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Urban storm runoff effects on exchangeable cations and percolating water constituents below recharge basins

Soil science 1989 v.148 no.1 pp. 39-45
groundwater recharge, alluvium, exchangeable cations, water quality, residential areas, soil water, soil profiles, runoff, California
Inorganic contaminants are present in storm-water runoff from urban residential areas. The disposition of the major cations and anions in the alluvium deposits of a recharge basin, percolating water, and the mound of soil water below the basin were investigated relative to a nearby control site. This investigation was a component of the USEPAʼs Nationwide Urban Runoff Program in Fresno, California.The study basin has received urban storm-water runoff from a residential area for 16 yr. The recharge effects to a depth of 21 m have been an increase in exchangeable Ca and K, a decrease in exchangeable Mg, and a minor increase in the exchangeable Na with depth. The specific electrical conductance of the percolating water increased from an input value of 0.056 dS m to 0.097 dS m at a depth of 20.7 m where the recharge mound had formed.The concentrations of the major dissolved cations and anions in the urban residential storm-water runoff are low. The results indicate that these ions are not detrimental to the physicochemical properties of the surface soils or deep alluvium strata or to the groundwater quality resulting from recharging urban residential storm-water runoff.These results are important to the continued conservation of urban storm water and the preservation of the chemical and physical properties of the retention/recharge basin surface soils and deep alluvium stratum essential for continuing efficient basin recharge.