Table 1.
Most relevant physicochemical parameters of the water of the ponds, the microbial biofilms, and waters of Río Agrio analysed. A brief explanation of the abbreviated names of the points at Río Agrio is given at the bottom of the table. ND: not detected; -: not measured.
| Sampling Point | Abbreviation | T (°C) a | pH a | Conductivity (μS cm−1) a | SO42− (mg/L) b | Cl− (mg/L) c | Fe (mg/L) d |
|---|---|---|---|---|---|---|---|
| Water samples | |||||||
| Las Máquinas | LMa | 36.0 | 3.2 | 663 | 119.5 | 5.30 | 7.0 |
| Laguna Verde Este | LVE | 31.5 | 3.0 | 1317 | 35.7 | 3.3 | |
| Baño 9 | B9 | 40.5 | 2.7 | 3720 | 2.10 | 7.0 | |
| Laguna Sulforosa | LS | 54.3 | 3.0 | 1133 | 291.8 | 56.7 | 3.7 |
| Las Maquinitas | LMi | 87.0 | 2.0 | 4520 | 346.8 | 1.80 | 32.8 |
| Biofilm samples | |||||||
| Las Máquinas | LMa biof | 36.0 | 4.8 | - | ND | ND | ND |
| Laguna Verde Este | LVE biof | 30.0 | 4.8 | - | ND | ND- | ND |
| Baño 9 | B9 biof | 30.0 | 2.7 | - | ND | ND | 2.4 |
| Las Maquinitas | LMi biof | 35.0 | 3.5 | - | ND | ND | 0.4 |
| Rio Agrio | |||||||
| Vertiente Río Agrio | VA2 1 | 29.0 | 1.0 | 15,450 | 6226.1 | 6780.2 | 560 |
| Unión dos Vertientes | U2V 2 | 9.0 | 1.5 | 10,690 | 2467.1 | 3567.3 | 470 |
| Río Agrio Superior | AS3 3 | 6.7 | 1.7 | 11,690 | 3274.3 | 4.7 | 111 |
| Cavellera de la Virgen | CV 4 | 15.9 | 2.0 | 3290 | 875.4 | 586.7 | 30 |
| Caviahue Lake | CL 5 | 8.3 | 2.0 | 946 | 266.0 | 48.2 | 7 |
| Salto del Agrio | SA 6 | 16.9 | 3.6 | 516 | 1481.6 | 30.4 | 3 |
a: Temperature, pH and conductivity were measured in situ with a Hanna HI 8424 NEW portable instrument accurately calibrated against calibration standards; b: The concentration of sulphate was determined by a turbidimetric method using an excess of barium chloride; c: The concentration of chloride was determined by titration with mercuric nitrate solution in the presence of diphenylcarbazone bromophenol blue indicator; d: Soluble Fe determined on filtered water samples by atomic absorption spectrophotometry using a Shimadzu AA-6650 spectrophotometer; 1: VA2: one of the two acidic thermal springs that are considered the origin of Río Agrio; 2: U2V: the point where the two original streams meet and form Upper Río Agrio (URA); 3: AS3: a point in the middle part of URA in the area of the snowmelt tributary streams; 4: CV: a point in the last part of URA in the area of the waterfalls before it discharges in Caviahue Lake; 5: Caviahue Lake; 6: SA: the big waterfall found in Lower Río Agrio.