Elucidating the enhancement of kaolinite flotation by iron content through density functional theory: A study on sodium oleate adsorption efficiency

This study delves into the intricate relationship between iron(Fe)content in kaolinite and its impact on the adsorption behavior of sodium oleate.The effects of different iron concentrations on adsorption energy,hydrogen bond kinetics and adsorption efficiency were studied through simulation and experimental verification.The results show that the presence of iron in the kaolinite structure significantly improves the adsorption capacity of sodium oleate.Kaolinite samples with high iron content have better adsorption properties,lower adsorption energy levels and shorter and stronger hydrogen bonds than pure kaolinite.The optimal concentration of oleic acid ions for achieving maximum adsorption efficiency was identified as 1.2 mmol/L across different kaolinite samples.At this concentration,the adsorption rates and capacities reach their peak,with Fe-enriched kaolinite samples exhibiting notably higher flotation recovery rates.This optimal concentration represents a balance between sufficient oleic acid ion availability for surface interactions and the prevention of self-aggregation phenomena that could hinder adsorption.This study offers promising avenues for optimizing the flotation process in mineral processing applications.

Assessment of water quality suitability for agriculture in a potentially leachate-contaminated region

Dump sites pose a significant threat to groundwater resources due to the possibility of leachate leakage into the aquifer.This study investigated the impact of leachate on groundwater quality in the southwest region of Zanjan City,Iran,where groundwater is utilized for drinking,agricultural,and industrial purposes.We analyzed 18 parameters of dump site leachate,including physicochemical,heavy metals,and bacterial properties,alongside 13 groundwater samples.Sampling was conducted twice,in November 2020 and June 2021,within a five-kilometer radius of the Zanjan dump site.We utilized the Leachate Pollution Index(LPI)to evaluate potential groundwater contamination by leachate leakage from nearby dumpsite.Additionally,due to the predominant agricultural activities in the study area,various indices were employed to assess groundwater quality for agricultural purposes,such as Sodium Adsorption Ratio(SAR),Soluble Sodium Index(SSI),Kelly Ratio(KR),and Permeability Index(PI).Our analysis revealed no observed contamination related to leachate in the study area according to the LPI results.However,with the persistent pollution threat,implementing sanitary measures at the dump site is crucial to prevent potential impacts on groundwater quality.Moreover,the assessment of groundwater quality adequacy for irrigation yielded satisfactory results for SAR,KR,and PI indices.However,during both the dry(November 2020)and wet seasons(June 2021),the SSP index indicated that 80%of the samples were not classified as excellent,suggesting groundwater may not be suitable for agriculture.Overal,our qualitative study highlights the significant impact of the dry season on groundwater quality in the study area,attributed to elevated concentration levels of the investigated parameters within groundwater sources during the dry season.

Effects of Groundwater with Various Salinities on Evaporation and Redistribution of Water and Salt in Saline-sodic Soils in Songnen Plain,Northeast China

Groundwater mineralization is one of the main factors affecting the transport of soil water and salt in saline-sodic areas.To investigate the effects of groundwater with different levels of salinity on evaporation and distributions of soil water and salt in Songnen Plain,Northeast China,five levels of groundwater sodium adsorption ration of water(SARw)and total salt content(TSC mmol/L)were conducted in an oil column lysimeters.The five treated groundwater labeled as ST0:0,ST0:10,ST5:40,ST10:70 and ST20:100,were prepared with NaCl and CaCl2 in proportion,respectively.The results showed the groundwater evaporation(GWE)and soil evaporation(SE)increased firstly and then decreased with the increase of groundwater salinity.The values of GWE and SE in ST10:70 treatment were the highest,which were 2.09 and 1.84 times the values in the ST0:0 treatment with the lowest GWE and SE.There was a positive linear correlation between GWE and the Ca^(2+)content in groundwater,with R^(2)=0.998.The soil water content(SWC)of ST0:0 treatment was significantly(P<0.05)less than those of other treatments during the test.The SWC of the ST0:0 and ST0:10 treatments increased with the increase of soil depth,while the other treatments showed the opposite trend.Statistical analysis indicated the SWC in the 0–60 cm soil layer was positively correlated with the groundwater TSC and its ion contents during the test.Salt accumulation occurred in the topsoil and the salt accumulation in the 0–20 cm soil layer was significantly(P<0.05)greater than that in the subsoil.This study revealed the effects of the salinity level of groundwater,especially the Ca^(2+)content and TSC of groundwater,on the GWE and distributions of soil water and salt,which provided important support for the prevention and reclamation of soil salinization and sodificaton in shallow groundwater regions.

