Papers by Ahmed El-Naggar
Molecules, 2021
In Saudi Arabia, more than 335,000 tons of cow manure is produced every year from dairy farming. ... more In Saudi Arabia, more than 335,000 tons of cow manure is produced every year from dairy farming. However, the produced cow manure is usually added to the agricultural soils as raw or composted manure; significant nitrogen losses occur during the storage, handling, and application of the raw manure. The recovery of ammonia from cow manure through thermochemical treatments is a promising technique to obtain concentrated nitrogen fertilizer and reducing nitrogen losses from raw manure. However, the byproduct effluents from the recovery process are characterized by different chemical properties from the original raw manure; thus, its impact as soil amendments on the soil carbon and nitrogen dynamics is unknown. Therefore, a 90-day incubation experiment was conducted to study the impact of these effluents on CO2 efflux, organic C, microbial biomass C, available NH4+, and NO3− when added to agricultural soil. In addition to the two types of effluents (produced at pH 9 and pH 12), raw cow ...
2020 Advances in Science and Engineering Technology International Conferences (ASET), 2020
In forensic science, soil can be one of the valuable evidence during investigations. Soils might ... more In forensic science, soil can be one of the valuable evidence during investigations. Soils might link an individual to a crime scene as soil transferred in a mud stabbing to footwear, tires, soil marks on vehicles, traces left on clothes can correlate the presence or absence of this person on a particular scene of the crime. The soil has extreme complexity not only in components but also in physical nature such as sediment, color, and structure. The aim of the present study was to investigate various physico-chemical properties of different types of soils. These soil properties can be beneficial in forensic investigations along with other evidences found in a crime scene. A number of experiments have been performed to achieve our goal. Particle Size Distribution Analysis PSDA was performed to differentiate between several soil samples based on their texture, through estimation of the size fractions of clay, silt and sand. A hydrometer method was used to estimate the percentages of sand, silt and clay in six samples of soils. We could allocate the soil samples to a textural class that helped us to define the type of soil and link this to a special location. Several soils were analyzed for organic matter content, ammonium, nitrate, carbonates, bicarbonates, chloride, calcium and magnesium in the soil samples. The high variability in results among the tested samples could refer to a unique fingerprinting for each soil type which is vital findings for forensic soil investigations in a crime scene.
Environmental monitoring and assessment, 2017
The present study was conducted in one of the most densely cultivated area of Al-Qassim region in... more The present study was conducted in one of the most densely cultivated area of Al-Qassim region in Kingdom of Saudi Arabia to (i) monitor trace metal (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) contents in surface and subsurface soils, (ii) assess the pollution and potential ecological risk levels of trace metals, and (iii) identify trace metal sources using enrichment factor (EF), correlation matrix, and principal component analysis (PCA). The pollution levels of the analyzed trace metals calculated by the geoaccumulation index (I geo) and contamination factor (C f) suggested that the soils were highly contaminated with Cd and moderately contaminated with Pb. Based on the average values of EF, soil samples were found to present extremely high enrichment for Cd, significant enrichment for Pb, moderate enrichment for Zn, and deficient to minimal enrichment for other trace metals. Among the analyzed trace metals, a very high ecological risk was observed only in the case of Cd at some samp...
Bulletin of Environmental Contamination and Toxicology, 2016
This study was conducted to identify and quantify polychlorinated dibenzo-p-dioxins (PCDDs) and p... more This study was conducted to identify and quantify polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in soil samples collected from selected industrial areas in the central and eastern regions of Saudi Arabia. All the investigated compounds of PCDDs/PCDFs were identified in the studied locations. The average concentrations of PCDDs (sum of seven congeners measured) ranged from 11.5 to 59.6 pg g-1 , with a maximum concentration of 125.7 pg g-1 at an oil refinery station followed by 100.9 pg g-1 at a cement factory. The average concentrations of PCDFs (sum of 10 congeners measured) accounted for 11.68-19.35 pg g-1 , with a maximum concentration of 38.67 pg g-1 at the cement factory. It was generally observed that the soil samples collected from industrial areas have substantially high toxicity equivalence (TEQ) values of PCDDs/PCDFs compared to soils of remote areas. Principal component analysis revealed that the cement factories and oil refineries were the primary sources of PCDDs and PCDFs.
Nutrient Cycling in Agroecosystems, 2007
A major challenge for low-external-input farming systems is to secure the N supply. Lack of synch... more A major challenge for low-external-input farming systems is to secure the N supply. Lack of synchrony between mineralization of organic N sources and plant N requirements is causing many growers to use different techniques to overcome this problem. One of these techniques is the application of soluble water extracts of different farm residues and plants. A field study was conducted to study the crop uptake of applied 15 N-labeled alfalfa and clover extracts as compared to the N uptake from 15 Nglycine and three levels of 15 N-(NH 4) 2 SO 4. The results show that total N accumulation in the field crops, squash and lettuce was primarily affected by the amount of added N (P 0.05) and not by the form in which the N was applied (P 0.05). The utilization efficiencies of N (pNdff) from plant extracts and glycine increased (P 0.05) gradually from 10, 20, to 30 days after application in contrast to (NH 4) 2 SO 4 which peaked in utilization efficiencies of 56% around 20 days after application. The pNdff reached 60%, 40% and 36% of the applied glycine, alfalfa and clover extracts, respectively in lettuce. Squash showed the same pattern during at 10, 20 and 30 days; however, the proportion of N derived from most of the treatments was higher in squash than in lettuce (P 0.05). These results indicate that plant extracts of clover and alfalfa can be used as efficient N fertilisers in low-external-input agroecosystems.
Adsorption Science & Technology, 2013
Fe(II) removal from acidic aqueous solutions using Conocarpus sp. biochar or chemically modified ... more Fe(II) removal from acidic aqueous solutions using Conocarpus sp. biochar or chemically modified biochar prepared by synthesizing Mg(OH)2 on biochar surface as well as their comparison with zeolite sorbent (natural clinoptilolite) was investigated. Batch experiments were conducted as a function of initial pH of 2-5, contact time of 5-180 minutes and initial concentration of 10-200 mg l-1 (0.18-3.58 mmol l-1). The sorption data indicated that the pseudosecond-order kinetic model was the best model to simulate adsorption of Fe(II) onto the all sorbents and could generally be described by the Freundlich model. The higher sorption capacities for Fe(II) ions were generally pronounced for chemically modified biochar (84.6-99.8%) followed by biochar (38.3-97.6%) than those that were achieved by zeolite (12.3-95.5%). Thus, remediating acidic wastewater contaminated with Fe(II) might be possible using Conocarpus biochar, especially the chemically modified biochar.
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Papers by Ahmed El-Naggar