Assessing the Risk of Internal Loading of Phosphorus from Drinking Reservoir Sediments

The natural process of lake and reservoir eutrophication through nutrient accumulation within sediments has been accelerated through anthropogenic sources of nitrogen and, especially, phosphorus (P). Stored nutrients can result in significant internal loading (during periods of low sediment redox potential or elevated pH) which may drive poor water quality despite best practice in catchment management. Internal P loading can promote proliferation of cyanobacterial and algal taxa responsible for Harmful Algal Blooms (HABs) as well as Taste and Odour (T&O) and cyanotoxin events. Here, we investigate the sediment and water column P content of eight reservoirs, by analysing iron-bound (Fe-P), calcium-bound (Ca-P) and labile P fractions.