Implication of Particulate Copper (Cu) in the Surface Runoff Transport of Cu From Land to Water Ways.

The export of Cu in runoff water from Cu contaminated soils to surrounding water systems has stirred public concern in south Florida.  The close association of Cu with organic and inorganic colloids leads us to assume that particulate form may contribute to the runoff water transport of Cu from land to water, but minimal work has been done in this regard. Laboratory incubation and chemical characterization were conducted to examine Cu enrichment and availability in particulates as compared with bulk soils. Copper concentration in particulate matter obtained from both soil and surface runoff water was higher than that in bulk soil but the mobility and availability of Cu in particulates depended on soil pH. Particulate Cu is highly correlated with total recoverable Cu in both bulk soil and surface runoff water. A greater proportion of Cu in particulates was organic bound, especially in the surface runoff particulates, as compared with bulk soil.Chemical speciation of Cu in surface runoff water showed that organic-Cu complexes are the dominant species and increased with total Cu concentration and pH. These results indicate that transport of Cu from land to water ways is related to the close association of Cu with both organic matter and soil pH, and particulates may play an important role because of its containing higher concentration of total and organic bound Cu, as compared with the bulk soil.