study was to develop a simple mathematical model for predicting radon concentrationfrom gamma radiation level in dwellings located in high background radiation areas (HBRAs) and a nearby normal background radiation area (NBRA) of Ramsar. Materials and Methods: The levels of gamma background radiation and indoor radon were measured in 350 dwellings located in normal and high background radiation areas (210 dwellings from HBRAs and 140 dwellings from NBRAs). Moreover, data about the most important environmental factors such as temperature and humidity as well as the inhabitants’ nutrition were collected. Results: The mathematical relationship between the gamma radiation level and indoor radon concentration in NBRAs and HBRAs is introduced in this study. The findings obtained in this study clearly indicate that in normal and high background radiation areas of Ramsar the majority of confounding factors such as the type of building materials and ventilation in different houses are almost identical. Therefore, the level of gamma radiation can be used as a strong predictive tool for radon concentration. Conclusion: As radon concentration in indoor air strongly varies with time, the simple mathematical methods developed in this study, can help health physicists and environmental scientists have an estimate of the mean radon level in these area.

In this study, the concentration-number fractal method was used for regional exploration studies, and determining the anomalies of copper, lead and zinc elements. For this purpose, 800 samples of stream sediments were selected from the rivers in the area (i. e. from Kahak and Aran geological maps, 1: 100, 000 sheets) and then the anomalies of these elements were mapped. The results show that strong copper anomalies are observed in the northern, central, southern and western parts of the area and the highest lead anomalies are located in the western part of the area. Strong anomalies of the zinc element are located in the central, southern and western parts of the region. These anomalies coincide with the lithological units of andesitic-basalt lava, volcanic breccia, tuffs, dacites, small scale masses of quartz-diorite, and small-scale masses of quartz-monzonite. The obtained map from combining anomalies and faults map reveals that the anomalies are mostly concentrated in fault zones and fault intersection points in the area and faults play a fundamental role in ore mineralization.

Introduction In many countries, baseline concentrations of heavy metals in soil have been studied,this information is used as a reference to assess soil quality status (Karim et al, 2015). Soil concentrations of elements in the soil are a function of the mineralogical composition of the parent material and weathering processes affecting soil formation as well as properties such as particle size, clay content and soil organic matter (Azimzadeh and Khademi, 2013). As a result, the natural concentration of elements in soils is widely variable and the use of baseline (threshold concentration of heavy metals) of other countries and the global average to identify the extent and risks of heavy metal pollution in soils of areas where environmental boundaries are not defined is incorrect (Ghanavati et al, 2019,Nazarpour, 2018). Fractal geometry studies natural phenomena and complex and irregular objects with mathematical relations. One of the major applications of fractal geometry is in estimating the thresholds and thus separating the abnormal community from the field based on their fractal dimension differences (Nazarpour et al, 2015). In this research, this model has been used to determine the baseline concentration of heavy metals. Materials and methods In this study, in order to evaluate the background concentration of some heavy metals in surface soils of Khuzestan province. The sampling method was that first, using random sampling distribution in GIS, the proposed neighborhoods in the study area were determined. The points were selected to cover the entire study area. Samples were taken in combination (mixture of 3 samples together, with a distance of 50 to 100 m) from a depth of zero to 20 cm from the soil surface and with an approximate weight of 500 g and a total of 87 samples were prepared. The samples were dried in room air for 48 hours, then crushed and passed through a 200 mesh polyethylene sieve. After preparing the samples, heavy metals were measured by induction coupled plasma spectroscopy (ICP-OES) of the model device (Model Varian735). Results and discussion According to the results, the studied heavy metals show a wide range of concentrations. The concentrations of Ni, Co and Pb were in the range between: 38-320, 5-16 and 5-41 mg/kg. The lowest and highest mean concentrations of the studied metals were related to Pb and Ni, 9. 09 and 66. 34 mg/kg, respectively. High concentrations of heavy metals indicate the impact of human activities in the region (Sadeghdoust et al, 2020). In this study, after sorting the data from high to low and determining the frequency of each concentration, logarithmic plots of cumulative frequency of metal concentration versus area were drawn. By obtaining the breaking points, the threshold of each metal was determined for the concentration-area method. Baseline values for Co, Ni and Pb were 6. 93, 47. 59 and 6. 26 mg/kg, respectively. The results showed that the application of fractal methods in separating the amount of baseline from other geochemical populations is very appropriate. Conclusion Geochemical maps prepared by fractal method of concentration-area have a very good adaptation to the conditions of the region in terms of natural conditions of the region, land use and especially the effect of industrial units on the concentration and abundance of heavy metals and heavy metal pollution in the region. The results show the effect of anthropogenic factors on the concentration of metals. In general, the results showed that different factors, including human and natural factors together, are always effective in the distribution and concentration of heavy metals. Therefore, in order to maintain the balance of the ecosystem, human health, identify adverse effects on the environment and its proper management, it is necessary to determine the concentration of the field or the limits of environmental safety according to climatic conditions, region and soil properties.

