Tolerance and remediation potential of aquatic plants for copper, nickel, lead and zinc in heavy metal-contaminated waters

In the semi-arid regions of Northwest China, research on phytoremediation technology has focused predominantly on soil matrices, with few studies investigating its efficacy in removing heavy metals from aqueous solutions. Four plants were selected for formal hydroponic experiments: <i>Iris sibirica</i> L. (<i>I. sibirica</i>), <i>Alternanthera philoxeroides</i> (<i>A. philoxeroides</i>), <i>Sedum aizoon</i> L. (<i>S. aizoon</i>) and <i>Hydrocotyle vulgaris</i> L. (<i>H. vulgaris</i>). The results revealed that <i>S. aizoon</i> presented the highest bioaccumulation ability for Cu, whereas <i>H. vulgaris</i> presented the strongest bioaccumulation of Zn, Ni and Pb. <i>S. aizoon</i> had a maximum removal rate of 90% for Cu. The removal rate of Ni by <i>A. philoxeroides</i> was greater than 61%. The removal rate of Zn by <i>H. vulgaris</i> and <i>S. aizoon</i> was greater than 69%. The highest removal rate of Pb by <i>I. sibirica</i> was 93.96%. These plants can serve as candidate species for the phytoremediation of specific heavy metals in river or tailings pond waters in Northwest China. This study holds practical significance for the remediation of water bodies contaminated with heavy metals in the semi-arid regions of Northwest China.