مجله محیط زیست و مهندسی آب
سال نهم شماره 3 (پاییز 1402)

The aim of this study was to evaluate the surface modification efficiency of raw zeolite by hexadecyl trimethylammonium cationic surfactant for cyanide sorption. Properties such as mineralogy, morphology and elemental composition of sorbents were determined. Batch and column tests were performed to evaluate the sorption efficiency of raw and modified zeolite from solution and released from the cyanide polluted pulp. The presence of clinoptilolite mineral and surfactant surface coating due to modification using surfactant was confirmed by X-ray diffraction analysis and electron microscopy images. The results of isotherm experiment showed that modification of zeolite with surfactant increased the adsorption capacity of cyanide by zeolite 7 times compared to the raw sample and the maximum adsorption capacity of cyanide by modified zeolite was 3.97 mg/g. The ability of surfactant-modified zeolite to sorb more cyanide than raw zeolite was confirmed by the results of the column test on the cyanide released from the pulp. It was observed that with increasing time, the concentration of cyanide in the outlet solution increases, but this increase in the cyanide concentration in the outlet solution of the column containing the modified zeolite is less than the raw zeolite.

The Caspian Sea is important in terms of environment and monitoring of biological pollutants due to its long coastlines and commercial activities of the industrial port of agriculture and tourism. Identifying marine environmental pollutants is the first step to rebuilding and protecting this valuable ecosystem. The purpose of this study was to determine the amount of Polychlorinated biphenyls in sediments and Barnacles of Anzali and Caspian ports in Guilan province, Iran. Therefore, Barnacle and sediment samples were collected in 2 stations whit 3 replications in Anzali and Caspian ports by VanVeen Grab sampler in summer according to the life cycle of Barnacles. After preparation and drying with freeze dryer, after analysis, it was read by gas chromatography. The highest concentration of PCBs in Barnacles in Anzali station was related to isomers PCB-81 & PCB-77 and the lowest was related to isomers PCB-114 and PCB-156. The highest concentration of PCBs in Barnacles in Caspian station was related to isomers PCB-28 and PCB-77 and the lowest was related to isomers PCB-114 & PCB-153. The highest PCB concentration in sediment in Anzali and Caspian ports was recorded similarly for isomers PCB-52 & PCB-28 and the lowest was related to isomers PCB-114 and PCB-156.

Rivers are considered to be among the most significant sources of fresh water, and their quality monitoring holds significant importance in terms of both spatial and temporal changes. In this study, the water quality of Golin River was investigated using the CWQI index for the construction of warm and cold-water fish breeding centers. Different parameters as: DO, pH, BOD5, NO3, Ec, turbidity, temperature, TDS, CaCO3, NO2, total hardness, CO2, Cu, NH3, and Fe were sampled twice a month from the water from April 2019 to March 2020. The results showed that the parameters of BOD5, TDS, CaCO3, NH3, Cu, and NO3 were in the unfavorable category in comparison with the standards of hot and cold-water fish farming. Comparison of CWQI index in cold-water fish farming in different months showed that the highest and lowest numerical values ​​of the index with values ​​of 70.02 and 60.37 were observed in February and December, respectively. Also, the numerical values ​​of the index in warm-water fish farming were observed as the highest and the lowest numerical values ​​of the index with the values ​​of 85.38 and 70.96, in April and February, respectively. The results of this study showed that according to the final value of CWQI index, in general, the water of Golin river was suitable for warm-water and cold-water fish farming in the desired range.

The present study was conducted to assess the water quality of the Balighli-Chai and Ghare-Sou Rivers, the main rivers of Ardabil Province, Iran. The levels of dissolved oxygen (DO), biochemical oxygen demand (BOD), nitrate (NO3) and phosphate (PO4) were measured and simulated using the QUAL2Kw model during low- and high-water periods. Also, self-purification capacity and total maximum daily load (TMDL) levels of water quality parameters were calculated. The obtained results indicated considerable differences between the levels simulated by the model from the measured data for both rivers. Most of the river sections had low self-purification capacities. Maximum self-purification capacity (%) were: high water period: DO = -226.61; BOD5 = 90/30; NO3 = 99.88; PO4 = 96.49; low water period: DO = -281.71; BOD5 = 89.13; NO3 = 94.74; PO4 = 90.21. TMDL scores for DO, BOD5 and NO3 were higher during the high-water period, but entire sections of both rivers showed high excess loads of PO4. The results showed that most ranges of both rivers didn't have appropriate water quality conditions. Therefore, it is necessary to make proper decisions to control pollution levels and improve water quality in this basin

Usually, the methods used to identify oil slicks work to identify different slick parts in terms of thickness. Since the spectrum of oil slicks is affected by seawater and the physical and chemical properties of the oil, in this study, using the spectral indices of hydrocarbons (FI, RAI, HI, RG, RR, WAF) and seawater (CHL, CDOM), different thicknesses of oil slicks are investigated and To be different. The IS (index separability) mathematical model based on classroom distance was used to evaluate the spectral indices used quantitatively. The results show that the spectral indices of hydrocarbons are more suitable for distinguishing the emulsion from seawater and other parts of the oil slick. Thus, the value of the IS parameter for the FI index in order to detect and differentiate emulsions with different evaluated segments such as seawater, shining part, code 4 and code 5 are equal to 1.542, 0.967 0.423 and 0.4236, respectively, which are compared spectral indicators of seawater have larger values. On the other hand, the spectral indices of seawater are suitable for detecting the thinner parts of the oil slick .

