RESUMO: A hérnia das crucíferas, causada por Plasmodiophora brassicae, é limitante à produção de Brassica spp. em todo o mundo. Pouco se conhece sobre os fatores relacionados ao desenvolvimento da doença em plantas de couve-comum (Brassica oleracea var. acephala) e em cultivos em áreas de montanha sob condições tropicais. Objetivou-se avaliar a severidade da hérnia das crucíferas em lavouras de couve-comum, identificar potenciais falhas no manejo e os fatores de solo e relevo relacionados a sua ocorrência. O estudo foi conduzido em 24 lavouras de couve-comum da Região Serrana do Rio de Janeiro (Brasil). Registraram-se as práticas de manejo do solo e da couve-comum adotadas na região e coletaram-se amostras de solo e plantas. Em seguida, determinaram-se os atributos do solo e do relevo, a severidade da doença, biomassa e os teores e acúmulo de nutrientes e Al nas plantas. Observou-se alta disseminação do patógeno nas áreas. Foram identificadas práticas inadequadas e recorrentes na região como o cultivo sequencial de espécies hospedeiras, baixa adoção a análise de fertilidade, calagem e de medidas de conservação do solo, e o uso comunitário de máquinas e implementos agrícolas sem limpeza prévia. Identificou-se associação da doença com solos mais ácidos, sujeitos a maior acúmulo de água e com elevados teores de Al3+; e a maior teor e acúmulo de Al nas raízes. Práticas de manejo devem ser adotadas na região visando a redução do potencial de inóculo de P. brassicae e o aumento da fertilidade do solo.

ABSTRACT: Clubroot disease, caused by Plasmodiophora brassicae, limits the production of Brassica spp. worldwide. Little is known about the factors related to the development of the disease in kale (Brassica oleracea var. acephala) plants and in crops in mountainous areas under tropical conditions. This study examined the severity of clubroot in kale crops as well as identify potential flaws in management and the soil and relief factors related to its occurrence. The study was conducted in 24 kale fields in the mountainous region of Rio de Janeiro (Brazil). Soil and kale growth management practices adopted in the region were identified and samples of soil and plants were collected. Subsequently, soil and relief attributes, disease severity, biomass and nutrient and Al contents and accumulation in the plants were determined. There was a high spread of the pathogen in the areas. Inappropriate and recurrent practices in the region were detected, e.g., sequential cultivation of host species, low adoption of soil fertility analysis and liming and conservation practices, and community use of agricultural machinery and implements without prior cleaning. The disease was associated with more acidic soils, subject to greater water accumulation and with high levels of Al3+ as well as with higher Al contents and accumulation in the roots. Management practices must be adopted in the region to reduce the potential inoculum of P. brassicae and to increase soil fertility.

RESUMO O cultivo de hortaliças se destaca pelo uso intensivo de insumos agrícolas, devido à exigência nutricional em curto período de tempo e alta susceptibilidade a pragas e doenças. Este estudo teve como objetivo identificar os principais fatores responsáveis pelas alterações nos teores pseudototais e biodisponíveis de Cd, Cu, Cr, Mn, Ni, Pb e Zn nos solos sob cultivo intensivo de hortaliças. Para tal, no ano de 2017, foram coletadas amostras de terra em 146 pontos no município de Petrópolis-RJ. As amostras foram coletadas na profundidade de 0-20 cm, em propriedades familiares com cultivo de hortaliças em pleno período de produção. Para determinação dos teores pseudototais dos elementos tóxicos foi utilizada a metodologia da EPA 3050B. O procedimento de fracionamento geoquímico foi realizado com base no método BCR. Também foram calculados os índices de poluição. Em geral, as áreas produtoras de hortaliças apresentaram baixa contaminação por Cu, Zn, Pb, Mn e Ni, exceto para Cd que apresentou severa contaminação. Nas áreas que apresentam os menores valores de declividade, houve aumento nos teores da maioria dos elementos tóxicos, refletindo a influência do relevo. De maneira geral, o manejo inadequado do solo, a aplicação intensiva de adubação fosfatada, potássica e orgânica, assim como, o revelo, foram as variáveis que mais influenciaram no enriquecimento e biodisponibilidade de elementos tóxicos no solo.

ABSTRACT Vegetable cultivation stands out for intensive use of agricultural inputs due to high nutritional requirements of plants within a short period and their high susceptibility to pests and diseases. This study aimed to identify the main factors responsible for changes in pseudo-total and bioavailable contents of Cd, Cu, Cr, Mn, Ni, Pb, and Zn in soils under intensive vegetable cultivation. Soil samples were collected from 146 sites in Petrópolis (RJ), Brazil, in 2017. The samples were collected at a depth of 0-20 cm in family farm systems during vegetable production period. Pseudo-total contents of toxic elements were determined by the EPA 3050B method. Geochemical fractionation procedure was used based on the BCR method. Pollution indices were also calculated. In general, vegetable producing areas presented low contamination by Cu, Zn, Pb, Mn, and Ni, except for Cd, which showed severe contamination. In areas with the lowest slopes, most of the toxic elements showed increasing contents, reflecting relief influence. Overall, inadequate soil management, intensive application of phosphate, potassium, and organic fertilization, and relief were the most influencing parameters on the enrichment and bioavailability of toxic elements in the soil.

