مجله تحقیقات آب و خاک ایران
سال پنجاه و چهارم شماره 12 (پیاپی 96، اسفند 1402)

Periphyton is a complex biological community comprising microorganisms and organisms from different physiological groups that collectively attach to various submerged surfaces in wetland ecosystems. Periphytic biofilms play a critical role in the wetland ecosystem’s dynamicity and possess a considerable capacity for decontamination. The following article examines the various aspects of periphytic biofilms’ capacity for removing some of the most critical environmental pollutants, including organic pollutants, pharmaceuticals, heavy metals, microplastics, and excess nutrients. The paper provides comprehensive discussions on the critical pollutant removal mechanisms employed by the periphytic communities. Additionally, the paper endeavors to contribute to the available knowledge regarding utilizing and developing periphyton-derived bioremediation technologies by presenting the most recent research findings, discussing common challenges in periphyton’s biotechnological application, and delineating crucial research gaps to postulate future research questions. Applying periphyton in pollutant removal aligns with the most recent paradigm of bioremediation technologies advocating the use of microbial consortia instead of single microbial species. In this regard, research results convey that the simultaneous presence of multiple microbial groups together in a biological community (such as periphyton) increases the microorganisms’ resistance to unfavorable environmental conditions and enhances the biological community’s capacity for decontamination. Based on the studies presented in this article, periphytic biological communities can employ different mechanisms to transform and biodegrade a wide array of pollutants.

Due to inherent limitations of global climate models, their outputs are significantly biased in comparison to observed values which could provide unreliable climate projections. This study evaluates the performance of 10 global climate models of the Coupled Model Intercomparison Project Phase 6 (CMIP6) for simulating precipitation in the Rafsanjan study area over calibration (1986-2005) and validation (2006-2014) period. For correcting simulated precipitation, various quantile mapping-based bias correction methods applied in these two periods. Evaluating the performance of various climate models and quantile mapping-based bias correction methods and approaches is carried out through multiple statistical metrics including NSE, PBIAS, MAE, and KGE as well as Taylor's diagram. Finally, simulated precipitation of selected model extracted for projection period under SSP1-2.6, SSP2-4.5 and SSP3-7.0 scenarios and corrected by suitable bias correction method. Results showed that the MPI-ESM1-2-LR model has better performance in simulating precipitation over calibration and validation periods compared to other climate models. The results of evaluating the performance of quantile mapping-based bias correction methods in both periods also showed that bernlnorm method performs better than others for the correction of simulated precipitation by climate models. In addition, the evaluation results of quantile mapping approaches including NTP, PT, and DDT in these periods demonstrated that NTP and PT have an acceptable performance compared to the DDT approach. Present study can help to improve the credibility of future climate projections using CMIP6 climate models.

Earth's climate is the result of complex interactions between its effective components and a function of solar radiation, which has a significant role on the afore said components. Among the most important climatic factors that are effective in the vegetation of humid, dry and semi-arid regions, we can mention the variables of vapor pressure and soil moisture, which play an important role in the process of plant photosynthesis. Chlorophyll plays a significant role in photosynthesis of plants, including coniferous. According to the research conducted in Chitgar and Nowshahr, the effect of two different components has been evaluated. The effects of the season on the fluorescence value of two components can’t be denied. The highest value of correlation in soil moisture and its effect on the amount of fluorescence in Chitgar forest park in autumn and winter seasons is estimated with R²=0.44 and 0.56, respectively. The RMSE were calculated 7.4 and 6.7(mg/m2), respectively. In Nowshahr, the highest correlation value with total depth moisture was obtained in summer season. The numerical value of R² is calculated as 0.21. Also, P-Value is estimated at 0.498. The effects of environmental stresses on the amount of soil moisture in different depths are undeniable, especially in the seasons when the plant activity is high and the amount of photosynthesis will be more exposed to drought and salinity stresses. Regarding the effect of vapor pressure in Nowshahr, the highest degree of correlation has been calculated with the fluorescence value in the autumn season. The peak of the rainy season in the north of the country can be estimated in the autumn season, and with the increase in relative humidity, the water vapor pressure will increase.

