**3.1. Southern soil regions (SSR)**

**Soil As and other element extraction and analysis by ICP-MS**

Minitab v. 15 was used for all statistical analyses.

854 Environmental Risk Assessment of Soil Contamination

trace elements analysed are presented in Table 1.

agricultural soils. (CRM = NCS ZC 73007).

reagents used.

**3. Results**

material.

Since the analysis by hydride generation of all Asconcentrations were below the LOD, As and

The analytical procedures used ICP-MS to extract As and other elements extraction from the soil are identical to those outlined in section 3.2.4 (Soil As extraction), as are the aristar grade

The certified reference material (CRM) as well as the LOD and spike recoveries for each of the

CRM (%) n=4 87 ±0.1 66 ±1.7 87 ±1.3 103 ±0.2 101 ± 0.01 90 ±1.2 88 ±5.1 Spike (%) n=4 97 ±0.7 96 ±7.4 112 ± 3.1 123 ±2.5 81 ±0.1 97 ±1.2 104 ± 5.4 LOD (mg/kg) 0.01 0.30 0.20 0.01 0.01 0.03 0.14

**Table 1.** Quality control measurements for analysis of Co, Zn, Cu, As, Cd, Pb and Mn concentration in Libyan

It should be noted that the concentration of Cd in all samples was below the LOD. The descriptive statistics for trace element concentrations in agricultural soil investigated in this study. They are provided for each region, with a summary of the As levels and other trace element concentrations in soils sampled from ESR, WSR and SSR. A one-way analysis of variance (ANOVA) showed that the differences in As levels between location means are highly significant (*P*<0.001,). ESR recorded the highest mean As the level in Libyan soil (8.10 ± 0.48 mg/kg), followed by WSR (1.97± 0.41mg/kg) and SSR (1.70 ± 0.58 mg/kg), i.e. As mean concentrations in ESR are nearly 4.8 and 4.1 times higher than in SSR and WSR, respectively. Conversely, the average As levels from the three regions were below 10 mg/g dry weight (dwt). The concentration of As in the agricultural soil, therefore, ranged from 0.01–18.94 mg/kg in ESR, 1.19–2.48 mg/kg in WSR and 0.73–2.92 mg/kg in SSR.The underlying rock structure in ESR is composed of Lower Palaeozoic rocks. The clay agricultural soils of ESR recorded the highest mean As the level in Libyan soil (8.10 mg/kg); this may have some relation to the parent

**Co Zn Cu As Cd Pb Mn**

other elements (Cd, Pb, Ni, Cu, P, Zn, Cu, Co and Mn) were analysed with ICP-MS.

In SSR, the sites used for sampling were ARL, JAF and TAS (sites are shown in Fig.1). The mean As levels in sites in SSR decreased from TAS > JAF >ARL. In general, As levels were low in SSR, ranging from 1–2.9 mg/g, 0.7–1.8 mg/g and 1.1–1.7 mg/g for the TAS, JAF and ARL sites, respectively.
