Eucalipto e biochar para fitoatenuação da poluição do solo por cádmio.

Abstract

Phytoattenuation is a promising technique to mitigate the deleterious effects of heavy metals toxicity, promoting an environmentally safe management of land use with crops of economic value. The use of biochars can reduce the mobility of metals and provide improvements in soil fertility, promoting safe management in polluted environments. In this sense, the present work aimed to (i) evaluate the immobilization and compartmentalization of Cd in the soil with the application of doses of a filter cake biochar (CB); (ii) assess changes in soil fertility in response to biochar application; (iii) to evaluate the growth, mineral nutrition and Cd accumulation in two eucalyptus species (Corymbia citriodora and the hybrid Eucalyptus urograndis × Eucalyptus urophylla) cultivated in a polluted soil treated with biochar; (iv) to evaluate the amelioration of the stress caused by Cd through the physiological parameters of the plants treated with biochar; and (v) evaluate the regeneration of polluted soil quality through microbiological indicators. Two experiments were carried out sequentially: the first experiment was a sorption assay. The soil was incubated with doses of biochar (0, 2, 4, 8, 12, 16, 24 and 30% m/m) for 64 days and at the end of this period, the availability and chemical fractionation of Cd in the soil were analyzed. and chemical attributes related to soil fertility; the second experiment was carried out in a greenhouse, with two species of eucalyptus grown in pots for 65 days in soil polluted by Cd, with and without the application of 5% CB. After cultivation, the growth parameters were evaluated; the levels of N, P and Cd in the tissues of the plants; chlorophyll a fluorescence parameters and photosynthetic pigments; and biomass together with soil microbial activity. From the results obtained, it was possible to infer that (i) the filter cake biochar can be indicated as a mitigating agent of soil pollution by Cd; (ii) both eucalyptus species associated with the application of 5% BT were tolerant to Cd toxicity; (iii) the cultivation of eucalyptus with the application of biochar promoted improvements in the microbiota of the soil polluted by Cd, a sensitive indicator of environmental quality; and (iv) phytotechnology using the eucalyptus species C. citriodora and the hybrid E. urograndis × E. urophylla plus the application with 5% CB showed potential to attenuate the effects of Cd in polluted areas.