The depth and width of the soil wetting pattern determine the spacing between irrigation laterals and the irrigation drippers that influence their numbers and the overall cost of the irrigation system. Therefore, researchers look for solutions to adapt the soil wetting pattern to the pattern of crop root growth as much as possible such as adjusting the irrigation depth and irrigation intervals, utilizing physical, capillary, and hydraulic barriers, as well as pulsed management. Pulsed drip irrigation can replace the usual method of continuous irrigation due to its ability to improve the distribution of soil moisture and consequently crop yield. It also, prevents the accumulation of water in a specific point of the soil and decrease evaporation by improving moisture distribution in the soils with heavy texture and in the soils with a light texture, can lead to a reduction of deep percolation bellow the crop root zone. The results of studies have shown that pulsed drip irrigation can have a positive effect on reducing the clogging of irrigation drippers by providing the possibility of using a dripper with a high flow rate. Therefore, the general results of the research show that the use of pulsed drip irrigation can improve crop yield and water productivity. The purpose of this study is to review the experiences of using different management methods to improve the soil wetting pattern in drip irrigation systems and also provide experimental equations for simulating the soil wetting pattern under drip irrigation systems with emphasis on pulsed management.

This study was conducted to investigate the effect of soil salinity on nitrogen mineralization in the presence and absence of wheat straw in three soils with textural classes of clay, loam and loamy sand under laboratory conditions as a factorial arrangement based on a completely randomized design with 3 replications. The studied factors were salinity (1, 10, 20 and 30 dS/m), wheat straw (0 and 2% by weight with C/N=89.5) and time (2, 5, 12, 20, 28, 37, 46, 53, 64, 73, 85 and 90 days). After investigation of different Iranian agricultural soils, three soils with low salinity (0.84-1.1 dS/m) and low organic carbon (0.22-0.98%) were selected. Considering the results, in the three soils, the amount of ammonium and nitrate in the treatment without straw was higher than those in the treatment with straw. In straw treatment, there was an initial descending trend in the amount of ammonium and nitrate for the three soils, but after a period of time, ammonium and nitrate content of the soil showed an ascending trend and returned to the initial value. With increasing soil salinity, the amount of soil ammonium increased in clay and loamy sand soils but decreased in the loamy soil. Nitrate content showed a descending trend for the three soils with increasing salinity. In general it is concluded that the presence of wheat straw in the soil can mitigate the negative effects of high concentrations of salt on nitrogen mineralization and reduce nitrogen losses.

Humic acid can improve water absorption by plants by improving soil structure and water retention in soil. These characteristics have caused the use of humic acid in the soils of dry areas to be considered. This study aimed to investigate the simultaneous effect of humic acid and deficit irrigation on soil physical and biological properties under the cultivation of bell pepper. A factorial-based experiment in a randomized complete design was carried out with three levels of humic-acid (0 (HA0), 2 (HA20), and 4 (HA40) g per pot) and four irrigation levels (60 (L60), 80 (L80), 100 (L100), 120 (L120), (percent of soil moisture depletion) with three replications in the research greenhouse of Payam Noor Bojnourd University. The results showed that the best treatments for improving soil physical properties, AS (aggregate stability), and decreasing PAD (percentage of aggregate destruction)), were L80HA40, L100HA40, and L120HA40 treatments. Also, by increasing the dose of HA and increasing the irrigation level up to L80, the activity of urease, alkaline phosphatase, and acid phosphatase enzymes increased and then decreased in L100 and L120.Therefor the highest amount of urease, alkaline phosphatase, and acid phosphatase enzymes (μg NH4+-N g-1 dry soil 2h-1) 678.98, 845.54 671.30 (μg PNP g−1 dry soil h -) were observed in L80L40, which were to be 4.6, 5.9, 2.8 and 0.6 times more than L60HA0 treatment, respectively. By increasing the amount of humic acid and increasing the irrigation levels up to L100, respiration rates increased and then decreased at L120, however, microbial activity followed by respiration at L80 and L100 were not significantly different.

Irrigation network is a set of hydraulic channels and related structures that is created with the aim of transferring, distributing and delivering water fairly as well as efficiently. However, due to constraints resulting from type of management and maintenance, climate changes, social and cultural characteristics of users, and financial issues, their performance are usually faced with major challenges. Qazvin irrigation network is one of the modern networks in the country and after more than 40 years of implementation of this network, many problems and challenges in the field of agricultural water management are observed in this network. The purpose of the present research is to identify the important challenges in the field of agricultural water management in Qazvin plain irrigation network, to investigate the importance of challenges and performance in relation to the challenges, and finally to provide practical strategies to improve the state of the system with a new approach by using Importance-Performance Analysis technique. The method of conducting the study to identify the challenges has been library studies and then using Delphi technique. Furthermore, the importance of the challenges has been identified by using Best-Worst method. Evaluating the responce of the officials authorities  to the challenges using Importance-Performance Analysis technique, demonstrates that the challenges of lack of enough motivation in farmers to reduce agriculture water consumption, lack of governmental supports for established organizations, lack of supervision on implementation of crop patterns and cultivation area, budget issues, and lack of sufficient training for farmers, in ordre are five challenges in the first quadrant of the importance-performance matrix that should be prioritized for improvement. Several practical solutions to solve the challenges for Qazvin plain irrigation network such as doing more support from government in terms of using suitable irrigation methoed while considering the approved crop pattern and providing clear information for the statue of current situation and making coordination among all types of involved sectors are presented in the results section.

