Table 2.
Mean yield (± standard error) of nitrate–N and lag times (years) calculated using cross-correlation (using pre-whitened data) and cumulative generalised additive models (GAMs) and the resulting mean lag time after filtering out sites that were either impacted by hydroelectric schemes or were recently disturbed causing uncharacteristically high sediment loads, or under minimally disturbed conditions (MDC), i.e. > 90% native forest, mountains or scrub.
| Code | Mean yield (kg N ha−1 yr−1) | Lag time | Mean transit time | References | ||
|---|---|---|---|---|---|---|
| Cross correlation | Cumulative GAM | Filtered mean | ||||
| AK1 | 18.4 ± 1 | (1.5) | (9) | Impacted | – | |
| AK2 | 7 ± 0.4 | 1.0 | 3.5 | 2.3 | – | |
| AX1 | 0.9 ± 0.1 | (5.7) | (4.5) | MDC | – | |
| AX2 | 0.8 ± 0.1 | – | (9.5) | MDC | – | |
| AX3 | 0.4 ± 0.1 | (3.0) | – | MDC | – | |
| AX4 | 1.4 ± 0.1 | – | – | – | – | |
| CH1 | 0.9 ± 0.1 | (5.8) | – | MDC | – | |
| CH2 | 5.6 ± 0.2 | 3.5 | 5 | 4.3 | – | |
| CH3 | 1.2 ± 0.1 | – | – | MDC | – | |
| CH4 | 3.9 ± 0.3 | – | 4 | 4.0 | 3.7 | 31 |
| DN1 | 3.3 ± 0.1 | 1.0 | 5.5 | 3.3 | – | |
| DN10 | – | – | – | MDC | < 1 | |
| DN2 | 2.9 ± 0.1 | 5.0 | 7.5 | 6.3 | – | |
| DN3 | 3.5 ± 0.1 | – | – | – | – | |
| DN4 | 2.7 ± 0.1 | (5.7) | – | Impacted | – | |
| DN5 | 6.3 ± 0.1 | 1.0 | 3 | 2.0 | – | |
| DN6 | 2.5 ± 0.1 | – | – | – | < 0.5 | 82 |
| DN7 | 3.2 ± 0.1 | – | 5.5 | 5.5 | < 0.5 | 82 |
| DN8 | 7.2 ± 0.3 | – | 4 | 4.0 | 1–2 | 83 |
| DN9 | 1.7 ± 0.1 | 3.0 | – | – | < 1 | 83 |
| GS1 | 7.5 ± 0.2 | 6.0 | – | 6.0 | – | |
| GS2 | 9.7 ± 0.2 | (1.5) | (9.5) | Impacted | – | |
| GS3 | 9.9 ± 0.2 | – | – | – | – | |
| GS4 | 4.2 ± 0.1 | – | – | – | – | |
| GY1 | 3.1 ± 0.1 | (6.0) | – | Impacted | – | |
| GY2 | 6.3 ± 0.2 | – | 4.5 | 4.5 | – | |
| GY3 | 0.6 ± 0.1 | (3.5) | – | MDC | – | |
| GY4 | – | – | – | MDC | – | |
| HM1 | 15.4 ± 0.4 | – | – | MDC | – | |
| HM2 | 29.7 ± 0.3 | – | 4.5 | 4.5 | – | |
| HM3 | 17.2 ± 0.2 | 1.5 | 3.5 | 2.5 | – | |
| HM4 | 21.1 ± 0.2 | – | 7 | 7.0 | – | |
| HM5 | 27 ± 0.5 | – | 7.5 | 7.5 | – | |
| HM6 | 22.4 ± 0.4 | – | – | – | – | |
| HV1 | 2.2 ± 0.1 | 12.3 | 6.5 | 9.4 | – | |
| HV2 | 11.2 ± 0.2 | – | – | – | 4–6 | 84 |
| HV3 | 6.5 ± 0.1 | 12.0 | – | 12.0 | 4–6 | 84 |
| HV4 | 1.0 ± 0.1 | (4.7) | – | MDC | 0.5–2 | 84 |
| HV5 | 3.1 ± 0.1 | – | – | – | – | |
| HV6 | 3.6 ± 0.1 | – | – | – | – | |
| NN1 | 2.5 ± 0.1 | – | – | – | – | |
| NN2 | – | – | – | MDC | – | |
| NN3 | 0.4 ± 0.1 | (2.5) | – | MDC | – | |
| NN4 | 2.2 ± 0.1 | 1.5 | 4 | 2.8 | – | |
| NN5 | 2.1 ± 0.1 | – | – | MDC | – | |
| RO1 | 2.3 ± 0.1 | – | 3 | 3.0 | – | |
| RO2 | 5.5 ± 0.1 | 1.0 | – | 1.0 | – | |
| RO3 | 6.6 ± 0.2 | – | – | – | – | |
| RO4 | 1.1 ± 0.1 | – | (6.5) | MDC | – | |
| RO5 | 6.6 ± 0.1 | – | – | – | – | |
| RO6 | 3.4 ± 0.1 | 3.5 | 6.5 | 5.0 | – | |
| TK1 | 7 ± 0.2 | 6.5 | 7.5 | 7.0 | – | |
| TK2 | 7.9 ± 0.2 | 0.5 | 3 | 1.8 | – | |
| TK3 | 3.5 ± 0.1 | 1.5 | 6.5 | 4.0 | – | |
| TK4 | 1.1 ± 0.1 | – | (4) | MDC | – | |
| TK5 | 15.1 ± 0.4 | – | – | – | – | |
| TK6 | 2 ± 0.1 | 5.6 | – | 5.6 | – | |
| TU1 | 6.6 ± 0.1 | (1.0) | – | Impacted | – | |
| TU2 | 1.4 ± 0.1 | – | – | MDC | – | |
| WA1 | 17.2 ± 0.2 | – | – | – | – | |
| WA2 | 18.8 ± 0.2 | – | 7.5 | 7.5 | – | |
| WA3 | 49.7 ± 0.5 | – | 4.5 | 4.5 | – | |
| WA4 | 6.1 ± 0.1 | – | 6 | 6.0 | 6–10 | 85 |
| WA5 | 7.3 ± 0.2 | – | 8 | 8.0 | 3–6 | 85 |
| WA6 | 9.2 ± 0.2 | – | 6.5 | 6.5 | 3–6 | 85 |
| WA7 | 13.7 ± 0.1 | – | 9.5 | 9.5 | 9–11 | 85 |
| WA8 | 13.6 ± 0.1 | – | – | – | 0.5–5 | 85 |
| WA9 | 14 ± 0.1 | – | – | – | 0.5–5 | 85 |
| WH1 | 0.6 ± 0.1 | – | (5.5) | MDC | – | |
| WH2 | 16.9 ± 0.3 | – | – | – | – | |
| WH3 | 8 ± 0.1 | – | 2.5 | 2.5 | – | |
| WH4 | 17.2 ± 0.2 | – | 3.5 | 3.5 | – | |
| WN1 | 2.1 ± 0.1 | – | – | – | – | |
| WN2 | – | – | – | MDC | – | |
| WN3 | 9.8 ± 0.2 | – | – | – | – | |
| WN4 | 10.2 ± 0.2 | – | 5.5 | 5.5 | – | |
| WN5 | 0.6 ± 0.1 | – | – | MDC | – | |
The mean hydrological transit time for baseflow is also given for reference. Lag times in parentheses were for sites that were either impacted or under MDC and excluded from further analysis.
1A lag time either could not be calculated or no data exists.