PubMed · 2026-06-17
Soils at the edges of a heavily polluted Chinese lake hold massive stores of phosphorus that heavy rainstorms can flush into the water, worsening the algae blooms that choke the lake. Two specific soil depth zones act as 'leaky layers' that rapidly release phosphorus during storms, undermining restoration efforts.
All soil layers contained extremely high total phosphorus (1.19–2.21 g per kg of soil), but the 0–10 cm and 30–40 cm layers released phosphorus the fastest and in the greatest amounts during simulated storms.
During leaching tests, phosphorus in the water leaving the soil exceeded the phosphorus in the water entering it — meaning storms mobilize both incoming runoff and phosphorus already stored in the soil.
The deepest layer tested (50–60 cm) initially absorbed phosphorus well, but released iron-bound phosphorus under prolonged waterlogged, low-oxygen conditions, indicating it provides only short-term buffering.