Estimating reference evapotranspiration (ET0) is a fundamental requirement of agricultural water management. However, the lack of necessary meteorological data makes it difficult to estimate ET0 using the FAO-Penman-Monteith equation wider areas. Therefore, this research examines the estimation of daily reference evapotranspiration using MODIS Land Surface Temperature (LST) from satellite imagery in two climates of Tabriz and Rasht. ET0 has been estimated using two random forests (RF) and random forests optimized with genetic (GA-RF) algorithms. The parameters used in both stations include the combination of daily land surface temperature (LSTday), nightly land surface temperature (LSTnight) and average land surface temperature at night, and day (LSTmean). The obtained results indicated that LSTmean has an excellent ability to estimate ET0 in both stations. In Tabriz station with a semi-arid climate, GA-RF-7 model with RMSE=0.516 and in Rasht station with a very humid climate, the GA-RF-5 model with RMSE=0.868, have the best performance among the studied models. Moreover, the evaluations revealed that the temperature of the earth's surface at night is as important as the temperature of the earth's surface during the day, and by combining these two parameters, satisfactory results may be obtained.

The volume of sediment transport rate during floods is one of the important issues in river engineering. This volume of sediments has caused countless damages to the hydraulic structures which are built along the rivers, every year. The purpose of this study was to investigate the effects of hydrograph unsteadiness parameter on bedload transport rate. For this purpose, a real unsteady flow hydrograph was created inside a 15 m long tilting flume by installing an interface board between the computer and the pump inverter. 20 cases of hydrographs with different unsteadiness parameters were tested and the scour rate was obtained during the hydrograph time. The results indicate that the maximum scouring rate always occurs near the peak of the flood hydrograph and the time lag between them was positive. For hydrographs with the same peak and different base time, the maximum scouring rate occurs in the hydrograph with more unsteadiness. The maximum scouring rate of the bed has a direct relationship with the unsteadiness parameter, and it can be said that an 88% decrease in the flow unsteadiness parameter leads to a 76% decrease in the maximum bedload rate. Also, the scour rate in the ascending limb of the hydrograph is higher than the descending limb, which by reducing the unsteadiness parameter, the distance between the limbs in the sediment hysteresis diagram decreases.

The awareness of floods and estimating the debris flow is a fundamental step for assessing risk and planning in the watershed. The village of Sijan, located in the Southern Alborz, is one of the areas threatened by debris flows. The research aimed to estimate the volume of debris flows along 700 m of a stream of Sijan Village time range from 2018 to 2021. The study method included surveying the stream in two-time intervals, which involved one concrete and four gabion checkdams, and calculation of erosion and sedimentation happened via debris flow using the Civil-3D software. Results showed that five check dams had 823 m2 and 750 m3 area and volume, respectively. Debris flows covered 25500 m2 after the flood in 2019, in which the estimated erosion and deposition volumes were 7250 m3 and 10100 m3 according to the elevation difference technique. The Sijan stream channel experienced sedimentation and erosion along the northern and southern banks. Implemented watershed management measures have played a vital role in mitigating the risk of debris flows, especially at the concrete check dam.

Land use/land cover (LULC) change, strongly affects surface water characteristics, especially in urban watersheds. The aim of this study was to determine LULC in the Samian Watershed and assessing its relationship with water quality parameters. In this study, LULC maps was obtained by ENVI software in four periods (1992 to 2016). Then, 9 water quality parameters at five river gauge stations were selected for further analysis. The Mann-Kendall test was performed to examine the trends in water quality parameters and Pearson test was used to assess the correlation between quality parameters and land uses. According to the results, rangeland decreased by 9.75%, irrigated agriculture increased by 8.45%, residential increased by 1.42% and rainfed agriculture increased by 3.29% compared to the first period. Average of TDS and EC in the study periods in Samian and Gilandeh stations, has been increased. The correlation analysis using Pearson test between quality data and LULC also shows that the EC, Ca, Cl, SO4, Mg and Na pameters of had a significant relationship with increasing residential, irrigated and rainfed land uses.

This study intended to investigate the decisions of different kinds made by farmers about preserving the Qare Qeshlaq wetland by saving water resources in the farmlands (2019-2022). Using survey data collected from 298 farmers of the rural areas on the edge of the wetland, as being randomly stratified, they were asked to participate in an interview along with filling out a self-implemented questionnaire (n=298). We gained insight into the association of being aware of wetland protection projects with participation in projects, subjective norms contribute to differentiating participants from non-participants in wetland protection projects. The behavioral intention to take care of the wetland also determines the strategy of using water saving-water technologies. The perceived effects of wetland protection projects affect the behavioral intention to save water resources. Furthermore, cultural bias has a negative effect on the behavioral intention to save water resources. Behavioral intention also has a positive and significant effect on the behavior of saving water resources, and the behavior itself affects the intention of wetland protection. In the concluding section, management implications were presented to increase the participation of farmers in saving water resources and wetland protection projects.