Monitoring and evaluation of transformers are essential to prevent their insulation failure. In this paper, the use of 2-furan-carboxaldehyde (2-FAL) and methanol (MeOH) concentrations as the main products of paper insulation degradation, and insulation condition markers, has been studied. In order to study the degradation process and production of degradation products, the thermal aging process of the transformer insulation system was implemented in laboratory conditions. The results of laboratory studies show that in the early stages of degradation the amount of MeOH is significant compared to 2-FAL. Also, the estimation of the degree of polymerization (DP) in the early stages of degradation (DP>800) through MeOH concentration and with decreasing DP (DP <800) through 2-FAL concentration is closer to the real value. The results of studies performed on 35 distribution transformers confirm the production of significant amounts of MeOH in the early stages of degradation. Also, the estimated DP values for the studied transformers were obtained through 2-FAL and MeOH concentration. The results show that estimating the amount of DP through MeOH concentration is associated with a probability of error of about 9% compared to estimating DP through 2-FAL concentration.

Air pollution is the presence of harmful substances in the air at concentrations sufficient to cause adverse effects. This includes solid, liquid, or gaseous pollutants, as well as radioactive and non-radioactive radiation, present at levels and durations that compromise human and environmental health, or damage property and cultural heritage. This research aims to model the extent and spatial distribution of air pollution from the Zagros Economic Zone Mini Refinery in Islamabad Gharb County, Kermanshah Province, Iran. A secondary objective is to quantify the contribution of background pollution to the overall pollution levels and its interaction with emissions from the refinery. The AERMOD model, requiring surface and upper atmospheric meteorological data, was employed. Minimum surface data included wind speed and direction, dry-bulb temperature, and cloud cover. Results indicate a maximum 24-hour sulfur dioxide concentration of 192 µg/m³ without considering background pollution, increasing to approximately 200 µg/m³ when background levels are included. In both scenarios, concentrations remained below permissible limits, although background pollution contributed a 4% increase. The methodological improvements presented in this research are generally applicable and not limited to a specific time or location.

Introduction: Determination of the background limit and separating anomalies from the background is very important in geochemical data analysis. This is more important for data which are collected from stream sediments samples. Nowadays, one of modern technique for separating anomalies from background is fractal methods. This is very useful and suitable for separating data distribution due to their spatial distribution and anomalies geometrical features. Concentration-perimeter method is very useful and high level confidence for separating of geochemical societies, especially in stream sediments data.Aim: In this study, background and anomalies were separated for Cu, Au, Mo, Ag and As in Zajkan area from Tarom in Zanjan province.Material and Method: First, 84 stream sediments samples were collected from the area and these were chemical analysis. Also, single and two variation statistical parameters were calculated. Next, based on the results area was grided and grades evaluated were done for these elements by grid evaluation method especially stream sediments. Then, Concentration-perimeter logarithmic diagrams were drawn for these elements and geochemical societies were separated. Finally, elements distribution maps were drawn in the area and their results were comprised by classical statistics and coefficient correlations.Results: Results from usage of fractal concentration- perimeter model shows that proved anomalies areas of these elements are situated in central and eastern parts of Zajkan.Conclusion: The comparison shows that fractal concentration- perimeter model is better than classical statistics.