685.5 mg/L = 685.5 ppm
| mg/L | ppm |
|---|---|
| 670.5 mg/L | 670.5 |
| 675.5 mg/L | 675.5 |
| 680.5 mg/L | 680.5 |
| 685.5 | 685.5 |
| 690.5 mg/L | 690.5 |
| 695.5 mg/L | 695.5 |
| 700.5 mg/L | 700.5 |
685.5 mg/L = 685.5 ppm
1 ppm = 1 mg/L (aqueous, density ≈ 1 kg/L) · 1 ppb = 0.001 mg/L · 1% = 10,000 ppm