مقالات رزومه دکتر سیده مریم محمدی

Dust storm (DS) is a harmful climatic phenomenon that causes damage to the environment and agriculture. The aim of this study was to investigate the trend analysis of seasonal and annual changes of DS during climatic period of 1977-2021 in arid climates of Iran in 42 synoptic stations. First, the long term changes of DS, before and after 2005 were compared togeather and investigated. Then, time series trend analysis was performed using regression method and spatial analysis by Menn-Kendall and Sen`s Slope methods. The results showed an increase of DS after 2005. The trend of time series also showed an increasing trend in most climates and stations, with the most intense increasing slope during the periods of 2005-2010 and after 2011. The results showed that the frequency of stations with a significant increasing trend in the semi-arid climates on a seasonal and annual basis were up to 93 and 64; and in arid climates up to 83 and 83 percent of the stations, respectively. On the other hand, the incremental changes of 45-year DS in the extra arid climate in winter, spring, summer, autumn and whole year were up to 68, 69, 68, 55 and 261 days; in arid climate up to 54, 31, 37, 45 and 187 days; and in semi-arid climate has reached 23, 21, 9, 12 and 58 days, respectively. Therefore, the temporal change of DS is towards the winter and spring seasons, which indicates the spread of this phenomenon to the wet seasons.

Areas where waste is buried based on engineering design, which is one of the waste disposal methods. Leachate accumulation in landfills can adversely affect downstream groundwater resources by infiltrating the aquifer. In this study, we tried to investigate the potential of leachate penetration and the plume contamination caused by leachate pools inside and outside the landfill, respectively, using two methods of electrical resistivity tomography (ERT) and vertical electric sounding (VES). For this purpose, at a distance of 60 and 580 meters from the leachate basin, VES data were collected with a transmitter length of 200 meters and ERT with a length of 120 meters and electrode distances of 2 meters. Examination of geotechnical and VES data in the study area shows an impermeable layer with an alternation of clay-madstone and calcareous-marl layers at a depth of about 10-15 meters the percentage of the clay were increased. The ERT data in profile number 1 shows that at a distance of 32-76 meters from the beginning of the profile at deptt of 9 meters there are areas with low electrical resistivity, which indicates the area of leachate penetration, but in the other section of profile leachate deep penetration are not visible due to the Madstone and Siltstone impermeable layers. However, in the ERT data in profile number 2, the presence of an impermeable layer prevents the infiltration of leachate to the downstream and lower depths, which indicates the proper selection of the landfill. Therefore, contrary to what can be seen in the VES data, the study area is not homogeneous in terms of permeability to leachate in the two dimensions of ERT, but the presence of an impermeable layer prevents the deep transfer and infiltration of leachate to the aquifer.

Heavy metals are the common pollutants of soils, which pose a potential threat to the public and particularly children's health. Therefore, this study was conducted to assess the source identification and potential ecological risk of Fe, Zn, Pb, Cd, Cr, and Ni in surface soils collected from the vicinity of Arad-Kouh processing and disposal complex, Tehran, Iran in 2020.

In this descriptive study, a total of 30 surface soil samples were collected from 10 sampling sites. After acid digestion of soil samples, the element contents were determined using ICP-OES. Also, pollution indices, potential ecological risk were computed. Moreover, principal component analyses (PCA) and hierarchical cluster analysis (HCA) were performed to find out the contamination sources and distinguish the different groups of analyzed elements from different sources, respectively. Furthermore, all statistical analyses were performed by SPSS software.

Based on the results obtained, the mean content of elements in soil specimens (mg/kg) was 26651.6 for Fe, 71.7 for Zn, 27.7 for Pb, 1.22 for Cd, 22.3 for Cr, and 32.8 for Ni. On the other hand, the soil quality of the study area was varied between 'minor enrichment' to 'moderately severe enrichment' based on the enrichment factor (EF) values, between 'low contamination' to 'high contamination' based on the pollution index (PI) values, and between 'unpolluted' to 'moderately polluted' based on the geo-accumulation index (I-geo) values and also showed 'moderate degree of contamination' based on the degree of contamination (DC) values. The computed values of Er showed that the potential ecological risk of Zn, Pb, Cr, and Ni was low and for Cd was moderate. Also, as the mean values of RI were 170.9, all the examined elements could be classified as a moderate ecological risk. The results of Pearson correlation coefficient, I-geo, PI, and IPI in accordance with PCA and HCA indicated that Zn, Cd, Cr, and Ni were originated from anthropogenic sources, while, Pb had a lithogenic origin.

Although the studied elements had moderate potential ecological risk, since the Cd with 93.3% of the mean RI values showed a higher potential environmental risk compared to other elements, therefore, source identification and source control of this element with potentially adverse effects on humans and also environmental health is recommended.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants with teratogenic, mutagenic and carcinogenic potential, which can pose potential risks to the environment and human health. Therefore, this study was conducted todetect and assess the potential ecological risk of PAHs in surface soils in the vicinity of Arad-Kouh Processing and Disposal Complex, Tehran, Iran, in 2020. In so doing, 30 surface soil samples were collected from 10 sampling sites adjacent to the Arad-Kouh complex. After extraction of analytes, the gas chromatography/mass spectrometry (GC–MS) method was used for determination of 16 PAHs in the samples. The results showed that the total concentrations of 16 PAHs (∑16PAHs) ranged from 863 to 1384 µg/kg with an average of 1123 µg/kg. Moreover, Chy and B(ghi)P showed no potential ecological risk, while other PAHs had a moderate potential ecological risk. Also, as computed values of RQ∑PAHs(MPCs for all the sampling sites were lower than 800, the total ecological risk of PAHs in surface soil samples of the study area was classified in the moderate-risk2 category. Based on the results, although the mean concentrations of B(a)A and B(ghi)p < /span> were higher than MPC established by Iranian Department of Environment, the mean concentrations of all of the 16 PAHs were lower than MPC established by MHWS. Overall, since PAHs have adverse effects on human health, detection and determination of concentration, source identification, and also periodical monitoring of these compounds in the environment is recommended in order to safeguard human health maintenance.