Water, pollution and management trade-offs
| English | 中文 | Pinyin |
|---|---|---|
| eutrophication/ˌjuːtrəfɪˈkeɪʃn/ | 富营养化 | fù yíng yǎng huà |
| pollutant load/pəˈluːtənt ləʊd/ | 污染负荷 | wū rǎn fù hè |
What would explain this observation?
- A downstream sample has less dissolved oxygen after a nutrient input. The explanation must connect biological processes with the water-system evidence.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- Eutrophication 富营养化 can begin with nutrient enrichment, followed by greater producer growth and increased decomposition after organisms die. Decomposer respiration can lower dissolved oxygen. Water availability depends on quantity, quality and access.
- eutrophication: Nutrient enrichment with ecological consequences; pollutant load 污染负荷: Mass of pollutant transferred per time.
Which can occur after dilution without pollutant removal?
Distinguish concentration from total pollutant load. Dilution can reduce concentration without removing the pollutant mass. A management plan should consider upstream causes, users and effects on other parts of the catchment.
Match each technical term to its precise meaning.
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Distinguish concentration from total pollutant load. Dilution can reduce concentration without removing the pollutant mass. A management plan should consider upstream causes, users and effects on other parts of the catchment.
- Collect approved water-quality observations at matched sites and times. Use calibrated instruments and consistent sampling depth. Avoid contact with contaminated water and do not infer potability from clarity.
Which two habits make the investigation or model in this case more defensible?
Collect approved water-quality observations at matched sites and times. Use calibrated instruments and consistent sampling depth. Avoid contact with contaminated water and do not infer potability from clarity.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: concentration is 2 mg per litre and flow is 500 litres per minute. Load = concentration × flow = 2×500 = 1,000 mg per minute = 1 g per minute. A lower concentration during high flow can still produce a high total load.
Concentration is 3 mg/L and flow 200 L/min. Find load in mg/min. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
Concentration is 3 mg/L and flow 200 L/min. Find load in mg/min.
The result is 600 mg/min. Known: concentration is 2 mg per litre and flow is 500 litres per minute. Load = concentration × flow = 2×500 = 1,000 mg per minute = 1 g per minute. A lower concentration during high flow can still produce a high total load.
Check the conclusion and its limits
- Clear water is not necessarily safe water. Nutrient enrichment does not directly use up oxygen; the pathway includes biological activity and decomposition.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
Clear water is always safe to drink. This claim is false: Clear water is not necessarily safe water. Nutrient enrichment does not directly use up oxygen; the pathway includes biological activity and decomposition.
Water, pollution and management trade-offs: Distinguish concentration from total pollutant load. Dilution can reduce concentration without removing the pollutant mass. A management plan should consider upstream causes, users and effects on other parts of the catchment.
Clear water is always safe to drink.
Clear water is not necessarily safe water. Nutrient enrichment does not directly use up oxygen; the pathway includes biological activity and decomposition.
Nutrient enrichment with ecological consequences: write the technical term.
eutrophication means Nutrient enrichment with ecological consequences.