Heavy‐Metal Losses from an Agroforestry Catchment

Abstract

Long‐term agricultural sustainability and water quality are impacted by different chemicals, including heavy metals. Heavy‐metal losses at the catchment scale depend largely on land‐management practices. Water‐quality indicators are required near soil‐quality indicators for different regions and farming systems. The purpose of this work is to analyze the heavy‐metal losses from a mixed agroforestry catchment. Iron (Fe), Magnesium (Mn), Zinc (Zn), and Copper (Cu) were measured in the drainage water of a 36.3 km² catchment located at the Valiñas River (Coruña, northwest Spain), and a total of 193 samples were collected during the course of 2003. The sampling strategy was a stratified point sampling involving more frequent sampling when flow was high. Water metal content was analyzed by inductively coupled plasma (ICP‐AES). The content ranges of dissolved heavy metals were as follows: Fe between 10 and 267 µg/L, Mn 0.2 and 77 µg/L, Zn 0.62 and 53.7 µg/L, and Cu 0.20 and 9.26 µg/L. Heavy metal content strongly varied along the study time, depending on storm flow but also on timing of animal‐waste applications.

Keywords:

• Water quality
• heavy metals
• soluble contents
• agroforestry catchment

Acknowledgments

This research was financially supported by Xunta de Galicia, project PGIDT 01AGR 10302PR, and Spanish Education and Science Ministry CICYT-MEC, project REN 2000‐0445‐C02‐01‐HD.