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Enhancing saline water productivity in arid regions is essential for sustainable agriculture. Adding biochar can improve the quantity and quality of tomato yield under higher levels of salinity and lower levels of irrigation. The experiment aimed to evaluate the effects of biochar on enhancing tomato fruit quality and yield under salinity and drought stress. The experiment combines two treatments for irrigation water quality (0.9 and 2.3 dS m−1), four irrigation levels (40, 60, 80, and 100%) of crop evapotranspiration (ETc), and the addition of 5% of biochar to treated soil (BC5%) and untreated soil (BC0%). The results showed that the decrease in the water quality and irrigation levels negatively impacted the yield and properties of tomato fruit, while 5% of biochar application positively improved the yield. Adding biochar decreased the tomato yield by 29.33% and 42.51% under lower-saline-irrigation water than the control, negatively affecting the fruit's physical parameters and mineral content. In contrast, adding biochar and irrigating with saline water at 60% of ETc improved the firmness and quality characteristics of the fruit by 56.60%, 67.19, 99.75, and 73.57% for vitamin C (VC), total titratable acidity (TA), total soluble solids (TSS), and total sugars (TS), respectively, compared to the control, and also reduced the sodium content of the fruits under all irrigation levels compared to untreated plants by biochar. Generally, biochar with saline water under deficit irrigation with 80 and 60% of ETc could be an excellent strategy to enhance the qualitative characteristics of tomato fruits and save approximately 20–40% of the applied water. [ABSTRACT FROM AUTHOR]

Batch and transport experiments were used to investigate the remediation of loamy sand soil contaminated with Cr(VI) using zero-valent iron nanoparticles (nZVI) stabilized by carboxymethylcellulose (CMC-nZVI). The effect of pH, ionic strength (IS), and flow rate on the removal efficiency of Cr(VI) were investigated under equilibrium (uniform transport) and non-equilibrium (two-site sorption) transport using the Hydrus-1D model. The overall removal efficiency ranged from 70 to over 90% based on the chemical characteristics of the CMC-nZVI suspension and the transport conditions. The concentration and pH of the CMC-nZVI suspension had the most significant effect on the removal efficiency and transport of Cr(VI) in the soil. The average removal efficiency of Cr(VI) was increased from 24.1 to 75.5% when the concentration of CMC-nZVI nanoparticles was increased from 10 to 250 mg L−1, mainly because of the increased total surface area at a larger particle concentration. Batch experiments showed that the removal efficiency of Cr(VI) was much larger under acidic conditions. The average removal efficiency of Cr(VI) reached 90.1 and 60.5% at pH 5 and 7, respectively. The two-site sorption model described (r2 = 0.96–0.98) the transport of Cr(VI) in soil quite well as compared to the uniform transport model (r2 = 0.81–0.98). The average retardation of Cr(VI) was 3.51 and 1.61 at pH 5 and 7, respectively, indicating earlier arrival for the breakthrough curves and a shorter time to reach maximum relative concentration at lower pH. The methodology presented in this study, combining column experiment and modeling transport using the Hydrus-1D model, successfully assessed the removal of Cr(VI) from polluted soils, offering innovative, cost-effective, and environmentally friendly remediation methodologies. [ABSTRACT FROM AUTHOR]

Due to the negative effects on people's health and the environment caused by the amount of soil pollutants caused by polycyclic aromatic hydrocarbons (PAHs) emitted from various sources, especially in industrial areas, and the spread of pollutants in nearby neighborhoods, as well as the extent to which children and adults, especially young people, are affected by soil intake, direct skin contact with the soil, or inhalation of contaminated soil dust due to their behavior. The aim of this study was to assess the extent to which industrial areas, particularly the auto industry in the city of Riyadh, are impacted by pollution brought on by PAHs (2 A and 2B), which are known to cause cancer. Naseem Industrial (NAI), Old Industrial (OLI), Gulf Industrial (GUI), Al-Shifa Industrial (SHI), and Umm Al-Hamam Industrial (UMH). Surface soil from the industrial districts, ranging in depth from 0 to 10 cm, as well as from the neighborhoods close by. The percentage of pollution by PHAs according to the Agency for Research on Cancer classified BaP, DBA, and BaA as probable human carcinogens (2 A) while BbF, BkF, and IND as possible human carcinogens (2B). IARC has evaluated Nap and CRY and classed them as potentially carcinogenic for humans. The extraction method is swift, easy, cheap, effective, rugged, and safe (QuEChERS) for the ∑8 PAHs and GC-MS used to estimate the results in the extracted samples. The sole risk identified as having potential for both adults and children was exposure to BaP and DBA in street dust in different land areas in Riyadh. Mean ILCRing and ILCRder values ​​and cancer risk based on mean total concentrations of PAHBaPequi for children and adults exposed to PAHs in street dust in different regions of Riyadh were found between 10−9 and 10−4, indicating a potential risk. [ABSTRACT FROM AUTHOR]