Abstract Oil exploration and production generate large quantities of waste, which may contain contaminants such as barium and lead. Therefore, more studies aimed at decreasing the levels of heavy metals in contaminated sites, using methods such as phytoremediation, are needed. In a preliminary assay, samples of soil contaminated with oil drilling waste were incubated with different concentrations (2 or 6 mmol L-1) of ethylenediaminetetraacetic acid (EDTA). Subsequently, an experiment was conducted in a greenhouse to evaluate the phytoremediation potential of the tree Cordia africana. EDTA induced mobilization and translocation of lead, manganese, and iron into the C. africana leaves but had no effect on barium. The quantity of heavy metal contaminants accumulated in the plant vegetative parts showed that C. africana cannot be used as a phytoextractor for the tested metals; however, it can be used as a phytostabilizer.

RESUMO A disposição indiscriminada de resíduos da indústria petrolífera levam a contaminação dos solos e mananciais, afetando toda a biota. O objetivo do trabalho foi avaliar a variabilidade espacial dos teores de bário e chumbo em área de disposição de resíduos de perfuração de poços de petróleo. O Latossolo estudado encontra-se no município de Santa Maria do Oeste, no estado do Paraná-Brasil. Para a determinação da variabilidade espacial dos metais criou-se uma grade de amostragem com 76 pontos. Em cada ponto, foram coletadas amostras de solo nas profundidades: 0-0.3, 0.3-0.6, 0.6-0.9 e 0.9-1.2 m para a determinação dos teores de bário e chumbo. A geração dos mapas de bário e chumbo foi realizada através de interpoladores geoestatísticos com determinação da dependência espacial, modelagem e validação de semivariogramas experimentais e sua interpolação. Selecionou-se 30 amostras com concentrações de bário e chumbo mais elevadas para realização de ensaios de lixiviação e solubilização. Na análise do semivariograma verificou-se dependência espacial, permitindo a confecção de mapas por krigagem para os dois metais. Os elevados teores encontrados foram decorrentes das atividades associadas à perfuração de poços, visto que, não foi encontrado correspondência direta com a geologia das rochas locais e a gênese. As concentrações dos metais foram superiores aos valores de investigação considerando o cenário Agrícola/AP-Máx, caracterizando a área sujeita a "Investigação", pertencendo a Classe 4, área contaminada. Apesar desses metais possuírem baixa solubilidade, demonstrando baixo risco de contaminação de águas subsuperficiais, podem apresentar risco de contaminação de corpos d'água por meio do carreamento desse solo.

ABSTRACT Indiscriminate disposal of waste from the oil industry has led to contamination of soils and water sources and toxic effects in the biota. Thus, this study aimed to assess barium (Ba) and lead (Pb) spatial variability in disposal sites for oil well drilling and prospecting wastes. The soil in the study area is classified as Red Latosol, and the area is located in Santa Maria do Oeste, Paraná State (Brazil). Barium and Pb spatial variabilities were determined using a 76-point sampling grid. The levels of metals were determined in soil samples collected at each sampling point, at the depth ranges of 0.0-0.3, 0.3-0.6, 0.6-0.9 and 0.9-1.2 m. Data were mapped using geostatistical interpolators for spatial dependence determination, modeling and validation of semivariograms, and respective interpolation. Thirty Ba and Pb high concentration samples were selected for leaching and solubilization assays. As semivariogram analysis showed spatial dependence, mapping by ordinary kriging was performed for both metals. The high levels found for both metals arose from well drilling activities, as no direct relationship was found between such levels with geology and genesis of the local rock. The concentrations of the metals were higher than the research values considering the Agricultural / AP-Max scenario, therefore, the study area was characterized as class 4 (contaminated). Although these metals have low solubility, i.e. low contamination risk to subsurface waters, they may pose contamination risks to water bodies by means of soil runoff.

RESUMO Valores de Referência de Qualidade (VRQ) para elementos potencialmente tóxicos são obtidos através dos teores naturais nos solos. No entanto, esta determinação a partir de valores médios ou de percentis não é adequada, diante da variabilidade existente na distribuição natural desses elementos nos solos. Diante disso, o objetivo do estudo foi propor uma nova metodologia de estabelecimento dos VRQs, usando como exemplo a Região do Médio Paraíba - RJ, a partir de grupos de solos definidos com base nos teores pseudo-totais de B, Ba, Co, Cr, Cu, Ni, Pb e Zn, mediante a utilização de análises multivariadas e de funções discriminantes. Foram utilizados 40 pontos, coletados nas profundidades 0-20 e 20-40 cm, para a determinação dos teores pseudo-totais, conforme a metodologia EPA 3051A. As amostras foram separadas em três grupos, para melhor representar a variabilidade existente nos solos da região. As funções de classificação foram obtidas com base nas variáveis Mn, Fe e Mg. Em geral, os grupos G1 e G2 apresentaram valores inferiores, em relação aos obtidos quando se utilizou o universo amostral. Enquanto que, G3 apresentou valores superiores. Os VRQs obtidos a partir de grupos de solos apresentaram diferenças substanciais que traduzem vantagens para o gerenciamento de áreas contaminadas da região.

