نشریه علوم آب و خاک (علوم و فنون کشاورزی و منابع طبیعی)
سال نوزدهم شماره 4 (پیاپی 74، زمستان 1394)

During the past few decades, the southern part of the Caspian Sea has more frequently experienced extreme climatic events such as drought and flood. Trend analysis of hydro-climatic variables was conducted using non-parametric Mann-Kendall test and regression test for Neka basin in the north of Iran. Trends of precipitation and stream flow characteristics including maximum flow, mean flow and low flow indices were analyzed at the annual, seasonal and monthly time scales from 1358 to 1391 (34 years). Results showed a general decrease in annual and winter precipitation and decrease in daily maximum precipitation, with an increased trend in daily maximum precipitation of spring season. A decreasing trend was observed in 7-day low flow in summer for all sub-basins. Annual and monthly mean flows specifically in winter in all sub-basins decreased, but annual maximum flow increased from upstream to downstream. Land use changes showed that deforestation and urbanization increased during 34 years in the mid and downstream sub-basins. The analysis showed that low flow indices and mean flows are strictly sensitive to climate change. Overall, from hydrological perspective, these results indicate that the study region is getting dryer and facing more severe drought events. The results of this study can predict future droughts to make better decisions for irrigation planning and management of water resources.

The concentrations of rare-earth elements (REEs) were determined with the aim of investigating the behavior of these elements in granitic rock, granitic soils and soils between rock and lichen in Shir-kuh of Yazd province. Rare earth element patterns of the P-rich granite were determined by the mixture of Eu-enriched feldspars, middle REEs to heavy REEs-enriched apatite and Light REEs-enriched monazite. Granite-normalized REEs patterns for soils and soil lichen-granite interface represented the same signatures and similar to parent rocks. The REEs levels of the soils lichen-granite interface were similar to the concentrations of the elements in the natural compositions (Upper Continental Crust and Post-Archean Australian Shale). PAAS-normalized Rare earth element patterns for three soils’ lichen-granite interface were identical to each other and PAAS and close to the reference axis (PAAS). The same signatures of REEs in granitic rock, granitic soils and soils lichen-granite interface in arid and semi-arid mountainous areas indicate that the elements are immobile and therefore, they can be used as a suitable tracer in soil provenance studies.

Heavy metals are known to have deleterious effects on human health. The main route of human exposure to heavy metals is the daily intake of food. This study was designed to investigate the heavy metal concentrations (Cu, Zn, Mn, Fe, Cr, Ni and Cd) in soil and major food crops (wheat, potato and corn) and estimate the health risks of metals to humans via soil and the crops consumed in Hamedan Province, using the total non-cancer hazard quotient. Daily metal intakes were estimated for three receptor groups and then compared with health guideline values. The non-cancer risk estimations showed that chromium, manganese, cadmium, zinc, Iron, Nickel and copper have oral Hazard Quotient values less than a value of one. The Hazard Index values were greater than 1 for all age groups, suggesting that adults and children in the study area may experience a potential non-cancer risk due to diet of heavy metal via wheat, corn and potato consumption and soil ingestion. Consumption of plant foods particularly wheat was found to be the major route of human exposure to heavy metal. The soil ingestion route is also important.

Soil contamination by Pb leads to a reduction in the quality and quantity of crop yield, because it is highly toxic in soluble ionic forms. The availability of this element for plant roots can reduce by the formation of compounds with low solubility and their sedimentation by phosphorous amendments.. Root symbiosis with mycorrhizal fungi can also increase plant resistance against heavy metals. This study was carried out as a factorial experiment in a randomized complete block design asa greenhouse experiment on sunflower plant at Shahrood University. Treatments included mycorrhizal fungi with two levels of inoculation, (with and without inoculation), organic and inorganic phosphorous fertilizers such as humic acid, diammonium phosphate, bone meal and bone meal蛩 acid. The results showed that inoculation with mycorrhizal fungi resulted in a significant increase (P&ge0.05) in percentage of mycorrhizal colonization and an increase in soil EC,shootdry weight and phosphous uptake by the plant. Phosphorus fertilizers significantly increased the available phosphorus in soil, dry weight and uptake of phosphorus by the shoots. The interaction effects of mycorrhiza and phosphorus fertilizers on soil exchange able Pbwere significant. The application of diammonium phosphate and mycorrhiza had the greatest impacton the reduction of Pb (by 25.48percent) in the soil exchange. Mycorrhizal plants had a lower rate of lead concentrations in shoots, which was equal to 78/14%, and also the application of phosphorus fertilizers significantly reduced Pb in plant shoots.

