Evaluation of contaminants spreading from sludge piles, applying geochemical fractionation and attenuation of concentrations model in a tropical reservoir.

Drinking water production may generate significant amounts of sludge, which may be contaminated with various metals. For the first time, the mobility/lability of contaminants from two water treatment sludge piles in the Juturnaíba Reservoir was evaluated by applying two geochemical approaches: sequential extractions and attenuation of concentrations model. Both procedures were applied to evaluate the mobility/lability of Al, Cr, Cu, Fe, Mn, and Zn on samples collected in the sludge piles and in the neighborhood of both water treatment plants. The results show that aluminum presents considerably higher concentrations in the sediments close to the sludge piles, with more labile phases; however, the attenuation of concentrations model indicates little spreading of this contaminant in the reservoir. Manganese was shown to be severely depleted in the sludge, indicating that it can be leached away, due to the reducing conditions of the pile. The other elements showed low concentrations and were shown not to affect the concentrations in the reservoir. While the geochemical fractionation indicates the possibility of dissolution to the water column, the attenuation of concentrations model gives information on the spatial dispersion of the contaminants, constituting interesting complementary approaches.

Soil heavy metal content on the hillslope region of Rio de Janeiro, Brazil: reference values.

The increasing concern regarding the preservation of soil quality suggests the adoption of quality reference values as a first step in environmental monitoring actions. In this context, the objective of this study was to establish soil quality reference values for Al, Zn, Mn, Cd, Fe, Pb, Ni, Cr, and Cu and to correlate several soil properties with the occurrence of these elements in the hillslope region of Rio de Janeiro State. Sixty-two samples were collected at depths of 0-20 and 20-40 cm and analyzed using the USEPA method 3051A. After clustering analysis, the samples were separated into three groups. Classification functions were obtained based on the variables pH - Mg - Fe - Mn, i.e., the variables that were best related to heavy metal content. We determined to establish the quality reference values for the 75th percentile of the three groups. The relief forms of the area, which facilitate the transport of soil fine-particle fractions and accumulation in lowlands, were revealed to be one of most important factors in understanding the distribution of soil heavy metals.

Analysing the behaviour of 90Sr and stable Sr in highly weathered soils: Soil to plant transfer factor and geochemical partitioning.

Public concerns over environmental protection have increased after Fukushima accident. The soil-plant transfer factor (Fv) is a critical parameter for environmental risk assessment. 137Cs Fv values determined in acid Brazilian soils could be two orders of magnitude higher than Fv values measured in soils affected by the Chernobyl accident. This paper studied the behaviour of 90Sr in Brazilian soils where very few 90Sr Fv data is available. All classes of studied soils (Ferralsol, Acrisol and Nitisol) showed that more than 80% of total 90Sr in soils remains potentially mobile, mainly at the bioavailable phase, more than 2 years after soil contamination in an experiment conducted in lysimeters. Higher 90Sr Fv for maize and cabbage was observed in the acid soils with low content of exchangeable Ca, lower Fv values occurred at Nitisol, the subtropical soil type. It seems that the behaviour of 90Sr in these soils are mainly controlled by ionic competition mechanisms occurring for root uptake and sorption sites, with stable Sr and major nutrients (Ca, Mg and K). The mineralogy also seems to play a relevant role, since goethite rich clay soil presented 90Sr Fv values higher one or two orders of magnitude than 90Sr Fv values observed at clayed soil goethite rich with trace of vermiculite, for all studied crops. The high rate of 90Sr migration down the soil profiles observed for the studied soils during the 2 first years after contamination suggests a high rate of transfer to groundwater, even transfer to leafy crop group can be also a relevant pathway. In the present study, maize, among other plant species, presented the lowest Fv values, even when compared with maize cultivated in temperate soil. Our results suggest that stable Sr may not be a very good analogue of 90Sr for determining plant Fv values: geometric mean of stable Sr Fv for maize was Fvmaize = 6.3E-1 ± 2.1E0 (n = 8) and for 90Sr was Fvmaize = 1.8E-2 ± 2.5E0 (n = 16), geometric mean of stable Sr Fv for cabbage was Fvcabbage = 1.4E0 ± 3.9E0 (n = 17) and for 90Sr was Fvcabbage = 7.9E-1 ± 4.4E0 (n = 18).

Separation of Escherichia coli from natural samples for identification of sources and microcosm inoculation.

Obtaining uncultured Escherichia coli from natural waters is an important step in the study of microbes in the environment, which are critical for bacterial decay and microbial source tracking. The quality of the samples used can influence the assays, because high contaminant concentrations, differing cell ages, and physiologic states can impair results. The proposed separation is based on a three-step filtration method applied to replicates of seven samples from a sewage plant affluent, collected in different periods. Aliquots of the leachate were inoculated into microcosms, aiming to observe the cultivability of the cells. The assay resulted in colimetry values ranging between 104 and 105 cells. In the leachate, averages of 1.05% of total coliforms and 1.10% of Escherichia coli were recovered from original samples. Although enduring unfavorable temperatures, salinities, and nutritional conditions, the inoculated microcosm populations grew approximately 310 times after 24 h. The final leachate contained cultivable cells in appropriate physiological states and quantities for inoculum in microcosm sets. The bacteria obtained from the leachate were also appropriate for surveys of microbial source tracking, because, in the developed procedure, organisms were separated from contaminants, while cell concentrations were sufficient for inocula.

