Evaluation of calcium, phosphorus and soil organic matter effects on lead accumulation in Cenchrus ciliaris L. grown near a cement factory in Jazan region, Saudi Arabia

Abstract

Heavy metals associated with cement production and their environmental impacts have received much attention recently. Lead (Pb) is the second most hazardous element after arsenic (As). However, information about its availability and uptake by plants in polluted soil as influenced by soil properties has shown some contradictions. We evaluated the influence of soil calcium (Ca), soil phosphorus (P), and soil organic matter (SOM) on Pb uptake by Cenchrus ciliaris L. based on distance from cement dust polluted soil near a cement factory in Jazan region, Saudi Arabia. We also evaluated the potential of Cenchrus ciliaris L. as a hyperaccumulator of Pb. Soil and plant samples were collected in triplicates from three zones based on distance from the fence of the factory: 10 – 100, 100 – 350, and 350 – 700 m. Concentrations of total Pb, total Ca, and total P in soil and plant tissues were detected using ICP-AES. SOM and other soil properties were also analyzed. Bioconcentration and translocation factors (BF&TF) of Pb were also calculated. Results showed that Pb concentration in Cenchrus ciliaris roots had a strong negative relationship with SOM (R2 = 0.93) and P concentration in soil (R2 = 0.97) but a moderate negative relationship with Ca concentration in soil (R2 = 0.69). The highest TF value was 1.87. It can be concluded that SOM, Ca, and P concentrations in soil negatively affected Pb availability and uptake by Cenchrus ciliaris. Also, based on the highest TF value, Cenchrus ciliaris could be used as a hyperaccumulator in Pb-contaminated soils.