Effects of lead contamination in soils on dry biomass, concentration and amounts of lead accumulated in three tropical pasture grasses

Abstract

A greenhouse pot-experiment was conducted to evaluate the phytoremediation abilities of three tropical pasture grasses (signalgrass, napiergrass and atratum) in response to two types of soils (Kunigami-maji and Shimajiri-maji) contaminated with three levels of lead (0, 150 and 300 mg kg -1 ). The results demonstrated that the dry biomass, lead concentration and the accumulated amounts were different among the plant species and between the soil types. The amounts of dry matter in three tropical pasture grasses grown on Kunigamimaji soil were higher than that on Shimajiri-maji soil. On both soils, lead concentration of roots was higher than that of shoots, and it was suggested that transportation of lead from roots to shoots was restricted in these plants. The lead accumulated amounts per plant grown on Kunigami-maji soil were higher than that on Shimajiri-maji soil. And, on Kunigami-maji soil, accumulation of lead was relatively high in both shoots and roots of signalgrass and atratum, while, in napiergrass, the high level of lead was found only in roots. Amounts of lead extracted from the shoots of signalgrass, napiergrass and atratum grown on Kunigami-maji soil contaminated with the highest lead level of 300 mg kg -1 were 1.64, 0.17 and 0.92 mg plant -1 , respectively. As Kunigami-maji had lower soil pH than Shimajiri-maji, it can be suggested that lower soil pH may enhance lead bioavailability and uptake by the tropical pasture grasses. In conclusion, signalgrass and atratum could be useful for phytoremediation of lead contaminated soil, especially on Kunigami-maji soil.

Lead Bioaccumulation in Root and Aerial Part of Natural and Cultivated Pastures in Highly Contaminated Soils in Central Andes of Peru

“…NP and CP increase the accumulated amount of Pb in the root to a higher Pb content in soil, as observed in another study [58]. Accumulation of Pb in the aerial part of the grass is also increased to a greater amount of Pb in soil and root.…”

“…Comparing the results obtained in both types of pastures, the accumulated amounts of Pb in the roots and the aerial part were similar in NP and PC. In both types of pasture, the concentration of Pb in the roots was higher than that of the shoots, which suggests that the transport of lead from the roots to the shoots is restricted and the root maintains a high Pb content in its structure, and the cumulative amounts of lead in the aerial part of the plants were greater than those reported in other studies [58].…”