SUMMARYMicrobial processes have been used as indicators of soil quality, due to the high sensitivity to small changes in management to evaluate, e.g., the impact of applying organic residues to the soil. In an experiment in a completely randomized factorial design 6 x 13 + 4, (pot without soil and residue or absolute control) the effect of following organic wastes was evaluated: pulp mill sludge, petrochemical complex sludge, municipal sewage sludge, dairy factory sewage sludge, waste from pulp industry and control (soil without organic waste) after 2, 4, 6, 12, 14, 20, 28, 36, 44, 60, 74, 86, and 98 days of incubation on some soil microbial properties, with four replications. The soil microbial activity was highly sensitive to the carbon/nitrogen ratio of the organic wastes. The amount of mineralized carbon was proportional to the quantity of soil-applied carbon. The average carbon dioxide emanating from the soil with pulp mill sludge, corresponding to soil basal respiration, was 0.141 mg C-CO 2 100 g -1 soil h -1 . This value is 6.4 times higher than in the control, resulting in a significant increase in the metabolic quotient from 0.005 in the control to 0.025 mg C-CO 2 g -1 C mic h -1 in the soil with pulp mill sludge. The metabolic quotient in the other treatments did not differ from the control (p < 0.01), demonstrating that these organic wastes cause no disturbance in the microbial community.Index terms: microbial respiration, microbial carbon, microbial nitrogen, metabolic quotient, organic sludge.(1) Part of the dissertation of the first author, for a post-graduate degree in Agricultural Sciences, 2, 4, 6, 12, 14, 20, 28, 36, 44, 60, 74, 86

Biochar from sewage sludge is a low-cost sorbent that may be used for several environmental functions. This study evaluates the induced effects of pyrolysis temperature on the physicochemical characteristics of sewage sludge (SS) biochar produced at 350 (SSB350), 450 (SSB450) and 600 (SSB600), based on the metal enrichment index, metal mobility index (MMI), and potential ecological risk index (PERI) of Cd, Cu, Pb, and Zn. Increased pyrolysis temperature reduced the biochar concentration of elements that are lost as volatile compounds (C, N, H, O, and S), while the concentration of stable aromatic carbon, ash, alkalinity, some macro (Ca, Mg, P2O5, and K2O) and micronutrients (Cu and Zn), and toxic elements such as Pb and Cd increased. Increasing the pyrolysis temperature is also important in the transformation of metals from toxic and available forms into more stable potentially available and non-available forms. Based on the individual potential ecological risk index, Cd in the SS and SSB450 were in the moderate and considerable contamination ranges, respectively. For all pyrolysis temperature biochar Cd was the highest metal contributor to the PERI. Despite this, the potential ecological risk index of the SS and SSBs was graded as low.

Preservation of mangroves, a very significant ecosystem from a social, economic, and environmental viewpoint, requires knowledge on soil composition, genesis, morphology, and classification. These aspects are of paramount importance to understand the dynamics of sustainability and preservation of this natural resource. In this study mangrove soils in the Subaé river basin were described and classified and inorganic waste concentrations evaluated.

The preservation of mangrove ecosystem requires knowledge on soil Morphology, Physical and Chemical Characteristics, for understanding the requirements for their sustainability and preservation. Seven pedons of mangrove soil, five under fluvial and two under marine influence, located in the Subaé River basin were described and classified.Samples of horizons were collected for physical and chemical analyses, including Pb and Cd. The moist soils were suboxidic, with Eh below 350 mV. The pH of the pedons under fluvial influence ranged from moderately acid to alkaline, and pedons under marine influence was around 7.0. Mangrove soils under fluvial influence were characterized with the highest Pb and Cd concentrations in the pedons, which could be perhaps due to it closeness to the mining company Plumbum, while the lowest Pb concentrations was registered in the pedon furthest from the factory. Because the pedons had at least one metal above the reference level they were considered potentially toxic. The soils were classified as Gleissolos Tiomórficos Órticos (sálicos) sódico neofluvissólico, according to the Brazilian Soil Classification System and as Thiomorphic orthic Gleysol (salic) sodicluvissol (potentially toxic, very poorly drained) according with FAO. The pedon under marine influence was classified in the same subgroup, but the metal concentrations met the acceptable standard.