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The influence of temperature and rainfall on nutrient levels, heavy metals, and etiologic agents in sludge samples collected at the Sewage Treatment Station of Juiz de Fora, Minas Gerais, Brazil, was verified over 24 months. The results showed high levels of nitrogen (4.7-5.2%), phosphorus (1.4-2.2%), potassium (0.076-0.106%), magnesium (0.113-0.386%), iron 5.03%) and zinc (38.2-6902.1 mg Kg-1). For most of the investigated samples, the concentration of zinc was above the maximum allowed value (2,800 mg Kg-1). The concentrations of arsenic, cadmium, chrome, copper, and lead were below the maximum values allowed by the legislation. Parasitological analyzes identified thermotolerant coliforms (0.49-160 NMP g-1) and helminth eggs (1 egg), however, in amounts less than allowed by legislation. These results are indicative of the efficiency of the sewage treatment process. The results showed a significant influence of the meteorological parameters on the concentrations of nitrogen, copper, lead, zinc and pathogens in the sludge. The results also showed a strong correlation between the concentrations of copper, lead and zinc indicating that the presence of these elements in the sewage sludge has a common origin. The results demonstrated the feasibility of using the investigated matrix as fertilizer when collected in rainy periods when it favors the dilution of the elements present in their soluble forms. [ABSTRACT FROM AUTHOR]

The aim of this research was to determine the heavy metals concentration in blood (Pb, Ni and Cd), serum (Cu and Zn), hair and milk (Pb, Ni, Cd, Cu and Zn) of cattle raised in industrial (with steel mill) and non-industrial areas in Minas Gerais, Brazil. The samples were collected during summer and winter, aiming to verify animals contamination related to environment and year season. The environment significantly influenced the concentration of Cu obtained on serum samples, with higher values for cattle from the industrialized area. The sampling time affected the concentration of Cu (serum), Zn (serum and milk), Pb (blood) and Cd (blood and hair), with higher values for summer, except for Cd measured on hair. Meaningful interactions (P<0.05) between environment and year season were identified for Cu (hair and milk), Zn (hair) and Ni (serum, hair and milk). The results obtained show that the presence of steel mills in a determined area does not mean, necessarily that higher concentration of heavy metals will be found in cattle biological matrices. The seasonality can influence the heavy metal concentration obtained from these matrices, fact that should be considered in environment monitoring programs. [ABSTRACT FROM AUTHOR]