Performance and environmental impact of antibiotics in animal production in Brazil
01/Jun/2010
Antibiotics are used in large quantities in livestock. Many of these molecules are not fully metabolized by the animals, leaving detectable residues in soil, surface water and groundwater samples. The occurrence of these residues in the environment can favor microorganism resistance to antibiotic agents, in addition to toxic effects on certain living organisms. In general, veterinary antibiotic molecules are amphoteric with many ionizable functional groups (different pKa values), rather variable molar masses (172 to 916 g mol-1) and low volatilization potential (vapor […]
Cadmium, chromium, lead and zinc in maize plants and oxisol after nine annual applications of sewage sludge
01/Oct/2008
A major limitation for using sewage sludge in agriculture is the risk of soil contamination with heavy metals and their possible transference to humans via food chain. The objective of this study was to evaluate the soil content of Cd, Cr, Pb, and Zn by two digestion methods (HNO3 + H2O2 + HCl and HClO4 + HF) in maize plants grown on a Typic Eutrorthox soil treated with sewage sludge for nine consecutive years, and the effects on dry matter […]
Nutrient extraction by macrophytes cultivated in a solid waste landfill leachate
01/Apr/2008
Plant nutrient extraction has been used to remove inorganic ions from soil or other polluted media. In this study, the nutrient extraction capacity of the macrophytes Typha sp. and Eleocharis sp., cultivated as monoculture and as consortium, was evaluated in a growing medium containing rubble and leachate of an urban landfill. The plants were grown in wooden boxes containing rubble and leachate as substrate, in a plastic greenhouse, for five months. The total concentration and amount of macro (N, P, […]
Individual and competitive sorption of heavy metals in Oxisols with contrasting mineralogy
01/Aug/2007
The pollution effect of trace elements in the environment depends mainly on the capacity of soil colloids to sorb and maintain them in high energy bonds. This study evaluated the adsorption of Cd, Cu, and Pb in A-horizon samples of Red Latosol and Red-Yellow Latosol (Udox), with similar texture and contrasting mineralogy. For this purpose, isotherms of adsorption, monoelement and multielement were built, based on the soil sample reaction in 5 mmol L-1 Ca(NO3)2 solution adjusted to pH 5.5, with […]
Distribution and decomposition dynamics of atrazine in an ultisol under wet tropical climate conditions
01/Feb/2006
The biodegradability and distribution of pesticides in the environment determine their pollution potential. The risk of contamination with atrazine herbicide was studied in an Ultisol under field conditions and complemented with a microcosm system study. This system allowed the use of 14C-atrazine under controlled conditions and to determine of the volatilization (0.33%), mineralization (0.25%) and leaching (4 to 11%) parameters, which are difficult to evaluate in the field. Ninety percent of the radioactivity remained in the soil, with 75% in […]
Effect of pH on cadmium adsorption and desorption in Brazilian Oxisols
01/Jul/2005
Adsorption and desorption reactions of metals in soils are influenced by the surface of the soil colloid attributes and solution composition. This study evaluated the effect of the pH on Cd adsorption (Cdads) and desorption (Cddes) in l7 Brazilian Oxisol samples that differed in their chemical, physical and mineralogical attributes. Samples of each soil, suspended in 5 mmol L-1 Ca(NO3)2 (pH adjusted to 4.5; 5.5, and 6.5; ratio soil:solution 1:67) were placed to react with 0.20 mmol L-1 Cd(NO3)2 (final […]
Lime amelioration of zinc and cadmium toxicities for Eucalyptus camaldulensis seedlings cultivated in contaminated soil
01/Aug/2004
The effects of lime rates on the growth of Eucalyptus camaldulensis in soil mixtures with increasing proportions of Zn and Cd contamination were evaluated. The experiment was carried out under greenhouse conditions and the metal contamination levels were obtained by mixing 0, 25, 50, and 100% of a contaminated soil with a non-contaminated one used as diluter. Lime rates were 0, 10, 20, 40, and 80 t ha-1 and the experiment was conducted in pots containing 1.5 kg of soil with treatments arranged […]
Cadmium, copper, and lead adsorption and desorption in Oxisol samples pre-treated with phophorus
01/Apr/2004
The movement of trace elements in soils is closely related to factors that contribute to their retention in the solid phase, for instance adsorbed anions. In the present work, it was evaluated the effect of phosphorus (P) pre-treatment on adsorption and desorption of Cd, Cu, and Pb in A and B horizon samples of two Latosol (Oxisols): a Yellow-Red Latosol and a Dark-Red Latosol. The P pre-treatment consisted of reacting soils samples for 72 h with 10.75 mmol L-1 Ca(H2PO4)2.H2 O (soil:solution […]
Vesicular arbuscular mycorrhizae fungi in soils polluted with heavy metals
01/Mar/2002
The arbuscular mycorrhizal fungi (AMF) are ubiquitous establishing symbiosis with a large number of plants in spite of soil contamination with heavy metals.This study aimed to evaluate AMF occurrence and diversity in soils of four locations cultivated with grass species and contaminated with heavy metals as a result of Zn extraction and industrialization. AMFs were found in all locations, with species predominance being affected by heavy metal concentration in soil. Twenty one species were identified, belonging to the following genus: […]
Survival of Bradyrhizobium and Azorhizobium in heavy metal contaminated soil
01/Mar/2002
An experiment was carried out at the Soil Science Department of Federal University of Lavras (MG), from November/1999 to January/2000, aiming to evaluate the survival of strain and isolates of rhizobia, in heavy metal contaminated soil.The possible relationship between rhizobia tolerance in culture medium and its survival in contaminated soil was also verified.From a group of 60strains/isolates tested at a previous study for metal tolerance in YMA medium, two out of the most tolerant microorganisms [BR-4406 (strain recommended as inoculant […]