The tomato is a vital component of agriculture and is the second-most important vegetable globally. Maintaining a high tomato production requires both water quality and quantity. Water-scarce regions like Saudi Arabia still lack an understanding of the impact of deficit irrigation and the use of a blend of saline and freshwater, especially their nuanced impact across growth stages. The purpose of this study was to evaluate the effects of six different irrigation amounts: full irrigation with 100% ETc (FI), regulated deficit irrigation with 60% ETc (DI), and deficit irrigation with 60% ETc, except for the initial (DI-int), development (DI-dev), mid-season (DI-mid), and late-season (DI-lat) stages. This was performed with three different water qualities: fresh (FW), saline (SW), and fresh-saline blend (1:1) (MW) water. FW and MW enhanced the growth, physiology, morphology, yield, and quality, while SW had the lowest values. DI reduced these parameters and lowered yields by 13.7%, significantly improving water use efficiency (WUE) by 44% and fruit quality. DI-mid or DI-lat slightly improved yields while remarkably decreasing WUE and fruit quality. DI outperforms deficit irrigation in all growth stages except one, and countries with limited freshwater resources can benefit from a mix of fresh and saline water with a 60% ETc deficit irrigation, resulting in greater water savings. [ABSTRACT FROM AUTHOR]

Improving the physical properties and water retention of sandy soils is of critical importance in arid and water-scarce regions such as Saudi Arabia. The impacts of organic amendments of different particle sizes coupled with natural clay deposits on improving the soil physio-chemical characteristics, nutrient availability, and growth of Sudan grass were investigated in this study. A loamy sand soil was amended with natural clay deposits at 2.5%, 5.0%, and 10% (w/w) application rates, and in combination with 1.0% (w/w) wheat straw of different particle sizes. The water infiltration, evaporation, and retention characteristics of the amended soil were studied for 9 weeks, and then Sudan grass was grown for 7 weeks. The impacts of the particle size of wheat straw on soil properties and nutrient availability were significant (p < 0.05) when combined with clay deposits. The highest application rate of clay (10%) demonstrated the highest water content (20.63–21.73%), and increased P and K availability to 35.54 and 6980 mg kg−1, respectively, in soil, which were 33% and 88% higher, respectively, compared to the control. Plant N, P, and K concentrations were increased to 0.95%, 0.26%, and 4.33%, respectively, which were 2–3.5-fold higher than the control. Therefore, the integrated application of natural clay deposits and wheat straw of fine particle size could be an effective strategy in improving plant production in water-scarce regions. [ABSTRACT FROM AUTHOR]

Water management in sandy soils (Typic Torripsamments) is crucial in sustaining agricultural production. The main goal of this research was to assess the impact of date palm biochar on the physical properties of sandy soil with different particle sizes of biochar (macro and nano). For nano-biochar preparation, stick chips were established into a tubular furnace with nitrogen air and heated to 400–450 °C, which was accompanied by a holding period of 4 h. The ball-milled biochar was inclined via ball grinding in a model number PQN2.110 planetary mill and within jars (500 mL), and the biochar-to-sphere mass ratio was 1:100. The sphere-milling apparatus was processed at a speed of 300 rpm for 13 h. Laboratory experiments were carried out at one rate—biochar 5%—and three depths (0.0–5, 5–10, and 10–15 cm). Applying macro-biochar reduced cumulative evaporation compared to the control by 4%, 24%, and 14% for the macro-biochar particles at soil depths. In contrast, biochar reduced cumulative evaporation compared to the control by 8%, 12%, and 4% for the nano-biochar particles at the soil depths tested. Adding biochar significantly raised the amount of retained water, with the highest level recorded at the 5–10 cm depth, while the variations were significantly lower between the macro and nano-biochar when in the direction of the soil surface (0–5 cm), indicating the significance of mixing biochar with the top 10 cm of the soil to increase its ability to reduce evaporation and increase the amount of water retained in the soils. It could be concluded that applying at the top of the coarse soil can positively impact soil hydro-physical properties and increase soil water availability to plants. [ABSTRACT FROM AUTHOR]

Heavy metals transport to groundwater relies on the characteristics of soil, such as carbonate and clay minerals, organic matter content, soil pH, and some other factors. Most of the heavy metals in calcareous soils are precipitated as metal carbonate minerals; consequently, their transport to the groundwater is not anticipated. Therefore, the current study focused on the impacts of calcium carbonate presence on the adsorption and transport of lead (Pb) and copper (Cu) in calcareous soil using batch and column experiments. To elucidate the contaminants removal mechanisms in calcareous soils, extensive laboratory batch investigations were conducted to study the equilibrium kinetic and adsorption isotherm characteristics of the two studied heavy metals. The quick adsorption of Pb2+ and Cu2+ by soil was seen in kinetics trials. In addition, Pb2+ and Cu2+ sorption onto the soil was best described by the pseudo-second order kinetic model (R2 = 0.9979 and 0.9995 for Cu2+ and Pb2+, respectively). To explain the equilibrium sorption data, the Freundlich isotherm showed the best fitness to Pb2+ (R2 = 0.96) and Cu2+ (R2 = 0.98), collectively. The Freundlich parameters revealed that the Pb2+ has favorable adsorption; however, Cu2+ has unfavorable adsorption onto the soil. The results of column experiments showed the higher binding of Pb2+ than Cu2+ to the top surface of the soil column, making the movement of these two metals very slow. In columns, most of the Pb2+ and Cu2+ ions were sorbed at an initial 5 and 10 cm, respectively. The findings of this study will help in understanding the fate of heavy metals in calcareous soils. [ABSTRACT FROM AUTHOR]