جستجوی مقالات مرتبط با کلیدواژه « کربنات کلسیم » در نشریات گروه « آب و خاک »

Mapping soil properties using hyperspectral and multispectral satellite images, along with statistical approaches, and machine learning models such as Random Forests (RF), has shown great progress in accurately preparing agricultural maps. This study aimed to compare the performance of PRISMA and Landsat 8 images in modeling calcium carbonate and clay percentage using a Random Forest model. Firstly, Surface soil data was collected from Abik region of Qazvin province from October 2020 to October 2022. Furthermore, PRISMA and Landsat 8 spectral datasets were extracted from images downloaded from the websites of these two satellites, and soil reflectance data were obtained. The Random Forest regression model was then calibrated to estimate soil properties. The results of this study showed that the best accuracy in estimating soil characteristics using PRISMA data was obtained by using Auxiliary Variables such as principal components analysis, spectral indices, and indices extracted from the digital elevation model. The use of these three data sets provided the uppermost value for following statistical indices for estimating calcium carbonate and soil clay percentage: coefficient of determination (R2), and Ratio of Performance to Inter Quartile range (RPIQ), Ratio Performance Deviation (RPD) and the lowest Root Mean Squared Error (RMSE) and Normalized Root Mean Squared Error (NRMSE). The best model for estimating clay percentage, using the Random Forest model and statistical indices, had an R2 of 0.90, RMSE of 4.11, NRMSE of 0.18, RPIQ of 0.95, and RPD of 2.29. The best model for estimating calcium carbonate, using the Random Forest model and statistical indices, had an R2 of 0.62, RMSE of 0.72, NRMSE of 0.20, RPIQ of 0.77, and RPD of 1.27. The results supported the expectation of the good ability of the PRISMA imager to estimate surface soil properties.

Different factors may affect potassium (K) content in calcareous soils. Potassium forms distribution as a function of various soil physicochemical properties was examined on seventy surface (0-20 cm) and subsurface (20-40 cm) soil samples of Kohgilouye and Boyerahmad province, southwest of Iran. Soil physical, chemical and mineralogical properties were determined according to standard methods. The soil was classified in Xeric and Ustic moisture regimes and Mexic, Termic, and Hyperthermic thermal regimes. As the result, the common clay minerals associations were found to be illite, smectite, chlorite and palygorskite with less content of vermiculite, kaolinite and quartz. Smectite, illite, and palygorskite were the main clay minerals occurring in humid and arid regions respectively. Soil soluble, exchangeable, non-exchangeable and structural K concentrations ranged from 1.2-12.1, 111-521, 153-1705 and 4584-10379 mg kg-1 at the surface and 0.2-5.0, 25-403, 72-1016 and 3227-9541 mg kg-1 at the subsurface soil samples respectively. Exchangeable, non-exchangeable, structural and total K concentrations positively correlated with soil clay content and cation exchange capacity (CEC), however negatively significant correlation was obtained with calcium carbonate content. Different forms of K (except soluble K) had positive and significant relationships with each other (r of 0.48-0.99) and this indicated the equilibration among K forms. Mineralogical studies indicated the positively influence of clay minerals, especially illite and smectite, on exchangeable and nonexchangeable soil K. While the structural and total K contents most affected by smectite and illitic clay minerals. Future studies are required about the mineralogy of soil sand and silt fractions and their influence on soil K status.

This research was carried out to assess the origin and clay minerals characteristics and their relationship with potassium forms in the calcareous soil of this region, with the humid climate conditions. Based on aerial photos and topographic maps, physiographic units were separated and soil sampling was done in each diagnostic horizon. The results showed that smectite was the main and dominant clay mineral in the study area. In well-drained pedons, the convincing process for smectite abundance seemed to be mainly the transformation of palygorskite and mica. According to the results, the exchangeable potassium in the surface horizon was higher than that of the subsurface horizons. The main reason for the higher level of exchangeable K in the soil surface, was more smectite and organic carbon. The results revealed that unlike exchangeable and non-exchangeable K, because of the suitable conditions like temperature and humidity in surface horizons, the relative mean of structural K in the surface soils was less than that in the subsurface. Also, since an increase in calcium carbonate resulted in a decrease in amount of clay and the amount of relative clay minerals (dilution effect), the amounts of exchangeable, non- exchangeable and structural K were decreased.