Riprap is used to control scouring around the bridge abutment. In order to study the stability of riprap around two bridge abutments with two different shapes, experiments were conducted in a laboratory flume made of Plexiglass in 180 degree bend. In this research, several experiments were done by placing the two bridge abutments made of Plexiglas in a series of riprap. Experiments included two different types of riprap with different densities, four different diameters and constant rate of discharge under pure water condition. In each experiment, flow depth was measured in terms of moving threshold, then stability was calculated by using the data obtained. The results showed that in the same conditions chamfered wing-wall is greater than vertical-wall. So, chamfered wing-wall is, on average, 9 percent more stable than the vertical wall.

Floods are considered as most destructive among all natural hazards which impose lots of damages on human societies. Hence, it is important to estimate such damages and losses and to determine flood impact areas for management plans. HEC-FIA software as a new model (Sep. 2012) was used in Ghohrood and Ghamsar watershed basins to estimate flood-driven losses and impacts. In this model, HEC-RAS and HEC-Geo RAS are used to produce inundation map in different return periods of flood as HEC-DSS file and by using the data collected in relation to regional agricultural land, building and human, human and financial losses are directly estimated. According to the results of this model, agriculture, building and human losses respectively in Ghohrood watershed are about 354 million rials with 24 buildings affected, and in Ghamsar watershed this is about 12879 million rials with 36 buildings damaged. The advantages of this model over the previous models are estimating the direct economic and human losses for what has occurred and for possible floods in the future. The results can help with watershed management, flood insurance and risk management.

Evaluation of pollutant transportation in soil is important from different environmental aspects such as soil and groundwater contamination. The purpose of this study is to measure 2, 4-D concentrations in a silty loam soil under two different treatments (normal and deficit irrigation) in a corn field and simulate the results using the PRZM-3 and LEACHP models. Total concentrations of 2, 4-D in the soil profile in 8, 13, 23, 30, 37, and 57 days after application for normal irrigation were 18.5, 16.36, 11.67, 10.47, 8.47 and 3.2 mg kg-1, respectively. For these dates, PRZM-3 model simulated 18.5, 16.36, 11.67, 10.47, 8.47 and 3.2 mg kg-1 of 2,4-D, respectively and LEACHP model simulated 23.34, 20.93, 16.7, 16.3, 12.9 and 11.41 mg kg-1 of 2, 4-D, respectively. Total concentrations of 2, 4-D in the mentioned dates for deficit irrigation were 20.2, 16.7, 11.22, 10.05, 8.8 and 7.3 mgkg-1, respectively. For these dates, PRZM-3 model simulation results were 21.9, 19.89, 14.2, 10.62, 9.6 and 8.22 mg kg-1, respectively and LEACHP model simulation results were 25.22, 21.3, 19.43, 18.58, 18 and 16.27 mg kg-1, respectively. The simulation results showed that performance of PRZM-3 model was better than LECHM model in both treatments. In this research, the half-lives of 2, 4-D for 0-10 cm and 10-20 cm of soil depth were 7 and 33 days in a normal irrigation, and 9 and 34.65 days in a deficit irrigation, respectively.

In addition to kinematic description of biological reaction, flow pattern plays an important role in designing constructed wetlands. This study investigates the effects of flow distribution on constructed sub-surface horizontal flow wetland with a length of 26 m, width of 4 m and 1% bed slope in order to understand internal hydraulic functioning patterns. Inlet configuration is selected as a variable parameter. Three different cases of inlet and outlet configurations were 1) midpoint, 2) corner, and 3) uniform. Outlet has been fixed in all configurations. Uranine tracer was used to determine the influences of flow distribution by drawing hydraulic retention time curve in different cases. Results showed that mean residence times for each configuration were equal to 4.53, 3.24 and 4.65 days, respectively. Retention time distribution curve provided conditions, not only for showing dispersion patterns throughout system but also for interpreting hydraulic parameters like hydraulic efficiency and effective volume. According to the retention time curve, effective volume was 87.5% in configurations 1 and 3, and 62.1% in configuration 2 following numerous short-circuiting ratios. Finally, the best configuration of inlet-outlet layout to improve the performance of effluent treatment and use the geometry effectively was found to be the uniform-midpoint based on physical experiments followed by midpoint–midpoint as the second best.

