ABSTRACT:The diversity of methods for heavy metal extraction from soils complicates comparison of results used by environmental agencies to establish quality reference values. The aim of this study was to evaluate three soil digestion methods regarding the solubilizing capacity of Ba, Cr, Cu, Fe, Mn, Ni, Pb and Zn, and to propose a standard method to establish Quality Reference Values (QRVs) for Brazilian Histosols. Twenty soil samples were selected to evaluate the USEPA 3051, USEPA 3051A and Aqua Regia methods in a closed system. The methods tested were statistically similar regarding Cu, Fe and Mn extraction from soils. However, the methods can not be considered similar for Ba, Cr, Ni, Pb and Zn; Aqua Regia recorded the highest levels, except for Ba. The Aqua Regia method proved suitable for metal extraction from soils with organic characteristics and can be used to establish QRVs.

A B S T R A C TThis study aimed to evaluate the effects of the application of two types of oil drilling wastes on the development and absorption of barium (Ba) and sodium (Na) by sunflower plants. The waste materials were generated during the drilling of the 7-MGP-98D-BA oil well, located in the state of Bahia, Brazil. The treatments consisted of: Control -without Ba application, comprising only its natural levels in the soil; Corrected control -with fertilization and without wastes; and the Ba doses of 300, 3000 and 6000 mg kg -1 , which were equivalent to the applications of 16.6, 165.9 and 331.8 Mg ha -1 of waste from the dryer, and 2.6, 25.7 and 51.3 Mg ha -1 of waste from the centrifugal. Plants cultivated using the first dose of dryer waste and the second dose of centrifugal waste showed growth and dry matter accumulation equal to those of plants under ideal conditions of cultivation (corrected control). The highest doses of dryer and centrifugal wastes affected the development of the plants. The absorption of Ba by sunflower plants was not affected by the increase in the doses. Na proved to be the most critical element present in the residues, interfering with sunflower development.Bário e sódio em plantas de girassol cultivadas em solos tratados com cascalho de perfuração R E S U M O Objetivou-se, neste trabalho, avaliar os efeitos da aplicação de dois resíduos gerados na perfuração de poços de petróleo no desenvolvimento e absorção de bário e sódio por plantas de girassol. Os resíduos foram gerados durante a perfuração do poço 7-MGP-98D-BA localizado na Bahia. As doses dos resíduos utilizadas foram: Testemunha -sem aplicação de bário; compreendendo apenas os teores naturais do solo; Testemunha -corrigida (com adubação e sem resíduo) e doses de 300, 3000 e 6000 mg kg -1 de bário equivalentes à aplicação de 16,6, 165,9 e 331,8 Mg ha -1 do resíduo do secador e 2,6, 25,7 e 51,3 Mg ha -1 do resíduo da centrífuga. As plantas cultivadas na primeira dose do resíduo do secador e na segunda dose do resíduo da centrífuga, apresentaram crescimento e acúmulo de massa seca iguais aos das plantas sob condições ideais de cultivo (Testemunha corrigida). As maiores doses dos resíduos do secador e da centrífuga afetaram o desenvolvimento das plantas. A absorção de bário pelo girassol não foi afetada com o aumento das doses. O sódio mostrou-se o elemento mais crítico presente nos resíduos, interferindo no desenvolvimento do girassol.

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