Tổ chức Baccalaureate Quốc tế · IB Diploma · Environmental Systems and Societies · HL Chủ đề 4 1:14 Giọng đọc tiếng Anh · phụ đề tiếng Anh + 中文 được ghi trực tiếp
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Biên bản ghi âm
These are selected topics, not the whole syllabus, and every example is fictional.
这些是精选主题，不是完整大纲，所有例子都是虚构的。
Nutrients can starve a river of oxygen, and a load is concentration times flow.
营养物质会使河流缺氧；负荷 = 浓度 × 流量。
Why does dissolved oxygen fall downstream of a nutrient input?
为什么营养物质输入的下游溶解氧会下降？
Nutrients do not use up oxygen directly.
营养物质并不直接消耗氧气。
They feed producer growth; the producers die; decomposers break them down, and decomposer respiration uses the oxygen.
它们促进生产者生长；生产者死亡；分解者分解它们，分解者的呼吸作用消耗氧气。
Every link in the chain is a biological process.
链条上的每一环都是生物过程。
Water carries 2 milligrams per litre of a pollutant at 500 litres per minute.
水中污染物浓度 2 毫克/升，流量 500 升/分钟。
The load is concentration times flow: 1,000 milligrams, or 1 gram, every minute.
负荷 = 浓度 × 流量：每分钟 1,000 毫克，即 1 克。
In a flood the concentration may halve to 1 milligram per litre while the flow triples to 1,500: the load rises to 1,500.
洪水时浓度可能减半到 1 毫克/升，而流量增至三倍 1,500：负荷升到 1,500。
Dilution lowers concentration without removing the mass.
稀释降低浓度，但不去除污染物的质量。
Check yourself.
自我检测。
3 milligrams per litre at 200 litres per minute is a load of 600 milligrams a minute.
3 毫克/升 × 200 升/分钟 = 每分钟 600 毫克。
Clear water is not evidence of safe water; it must be tested.
清澈的水不代表安全，必须检测。