Potential risk of soil irrigation with treated wastewater over 40 years:a field experiment under semi-arid conditions in northeastern Tunisia

In Tunisia,water scarcity is only adding pressure on water demand in agriculture.In the context of sustainable development goals,Tunisia has been reusing treated wastewater(TWW)as a renewable and inexpensive source for soil fertigation and groundwater(GW)recharge.However,major risks can be expected when the irrigation water is of poor quality.This study aims for evaluating the potential risk of TWW and GW irrigation on soil parameters.Accordingly,we evaluated the suitability of water quality through the analysis of major and minor cations and anions,metallic trace elements(MTEs),and the sodium hazard by using the sodium adsorption ratio(SAR)and the soluble sodium percentage(SSP).The risk of soil sodicity was further assessed by SAR and the exchangeable sodium percentage(ESP).The degree of soil pollution caused by MTEs accumulation was evaluated using geoaccumulation index(Igeo)and pollution load index(PLI).Soil maps were generated using inverse spline interpolation in ArcGIS software.The results show that both water samples(i.e.,TWW and GW)are suitable for soil irrigation in terms of salinity(electrical conductivity<7000μS/cm)and sodicity(SAR<10.00;SSP<60.00%).However,the contents of PO_(4)^(3-),Cu^(2+),and Cd^(2+)exceed the maximum threshold values set by the national and other standards.Concerning the soil samples,the average levels of SAR and ESP are within the standards(SAR<13.00;ESP<15.00%).On the other hand,PLI results reveal moderate pollution in the plot irrigated with TWW and no to moderate pollution in the plot irrigated with GW.Igeo results indicate that Cu^(2+)is the metallic trace element(MTE)with the highest risk of soil pollution in both plots(Igeo>5.00),followed by Ni^(2+)and Pb^(2+).Nevertheless,Cd^(2+)presents the lowest risk of soil pollution(Igeo<0.00).Statistical data indicates that Ca^(2+),Na+,Ni^(2+),and Pb^(2+)are highly distributed in both plots(coefficient of variation>50.0%).This study shows that the use of imagery tools,such as ArcGIS,can provide important information for evaluating the current status of soil fertility or pollution and for better managing soil irrigation with TWW.

Spatio-temporal variations of soil water content and salinity around individual Tamarix ramosissima in a semi-arid saline region of the upper Yellow River, Northwest China

Ecological restoration by Taman＇x plants on semi-arid saline lands affects the accumulation, distribution patterns and related mechanisms of soil water content and salinity. In this study, spatio-temporal variations of soil water content and salinity around natural individual Tamarix ramosissiraa Ledeb. were invetigated in a semi-arid saline region of the upper Yellow River, Northwest China. Specifically, soil water content, electrical conductivity （EC）, sodium adsorption ratio （SARa）, and salt ions （including Na＋, K＋, Ca2＋, Mg2＋ and 8042-） were measured at different soil depths and at different distances from the trunk of T. ramasissima in May, July, and September 2016. The soil water content at the 20-80 cm depth was significantly lower in July and September than in May, indicating that T. ramosissima plants absorb a large amount of water through the roots during the growing period, leading to the decreasing of soil water content in the deep soil layer. At the 0-20 cm depth, there was a salt island effect around individual T. ramosissima, and the ECe differed significantly inside and outside the canopy of T. ramosissima in May and July. Salt bioaccumulation and stemflow were two major contributing factors to this difference. The SAR at the 0-20 cm depth was significantly different inside and outside the canopy of T. ramosissima in the three sampling months. The values of SAR~ at the 60-80 cm depth in May and July were significantly higher than those at the 0-60 cm depth and higher than that at the corresponding depth in September. The distribution of Na＋ in the soil was similar to that of the SAI, while the concentrations of K＋, Ca2＋, and Mg2＋ showed significant differences among the sampling months and soil depths. Both season and soil depth had highly significant effects on soil water content, ECe and SARa, whereas distance from the trunk of T. ramosissima only significantly affected ECe. Based on these results, we recommend co-planting of shallow-rooted salt-tolerant species near the Tamarx plants and avoiding planting herbaceous plants inside the canopy of T. ramodssima for afforestation in this semi-arid saline region. The results of this study may provide a reference for appropriate restoration in the semi-arid saline regions of the upper Yellow River.

