Table 2 Total IN concentration and decreased proportion of IN of solutions (crude and filtrate rainwater) under heat treatment at −6 °C, −8 °C, and −10 °C.
Sample | Onset freezing temperature (°C) | Onset freezing temperature after heat treatment (°C) | Decrease of onset freezing temperature by heat treatment (°C) | IN mL−1 [total (% heat-sensitive)] | ||
|---|---|---|---|---|---|---|
Temperature (°C) | ||||||
−6 | −8 | −10 | ||||
Crude rainwater | ||||||
2013-05 | −3.6 | −4.6 | 1.0 | 32 (26) | 143 (28) | 237 (16) |
2013-06 | −4.2 | −4.4 | 0.2 | 13 (62) | 85 (78) | 190 (54) |
2013-07 | −3.6 | −4.4 | 0.8 | 26 (24) | 109 (22) | 184 (9) |
2013-08 | −2.8 | −3.8 | 1.0 | 52 (41) | 155 (39) | 252 (28) |
Filtrate | ||||||
2013-05 | −3.8 | −4.4 | 0.6 | 21 (17) | 96 (17) | 206 (13) |
2013-06 | −4.8 | −5.6 | 0.8 | 0 (0) | 13 (39) | 65 (18) |
2013-07 | −4.4 | −4.6 | 0.2 | 21 (19) | 101 (32) | 180 (7) |
2013-08 | −3.4 | −4.0 | 0.6 | 51 (61) | 127 (35) | 222 (16) |
