Comparing the Uptake of Arsenic by Barley and Oats Growing in a Semiarid Area Irrigated with Either Groundwater or Treated Wastewater

Abstract

Groundwater and domestic wastewater are often used in conjunction with surface water to irrigate crops in semiarid areas. A concern associated with this practice is the potential accumulation of arsenic (As) and heavy metals in soil and plants, especially in places where irrigation water contains geogenic As. Studies on arsenic uptake in cereal crops growing under dry and oxidizing conditions are scarce. A one-year field experiment was conducted to evaluate the uptake and translocation of As in barley and oats irrigated with either groundwater (GW) or treated domestic wastewater (TWW) in northern Mexico. The content of As, as well as toxic metals Cd and Pb, were determined in soil and 24 sets each of barley and oat plants. Metal(loid)s accumulated more in the roots and leaves, and less in the stems and grains. Barley grains contained 0.2 mg/kg of As under GW or TWW, whereas oat grains contained twice this amount. Bioconcentration (BCF) and translocation (TF) factors were < 1 for As and Cd in plants irrigated with both GW and TWW indicating that neither barley nor oats are As-accumulators, and their grain and leaves can be safely used for fodder. However, oats irrigated with TWW bioaccumulated Pb in leaves. Conscientious monitoring of As and associated metals in soil and crops irrigated with TWW and GW is recommended.