Table 4.
Geometric mean ratios of Mn fractions to Mn (sum) stratified by particle size for three heavy equipment plants.
| Plant | Parameter | Total particulate | Respirable particulate | Both total and respirable particulate | |||
|---|---|---|---|---|---|---|---|
| n (n < LOD) | GM (GSD) | n (n < LOD) | GM (GSD) | n (n < LOD) | GM (GSD) | ||
| A | Sol Mn:Mn(sum) | 37 (0) | 0.04 (1.9) | 9 (0) | 0.02 (2.8) | 46 (0) | 0.03 (2.3) |
| Mn(0,2+):Mn(sum) | 37 (0) | 0.43 (1.2) | 9 (0) | 0.37 (1.1) | 46 (0) | 0.42 (1.2) | |
| Mn(3+,4+):Mn(sum) | 37 (0) | 0.39 (1.2) | 9 (0) | 0.44 (1.1) | 46 (0) | 0.40 (1.2) | |
| Insol Mn:Mn(sum) | 33 (4)a | 0.09 (2.4) | 9 (0) | 0.15 (1.3) | 42 (4)a | 0.10 (2.3) | |
| B | Sol Mn:Mn(sum) | 23 (0) | 0.05 (1.3) | 10 (0) | 0.03 (1.3) | 33 (0) | 0.04 (1.5) |
| Mn(0,2+):Mn(sum) | 23 (0) | 0.35 (1.2) | 10 (0) | 0.34 (1.2) | 33 (0) | 0.35 (1.2) | |
| Mn(3+,4+):Mn(sum) | 23 (0) | 0.43 (1.2) | 10 (0) | 0.43 (1.2) | 33 (0) | 0.43 (1.2) | |
| Insol Mn:Mn(sum) | 23 (0) | 0.15 (1.4) | 10 (0) | 0.17 (1.5) | 33 (0) | 0.16 (1.4) | |
| C | Sol Mn:Mn(sum) | 20 (0) | 0.08 (1.4) | 10 (0) | 0.05 (1.2) | 30 (0) | 0.07 (1.4) |
| Mn(0,2+):Mn(sum) | 20 (0) | 0.37 (1.2) | 10 (0) | 0.34 (1.1) | 30 (0) | 0.36 (1.2) | |
| Mn(3+,4+):Mn(sum) | 20 (0) | 0.39 (1.2) | 10 (0) | 0.32 (1.2) | 30 (0) | 0.36 (1.2) | |
| Insol Mn:Mn(sum) | 19 (1)a | 0.14 (1.4) | 10 (0) | 0.28 (1.3) | 29 (1)a | 0.18 (1.6) | |
Sol Mn, manganese concentration dissolved in first sequential extraction solution: 0.01 molar ammonium acetate, room temperature (over 90 min); Mn 0, 2+, manganese concentration dissolved in second solution: 25% acetic acid, 75°C (over 90 min); Mn 3+, 4+, manganese concentration dissolved in third solution: 0.5% hydroxylamine-hydrochloride in 25% acetic acid, 75°C (over 90 min); Insol Mn, manganese concentration dissolved in fourth solutions: hydrochloric acid, 95°C (over 15 min) and nitric acid, 95°C (over 15 min); Sum Mn, addition of all four previous extraction manganese concentrations.
aSome samples were below the limit of detection (lod); minimum detectable concentration (MDC) were calculated and these were applied as censored data to calculate GM (GSD) using maximum likelihood method.