Mobarakeh Steel Complex has been using treated industrial wastewater for irrigation of green space to combat water shortage and prevent environmental pollution. This study was performed to assess the impact of short-, middle-, and long-term wastewater irrigation on soil quality attributes in green space of this complex. Soils were sampled from the wet bulb produced by under-tree trickles in three depths of forested lands irrigated with treated wastewater (for 2, 6 and 18 years) or groundwater. Several chemical, physical and biological characteristics of the soil samples were determined in the laboratory and compared to those of the native unirrigated soils as the controls. The results showed that pH was significantly reduced in the wastewater-irrigated soils as compared to the control. Organic matter content and cation exchange capacity significantly increased in the irrigated soils due to the incorporation of tree leaves into soil. Soil salinity also increased as the irrigation period increased because of the relatively high salinity of water and wastewater used for irrigation. Microbial basal respiration and arginine ammonification were greater in the irrigated soils in comparison to the control. In general, forestation and irrigation management have improved most of the soil quality indexes in the Mobarakeh Steel Complex green space, but some soil characteristics, such as salinity, need to be monitored and improved in future.

This experiment was conducted to evaluate the effect of vermicompost, pistachio kernel and shrimp shell on the immobilization and availability of Cd, Pb and Zn in corn in polluted soils. Treatments consisted of two levels of pistachio kernel, shrimp shell and vermicompost (5 and 10 % w/w). In control treatment, no amendment was added to the soil. The experiment was carried out as a completely randomized design with 3 replications. Plants grew for two months in the greenhouse. Then, all the plants were harvested and their shoots and roots were separated, washed with distilled water and oven dried at 65 °C to a constant mass. The measured characteristics were dry weight of shoots and roots, leaf area, greenness index, chlorophyll fluorescence, maximal quantum yield of PS photochemistry (Fv/Fm), performance index (PI), and total concentrations of Cd , Pb and Zn in shoots and roots. Results showed that plant growth parameters (dry weight of shoots and roots, leaf area) and photosynthetic characteristics (chlorophyll fluorescence, Fv/Fm, and PI) were higher in plants grown in vermicompost and pistachio kernel treatments as compared to those grown in control. Plants died in shrimp shell treatment after two weeks. The concentration of Cd, Zn and Pb in shoots and roots of plants grown in vermicompost and pistachio kernel treatments were lower than those grown in control.

Technosols are modified soils affected by human activities. This study investigated genesis, classification and physicochemical properties of four pedons of Technosols developed on refused oil refinery materials and compared them with two unpolluted pedons. Mineralogical studies showed smectite as a dominant clay mineral with other clay minerals. These clay minerals adsorb oil compounds in their interlayer spaces and reduce their mobility and decomposition. Different micromorphological features resulting from oil compounds in soils, including depletion zones, types of coatings (quasi and hypocoating) and features due to horizontal and vertical movement of oil compound in soil showed dynamics of oil compounds and their effects on soil forming process. The refused petroleum compounds decrease pH and increase organic carbon, amorphous form of Iron in soils. Taking into account the presence of high amounts of gypsum and carbonate in polluted soil, the studied soils were classified as Typic Calcigypsids in Soil Taxonomy but in WRB system, due to the presence of impermeable geomembrane within 100 cm of soil surface, they were classified as Linic Technosols, showing the more precision of WRB system in their classification.

