Spatial contamination and health risks of heavy metal(loid)s

Overview

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Key numbers

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• Merck (Darmstadt, Germany). The purity of the plasma torch argon was greater than 99.99 %.
• All laboratory glassware was soaked in a 10 % (v/v) HNO3 solution bath for 24 h and was
• 2, Zn = 1), C0i is the concentration of each metal, and Cni is the corresponding background
• Table 1: Reference dose (RfD) of MTE used for the calculation of the Average Daily Doses (ADD)
• years), ABS is the absorption fraction (0.1, assuming that 10% of MTE in the soil contacting
• Arzew and surroundings are summarized in Table 2, together with soil background values
• Total As concentrations of 95% of the samples were under 20.0 mg kg-1, the median value
• indicate that more of 95% samples soils presented a geochemical threshold value below 20
• areas (mean: 15.63 mg kg-1; max: 48.06 mg kg-1) and exceed the French regulatory limit (37
• Table 2 : Summary of MTE concentrations (mg kg-1) together with basic statistical parameters as spread among functionnal areas studied
• Industrial zone (N=14) Min - Max 4.92 - 19.4 3.77 - 12.98 11.33 - 193.36 10.31 - 40.53 6.38 - 50.74 30.15 - 56.98 70.41 - 285.7
• Agricultural zone (N=17) Min - Max 4.92 - 19.4 3.9 - 12.98 12.09 -93.2 10.31 - 63.31 8.41 - 46.99 30.15 - 83.64 41.23 - 99.27
• agreement with pedogeochemical background values. 100% of the samples are below the
• French regulatory limit concerning Co (30 mg kg-1). Mean Co levels are 10.13 mg kg-1 (min:
• 3.43; max: 21.83) and relatively close to the BG1 and BG2 levels (Table 1), with at least an
• Total Cr concentrations have a median of 60 mg kg-1 with a high range (14.42 - 193 mg kg-1).
• (S4, Table 1 and Figure 3). However, the whole sampling sites (except the agricultural area)
• present a relatively high level of Cr, with 90% of samples having Cr at more than 80 mg kg-1,
• (eco)toxicological PNEC values derived by the European REACH regulation (Table 1).
• Total Cu concentrations have a mean of 25.91 mg kg-1 and a median of 20.77 mg kg-1.
• areas, with levels higher than 60 mg kg-1 (max: 63.31 in S5; max: 223.7 in S6) (Table 1 and
• S1). Total Ni concentrations have a median of 28.54 mg kg-1 and a mean of 26.94 mg kg-1
• kg-1) and 50% are below the PNEC value (65 mg kg-1). The highest concentrations are found
• Total Pb concentrations have a median of 52.11 mg kg-1 with a high range (13.27-220.5 mg
• are found in S6, area representing the road zone, with 50% of samples (N=27) exceeding 100
• of lead in soils (Turner and Lewis 2018). Moreover, in Algeria 89% of the gasoline
• this metal (Table 2). Their median and mean concentrations are 83.34 and 93.27 mg kg-1,
• 0.01) are presented in Table 3. Co demonstrates a significant positive relationship with Cr
• significant at p < 0.01, confirming that MTE concentrations were suitable for PCA. According
• considered and explain 75.551% of the total variance (Table 4)
• Table 4: Total variance of explained and component matrices
• The first principal component (PC1) explains 29.6% of the total variance. It includes
• values of 0.602 and 0.689, respectively), explaining 16.1% of the total variance. Their
• PC3 accounts for 15.1% of the total variance and is dominated mainly by As (0.758), with a
• low contribution of Cu (0.540), Cu being mainly associated to PC4 (0.644). Mean
• However, we observe that the highest mean is found in the industrial area (S4), whereas the
• Cu and Pb are linked together in PC4 (14.8%) with respective loadings value of 0.644 and
• under study. In all the areas studied, the mean Igeo are found between 0 and 1.00 for As, Co,
• Also noteworthy is the fact that Igeo value for Cr exceed 1.0 in 71.6% of the whole samples,
• 46% from S4, and 37.5% from S1. The same observation can be made with respect to Pb with
• the finding of the 1.00 value is exceeded in 100% of the samples issued from S6, and where
• (Figure 5), except in S6 (road zone), where 7 samples (26%) exceed the value of 40 whose 2

Methods (brief)

• analysis of 84 soils sampled in the region of Arzew (Algeria). This city gathers one of the
• 2.2 Sample collection
• A sum of 84 topsoil samples (0-20 cm) were collected from six functional sections around the
• working and/or living in this area. 9 samples were collected from coastal area (S1, beach
• zone), 13 collected from port area (S2, harbour zone with private recreational vessels and
• surrounded by several residential quarters), 4 collected from downtown Aïn El Bia (S3), 14
• collected from the industrial area (S4, sample points scattered around the petrochemical
• platform), 17 collected from the agricultural area adjacent to the industrial site (S5), and 27
• N13 to the West and North (Figure 2b). Another two unaffected soil samples (BG1 and BG2)
• were also collected from an area 15 km away from the petrochemical platform area
• study area, recorded with a GPS and, collected in clean polythene bags to avoid
• 2.3 Sample preparation and analysis
• Soil samples were sieved to 2 mm mesh, air-dried at room temperature and then ground
• analyses. The acid digestion of the sampled soils (0.5 g) was carried out in a microwave
• Germany) were used for sample mineralization. This microwave digestion system was
• After digestion and cooling, the mineralized products were filtered with a 0.45-μm mesh and
• by Inductively coupled Plasma-Atomic Emission Spectroscopy (ICP-AES, Jobin Yvon
• The emission lines for the analysis by ICP-AES were (nm): As (193.696), Cd (214.438), Co

Implications

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Wiki pages this source may touch

• Root-Vegetable Purees
• Baby Wipes
• Cadmium
• Lead
• Arsenic
• Nickel
• Tin
• Chromium

Verification notes

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Update history

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