Combined Effects of Water Quality and Furrow Gradient on Runoff and Soil Erosion in North China

Irrigation-induced soil erosion seriously affects the sustainability of irrigated agriculture. The effects of irrigation water quality and furrow gradient on runoff and soil loss were studied under simulated furrow irrigation in laboratory using a soil collected from an experimental station of China Agricultural University, North China. The experimental treatments were different combinations of irrigation water salt concentrations of 5, 10, 20, and 30 mmol c L-1 , sodium adsorption ratios (SAR) of 0.5, 5.0, and 10.0 (mmol c L-1 ) 0.5 , and furrow gradients of 1%, 3%, and 5%, with distilled water for irrigation at 3 furrow gradients as controls. The experimental data indicated that total runoff amount, sediment concentration in runoff, and total soil loss amount generally decreased with increasing salt concentration in irrigation water but increased with its sodicity and furrow gradient. The effects of water quality and furrow gradient on soil loss were greater than those on runoff, and the increase of furrow gradient decreased the influence of water quality on soil loss. When the salt concentration increased from 5 to 30 mmol c L-1 at SAR of 10.0 (mmol c L-1 ) 0.5 , total runoff amount, sediment concentration, and total soil loss amount decreased by 3.89%, 52.1%, and 53.92%, and 10.57%, 38.86%, and 42.03% at the furrow gradients of 1% and 5%, respectively. However, they respectively increased by 3.37%, 45.34%, and 55.36%, and 3.86%, 10.77%, and 13.91% when SAR increased from 0.5 to 10.0 (mmol c L-1 ) 0.5 at the salt concentration of 5 mmol c L-1 . Irrigation water quality and furrow gradient should be comprehensively considered in the planning and management of furrow irrigation practices to decrease soil loss and improve water utilization efficiency.

Characteristics of produced water during coalbed methane （CBM） development and its feasibility as irrigation water in Jincheng, China

Water resources are scarce in Jincheng. Huge quantities of water are pumped out in the dewatering course, and the disposal of CBM water is one of the most important problems during the extracting of CBM. Based on the data of CBM water production, chemical characteristics, the irrigational conditions for major crops, and China irrigation water standard, the feasibility of CBM water as irrigation water is discussed. The result shows the CBM water quality doesn＇t fully meet irrigation water quality standards in Jincheng, its high salinity and sodium adsorption ratio （SAR） in CBM water might affect crops growth and lead to yield loss, and can＇t be used as irrigation water directly, but with the treatment of the reverse osmosis （RO） to lower the salinity and SAR of CBM water, the CBM water can be used as irrigation water.

Hydrogeochemical characteristics of groundwater and quality assessment for the purposes of drinking and irrigation in Bougaa area,Northeastern Algeria

In the northern part of Algeria,the intensive exploitation of groundwater resources and pollution has considerably affected the aquifer water quality,especially in rural areas where groundwater is the main source of water supply for most uses.This study was performed to evaluate the groundwater quality and its suitability for drinking and irrigation purposes through the hydrogeochemical study on the groundwater in Bougaa region(Northeastern Algeria).Fourteen groundwater samples were collected and analyzed for p H,T,EC,TDS,and major ions.Most samples are suitable for drinking based on the permissible limits of the Bureau of Indian standards(Indian standard specification for drinking water(IS 10500:2012),but only 35%of the samples are good enough for drinking purposes based on the water quality index of the groundwater.Assessment of groundwater samples from various parameters and methods such as"Electrical conductivity,Sodium adsorption ratio,Soluble sodium percentage,Magnesium adsorption ratio,Residual sodium carbonate,Permeability index,Kelly’s ratio,Wilcox’s diagram,and US salinity laboratory classification"showed that groundwater in the area is chemically suitable for irrigation uses.The Piper trilinear diagram suggests that the groundwater mainly belongs to the hydrochemical facies Ca–Mg–Cl and Na–Cl.The combination of ionic ratios,Gibbs plots,and saturation indices show that water–rock interaction,particularly the dissolution of carbonate,evaporation minerals,and ion exchange processes affects hydrogeochemistry of the area.Additional processes such as evaporation and anthropogenic pollution from various sources can also have major impacts on groundwater salinity.