ABSTRACT Quality Reference Values (QRVs) for potentially toxic elements are obtained from background levels in soils. However, this determination from mean values or percentiles is not appropriate given the variability in the natural distribution of these elements in soils. Therefore, the objective of this study was to propose a new methodology to establish the QRVs, using the Médio Paraíba region (RJ, Brazil) as an example, from groups of soils defined based on the pseudo-total levels of B, Ba, Co, Cr, Cu, Ni, Pb, and Zn through the use of multivariate analyses and discriminant functions. A total of 40 points, collected at depths of 0-20 and 20-40 cm, were used for the determination of pseudo-total contents, according to the EPA 3051A methodology. The samples were separated into three groups to better represent the variability of the soils of the region. The classification functions were obtained based on the variables Mn, Fe, and Mg. In general, the groups G1 and G2 presented lower values than the ones obtained when the sample universe was used, whereas G3 presented higher values. The QRVs obtained from the soil groups presented substantial differences that translate into advantages for the management of the contaminated areas of the region.

ABSTRACT A first large-scale systematic survey of natural radioactivity contents of soils of the state of Rio de Janeiro is presented, focused on the establishment of Quality Reference Values (QRVs). Undisturbed soil samples were collected from 243 areas and analyzed by gamma spectrometry. The activity contents varied largely, ranging from 12.2 to 1,029 Bq kg−1 for 40K (geometric mean of 111.1 Bq kg−1), from 3.5 to 99.8 Bq kg−1 for 226Ra (geometric mean of 29.7 Bq kg−1), and from 5.4 to 314.5 Bq kg−1 for 228Ra (geometric mean of 67.1 Bq kg−1). The highest contents of radium isotopes were found in soils developed on igneous rocks (Leptosol), and the lowest in a soil of sedimentary origin (Podzol). Among the different soil types, the radioisotope contents differed substantially. Separate QRVs were calculated for each radionuclide by the 75th and 90th percentile approach, and the QRVs were estimated for each soil type. The results emphasized the restrictiveness of QRVs based on the 75th percentile or of a single overall QRV for all soils. Therefore, rather than estimating a separate QRV for each radionuclide for the State, we suggest the use of an upper threshold value, defined as the 90th percentile, and a specific QRV for each soil type area.

ABSTRACT The most abundant and critical elements in residues from well drilling and prospecting are barium and sodium. Ecotoxicological tests have been used to evaluate the toxicity caused by toxic substances present in the soil. The objective of the present study was to verify the effect of the application of drilling residue from oil wells on Oligochaeta activity. After incubation of the soil with residue doses – BaSO4 and NaCl – three ecotoxicological tests were performed in which the species Eisenia andrei was used as a bioindicator. The avoidance behavior test showed that there was a negative effect of the application of the residue at a dose of 234 t ha-1 on Oligochaeta activity. However, the application of BaSO4 alone did not show damage to the earthworms, unlike what was observed for NaCl application. These results indicate that sodium was the element that most restricted the activity of these organisms.

RESUMO As concentrações de metais na solução do solo são reguladas, principalmente, pelos processos de sorção. Neste estudo foi avaliada a dinâmica de sorção de Cd e Pb em 19 amostras de solos da Região do Médio Rio Paraíba - RJ, Brasil, através da comparação dos parâmetros de diferentes modelos de isotermas obtidos pelo software ISOFT após ensaios de sorção pelo método da batelada. Os resultados mostraram que a isoterma Linear é mais adequada para representar a sorção de Cd e o modelo de Freundlich para Pb e que a adsorção de Cd é fortemente influenciada pelo pH e pelas concentrações de Fe e Ca, enquanto que a adsorção de Pb é mais influenciada pelo pH, e pelas concentrações de Mn e Ca.

ABSTRACT Metal concentrations in soil solution are mainly regulated by sorption processes. In this study, Cd and Pb sorption dynamics have been assessed for 19 soil samples from the Middle Region of Paraíba River - RJ, Brazil, through parameters of different models of isotherms obtained by the ISOFT software following a sorption testing using the batch method. Results showed that the linear isotherm is more appropriate to describe Cd sorption and the Freundlich model for Pb. Cd sorption is strongly affected by pH and concentrations of Fe and Ca; while Pb sorption is mostly influenced by pH and the concentrations of Mn and Ca.

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.

Two parallel tests were carried out to evaluate barium solubility in soils treated with barite under reducing conditions: one in leaching columns and another with potted plants cultivated with rice. Soils were treated with three doses of barite and kept at two humidity levels. The reduction (-200 mV) condition promoted an increase in barium in the geochemical fraction of higher liability, higher concentrations of barium in the leached extracts, and higher absorption by rice plants. As a result of increased uptake and accumulation of barium, the plants showed stunted growth