Figures (7)  Tables (7)

    • Figure 1. 

      Map of the study area showing (a) Nigeria, (b) Sokoto State, and (c) sampling points (drawn using ArcGIS 10.3 software).

    • Figure 2. 

      Map showing wind direction during the study period. (a) Nigeria, (b) Sokoto State, and (c) sampling points (drawn using ArcGIS 10.3 software).

    • Figure 3. 

      Microplastic shapes identified in the water samples showing (a) fiber and pellet, (b) fiber and foam, (c) microbead and microfilm and (d) fiber.

    • Figure 4. 

      Distribution (%) of microplastic size in the water samples.

    • Figure 5. 

      Distribution (%) of microplastic colors in the water samples.

    • Figure 6. 

      Representative ATR-FTIR spectra of microplastics from each sampling axis.

    • Figure 7. 

      Distribution (%) of polymer types in the water samples.

    • Location GPS coordinate Concentration (items/L)
      North N 13°0842, E 5°24′3289 460 ± 20
      South N 13°0652, E 5°23′7822 200 ± 20
      East N 13°0342, E 5°10′1549 180 ± 10
      West N 13°0721, E 5°22′3259 150 ± 10
      Values are presented as mean ± SD (n = 9).

      Table 1. 

      Concentrations of microplastics in water samples

    • Source SS df MS F p-value η2
      Between groups
      (sampling axes)      		 553,275.0 3 184,425.0 737.7 1.33 × 10−29 0.986
      Within groups (error) 8,000.0 32 250.0
      Total 561,275.0 35
      One-way ANOVA testing spatial differences in microplastic concentration (items/L) among sampling axes (north n = 9, south n = 9, east n = 9, west n = 9). F (3,32) = 737.7, p < 0.001, η2 = 0.986 indicates 98.6% of variance explained by location. Tukey HSD post hoc: north significantly higher than all others (p < 0.001); no differences among south/east/west (p > 0.05).

      Table 2. 

      Spatial distribution of microplastics around the axes of the cement plant

    • Location GPS coordinate Concentration (items/L)
      Cement plant N 13°0618, E 5°17'1114 510 ± 110
      2 km north of cement plant N 13°0798, E 5°17'1114 110 ± 20
      2 km south of cement plant N 13°0876°, E 5°23'3411 90 ± 10

      Table 3. 

      Concentrations of microplastics in water around the Sokoto cement plant compared with cement-free environments

    • Microplastic shape North South East West
      Fiber 100 42 35 23
      Microfilm 0 33 20 8
      Microbead 0 10 25 38
      Foam 0 10 10 21
      Pellet 0 5 10 10
      Total (%) 100 100 100 100

      Table 4. 

      Distribution of microplastic shapes in the water samples

    • Sample Absorbance
      peak (cm−1)      		 Functional group Polymer type[3]
      South 2,915–2,848 C–H stretching
      (aliphatic hydrocarbons)      		 PE, PP
      1,630–1,680 Amide I and II bands NY
      1,715–1,730 C=O stretching
      (ester group)      		 PET
      600–700 C–Cl stretching PVC
      West 2,915, 2,848 C–H stretching PE
      989.6, 907.6 C–H bending/rocking PE
      793.9, 743.6 C–Cl stretching PVC
      1,715–1,730 C=O stretching (ester) PET
      North 2,915–2,848 C–H stretching PE
      1,715–1,730 C=O stretching
      (ester group)      		 PET
      993.3, 903.9 C–H bending PVC
      782.7, 743.6 C–Cl stretching PVC
      East 2,915-2,848 C–H stretching PE
      1,728.6 C=O stretching
      (ester group)      		 PET
      989.1, 908.3 C–H bending, C–Cl stretching PVC
      1,450–1,375 CH3 bending PP
      PP = Polypropylene, PE = Polyethylene, PVC = Polyvinyl Chloride, PET = Polyethylene Terephthalate, NY = Nylon.

      Table 5. 

      Absorbance peaks, functional groups, and polymers identified in the water samples

    • Location PE (%) PET (%) PVC
      (%)      		 PP
      (%)      		 NY
      (%)      		 Total PRI Risk level
      North 40.0 33.3 26.7 0.0 0.0 1507.7 IV (> 1,000)
      South 30.0 17.7 16.7 20.0 15.6 1738.5 IV (> 1,000)
      East 33.3 23.3 26.7 16.7 0.0 1410.7 IV (> 1,000)
      West 43.3 30.0 26.7 0.0 0.0 1530.8 IV (> 1,000)
      Risk level IV indicates very high risk. The PRI indicates relative polymer hazard potential and does not represent a quantitative drinking water exposure risk assessment.

      Table 6. 

      Risk index of polymers in the water samples

    • Location PLI
      North 3.07
      South 1.33
      East 1.20
      West 1.00
      PLI zone 1.54
      Pollution load index greater than 1 signifies water pollution.

      Table 7. 

      Pollution load index (PLI) of the water samples