Quality Assessment of Different Industrial Effluents for Irrigation in Agriculture

A laboratory experiment was undertaken in Soil Science Division of BRRI （Bangladesh Rice Research Institute） during 2010 to assess the quality of industrial effluents and city waste as a source of irrigation water for agriculture. The treatments of the studies were the effluents of five different industrial sources like polyvinyl, dyeing, pharmaceuticals, beverage, tannery, mixed waste water （contaminated with effluents from many industries）, CWW （city waste water） and underground water as control. The industrial effluents, MWW （mixed waste water）, CWW and control water were tested for electrical conductivity, pH, and soluble ions such as Na^＋, Ca^2＋, Mg^2＋, K^＋, HCO3-, CO3^2-, NH4^＋-N and H2PO4^-. Micronutrients （Fe, Mn, Cu and Zn） and heavy metals （As, Pb, Cd, Cr and Ni） were analyzed from the samples. Beverage industry effluent showed acidic reaction, while the other industrial effluents showed alkaline reaction （pH 7.25-9.07）. Pharmaceutical, dyeing and tannery effluents showed EC of 3.40, 4.30 and 9.49 dS m^-1, respectively, compared to 0.54 dSm^-1 of the control. All the effluents except polyvinyl and beverage effluents and CWW recorded higher carbonate and bicarbonate content than that of control. Industrial effluents and CWW were higher in micronutrient content as compared to control. Dyeing, pharmaceutical and tannery effluents contained 2.51, 3.94 and 4.29 mg L^-1 lead, 0.15, 0.14 and 0.38 mg L^-1 chromium and 0.25, 0.24 and 0.16 mg L^-1 nickel, respectively which might be concemed for health hazard through food chain.

Soil Properties and Wheat Growth and Nutrients as Affected by Compost Amendment Under Saline Water Irrigation

A greenhouse experiment was conducted to test and compare the suitability of saline compost and saline irrigation water for nutrient status amendment of a slightly productive sandy clay loam soil, to study the macronutrient utilization and dry matter production of wheat （Triticum aestivum c.v. Gemmiza 7） grown in a modified soil environment and to determine the effects of compost and saline irrigation water on soil productivity. The sandy clay loam soil was treated with compost of five rates （0, 24, 36, 48, and 60 m3 ha-1, equivalent to 0, 3, 4.5, and 6 g kg-1 soil, respectively） and irrigation water of four salinity levels （0.50 （tap water）, 4.9, 6.3, and 8.7 dS m-l）. The results indicated that at harvest, the electrical conductivity （EC） of the soil was significantly （P 〈 0.05） changed by the compost application as compared to the control. In general, the soil salinity significantly increased with increasing application rates of compost. Soluble salts, K, C1, HCO3, Na, Ca, and Mg, were significantly increased by the compost treatment. Soil sodium adsorption ratio （SAR） was significantly affected by the salinity levels of the irrigation water, and showed a slight response to the compost application. The soil organic carbon content was also significantly （P 〈 0.05） affected by application of compost, with a maximum value of 31.03 g kg-1 recorded at the compost rate of 60 m3 ha-1 and the irrigation water salinity level of 8.7 dS m-1 and a minimum value of 12.05 g kg-1 observed in the control. The compost application produced remarkable increases in wheat shoot dry matter production. The maximum dry matter production （75.11 g pot-1） occurred with 60 ma ha-1 compost and normal irrigation water, with a minimum of 19.83 g pot-1 with no addition of compost and irrigation water at a salinity level of 8.70 dS m-1. Significant increases in wheat shoot contents of K, N, P, Na, and C1 were observed with addition of compost. The relatively high shoot N values may be attributed to increases in N availability in the tested soil caused by the compost application. Similarly, significant increases in the shoot contents of Na and C1 may be ascribed to the increase in soil soluble K and Cl. The increases in shoot P, N, and K contributed to the growth stimulation since P supplied by the compost was probably responsible in saline and alkaline soils where P solubility was very low.

