Heavy Metal Removal in a Constructed Wetland and Benefits for the Development of the Toad Bufo raddei

Heavy metal (HM) pollution in aquatic environments is of worldwide concern because of the toxicities of HMs in animals and humans. Constructed wetlands (CWs) have successfully been used as cost-effective natural systems to remove various contaminants. However, the effects of CW on the survival of animals have not been studied in any depth. We established a CW to remove HMs from water in Baiyin City, in the upper Yellow River (YR) region, which has a highly developed mining industry. The BM removal efficiency of CW as well as its effect on the development of the toad Bufo raddei were studied. The HM removal efficiencies by the CW were in the order Cd>Pb>Zn>Cu, and the decrease of the KM concentrations in the water also caused the decrease of the HM concentrations in B. raddei toads living in the CW. The toads in the CW had larger body sizes and less oxidative stress than toads living in the YR, and no malformations were found in the toads living in the CW. These results indicate that CW systems such as that used in this study could protect amphibians from developmental problems caused by HIM pollution. We recommend that CW systems are used to treat polluted water and protect amphibians.