In this research, the reaction of Satsuma mandarin (on Swingle citromelo rootstock) to calcareous soils was investigated in pots with soils from east of Mazandaran province, using a randomized complete block design. The highest mean of shoot dry weight was obtained in soils with 14% total lime and 5% active lime. The highest chlorosis was observed in soils from west of Neka and east of Sari with 30 and 45% total lime and 14 and 16% active lime, while the least chlorosis was obtained in soils with no lime or with 3% active lime and 2% to 9% total lime. Total and active iron concentration in leaves and root did not have a significant relationship with degree of leaf chlorosis and soils with 2% total lime (south of Babol) and 9% total lime (west of Ghaemshar had the highest total iron concentration in root and the least symptoms of leaf chlorosis. Mean iron concentration in root was about 7.5 times that of leaves that showed iron accumulation and deposition in root. Mean Mn concentration in leaves in most soils was lower than optimum (>25 mgkg-1) while soils available Mn was more than optimum (2.5 mgkg-1) for citrus trees. Mean Mn concentration in roots was about 3.3 times that of leaves. In contrast, although available Zn of some soils was lower than optimum, in most soils, Zn concentration of leaves was in the optimum range. In general, according to results of this research, Satsuma mandarin on Swingle citromelo rootstock is inappropriate in soils with total lime more than 14% and active lime more than 5%. Also, due to low absorption and transmission efficiency from roots to shoots and severe deficiency in leaves, Mn is the most limiting microelement for this rootstock-scion combination.

Soil contamination by heavy metals around big cities and intensive vegetable cropping in these soils may be a threat to human health. A factorial greenhouse-experiment was conducted to evaluate the effects of different levels of cadmium (Cd) (0، 5، 10، 20 and 40 mg/kg) and soil calcium carbonate (13. 5، 44. 5 and 67. 5 percent) on some growth indices of two common vegetables، namely، radish (Raphanus sativus) and spinach (Spinacea oleracea)). Leaf area and wet weight of spinach and radish and wet weight of radish root were used to assess their marketing properties. Cd concentration in both plants was increased by soil Cd levels and it had a dramatically decreasing effect on plant growth indices and marketing properties of both vegetables، especially those of spinach، but soil calcium carbonate had no significant effect in this regard. All measured plant growth factors i. e. wet weight، dry weight، chlorophyll A and B were dramatically changed and depressed by Cd toxicity. Applied Cd at 40 mg kg-1 decreased leaf area and wet weight of spinach by 77% and 86 percent، respectively. In radish، these figures were about 36% and 32 percent. Radish root wet weight was decreased to 49 percent when compared to no-Cd treatment. Spinach showed a lower marketing value than radish despite the fact that Cd concentration in radish leaf was higher than that of spinach. Soil Cd concentration had less effect on radish marketing property (root wet weight). Radish root marketing properties were less affected despite having higher Cd concentration. This means that، in comparison with spinach، there is more risk to human health of a high Cd radish entering into human food chain.

In this research, the effect of calcium carbonate, existing in natural environments, on removal, advection and dispersion of cadmium using batch reactor experiments, is studied. The results showed that 99.2% of Cadmium with initial concentration of 1.5 ppm will be removed by CaCo3 with concentration of 330 ppm. Regarding to high ability of CaCo3 in cadmium sorption and the existence of CaCo3 in soils and waters, one can conclude that CaCo3 has a great influence on self purification of natural environments and it must be considered in heavy metal transport transformation modeling. Firstly, by increasing salinity in the range of natural condition, sorption will decreased very fast but after the salinity of 2500 S/cm, the amount of this reduction will decrease. At last, the amount of sorption could be decreased by 50%. Investigation of Langmuir and Freundlich isotherms showed that the governing isotherm for cadmium sorption to CaCo3 on the basis of current data is Freundlich. Furthermore, comparing the linear and nonlinear methods in estimating Freundlich parameters show that the non linear sum of square of errors 0.3 of linear method. So it is better to use non linear method in estimation of parameters.

