Highway runoff and potential for removal of heavy metals in an infiltration pond in Portugal

摘要: Highway runoff from IP 4, a mountain road in the north-east of Portugal, has been monitored using system integrating raingauge, flowmeter and an automatic water sampler. Average daily traffic (ADT) is 6000 study catchment 5970 m2 total area 2500 pavement. A single stormwater outlet discharges into infiltration pond with overflow to creek. Sampling was carried out before entered pond. Among parameters analysed water, heavy metals cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb) zinc (Zn) were emphasised because their toxicity. Concentrations Cd Cr usually lower than detection limit (1 microgram/l). Copper levels found between 1 54 micrograms/l; 200 micrograms/l 50 1460 micrograms/l. first flush effect observed, meaning that 50% volume for each event typically transported 61 69% suspended solids, Zn, Cu Pb loads. Runoff totally infiltrated are being sorbed soil. Soils used ponds should have specific characteristics order perform effectively ensure groundwater protection. Not only well-known soil texture composition relevant: sorption capacity--the extension reversibility processes--is main importance this kind highway treatment. Experiments concerning soils, followed by desorption at pH values 2, 4 6 conducted laboratory. These experiments performed existing two other common types Portuguese soils. The three showed different behaviours, which must be related characteristics; seemed play significant role controlling processes. As expected, as lowering value increased rate. one lowest capacity, however, it relatively high strength means considered reliable, treatment