A critical review on soil structure: research methods, structured indexes, and constitutive models

Detection of heavy metal elements by using advanced optical techniques

“…The solid portion of soil makes up roughly 45% of its composition, while organic matter accounts for 5%, and the remaining 50% is pore space that is evenly divided between air and water as shown in Figure 1.1 [1]. The main components of agricultural soils include mineral particles, organic matter, water, and air [2] [3]. The mineral particles are categorized based on their size, such as sand, silt, and clay, and they are derived from the parent material.…”

“…Organic matter consists of decomposed plant and animal residues, and water in agricultural soils plays a critical role in plant growth by transporting nutrients and essential elements to plant roots. Air in the soil is important for soil respiration and the exchange of gases with the atmosphere [2] [3]. The soil of a particular location undergoes a series of weathering processes influenced by various factors, such as climate, biology, and geology leading to its evolution.…”

“…These heavy metals are naturally occurring elements in the earth's crust and are persistent, remaining in aqueous and terrestrial environments for extended periods [12], [27]. The term "heavy metals" generally refers to a group of metals and metalloids with densities greater than or equal to 3 g/cm 3 , which can have harmful biological effects and ecological consequences when present in sufficient concentrations [28]. The most important heavy metals include Ti, Va, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Rb, Sr, Zr, Ag, Cd, Sn, Sb, Te, Ba, Ce, Pt, Au, Hg, Th, Pb, Bi, and U [29].…”