Effluent-dominated streams. Part 1: Presence and effects of excess nitrogen and phosphorus in Wascana Creek, Saskatchewan, Canada
Bibliographic record
Abstract
Regina, Saskatchewan, Canada (population 190,400) treats its sewage at a modern sewage treatment plant (STP) on Wascana Creek. In the winter, treated sewage effluent makes up almost 100% of stream flow. Four surveys conducted from 2005 to 2007, in differing seasons, indicated significantly higher nitrogen (N) and phosphorus (P) concentrations at sites downstream of the STP compared to an upstream control site. Downstream, Wascana Creek is N hypersaturated (total dissolved N >3 mg/L) and soluble reactive phosphorus (SRP) makes up a greater percentage of total P (TP). Diminished nutrient retention capacities for both N and P are directly attributable to STP effluent. Creek SRP concentrations are less than estimates of equilibrium P concentrations (EPC(o)), indicating that creek sediments may be a source of P, further exacerbating hypereutrophic ambient SRP concentrations. As well, NO(2) + NO(3)-N concentrations far surpass World Health Organization limits for drinking water (10 mg/L) and sensitive taxa, while NH(3)-N, NH(4)-N, and NO(2) + NO(3)-N exceed Canadian Water Quality Guidelines for Protection of Aquatic Life and those for the U.S. Environmental Protection Agency. High NH(4)-N concentrations may be responsible for depressions not only in algal biomass and production observed downstream but reductions in primary to bacterial production ratios (PP:BP). In spring and fall, these reductions push PP:BP from net autotrophy to heterotrophy. The Wascana Creek study highlights the considerable problems associated with excess nutrients in effluent-dominated ecosystems (EDS). It also underlines the need for better controls on NH(4)-N additions from STPs in such EDS, especially in a day and age when freshwater supplies are dwindling and negative effects of climate change are expected.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.005 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".