The availability of heavy metals in the soil is related to their partitioning between solution and solid phases and expressed by sorption isotherm. Twenty surface soil samples (0-30 cm) belonging to five soil subgroups were taken from agricultural regions of Western Azerbaijan province. The sorption isotherms of Pb were determined by equlibrating the soil with solutions containing 0, 100, 300, 500, 700, 900, 1100 and 1300 mg Pb L-1 from Pb-nitrate source in 0.01 M NaNO3 as background electrolyte. Illite was the dominant clay mineral in Typic Calcixerepts (TC), Typic Haploxerepts (TH) and Typic Endoaquepts (TE) whereas in Vertic Calcixerepts (VC) and Vertic Endoaquepts (VE) the clay mineralogy was dominated by smectite. Active and equivalent calcium carbonate and clay contents ranged from 4.3 to 7.8%, 6.2 to 16% and 31 to 45%, respectively. The linaer, Langmuir and Freundlich isotherm equations were fitted to the experimental data of Pb sorption and desorption. Both the Freundlich (0.98< R2)

Calcareous and gypsiferous soils are restricting factors for uptake of some plant nutrient elements and plant production. Most soils in Iran are calcareous and gypsiferous. Therefore, the aim of this study was the evaluation of calcium carbonate (Caco3) and gypsum effect on availability of some nutrients and corn growth. This study was conducted in a greenhouse at Vli-e-Asr University of Rafsanjan. Treatments were arranged in a factorial manner as a completely randomized design with three replications. Treatments were three levels of Caco3 (0, 20 and 40 g/100g soil), gypsum at three levels (0, 15 and 30 g/100g soil) and two soil textures (Sand and Silt clay loam). Results indicate that irrespective of soil texture, Caco3 application significantly decreased leaf area (by 80% and 15% for sand and silty clay loam texture, respectively), dry weight (by 80% and 15% respectively), plant height (regressed on Caco3 percentage by slopes -0.7 and -0.15 for sand and silty clay loam respectively), and shoot Fe (-9.67 and -11.3) and Zn (-0.24 and -1) uptake, but had no significant effect on shoot Cu uptake. In sandy soil, application of gypsum, significantly decreased leaf area (80%), dry weight (62%), and shoot Cu uptake (slope= -1.93), but had no significant effect on plant height and shoot Zn uptake. Gypsum application significantly reduced shoot Fe uptake (slope= -24.86) in fine textured soil, but it had no significant effect in coarse textured soil.

A study was conducted to evaluate the effect of incubation time, sewage sludge and clay content on the distribution of nickel and cadmium in different fractions of selected calcareous soils. To meet this purpose, an experiment with two different soils (4 and 30 percent CaCO3), two different textures (8 and 40 percent clay), two levels of nickel (0 and 100 mg.kg-1), two levels of cadmium (0 and 25 mg.kg-1) and organic matter in the form of sewage sludge in two levels (0 and 50 t ha-1) was carried out. Two incubation times (0 and 60 days) and three replications in a completely randomized design were mentioned. The samples were incubated for two months at temperature of 25±2 °C and soil moisture condition close to field capacity. Distribution of Cd and Ni in fractions soluble+exchangeable, organically bound, carbonate bound and residual fractions was determined by a sequential extraction method. The results illustrated that, in both soils, residual form of Ni and carbonate form of Cd were dominant and showed a significant change with sewage sludge treatment and time. Sewage sludge application increased the amount of organic and carbonate bound of Ni and Cd significantly. The proportion of organic and carbonate bond Cd and Ni was higher in soil with 33 percent lime. In contrast, in soil with 4 percent lime, the percentage of Ni and Cd in the residual fractions was higher. Residual fraction of Ni and Cd in Clay soil was significantly higher than sandy loam soil. Increasing the amount of Ni and Cd increased all fractions of these metals significantly. The organic forms of Ni and Cd decreased significantly in the course of time. In general, based on the results, it may be concluded that calcium carbonate, clay percent and sewage sludge treatment play a key role in the distribution of Ni and Cd in different fractions of soils.

AbstractA previous study on agricultural drains in Khuzestan province of Iran has indicated that carbonate calcium is the main component of the deposited salts in drainage envelops. To investigate the process of precipitation of carbonate calcium under different conditions including chemical, bio-chemical, aerobic and an-aerobic, a through laboratory investigation on geotextile drain envelop was conducted. The results of the studies showed that activity of the micro-organisms in aerobic conditions causes an increase in the bicarbonate content and consequently, increase in the pH of the medium. Any increase in pH would intensify the precipitation of carbonate calcium. The results also indicated that due to the activity of micro-organisms, more than 90% of existing calcium would be precipitated. While in a chemical environment, only 30% of existing calcium would precipitate. Thus, in a biochemical environment, micro-organisms would cause more calcium to be deposited. The results also indicated that the activity of the bacteria would cause formation of bio-films which in turn would provide a more suitable environment for precipitation of salts. By intensifying deposition of salts, there is higher potential for clogging of the drainage envelops including geotextile filters.