The dissolution of carbon dioxide in water is one of the sources of soil carbonates, which have an inverse relationship with water temperature. The origin of soil-forming carbonates formed in glacial sediments, and the effect of glacial processes on their formation were investigated. This study was conducted in the year 2021 in Alborz province, and eight profiles located in Karaj and Hashtgerd regions with glacial-alluvial parent materials were described and sampled. Physical and chemical characteristics, including soil texture before and after the removal of carbonates by the hydrometer method, pH, and EC in saturated extract, organic carbon by the Walkley-Black method, Calcium Carbonate Equivalent (CCE) measured by the calcimetric method in 27 samples were determined. Cation Exchange Capacity (CEC) measured by the ammonium acetate method. Soil description and classification were performed based on the American classification system. A micromorphological study of undisturbed samples, before and after the removal of carbonates, was carried out following their impregnation with polyester resin, cutting, sawing, mounting on glass slides, and reducing the thickness to about 30 microns. Imaging was done with a polarizing microscope, and the analysis and interpretation of the results were carried out according to the guide for the analysis of thin sections. The results showed that the petrocalcic horizons formed on glacial tills and moraines are the result of the long-term infiltration of cold water rich in dissolved carbonates into the soil. This model of the formation of secondary carbonates in the soil is different from other models that mainly consider the origin of carbonates to be the dissolution and recrystallization of primary carbonates or the biological respiration of roots and living organisms.

Soil has various tasks or functions, including the ability to produce crops, store carbon, store water, cycle nutrients and purify water. Soil functions have a high correlation with soil quality. Soil quality indices are often regional and to determine it, it is not possible to consistently use a set of idicators and indices in all regions. In this research, Additive Soil Quality Index (SQIa), the Weighted Additive Soil Quality Index (SQIw) and the Nemero Soil Quality Index (NQI) and the effect of effective characteristics on soil quality in surface soil (0-30 cm) and in the yield of 206 wheat field of East Azarbaijan Province (Tabriz Plain) in 2017 was investigated by measuring physical and chemical properties of soils and wheat grain yield. Organic carbon, bulk density, aveilble potassium and aveilble phosphorus and electrical conductivity were selected as The minimum data set (MDS) using principal component analysis (PCA). Then SQIa, SQIw and NQI were determined using TDS and MDS. The results showed that there is a correlation between wheat yield and soil quality indices using MDS (r=0.60-0.63) and using TDS (r=0.56-0.60) also there was a significant correlation (p <0.01) between the use of TDS and MDS in NQI (r=0.81), SQIw(r=0.84) and SQIa (r=0.88) (p<0.01). Therefore, all three investigated indices are suitable for the study area and using MDS is more suitable than the method of using TDS due to relatively higher correlation and number of features and lower cost.

The water productivity index (WP), which is defined as the crop produced per unit of consumed water, has been considered as a key indicator for the optimal use of water in the agricultural sector. It has been heavily relied upon in the Iran's agricultural water policies and plans. However despite several years have passed since the introduction of this concept and index, unfortunately, water crisis still exists and is expanding in the country and measures to increase WP in agricultural products have not yet been able to effectively solve the country's water issues. In this review-analytical paper, the issues and challenges of using this index in practice have been discussed and the shortcomings, challenges, measures, and infrastructure necessary for the proper use of this index have been discussed and analyzed. According to the results, there are hidden issues and challenges (in 8 groups) in its application. The most important of which are the need to deeply understand the concept and definition of WP in the country's expert and management community, and the problems and issues of using the index from the aspect of lack of the required infrastructure for the proper impacts of improving WP in mitigating water scarcity. According to the identified issues and challenges, it was concluded that improving WP could not be a sole measure to solve the country's water crisis, because it fulfills just initial conditions. In order to fulfill conditions sufficiently and to implement related comprehensive measures and interventions, the necessary hardware, software, legal, and policy infrastructures must be provided.