Heavy metals in the soil and castor bean plants fertilized with sewage sludge stabilized by different processes/Metais pesados no solo e em mamoneira adubada com lodo de esgoto submetido a diferentes processos de estabilizacao

This study evaluated the levels of heavy metals in the soil and castor bean plant after fertilization with sewage sludge (SS) subjected to different stabilization processes. The study was conducted in a Haplic Cambisol with the following treatments: control (CO), fertilization with solarized sewage sludge (SSS), composted sewage sludge (CSS), vermi composted sewage sludge (VSS), limed sewage sludge (LSS), and mineral fertilizer (MF). The experimental design included a subdivided plot scheme with fertilization being the primary factor and soil layers or leaf parts being the secondary factor. The data obtained were analyzed using analysis of variance and the Scott-Knott test with 5% significance. Fertilization with SSS, CSS, and LSS led to the highest increase in Zn in the soil, mainly in the surface layer. In the leaf tissues, Zn and Cu levels were higher with the CO and SSS treatments, whereas the Ni level was higher with SSS, CSS, VSS, and MF treatments. In general, Zn and Cu levels were higher in the leaf limb than in the petiole, whereas Ni, Pb, and Cr levels were higher in the petiole than in the leaf limb. In any case, no symptoms of toxicity in the plants and no risk of soil contamination were observed with any of the fertilization treatments. Key words: biosolid, waste management, oilseeds, Ricinus communis L. O objetivo deste trabalho foi avaliar os teores de metais pesados no solo e na planta de mamoneira em resposta a adubacao com lodo de esgoto (LE) submetido a diferentes processos de estabilizacao. O experimento foi desenvolvido em Cambissolo Haplico com os tratamentos: testemunha, adubacao com LE solarizado, LE compostado, LE vermicompostado, LE caleado e adubacao mineral. O delineamento experimental foi em esquema de parcelas subdivididas, sendo as adubacoes o fator primario e as camadas do solo ou as partes da folha o fator secundario. Os dados obtidos foram submetidos a analise de variancia e teste de Scott-Knott a 5% de probabilidade. No solo, as adubacoes com LE solarizado, compostado e caleado promoveram os maiores incrementos dos teores de Zn, principalmente na camada superficial. No tecido foliar, os teores de Zn e Cu foram mais elevados na testemunha e no LE solarizado, enquanto o Ni foi mais elevado nos LE solarizado, compostado, vermicompostado e na adubacao mineral. De modo geral, os maiores teores de Zn e Cu ocorreram no limbo foliar em comparacao ao peciolo, enquanto os teores de Ni, Pb e Cr foram mais elevados no peciolo do que