Evaluation of the corrosivity of the soil through its chemical composition.

The study of the soil as a corrosive environment has become necessary, since material deterioration caused by physico-chemical interactions between the material and the environment has been displayed. In this work, the corrosivity of the soil in the Southeastern region of Brazil has been studied. In this region, 16 samples have been collected at varied points located at the vicinity of a slurry pipeline. For a better understanding of the soil corrosivity, the following analyses were conducted in solutions prepared with the soil samples: chromatographic analyses for ion determination; plasma emission for metal determination and pH measurements. It was concluded that the number of elements present in the soil composition is important for the determination of the corrosivity action of this environment. The assessment of the soil corrosivity is important to select efficient methods to protect buried structures and avoid soil contamination induced by pipeline failures.

Removal of ammonia nitrogen from distilled old landfill leachate by adsorption on raw and modified aluminosilicate.

This study aimed to evaluate the ammonia-nitrogen removal by aluminosilicates, using both standard solutions as pretreated landfill leachate. Three types of commercial clays and one commercial zeolite were initially tested using standard solution; however, only one clay with the best removability and the zeolite were tested with pretreated leachate. The chosen clay sorption capacity with the standard solution reached 83%, while with the pretreated leachate solution has reached 95% and zeolites have reached, respectively, a removal of 73% and 81%. For this two adsorbents' studies of equilibrium and kinetic of the sorption were also performed. The Langmuir model was more adequate to describe the ion exchange equilibrium and the sorption mechanism fit the pseudo-second-order kinetic model. Moreover, the pretreatment used on leachate proved to be essential not only for ammonium detection in solution, but also to facilitate its sorption in aluminosilicates. This alternative of ammonia-nitrogen removal also generates a product derived from treatment that can be used as agricultural feedstock in the form of fertilizer.

Effects of untreated and treated oilfield-produced water on seed germination, seedling development, and biomass production of sunflower (Helianthus annuus L.).

This study aims to evaluate possible toxic effects of oil and other contaminants from oilfield-produced water from oil exploration and production, on seed germination, and seedling development of sunflower (Helianthus annuus L.). In comparison, as treated by electroflocculation, oilfield-produced water, with lower oil and organic matter content, was also used. Electroflocculation treatment of oilfield-produced water achieved significant removals of chemical oxygen demand (COD) (94 %), oil and grease (O&G) (96 %), color (97 %), and turbidity (99 %). Different O&G, COD, and salt levels of untreated and treated oilfield-produced water did not influence germination process and seedling biomass production. Normal seedlings percentage and vigor tended to decrease more intensely in O&G and COD levels, higher than 337.5 mg L(-1) and 1321 mg O2 L(-1), respectively, using untreated oilfield-produced water. These results indicate that this industrial effluent must be treated, in order to not affect adversely seedling development. This way, electroflocculation treatment appears as an interesting alternative to removing oil and soluble organic matter in excess from oilfield-produced water improving sunflower's seedling development and providing a friendly environmental destination for this wastewater, reducing its potential to harm water resources, soil, and biota.

Pyrene photochemical species in commercial clays.

The photochemistry of pyrene, a polycyclic aromatic hydrocarbon, adsorbed on kaolinite, sodium montmorillonite and acid bentonite K10® was investigated to determine how the concentration and structure of the clay minerals affect the formation of different species of pyrene. Fluorescence emission spectra were obtained using reflection geometry for pyrene at the concentrations ranging from 0.5 to 100.0 µmol g(-1) (pyrene:clay). Two pyrene photochemical species were observed, the monomer, which fluoresces at 396 nm, and its excimer which fluoresces at 470 nm. The formation of excimers occurred first on the kaolinite, due to the smaller surface area. In the acid montmorillonite, the fixed interlamellar space provided greater specific area, leading to lower formation of excimers. Emission from pyrene crystals was also detected for samples with high loadings.

Differentiation in the fertility of Inceptisols as related to land use in the upper Solimões river region, western Amazon.

The Upper Solimões river region, western Amazon, is the homeland of indigenous populations and contains small-scale agricultural systems that are important for biodiversity conservation. Although traditional slash-and-burn agriculture is being practiced over many years, deforestation there is relatively small compared to other Amazon regions. Pastures are restricted to the vicinity of cities and do not spread to the small communities along the river. Inceptisols are the main soil order (>90%) in the area and have unique attributes including high Al content and high cation exchange capacity (CEC) due to the enrichment of the clay fraction with 2:1 secondary aluminosilicates. Despite its importance, few studies have focussed on this soil order when considering land use effects on the fertility of Amazon soils. Thus, the objective of this study was to evaluate changes in soil fertility of representative land use systems (LUSs) in the Upper Solimões region, namely: primary rainforest, old secondary forest, young secondary forest, agroforestry, pasture and agriculture. LUSs were significantly differentiated by the chemical attributes of their topsoil (0-20 cm). Secondary forests presented soil chemical attributes more similar to primary rainforest areas, while pastures exhibited the highest dissimilarity from all the other LUSs. As a whole, soil chemical changes among Inceptisols dominated LUSs showed patterns that were distinct from those reported from other Amazon soils like Oxisols and Ultisols. This is probably related to the presence of high-activity clays enriched in exchangeable aluminum that heavily influenced the soil chemical reactions over the expected importance of organic matter found in most studies conducted over Oxisol and Ultisol.