Pollution load index for heavy metals in Mian-Ab plain soil, Khuzestan, Iran

Soil pollution by heavy metals is a major concern in agricultural area. Potential impact of heavy metals in agricultural soil on human health by accumulating in food chain demonstrated elsewhere. In this regard Mian-Ab plain as a major agricultural site of Khuzestan province considered for Arsenic, cadmium and lead concentration as the main potential toxic pollutants in soil. 50 topsoil samples were collected and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Also Contamination level of selected heavy metals in Mian-Ab Plain, was assessed by single factor contaminant index (PI) and pollution load index (PLI). Results show mean concentration of arsenic, cadmium and lead were 2.52, 0.30 and 7.21 mg kg−1. Base on PLI results 12 point (24%) of the studied area show moderately polluted and 38 point (76%) show unpolluted area.


a b s t r a c t
Soil pollution by heavy metals is a major concern in agricultural area. Potential impact of heavy metals in agricultural soil on human health by accumulating in food chain demonstrated elsewhere.
In this regard Mian-Ab plain as a major agricultural site of Khuzestan province considered for Arsenic, cadmium and lead concentration as the main potential toxic pollutants in soil. 50 topsoil samples were collected and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Also Contamination level of selected heavy metals in Mian-Ab Plain, was assessed by single factor contaminant index (PI) and pollution load index (PLI

Value of the data
Arsenic, cadmium and lead are the main potentially toxic pollutants. Mian-Ab Plain is one of the most agricultural sites in Khuzestan province. Soil pollution by heavy metals is the major concern in developing countries.
1. Data Table 1 shows Descriptive statistics of selected heavy metals in Mian-Ab plain soil also Figs. 1-3 show distribution of Arsenic, cadmium and lead in Mian-Ab plain respectively. Table 2 shows single pollution indices and pollution load index of selected heavy metals. Table 1 Descriptive statistics of selected heavy metals in Mian-Ab plain soil.

Item
Ar

Sampling and analysis procedure
Mian-Ab plain has an area of 28,100 ha, and is located between 31°40′ and 32°05′ northern latitudes and 48°45′ and 49°00′ eastern longitudes, north of Khuzestan province, and south west of Iran. Mian-Ab Plain is bounded between Shotait River and Gargar River [1]. Geologically, the study area is widely characterized by quaternary unconsolidated alluvial sediment. A systematic sampling procedure was performed to provide a sampling scheme over the entire plain. Therefore, in March 2016 (dry season), 50 topsoil samples (0-20 cm) were collected using a stainless steel hand auger (Fig. 4). In each sampling point, a total of 1 7 0.5 kg of soil was taken from the mixed samples using a quartile method. The collected soil samples were stored in polyethylene bags until transport to the laboratory.
In the laboratory, all samples were air-dried at room temperature and sieved through a 2-mm sieve. Finally, the dried soil samples were sent to the MS Analytical, Canada. The soil samples were digested using the Aqua Regia, and the concentration of 3 potentially toxic elements (PTEs) including (As, Cd, Pb) was measured using inductively coupled plasma mass spectrometry (ICP-MS) [2-6].

Quality assurance (QA) and quality control (QC)
Analytical duplicates/replicates, standard reference material (OREAS 24b, and GBM908-10), and blank reagents were used for QA/QC. Recoveries ranged from 95.6% to 98.74% and the detection limits for As, Cd and Pb were 0.1, 1.88 and 0.2 respectively.

Soil pollution assessment
Contamination level of selected heavy metals in Mian-Ab Plain, was assessed by single factor contaminant index (PI) and pollution load index (PLI) using Eqs. (1) and (2) [7]. Where PI is the single factor pollution index of each metal, C n and B n is the concentration of metal in the soil sample and background, respectively (mg/Kg). PI o 1 (Non polluted); 1 r PI o 2 (Slight polluted); 2 r PI o 3 (Moderately polluted); PI o 3 (Highly polluted).
PLI is pollution load index, n is the number of pollutant assesses (i.r., 3). PI is the single factor pollution index of each metal.