Soil physical and chemical properties, and test conditions might affect soil structural stability. In this study, the effects of test conditions as well as intrinsic soil properties on structural stability were investigated for selected soils from Hamedan Province. Mean weight diameter (MWD) and tensile strength (Y) of aggregates were determined by wet sieving method and indirect Brazilian test, respectively. The soil samples were pre-wetted slowly to matric suction of 200 kPa before the wet sieving. The pre-wetted samples were wet-sieved for 5, 10 and 15 min in order to simulate different hydro-mechanical stresses imposed on soil structure. Tensile strength of soil aggregates were also measured at air-dry and 500 kPa matric suction conditions. Short duration shaking (i.e. 5 min) could effectively discriminate the Hamedan soils in terms of structural stability due to their fairly low aggregate stabilities. The soil organic matter content had the highest impact on MWD followed by both clay and CaCO3 content. The same was true for the Y values i.e. OM played the highest role in mechanical strength of soil aggregates. The highest coefficient of determination (R2) was obtained between Y and the intrinsic soil properties for matric suction of 500 kPa. The organic matter content had an important role in water and mechanically stable soil aggregates. The results indicated that short-duration wet sieving (i.e. 5 min) and measurements of tensile strength at matric suction of 500 kPa could be recommended for aggregate stability assessment in Hamedan soils

Transport and filtering of pathogenic bacteria through porous media and groundwater resources are important and، therefore the effect of various factors on bacteria transport and filtering has been given a great attention nowadays. In this study، effects of calcium sulfate and carbonate on Psedomonas fluorescens filtration and filtering parameters were investigated in saturated sand columns under steady-state flow. The calcium carbonate levels included 0، 5، 10 and 20 %w/w and calcium sulfate levels consisted of 0، 5 and 10 % w/w which were thoroughly mixed with sand (0.15-0.25 mm). The experiment was considered factorial in completely randomized design with three replicates. The treated sands were poured into pyrex cylinders with length of 20 cm and diameter of 7 cm. Then، steady-state saturated flow with constant flux was applied to the columns. When the steady-state flow was established، the bacteria suspension with concentration of 106 CFU cm-3 (C0) was injected as step input into the columns. The leaching then was continued up to 5 times of pore volume (PV). The effluent concentration of the bacteria (C) was measured at 0.25 PV intervals. Then، the sand columns were divided into 0-5، 5-10، 10-15 and 15-20 cm layers in order to measure the filtered bacteria in each layer. The results showed that the effects of calcium carbonate on retaining of the bacteria in the 5-10 and 10-15 cm layers were significant at 1% level. It was significant at 5% for the 15-20 cm layer. The effect of calcium sulfate was also significant at 5% for the 10-15 cm and 15-20 cm layers. The interactive effects of treatments on bacteria adsorption was significant for the 5-10، 10-15 and 15-20 cm layers. The retained concentration profile and the filtration coefficient were significantly affected by the treatments، showing higher bacteria adsorption at lower depths and predominance of physical filtering. The results showed the high filtering capacity of carbonate and sulfate minerals which could ultimately reduce bacteria transport in saturated porous media towards groundwater resources.

Phosphorus (P) and iron (Fe) are essential nutrients for plants. Iron availability is low in calcareous soils of Iran due to the excessive amounts of CaCO3 and high pH. Overfertilization of P fertilizers may also decrease Fe availability. The objective of this study was to evaluate the effect of P and Fe on the growth and chemical composition of corn (Zea mays L.) under greenhouse conditions. Treatments consisted of a factorial arrangement of P rates (0, 40, 80, 120 and 160 mg kg-1 as KH2PO4) and Fe rates (0, 2.5, 5 and 10 mg kg-1 as Fe EDDHA) in a completely randomized design with four replications. Plants were grown for 8 weeks in a loamy soil, calssified as Chitgar series (fine-loamy, carbonatic, thermic, Typic Calcixerepts). Results showd that P application up to 80 mg kg-1 increased corn top dry matter. Corn P concentration and total uptake increased by P application but decreased by Fe application. Application of Fe up to 5 mg kg-1 increased dry matter but decreased it at higher rates. Concentration and total uptake of Fe increased by Fe application but decreased by P application. Zinc and copper concentrations decresed significantly when P was added. Manganese concentration increased at 40 mg P kg-1 but decreased at higher rates. Iron application decreased zinc and manganese concentrations but had no effect on copper.