Arsenic tolerating plants from mine sites and hot springs in the semi-arid region of Chihuahua, Mexico

Phytoremediation is an emergent field of great potential for the removal of metals, metalloids and other contaminants from soil, water and sediments. The use of native plants with high tolerance and capacity to accumulate the metal to be removed is a very convenient approach. High levels of arsenic (As) have been found at several natural sources in the northern and and semi-arid regions of Mexico. The state of Chihuahua is, among others, one in which As has been detected in sources of natural drinking water. The aim of the present work was to identify indigenous plants in the state of Chihuahua with As tolerance and accumulating capacity. Water samples from different mine sites and hot springs were inspected. At these sites, the As concentration varied in the range of 110-191 μg/l in water and 40-2100 μg/g in soils. A native plant identified as Eleocharis sp. (Cyperaceae), collected from the nearby surroundings of a hot spring site, was found to contain an As concentration of 301 μg/g. The arsenic bioconcentration (BCF) and translocation (TF) factors for this plant exceeded 1 (5.22 and 7.37, respectively), which classifies it as an arsenic-tolerant plant with potential use in phytoextraction. The TF of Brickellia veronicaefolia, Nicotiana glauca and Baccharis salicifolia were above one, but they had very low BCF coefficients, which limited their potential to be considered for a phytoremediation process.