The Effect of Temperature on the Accumulation of Cadmium, Copper, Zinc, and Lead by Scirpus acutus and Typha latifolia: A Comparative Analysis

Abstract

Wetland plants have a capacity for metal sequestration and have been used to remediate such environmental contaminants. How this capacity will be affected by a warming environment is not well-known. Our objective was to identify the effect of small environmentally realistic increases in temperature on metal (cadmium, zinc, lead, and copper) accumulation in Typha latifolia as compared with Scirpus acutus. These common wetland plant species were grown in metal-contaminated sediments at 13°C, 16°C, and 18°C for 3 months to determine the effect of environmentally realistic temperatures on metal accumulation. Cd109 was used as a radiotracer to study the effect of temperature on uptake kinetics. Growth of the two wetland plants differed markedly; S. acutus displayed linear growth reaching a maximum height of ca. 100 cm; by contrast, T. latifolia grew to ca. 40 cm by day 60 with no further growth occurring over the remainder of the 105-day growth period. S. acutus accumulated more cadmium, lead, and zinc from contaminated sediments than T. latifolia, but only within roots and rhizomes. Although not significant, uptake of cadmium, lead, and zinc by both plants was enhanced under warmer conditions and was most pronounced in S. acutus. This was supported by the radiotracer studies which indicated that under the higher temperatures, there was increased rates of Cd109 uptake by shoots of S. acutus. By contrast, temperature did not affect Cd109 uptake rate constants in T. latifolia. S. acutus appears to be more effective at sequestering metals from contaminated sediments; this species as compared to T. latifolia may also be more affected by a warming climate. In the design of wetlands for metal remediation, differences in how these two plants sequester metals from their environment should be considered.