h. khodaverdiloo

This study was conducted in the summer of 2021 to evaluate and validate the gravimetric soil water content measurements using a field oven. Ten soil types with a salinity of saturated paste (ECe) less than 4 dS m-1 and three saline soils were studied around Urmia Lake. Plots with dimensions of 1 m × 2 m were prepared for the selected soils to measure gravimetric soil water content and soil physical and chemical properties. The gravimetric water content (θm) values measured using the field oven (i.e., θmFO), were compared with those measured by a standard lab oven (i.e., θmLO). The soil water content values measured in the lab, regarded as a benchmark, were measured at 105 °C for 24 h. Temperatures of 120, 140, and 160 °C with three durations of 10, 15, and 20 min were used to dry the soil samples in the field oven. There was very good compatibility between the values of θmFO and θmLO when the soil samples were dried in the field oven for 15 or 20 min at all three temperatures. Significant linear relations were obtained between the θmFO and θmLO values as the slopes of linear relations were close to 1, the intercepts of relations were negligible and the distributions of measured data around the line 1 to 1 were unbiased. The minimal effects of soil organic matter content, clay content, salinity, and bulk density on water content measurements by the field oven indicate an important advantage of this method. These results confirm the high efficiency of the field oven for fast and reliable measurements of water content in different soils.

Poor seedling establishment and total plant biomass reduction in contaminated soils, decrease the efficiency of phytoremediation techniques. In this study, the effects of different types of seed pretreatments (such as salicylic acid, and potassium nitrate) and three concentrations of lead (0, 200, 400 and 600 mg lead/kg soil) on sunflower seedling growth under greenhouse conditions were evaluated. These factorial experiment was conducted in completely randomized design with three replications in research greenhouse of Shahrekord University, in 2015. In general, the studied traits significantly decreased with increasing concentrations of lead. In most toxic concentrations of lead, Potassium nitrate and salicylic acid prevented the decreasing of dry weight of root compared to control up to 42%. Potassium nitrate prevented the decreasing of dry weight of leaf and chlorophyll a (with 24% and 60%, respectively), Salicylic acid prevented the decreasing of chlorophyll b (55%) compared to control. Shoot dry weight didn’t affect by seed priming treatments. Increasing in concentrations of lead elevated carotenoids, proline content and electrolyte leakage. Salicylic acid treatment reduced of electrolyte leakage (by 21%). Potassium nitrate prevents the increasing of carotenoids (by 24%), however increased proline content from 104 to 111 µm/g. Generally it could be concluded that salicylic acid and potassium nitrate increase seedling tolerance to lead toxicity through reducing carotenoids content, electrolyte leakage and increasing proline content. This technique can be used to increase the efficiency of phytoremediation of soils contaminated with lead.

In order to study the effect of apple (Golden delicious variety) pruning residue biochar on chemical forms of Cd, Pb, Cu and Zn in a contaminated soil, an experiment was conducted as a factorial in a completely randomized design (CRD) in three replications with 4 levels of biochar (0, 2, 5 and 10 %) and 4 levels of incubation time (1, 2, 4 and 8 weeks). Chemical distribution of metals in soil was determined using Tessier sequential extraction method during the mentioned incubation times and the reduced partition index (IR) and mobility factor (MF) of the metals were calculated. Application of the biochar significantly (p ≤ 0.05) decreased the exchangeable and carbonate fractions and increased organic and iron and manganese oxide bound fractions in comparison to the control treatment. With increasing the biochar level and incubation time, the IR values were increased, but MF values decreased, demonstrating a decrease in the mobility of metal in soils. It was concluded that the addition of the apple biochar in soil may led to transformation of the metals from unstable forms (e.g. exchangeable and carbonate forms) to stable forms (e.g. iron and manganese oxide bound and residual forms), and consequently decreased the mobility of the metals in soil.

Cation exchange capacity (CEC) is one of the main factors in monitoring and management of soil quality in order to achieve sustainable production. Although CEC can be measured directly, these measurements are difficult, time-consuming and costly, especially for aridisols. One alternative method is the use of pedotransfer functions (PTF), in which CEC of soils is estimated through available soil information. A dataset including 1141 data points was used for development and accuracy test of functions and another independent data set with 232 data points was used for validation of the PTFs. The results showed that, grouping the soils based on clay and organic carbon contents are generally reduced the coefficient of variation of clay, organic carbon and CEC. In general, the grouping of soils declined the correlation of clay and organic carbon with CEC. In soils with organic carbon contents of less than 0.5%, CEC was predicted with reasonable accuracy using only the clay. Generally, grouping the soils enhanced the accuracy of the PTFs, while in most cases decreased their reliability. However grouping the soils based on their clay content, except for soils with clay content ≥ 35%, was more effective in improving the accuracy and reliability of the functions. Clay (except for soil with clay content of ≥ 35%) was the most influential factor in predicting the CEC of the soils, so that including the other variables were not significantly improve the accuracy and reliability of the functions.