Dynamics of Soil Moisture and Salt Content After Infiltration of Saline Ice Meltwater in Saline-Sodic Soil Columns

Saline ice meltwater can be used for irrigation and leaching of salts in salt-affected soil regions.A laboratory experiment was conducted using soil columns to investigate the redistribution of soil moisture, salt and sodium adsorption ratio(SAR) in saline-sodic soil under the infiltration of saline ice meltwater.Soils were treated using saline water of three irrigation volumes(1 600, 2 400 and 3 200 mL) at four salinity levels.These four salinity levels included salt free(0 g L^(-1)), low salinity level(1.4 g L^(-1)), moderate salinity level(2.7 g L^(-1)) and high salinity level(4.1 g L^(-1)).The prepared saline water was frozen into ice, and then the ice was put on the surface of soil columns.After 96 h, the infiltration rate and soil moisture content of saline ice treatments were greater than those of salt-free ice treatments, increasing with the increase of ice salinity.Infiltration of saline ice meltwater increased soil moisture content in the upper layers for all treatments.Both salt contents and SAR values in the upper soil layers decreased in all saline ice treatments and were lower than those in salt-free ice treatment.However, this trend was reversed in the deeper(below 20 cm) soil layers.The highest desalting rate and lowest SAR were observed in high-salinity treatment under three irrigation volumes in the 0–15 cm soil layer,especially under irrigation volume of 2 400 mL.These results indicate that saline ice(0–20 cm) meltwater irrigation is beneficial to saline-sodic soil reclamation, and the best improvement effect would be achieved when using high-salinity ice under optimal irrigation volume.

Short-term effects of biochar and gypsum on soil hydraulic properties and sodicity in a saline-alkali soil

Salt and sodicity of saline-alkali soil adversely affect the construction of ecological landscapes and negatively impact crop production.The reclamation potential of biochar(BC,wheat straw biochar applied at\%by weight),gypsum(G,0.4%by weight),and gypsum coupled with biochar(GBC)was examined in this laboratory-based study by evaluating their effects on a saline-alkali soil(silt loam)with no amendment as a control(CK).Saline ice and fresh water(simulated rainfall)were leached through soil columns to investigate changes in salt content,sodium adsorption ratio(SAR),alkalinity,and pH of the leachate and the soil.Results showed that saturated water content and field water capacity(FWC)significantly increased by 4.4%and 5.6%,respectively,in the BC treatment after a short incubation time.Co-application of biochar and gypsum(GBC)increased soil saturated hydraulic conductivity(Ks)by 58.4%,which was also significantly higher than the sole addition.Electrical conductivity(EC)of the leachate decreased sharply after saline ice leaching;subsequent freshwater leaching accelerated the removal of the rest of the salts,irrespective of the amendment application.However,the application of gypsum(G and GB)significantly enhanced the removal of exchangeable Na^+and reduced leachate SAR.After leaching,the soil salt content decreased significantly for all treatments.The application of gypsum resulted in a significantly lower soil pH,exchangeable sodium percentage(ESP),SAR,and alkalinity values than those recorded for the CK and BC treatments.These results demonstrated that the co-application of gypsum and biochar could improve saline-alkali soil hydraulic conductivity and decrease leaching-induced sodicity over a short period.

Soil Erosion as Affected by Polyacrylamide Application Under Simulated Furrow Irrigation with Saline Water

The reduction of soil and water losses under furrow irrigation with saline water is important to environmental protection and agricultural production. The objective of this study was to determine the effect of polyacrylamide (PAM) application on soil infiltration and erosion under simulated furrow irrigation with saline water. Polyacrylamide was applied by dissolving it in irrigation water at the rates of 1.5, 7.5, and 15.0 mg L-1 or spreading it as a powder on soil surface at the rates of 0.3, 1.5, 3.0, and 6.0 g m-2, respectively. The electrolyte concentration of tested irrigation water was 10 and 30 mmolc L-1 and its sodium adsorption ratio (SAR) was 0.5, 10.0, and 20.0 (mmolc L-1)0.5. Distilled water was used as a control for irrigation water quality. Results indicated that the electrolyte concentration and SAR generally did not significantly affect soil and water losses after PAM application. Infiltration rate and total infiltration volume decreased with the increase of PAM application rate. Polyacrylamide application in both methods significantly reduced soil erosion, but PAM application rate did not significantly affect it. The solution PAM application was more effective in controlling soil erosion than the powdered PAM application, but the former exerted a greater adverse influence on soil infiltration than the latter. Under the same total amounts, the powdered PAM application resulted in a 38.2%-139.6% greater infiltration volume but a soil mass loss of 1.3-3.4 times greater than the solution PAM application.