JWSS - Journal of Water and Soil Science

Water and soil pollution with heavy metals has become a worldwide environmental issue. Therefore, development of efficient and low-cost methods for removal of metals from water or metal stabilization in soil has been identified as priority research areas. Biochar, produced from plant biomass and agricultural wastes, has recently been used to remove heavy metals from aqueous solutions as an effective sorbent. In this study, biochars were made from pyrolysis of palm tree residues at different temperatures of 200, 400 and 600 °C. The prepared biochars were then used to remove Ni from aqueous solutions in batch systems without pH adjustment and with pH adjustment at 7. To investigate Ni sorption rate, kinetic experiments were also carried out at a Ni concentration of 10 mg/L. The results of kinetic tests showed that the biochar prepared at 600 °C had more Ni sorption rate with equilibration time of about 5 h. Power function and Elovich models were the best equations fitted the kinetic data. Langmuir and Freundlich isotherms described sorption of Ni on the sorbents very well. According to the Langmuir model predictions, the biochar produced at 600 °C and the palm raw residues had highest and the lowest capacity to sorb Ni from the solution, respectively, and the biochars produced at 200°C and 400°C were intermediate in this respect. Both the capacity and affinity of the biochars for Ni sorption increased with pH. Overall, under the experimental conditions applied in this study, the biochar prepared at 600 °C showed the highest efficiency for Ni removal from aqueous solution.

Over the years, since the beginning of the national and infrastructural project of Development and Renovation of Paddy Fields of Iranian Northern provinces, it has been essential to evaluate water distribution and delivery Performance of the project to get its feedback in the pursuit of the desired goals. However, the results of the evaluation of a system can reliable when they are based on quantitative indicators, not on personal opinions and empirical judgment. So, in this study, Total Error (TE) of performance of water delivery system, a statistical indicator, and its component including adequacy, water management capability and equity errors were calculated and compared for two concrete and earthen irrigation canals. This analysis was done based on calculating water demand and measuring the volume of delivered water between outlets during the irrigation season in the paddy fields of Esmaelkola of Joybar city, in 2015. According to the results, although the concrete channel (0.28) had less error than the earthen channel (0.43) and in the concrete channel, as compared to the earthen channel, the share of the components of adequacy and water management capability from the total error was dropped from 47% to less than 10%, but the error in the water delivery of the concrete channel was still high due to the error in the equity of distribution, whose value was 0.25 (90% of the total error). Therefore, in order to reduce the performance error, after channel lining, it would be necessary to make fundamental changes in the intake and flow control structure in addition to the training of irrigators regarding water delivery based on water demand.

Soil quality is the permanent soil ability to function as a live system within ecosystem under different land uses. Investigating the impact of land use type on soil quality indicators could help to distinguish sustainable managements and therefore, to inhibit soil degradation. In order to evaluate the effect of different land uses on soil quality indicators, a research based on a randomized complete design in Rabor region, Kerman Province, Iran, was conducted. A total of 104 samples were taken from the soil surface (0-15 cm) of four land uses including: pasture (28 samples), forest (25 samples), agronomy (27 samples) and garden land use (24 samples). Soil quality indicators were measured as: soil organic matter, particulate organic matter, and bulk density, plant available water capacity, S index, cation exchange capacity (CEC), electrical conductivity (EC), soil pH, and phosphatase enzyme. According to the results, land use types had a significant effect on all indicators except S index at 1% probability level. The maximum amount of soil pH, bulk density and phosphatase enzyme was obtained from forest land use. On the other hand, the maximum amount of the other indicators was attained from the garden land use. Totally, garden land use, due to having high organic matter, could improve the soil quality. However, the pasture land use had the worst soil quality due to the weak cover and the low organic matter.

One of the crucial problems that exist in the irrigation networks is the fluctuation of the water surface flow in the main channel and changes in the flow rate of the intake structure. One of the effective methods to decrease these fluctuations is increasing the weir crest length at the given width of the channel with the use of the labyrinth weirs can be achieved for this purpose. The labyrinth weir is the same linear weir that is seen as broken in the plan view. In this study, a labyrinth weir with a length of 3.72 m, three different heights of 15, 17, and 20 cm, three different shapes of dentate (rectangular, triangular, and trapezoidal), and a linear weir were used in a recirculating flume with 15 m length and 1 m width. The result showed that for a given length and height of weir, with the increasing of the upstream water head to the weir height ratio (), the discharge coefficient decreases. The results showed that by increasing weir height, the discharge coefficient decreases for a given length of the weir. Linear weir and labyrinth weir without dentate create more water depth at the upstream by 3.3 and 1.2 fold compared with dentate labyrinth weir.