Soil quality maintenance is essential for sustainable food production, waste decomposition and etc. For sustainable management of soil, it is necessary to evaluated soil quality. Soil physical quality drastically affect by tillage methods. Since conventional tillage increases soil erosion, it is better to replace other farming tillage methods. In this study effect of three tillage methods including conventional tillage (tillage with moldboard), chisel plow and disk plow with notillage as controlled treatment on the bulk density, porosity, saturated hydraulic conductivity field, organic matter, aggregate size distribution, soil aggregates stability investigated. Complete randomized blocks were used as statistical design for field experiments. The results showed tillage operations compared with controlled treatment decreased organic matter, bulk density and aggregates stability in the soil surface layer (0-10 cm) significantly (p ≤ 0.01). Tillage operations increased soil porosity in the soil surface layer (0-10 cm) significantly. The treatments effects on saturation hydraulic conductivity and aggregate size distribution were not significant. Generally no-tillage or the controlled treatment maintains more soil physical quality compare with other tillage operations. In order to maintain soil physical quality, cultivation without tillage is recommended.

Vehicles contaminate soils and plants along the roadside by different ways and finally these contaminants enter the food chain. The aim of this study was to assess Pb، Cd، Zn and Ni contamination of soils and plants around the Urima-Salmas highway with heavy traffic. Geoaccumulation index (Igeo) was calculated for characterizing the contamination levels of heavy metals in the soils. Metal accumulation index (MAI) was also employed for assessing simultaneous accumulation of the studied metals by each plant. Results showed that concentrations of these metals were higher than those of the control samples (p ≤ 0. 05) for soils and most of the plants grown in the roadside. In comparison with background areas، surface soils and plants grown along the roadside were relatively contaminated. Also soils and plants of the roadside were specifically contaminated with Pb. Therefore، animal grazing in this site would be of potential transfer risk of these metals (especially Pb) to the food chain. In general، concentration of the metals، specifically Pb، was higher in plants which were closer to the road. In comparison with other plants studied، Yarrow plant (Achillea millefolium) with MAI = 100. 01 had better ability for simultaneous absorption of different metals. According to the results of this study، actions are needed to be applied for better management of the soils and grazing of the plants in the roadsides.

Sorption and desorption of heavy metals by soil solid phase are of crucial role on their behaviour. To assess sorption and desorption of Zn, Cu, Fe, and Mn, four non-acidic and four acidic soil samples were collected from Guilan and West Azerbaijan provinces, respectively. A linear regression procedure was utilized for fitting the linearized forms of the Langmuir and Freundlich isotherm equations to the sorption data. Results showed that for all the studied metals either in non-acidic or acidic soils, the Freundlich equation (R2>0.88) described the sorption data better than the Langmuir equation (R2=0.28-0.90). The amount of sorption parameters for all studied soils was higher in non-acidic soils in comparison with acidic ones. Sorption behaviour of metals differently varied among soils. The highest value for the adsorption maxima was achieved for Fe in both soil types. However, the lowest adsorption maxima were observed for Zn and Mn in acidic and non-acidic soils, respectively. Mean immobilization percent of metals in acidic soils for Mn, Fe, Zn and Cu were 13.2, 11.6, 11.7 and 6.6 percent respectively, and lower than that of non-acidic soils. The lowest and highest immobilization percent for Fe and Mn was observed in soil (5) and soils (3, 4), respectively. Soil (8) showed low Cu and Zn immobilization potential, however soil (4) and soil (1) highly immobilized Cu and Zn, respectively. It is concluded that from an ecological point of view higher sorption potential of studied soils in particular non-acidic soils can be considered in decreasing heavy metals toxicity risks processes.

