Table 4.
Chemical health status of three zones of Lake Soyang based on modified water pollution index (WPI) during 1992–2013.
| Category | Model Metrics (M) | Scoring Criteria | Mean ± Standard Deviation Scores | ||||
|---|---|---|---|---|---|---|---|
| 5 | 3 | 1 | Rz | Tz | Lz | ||
| Nutrient Regime | M1: Total Nitrogen (mg/L) | <1.5 | 1.5–3.0 | >3 | 1.81 ± 0.47 (3) |
1.74 ± 0.44 (3) |
1.50 ± 0.29 (5) |
| M2: Total Phosphorus (µg/L) | <30 | 30–100 | >100 | 20.7 ± 16.7 (5) |
19.8 ± 23.2 (5) |
16.5 ± 23.1 (5) |
|
| M3: TN:TP ratio | >50 | 20–50 | <20 | 120.4 ± 74.6 (5) |
129.4 ± 80.6 (5) |
158.4 ± 110.3 (5) |
|
| Organic Matter | M4: Biological Oxygen Demand (mg/L) | <1 | 1–2.5 | >2.5 | 1.27 ± 0.32 (3) |
1.19 ± 0.27 (3) |
1.04 ± 0.3 (3) |
| Ionic Contents and Solids | M5: Total Suspended Solid (mg/L) | <4 | 4–10 | >10 | 7.38 ± 18.9 (3) |
6.16 ± 16.2 (3) |
4.58 ± 13.7 (3) |
| M6: Electrical Conductivity (µS/cm) | <180 | 180–300 | >300 | 70.88 ± 16.25 (5) | 70.16 ± 14.75 (5) | 68.37 ± 23.84 (5) |
|
| Primary Production Indicator | M7: Sestonic Chlorophyll (µg/L) | <3 | 3–10 | >10 | 4.55 ± 7.52 (3) |
4.61 ± 4.98 (3) |
2.9 ± 3.29 (5) |
| Final Scores of WPI | 27 | 27 | 31 | ||||
| Water Quality | Good | Good | Excellent | ||||
Rz = Riverine zone; Tz = Transition zone; Lz = Lacustrine zone.