Effects of Light Regime, Temperature, and Plant Age on Uptake of Arsenic by Spartina Pectinata and Carex Stricta

Abstract

We report here on efforts to show that a combination of native wetland plant species might perform better than a monoculture in wetlands designed for arsenic remediation by supplementing weaknesses. Carex stricta and Spartina pectinata were used in hydroponic experiments. (i) Arsenic uptake was first assessed at two ages via exposure to control or arsenic-laden solutions (0 or 1.5 mg As L⁻¹ as Na₂HAsO₄) for two weeks. Age had no significant effect on arsenic concentrations in roots, but translocation factors were greater in older plants of C. stricta and S. pectinata (0.45 and 0.07, respectively) than in younger plants (0.10 and 0.01, respectively). (ii) Seasonal effects were assessed by determining uptake kinetics for both species in conditions representative of spring temperatures (15/5°C) and light regimes (1050 μmol m⁻² s⁻¹, 13 h day⁻¹) and summer temperatures (28/17°C) and light regimes (1300 μmol m⁻² s⁻¹, 15 h day⁻¹). Both species had comparable rates of arsenic uptake into roots in summer conditions (44.0 and 46.5 mg As kg⁻¹ dry wt. h⁻¹ in C. stricta and S. pectinata, respectively), but C. stricta had a higher maximum net influx rate in spring conditions (24.5 versus 10.4 mg As kg⁻¹ dry wt. h⁻¹).

KEYWORDS:

• seasonal variation
• kinetics
• wetland plants
• phytoremediation

ACKNOWLEDGMENTS

The authors would like to thank Deanna Bobak for laboratory assistance; Doug Sturtz for operation of the ICP-OES; and Defne Apul, Jonathan Frantz, Alison Spongberg, and Michael Weintraub for comments during the preparation of this manuscript. This research was funded by the United States Department of Agriculture (Grant No. 2006-38894-03732). This is contribution number 2010-05 of the University of Toledo Lake Eric Center.