Heavy Metals Content of Commercial Inorganic Fertilizers Used in the Kingdom of Saudi Arabia

Abstract

In recent years much concern has been given to toxic heavy metals, which enter the human food chain. Application of inorganic fertilizers is considered one of the potential routes of such entry, in this work 74 samples of commercial fertilizers marketed in the Kingdom of Saudi Arabia were analyzed for their heavy metal concentrations. Fertilizer samples included 20 samples of phosphatic fertilizers [monoammonium phosphate (MAP), diammonium phosphate (DAP) and triple superphosphate (TSP)], 11 samples of liquid fertilizers. 31 samples of water-soluble multiple nutrient fertilizers (WSMF) and 12 samples of solid multiple nutrient fertilizers (SMNF). Concentrations of heavy metals varied according to the type of fertilizer and the tested metal; Cr levels were the highest and Co was the lowest. Results revealed that Cd ranged from < l to 36.8 mg.kg-1, with a median of 33.2 mg.kg-1 for the phosphatic fertilizers, 9.5 mg.kg-1 for the liquid fertilizers, 19.7 for the SMNF, and 2.9 mg.kg-1 for the WSMF. The median values of Pb, Ni, Co and Cr in the phosphatic fertilizers were 14.3, 72.1, 1 1.8 and 249.3 mg.kg-1, respectively. However, the corresponding median values of these elements, in the liquid fertilizers, were 9.9, 15.6, 11.2 and 64.0 mg.kg-1 and 15.3, 43.0, 12.5 and 170.7 mg.kg-1 in the SMNF. The median contents of three heavy metals in the WSMF samples were 9.8 mg.kg-1 for Pb, 5.6 mg.kg-1 for Co. and 7.4 mg.kg-1 for Ni. The Cd. Co. Cr and Ni concentrations were lower than the tolerance limits for heavy metal addition (Cd 100 mg.kg-1, Cr, 100 mg.kg-1 and Ni, 50 mg.kg-1), and they were in a range similar to those found internationally. It is estimated that the application of an average dose of 80 kg P ha-1 annually in Saudi Arabia, contributes 13 g of Cd ha-1 to the soil.

Heavy metals concentration in soils under rainfed agro-ecosystems and their relationship with soil properties and management practices

“…The pH value and the percentage of clay content determine the solubility of metals in the soil and their availability for uptake by plants (Golia et al 2008). Heavy metals content usually decreases from clay to coarse silt due to relatively high surface area of clay minerals and weak pH dependence of CEC (Modaihsh et al 2004). From our study, it is evident that there is an obvious relationship between clay content and the amount of heavy metals in soils.…”

“…Heavy metals can also accumulate in the soil due to application of liquid and solid manure (or their derivatives, compost or sludge) or inorganic fertilizers (Huang and Jin 2008). A previous study on heavy metal contents in phosphatic fertilizers (DAP) revealed the following order: Co (11.8) \ Cd (33.2) \ Ni (72.1) \ Cr (249.3) mg kg -1 (Modaihsh et al 2004). In general, DAP (diammonium phosphate) fertilizers contain 10 mg kg -1 Cd; 71 mg kg…”

Health risk assessment of heavy metals via consumption of spinach vegetable grown in Elalla River

“…The presence of heavy metals in surface water is caused by weathering of soils, rocks and by anthropogenic activities that disturb the natural distribution of heavy metals in surface water [1]. Soils may become contaminated by the accumulation of heavy metals through emissions from the rapidly expanding industrial areas, mine tailings, disposal of high metal wastes, leaded gasoline and paints, land application of fertilizers, animal manures, sewage sludge, pesticides, wastewater irrigation, coal combustion residues, spillage of petrochemicals, and atmospheric deposition [2,3]. Long term use of sewage effluent for irrigation contaminates the soil and vegetables to such extent that it becomes toxic to plants and causes the deterioration of the soil that contains considerable amount of potentially harmful substances of heavy metals like Cr, Fe, Cu, Pb, Zn and Cd [3].…”

Bioremediation of Heavy Metals from Soil and Aquatic Environment: An Overview of Principles and Criteria of Fundamental Processes

“…The most significant natural sources are weathering of minerals, erosion and volcanic activity, while the anthropogenic sources depend upon human activities such as mining, smelting, electroplating, use of pesticides and phosphate fertilizer discharge, as well biosolids (e.g., livestock manures, composts, and municipal sewage sludge), atmospheric deposition, etc. [14,[43][44][45][46]47]. The disturbance of nature's slowly occurring geochemical cycle of metals by man results in accumulation of one or more of heavy metals in the soil and waters, and above defined levels, this is enough to cause risk to human health, plants, animals and aquatic biota [48].…”