Water pollution: BOD, COD, eutrophication
Environmental Chemistry · Chemistry
Study notes
A river's BOD is 30 ppm upstream, 5 ppm downstream of a town's outfall. Interpret. Step 1: High BOD upstream (30) = organic pollution entering. Step 2: Wait — downstream LOWER? Self-purification: microbes consumed organics, re-aeration restored O₂. Step 3: Actually check: outfall usually RAISES BOD downstream. Recheck sampling! Step 4: BOD tracks pollution load — but hydrology complicates. Measure carefully!