EVPP 108 Lecture Notes - Lecture 6: Magic 2Ch, Lead, Aquifer
23 Aug 2016
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Document Summary
The productivity of an ecosystem reflects the rate at which its producers photosynthesise. As time passes, nearby mountains or hillsides erode and sediments are washed: these sediments carry nutrients which fertilise the system. In a natural system many 1000s of years may elapse before an oligotrophic water becomes eutrophic. When this slow process is sped up by human activities it is called cultural eutrophication. How do phosphates limit fresh water productivity: when p is added as a single dose, the productivity increase is short lived. Because p is continuously removed from the system by deposition in to bottom as sediments. If p is added continuously (sewage, fertilise run-off, detergent), the productivity of a lake will remain high. The amount of oxygen that will be consumed when a biodegradable substance is decomposed in a aquatic system. When sewage is discharged into fresh water stream, the stream becomes polluted. Oxygen does not deplete, but there is a chance for it.
