Abstract: The sediment in the Aha Reservoir has a moderate potential hazard classification, which with the largest contribution to the potential hazard being from Cd. This study comprised a pot experiment to compare the accumulation of Cd in roots and shoots of Oxalis triangularis, Lolium perenne and Tagetes patula so as to assess the potential suitability of those species for remediation applications. Sediment from the Aha Reservoir was used either alone (control) or mixed with perlite, wood sawdust, mushroom residue or tea garden soil to test a range of planting substrates. It was found that: 1) Excluding the control, the soil chemical property ranges were: organic matter content of the substrate, 78.30 to 95.31 g·kg^-1; available nitrogen, 109.33 to 124.45 mg·kg^-1; available phosphorus 17.20 to 24.7 mg·kg^-1; available potassium, 178.12 to 206.46 mg·kg^-1; pH, 7.62 to 7.71; total porosity, 42% to 75%; electrical conductivity, 1.47 to 1.62 ms·cm^-1; and Cd concentration, 0.88 to 1.14 mg·kg^-1. Those specifications exceeded the requirements of the standard, CJ/T 340-2011, and pH, total porosity and Cd were values were suitable for the growth needs of common plants. Considering all soil properties, T₅ was the substrate with the best physical and chemical plant growth environment. 2) The fresh weigh and dry weight of O. triangularis, L. perenne and T. patula were 127.63, 37.51, and 61.02 g·pot^-1 and 15.37, 4.62, and 9.91 g·pot^-1, respectively. The ranking for biomass was O. triangularis>T. patula>L. perenne. 3) The concentrations of Cd in O. triangularis, L. perenne and T. patula ranged from 0.10 to 0.14, 0.21 to 0.31 and 0.93 to 1.22 mg·kg^-1, respectively. The cumulative Cd uptake of Cd by T. patula was 7.46 to 12.60 μg·pot^-1, which was much larger than the values of 1.03 to 2.24 μg·pot^-1 and 2.73 to 3.72 μg·pot^-1 for O. triangularis and L. perenne, respectively. 4) The bioconcentration factor of L. perenne roots ranged from 3.96 to 5.01, while corresponding values for the aboveground organs and roots of T. patula were 0.93 to 1.11, and 0.37 to 1.06, respectively, and for O. triangularis and the shoots of L. perenne were less than 0.31. In addition, the translocation factors of O. triangularis, L. perenne and T. patula were 0.67 to 3.23, 0.05 to 0.07 and 1.00 to 2.52, which highlights plant species differences, with L. perenne accumulating Cd in the root system, O. triangularis and T. patula accumulating Cd in the shoot system. In conclusion, T. patula, O. triangularis and L. perenne are all capable of healthy growth and Cd extraction from a Cd-rich sediment substrate, and among the three, O. triangularis is recommended for lake sediment remediation projects, because of its higher biomass production.

Key words: sediment substrate, Cd, green plants, planting, enrichment characteristics