Cadmium and Zinc Accumulation in Aquatic Bryophytes Immersed in the Arkansas River, Colorado: Comparison of Fall versus Spring

ABSTRACT

A bryophyte, Hygrohypnum ochraceum, was used as an indicator of heavy metals in the upper Arkansas River below the historical mining district at Leadville, Colorado. Plants were immersed in the river at nine sites near Leadville for 10 days during fall 2000 and spring 2001. Cadmium and zinc tissue-metals in plants were higher in the fall than in spring. The plants showed site-to-site differences in concentrations of cadmium and zinc in the Arkansas River, and metals were markedly higher in California Gulch, a contaminated tributary draining the mining district of Leadville, Colorado. There were strong correlations between total cadmium in Arkansas River water and cadmium in bryophyte tissues and between dissolved and total zinc in the Arkansas River water and zinc in the bryophytes. Our study suggests that bryophytes could potentially be valuable monitoring organisms for assessing site and seasonal bioavailability of metals.