Chemical fertilizers have important role in modern agriculture, and in the other hand led to rigid environmental pollution. Urea fertilizer is one of the most widely used and least expensive nitrogen fertilizers in Iran. Since it is high solubility in water a significant of it, if irrigation or precipitation is heavy, easily washed and led to change to change the quality of groundwater, rivers or seas. Hence, in this study the effects of deficit irrigation and fertilization on pollution using SWAT for Tashk-Bakhtegan basin (land area between Dorudzan dam and Khan Bridge) were simulated. This model by comparing model outputs with actual observations of hydrological, crop yield (wheat, barely, corn and rice) and nitrate by using SUFI2 algorithm in SWAT_CUP software were calibrated and validated. Then the calibrated model used to evaluate different management strategies (e.g. irrigation and fertilizer amount). When the impacts of different levels of urea (0 to 70 percent reduction in urea application) were modeled, yield of these crops reduced between 1 to 27, 0.8 to 24, 0.42 to 21 and 0.47 to 9 percent for wheat, barely, corn and rice, respectively. However, these tends to decline nitrate leaching 16-81, 18-80, 15-85 and 12.5 to 83.6 percent, respectively for these crops. Therefore, by comparing yield and nitrogen loss changes, this result can conclude that a significant reduction in nitrogen loss by minimum cost on yield can achieved by optimize fertilizer application.

The importance of decreasing the cost of soil structures due to the budget constraints makes engineers avoid handling large volumes of soil, thus making maximum use of local materials. Soil performance change in order to improve engineering applications of soil is called soil stabilization. Soil stabilization methods can be mechanical, electrical, thermal, chemical, etc. Gypsiferous soil including soils used in civil affairs and special structures in the vicinity of water needs to be established. This study is conducted to evaluate changes of shear strength of gypsiferous soil, using chemical method by addition of “A polyurethane Mastic”. The studied gypsiferous soil was prepared from 3km north-west of Ramhormoz in Khuzestan province. Soil samples containing 0%, 1%, 2%, 3%, 5% and 7% of the said material additive were compressed with optimum moisture content obtained from standard Procter test, and finally, were tested under the direct shear test at shear rate of 0.5 mm per minute. After achieving cohesion parameters of soil, the best mix of the additive “A polyurethane Mastic” was found to be 5%.

The most important cause of concern about the stability of bridge foundation is the occurrence of scour around bridge piers. Therefore, different methods have been proposed to prevent or reduce scouring around bridge piers. The use of groynes is one of the modern methods to control and reduce local scour. In the present study, the effect of a solid groyne on reduction of the scour depth around a cylindrical bridge pier, located in the bend of a laboratory flume is assessed. Experiments were conducted for groyne model angled at 50˚, 90˚ and 120˚ to the downstream channel sidewall with three flow rates of 47, 49 and 51 liters per second in a sediment free condition. Results showed that in at ratios of velocity to critical velocity and all groyne angles, in comparison with no groyne, the scour depth was reduced. At all ratios of velocity to critical velocity, the best operation was related to normal groyne and the average operation of repelling groyne was better than attracting groyne. The operation of normal groyne decreased and attracting groyne function improved as the flow rate increased. Also, the normal groyne (ratio of velocity to critical velocity equal to 0.87) had the best effect on reducing the scour depth (by about 71.4 percent).

Simulation of water and solute transport in soil is very useful for optimum management of water and fertilizer use. In this study, the HYDRUS-1D model was used to simulate water and nitrate transport in furrow irrigation of sugarcane. For this putpose, a large-scale experiment was performed as a split plot design based on the randomized complete blocks with 3 replications in a 25-hectare piece of land in the Dehkhoda Sugarcane Agro-Industry Company from March 2012 to October 2013. The main factor was split application of fertilizer at three levels: two, three and four splits. The sub-main factor was fertilizer amount, applied at three levels (i.e. 350, 280 and 210 kg urea corresponding to 100%, 80% and 60% fertilizer requirements, respectively). Soil hydraulic parameters were estimated through inverse modeling using moisture data collected during more than 4 months of the sugarcane growing season. Solute transport parameters were then estimated using the hydraulic parameters and nitrate concentration data. In this study, statistical criteria including R2, RMSE, ME and SSQ were used to compare the observed and simulated values of moisture content and nitrate concentration. The results indicated that R2 for simulated moisture content and nitrate concentration in four splits and 60% fertilizer requirement treatment (i.e. calibrated treatment) were 62.7 and 91.2 percent, respectively. Cumulative infiltration depths were about 46 and 58 mm for calibration and validation treatments, respectively. For these treatments, the cumulative evapotranspiration rates were 50 and 60 mm, respectively. Soil moisture content in the surface layer varied from 21 to 45 and 21 to 42 percent, for calibration and validation treatments, respectively while the changes in the deep layer moisture content were 33 to 38 percent, for both treatments.