Speciation of Cu and Zn in Drainage Water from Agricultural Soils

• Published in: Environmental science & technology 2002-11, Vol.36 (22), p.4824-4830
• Main Authors: Aldrich, Annette P, Kistler, David, Sigg, Laura
• Format: Article
• Language: English
• Subjects: Agriculture; Agronomy. Soil science and plant productions; Applied sciences; Bioavailability; Biological and medical sciences; Biological Availability; Copper; Copper - analysis; Copper - chemistry; Drainage; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environmental Monitoring; Exact sciences and technology; Fertilizers; Fundamental and applied biological sciences. Psychology; Fungicides; Fungicides, Industrial; Ligands; Metals; Natural water pollution; Pesticides; Pollution; Pollution, environment geology; Rain; Rainwaters, run off water and others; Soil and water pollution; Soil Pollutants - analysis; Soil science; Soils; Solubility; Water; Water Movements; Water Pollutants - analysis; Water treatment and pollution; Zinc; Zinc - analysis; Zinc - chemistry
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es025813x

Inputs of copper and zinc from agricultural soils into the aquatic system were investigated in this study, because of their heavy agricultural usage as feed additives and components of fertilizers and fungicides. As the mobility and bioavailability of these metals are affected by their speciation, the lipophilic, colloidal and organic fractions were determined in drainage water from a loamy and a humic soil treated with fungicides or manure. This study therefore investigates the impact of agricultural activity on a natural environment and furthers our understanding of the mobility of metals in agricultural soils and aquatic pollution in rural areas. Marked increases in the total dissolved metal concentrations were observed in the drainage water during rain events with up to 0.3 μM Cu and 0.26 μM Zn depending on the intensity of the rainfall and soil type. The mobile metal fractions were of a small molecular size ( 99.9% by abundant organic ligands (log K 10.5−11.0). About 50% of dissolved Zn were electrochemically labile, and the other 50% were complexed by strong organic ligands (log K 8.2−8.6). Therefore very little free metal species were found suggesting a low bioavailability of these metals in the drainage water even at elevated metal concentrations.