Sh. Ayobi, M. H. Alizadeh,
Volume 10, Issue 2 (7-2006)
Abstract
Conventional soil survey methods for soils within the watersheds in Iran require a significant budget with many soil surveyors and much time. Additionally, no accurate and reliable information exists on the spatial variability of superface soil parameters in order to predict the soil loss by different models (RUSLE, PISAC, EUPOSEM, MORGAN). Also information on planning and management activities is lacking. These limitations call for methods of estimating soil properties using minimum sampling derived from important terrain parameters. This study was performed to develop soil-landscape models in three geological units (E2Sc, Ku, Plc), in a part of Mehr- watershed, Sabzevar. Six soil variables selected for this study were topsoil clay, gravel, sand, organic matter content, field capacity and bulk density measured at 316 sites on a regular 100m grid. Topographic attributes were calculated by a digital elevation model with 100m spacing. Finally, multiple linear regression analyses relating soil to topographic attributes were performed and then models were validated by additional sample points (78 of 316). The developed regression models showed significant relationships between surface soil properties and topographic attributes such as elevation, slope, aspect, wetness index, stream power index and sediment transport index. The mean errors and root mean square errors in the validation of the models were low and acceptable. The regression equations could explain only 26 to 72 % of the variability measured in the soil attributes in the watershed scale with 100m spacing.
M. Mohammadi, B. Lorestani, Soheil Sobhan Ardakani, M. Cheraghi, M. Kiani Sadr,
Volume 25, Issue 4 (12-2021)
Abstract
Polychlorinated biphenyls (PCBs) can adversely affect human and environmental health according to long-term half-life and persistence in the environment. Therefore, this study was conducted to detect, identify, and health risk assessment of PCBs in surface soils collected from the vicinity of Arad-Kouh processing and disposal complex, Tehran, in 2020. A total of 30 surface soil samples was collected from 10 sampling sites near the Arad-kouh complex. After extraction of analytes, the gas chromatography/mass spectrometry (GC–MS) method was used to determine PCBs in soil samples. Based on the results, 15 congeners of PCBs were detected in the analyzed soil samples. Also, the minimum, maximum, and mean concentrations of total PCBs (µg/kg) were 269, 434, and 359, respectively. Moreover, the results of PCA and significant contribution values of low molecular weight homologs indicated that the presence of PCB compounds in the soil samples was connected with combustion processes in the soil. Besides, as among the detected PCBs, the TEF values only established for PCB105 showed that exposure to contaminated soil could be lead to a moderate level of carcinogenic risk through PCB105. Given that PCBs have adverse effects on the environment and human health, detecting, determining the concentration, source identification, and periodical monitoring of these compounds in different mediums to human health maintenance is strongly recommended.
S. Yousefi, S.n. Emami, M. Nekooeimehr, S. Mardanian,
Volume 29, Issue 2 (7-2025)
Abstract
In the present study, the Road Sediment Delivery Model (SEDMODL) and Geographic Information System (GIS) were utilized to estimate the average annual sedimentation caused by the forest road network in the oak forests in the west of Iran, Chaharmahal and Bakhtiari Provinces (Nazi forest road with a length of 5171 meters). Sedimentation from the study forest road network was estimated based on three basic factors in the model. Also, 30 erosion benchmarks were installed to measure the erosion and sedimentation rate at different distances from the road and in different parts of the study road and changes were measured during a year. The results showed that the average soil erosion at different distances from the Nazi road based on erosion benchmarks is 5.7 mm per year. In addition, the estimated erosion and sedimentation rate of the entire study road network based on the SEDMODL model is 2875 and 570 tons per year per kilometer, respectively. Model evaluation using erosion benchmarks showed that SEDMODL is a suitable model for estimating soil erosion on forest roads in the west of Iran (R2=0.78 and RMSE=0.73). It should be noted that statistical analysis of erosion hot-spot analysis showed that 39 percent of forest roads in Nazi showed very high erosion. Based on the results of the present study, it is suggested that conservative, protective, and road maintenance measures in areas with high erosion risk should be prioritized by decision-makers.