zoil contamination with heavy metals، including Cd and Pb، is of serious concern. The aim of this study was to investigate the efficiency of Atriplex verucifera، Salicornia europaea and Chenopodium album for simultaneous remediation of soil exchangeable sodium percentage and Cd and Pb contamination in two soils with different properties. Two soils، including a saline-sodic-calcareous (S1) and calcareous (S2) soil، were selected. Different concentrations of Pb and Cd were then added to the soils. The contaminated soils were incubated under a wetting-drying cycle for nearly seven months. The plants، seeds were grown in pots containing different treatments of polluted soils and in control treatment (no Cd and Pb contaminations). The plant yields and concentrations of Pb، Cd and Na in the soil and plant samples were measured. A considerable accumulation of soil Cd by Salicornia and Pb accumulation by Atriplex and Salicornia was observed under unsuitable conditions of the saline-sodic soil، whereas Atriplex and Chenopodium had high capability for Cd in the soil S2. Also these plants caused the reduction of ESP in soil S1. The results revealed that these plants could be used for remediation of Pb and Cd contaminated soils. In this study، Salicornia with lower rate of yield reduction had the highest tolerance to Cd-stress. Understanding the complex plant and soil (salinity-sodicity and soil metal concentration) factors controlling the metals concentrations in the plants will help to design phytoextraction technology for arid، salt-affected regions.

Nowadays, environmental pollution by heavy metals is one of the most serious threats of the world which needs effective remediation actions. The aim of this study was to investigate the potential use of Atriplex [Atriplex verucifera], Salicornia [Salicornia europaea] and Chenopodium Album in simultaneous uptake and accumulation of Na and Cd or Pb in two calcareous soils with different properties. Two soils, including a saline-sodic-calcareous (S1) and a calcareous (S2) soil, were selected. Different concentrations of Pb (0, 250, 500 and 1000 mg Pb kg-1 soil) and Cd (0, 10, 30 and 100 mg Cd kg-1) were then added to the soils.. The contaminated soils were incubated under a wetting-drying moisture regime for nearly seven months. The plants seeds were grown in pots containing different treatments of polluted soils and in control treatment (no Cd and Pb contaminations). The plant yields and concentrations of Pb, Cd and Na in the soil and plant samples were measured. Results showed that relative yield of Salicornia was more in soil S1, whereas those of Atriplex and Chenopodium Album were more in soil S2. In saline- sodic soil, the values of Na bioconcentration factor (BCENa) in control treatment were 67, 202 and 57 for Atriplex, Salicornia and chenopodium album respectively. The high value of BCENa in Salicornia revealed the ability of this plant in absorption and accumulation of Na from soil. A considerable accumulation of soil Cd by Salicornia and Pb accumulation by Atriplex and Salicornia was observed under unsuitable conditions of the saline-sodic soil, whereas, Atriplex and Chenopodium had high capability for Cd in the soil S2. These results revealed that these plants could be used for remediation of Pb and Cd contaminated soils. In this study, Salicornia with lower rate of yield reduction had the highest tolerance to Cd-stress and it seems that one can use this plant for phytiremediation of Cd and Pb from saline- sodic soil even in high concentrations of Cd and Pb.

Phytoremediation is a new technology that employs plants to remediate contaminated soils. This method compared to those that involve the use of large scale energy consuming equipments is an inexpensive method. Phytoremediation models are useful tools to further understanding the governing processes and also to manage the contaminated soils. A thorough literature review indicates that very few models have been developed for phytoremediation due to the complexity of the phenomena. The objective of this study was to develop a simple model for phytoremediation of lead and cadmium. A new formulation of phytoremediation was established based on soil and plant responses to heavy metal pollution. A large quantity of a sandy loam soil was thoroughly mixed to ensure homogeneous different concentration levels by lead and cadmium. These contaminated soils were transferred to some plastic pots. Land Cress (Barbarea verna) and Spinach (Spinacia oleracea L.) seeds were germinated in pots containing 8 kg of contaminated soil. Plants were harvested at five time intervals. The concentrations of Pb and Cd in the plant and soil samples were digested by wet oxidation and 4 M Nitric acid digestion methods, respectively, and were determined by flame and graphite furnace atomic absorption spectrometry methods. Proposed models then were calibrated using the collected data and validated quantitatively. The results indicated that the soil adsorption isotherms followed a linear form for both Pb and Cd concentrations. The results also indicated that the phytoremediation rate of Pb by Land Cress and Spinach are first-order function of Pb concentration in soil. In contrast, a zero-order function of soil Cd contaminations was obtained. Combining these two results of soil and plant responses to Pb and Cd pollution, a simple model with reasonable performance was derived to predict the time needed for remediation of soil Pb (R2 > 0.98). However, in the case of Cd, the derived models appeared to be useful to make only some overall estimations of the remediation (R2≈0.70).