Estimation of primary drainage three-phase relative permeability for organic liquid transport in the vadose zone

The modeling of transport of organic liquid contaminants through the vadose zone often requires three-phase relative permeabilities. Since these are difficult to measure, predictive models are usually used. The objective of this study is to assess the ability of eight common models to predict the drainage relative permeability to oil in a three-phase system (water-oil-air). A comparison of the models' estimates using data set from Oak [Oak, M.J., 1990. Three-phase relative permeability of water-wet Berea. In: Seventh Symposium on Enhanced Oil Recovery, Paper SPE/Doe 20183. Tulsa, OK, April 22-25] showed that they provide very different predictions for the same system. The goodness of the models does not increase with the amount of data or computation that the models require. Also, the calculations showed how different interpretations of the models and of the terminology associated with them can significantly impact the predictions. Thus, considerable error may be introduced into the simulations of organic liquid transport in the vadose zone depending on the selection and interpretation of the three-phase relative permeability model.     

Pesticides in the surface waters of the Camanducaia River watershed,Brazil

Abstract

Camanducaia River is part of the Piracicaba watershed responsible for pumping water into the Cantareira System, which is one of the main water sources for the metropolis of São Paulo and Campinas, Brazil. Intensive use of pesticides and hilly topography represents a situation of high risk for river water contamination. Therefore, water samples from 12 locations were collected along the Camanducaia River and its tributaries, over a period of 4?mo during the rainy season, and analyzed by GC-MS/MS or UPLC- MS/MS for the presence of 46 pesticides. Seven pesticides (fipronil, methyl parathion, metolachlor, atrazine, carbofuran, diuron, and simazine) were positively detected. Only atrazine (the most frequently detected) and diuron were present at concentrations above the limit of quantification of the analytical method (0.32 and 0.57?μg L^?1 for atrazine and diuron, respectively). Pesticides detection frequency was higher than expected for a river system where only 11.8% of the land area is under agriculture. The vulnerability of the Camanducaia basin to pesticide contamination is attributed to the high annual precipitation (> 1.5?m y^?1 in the headwaters), associated with topographical features (steep terrain) and soil types that favor surface runoff, which has been exacerbated by poor soil management practices.     

The contribution of azo dyes to the mutagenic activity of the Cristais River

To verify whether dyes emitted within the discharge of a dye processing plant were contributing to the mutagenicity repeatedly found in the Cristais River, Sao Paulo, Brazil, we chemically characterized the following mutagenic samples: the treated industrial effluent, raw and treated water, and the sludge produced by a Drinking Water Treatment Plant (DWTP) located approximately 6 km from the industrial discharge. Considering that 20% of the dyes used for coloring activities might be lost to wastewaters and knowing that several dyes have mutagenic activity, we decided to analyze the samples for the presence of dyes. Thin layer chromatographic analysis indicated the presence of three prevalent dyes in all samples, except for the drinking water. This combination of dyes corresponded to a commercial product used by the industry, and it tested positive in the Salmonella assay. The structures of the dye components were determined using proton magnetic resonance and mass spectrometric (MS) methods, and the dyes were tested for mutagenicity. The blue component was identified as the C.I. Disperse Blue 373, the violet as C.I. Disperse Violet 93, and the orange as C.I. Disperse Orange 37. The dyes showed mutagenic responses of 6300, 4600, and 280 revertants/microg for YG1041 with S9 respectively. A bioassay-directed fractionation/chemical analysis showed that the C.I. Disperse Blue 373 contributed 55% of the mutagenic activity of the DWTP sludge. We showed that these dyes contributed to the mutagenic activity found in the Cristais River environmental samples analyzed and are indirectly affecting the quality of the related drinking water. Therefore, we believe that this type of discharge should be more thoroughly characterized chemically and toxicologically. Additionally, human and ecological risks associated with the release of dye processing plant effluents should be more fully investigated, especially where the resultant water is taken for human consumption.     

Euglena gracilis as a model for the study of Cu2+ and Zn2+ toxicity and accumulation in eukaryotic cells

We have observed the effect of copper and zinc on the biology of Euglena gracilis. The cells displayed different sensitivities to these metals, as the apparent LC50 for Cu2+ was 0.22 mM, and for Zn2+ it was 0.88 mM. While Zn2+ was able to increase cell proliferation even at 0.1 mM, the minimal CuCl2 concentration tested (0.02 mM) was sufficient to impair cell division. Higher concentrations of these metals not only inhibited cell division in a concentration-dependent manner, but also interfered with the metabolism of E. gracilis. A higher accumulation of proteins and lipids per cell was observed at the DI50 concentration for metal-treated cells. These results suggest that the test concentration of both metals leads to a failure in completing cell division. Ultrastructural analysis indicated a chloroplast disorganization in copper-treated cells, as well as the presence of electron dense granules with different shapes and sizes inside vacuoles. Microanalysis of these granules indicated an accumulation of copper, thus suggesting a detoxification role played by the vacuoles. These results indicate that E. gracilis is an efficient biological model for the study of metal poisoning in eukaryotic cells. They also indicate that copper and zinc (copper being more poisonous) had an overall toxic effect on E. gracilis and that part of the effect can be ascribed to defects in the structure of chloroplast membranes.     

An ultrastructural study of Crassostrea angulata (Mollusca,Bivalvia) spermatogenesis

The cytoplasm of Crassostrea angulata (collected from the Atlantic coast of Northern Spain, Galiza, between 1992 and 1993) spermatogonia contains a few proacrosomal dense vesicles and intermitochondrial round granulo-fibrillar dense bodies. In primary spermatocytes, large cytoplasmic spaces appear occupied by large round and more scattered granulo-fibrillar dense bodies which are intermingled with cord-like dense structures and are in close association with mitochondria and the rough endoplasmic reticulum. As a result of Golgian activity, the number of dense proacrosomal vesicles increases and a flagellum arises from the centrioles. During the second meiotic division, several round dense bodies surrounding cord-like dense structures as well as dense proacrosomal vesicles, were observed between chromosomes. During spermiogenesis, no Golgian activity was noticed, and only the rough endoplasmic reticulum was observed in close association with proacrosomal vesicles. Similar results were observed for Ostrea edulis (collected from the Atlantic coast of southern Portugal, Algarve, between 1992 and 1993). Spermatozoa of both species are of the aquasperm type, and although their ultrastructure is quite similar, silver and phosphotungstic acid-chromic acid stainings enabled us to clearly distinguish both species at the ultrastructural level. The different morphological aspects of spermatogenesis in the Pteriomorphia and the use of silver and PTA stainings in the Mollusca are reviewed and discussed.     

Interpolation performance of a spatio-temporal model with spatially varying coefficients: application to PM<Subscript>10</Subscript> concentrations in Rio de Janeiro

In this work we present a Bayesian analysis in linear regression models with spatially varying coefficients for modeling and inference in spatio-temporal processes. This kind of model is particularly appealing in situations where the effect of one or more explanatory processes on the response present substantial spatial heterogeneity. We describe for this model how to make inference about the regression coefficients and response processes under two scenarios: when the explanatory processes are known throughout the study region, and when they are known only at the sampling locations. Using a simulation experiment we investigate how parameter inference and interpolation performance are affected by some features of the data and prior distribution that is used. The proposed methodology is used to model the dataset on PM₁₀ levels in the metropolitan region of Rio de Janeiro presented in Paez and Gamerman (2003).     

Behavioral ecology of the neotropical termite-hunting ant Pachycondyla (= Termitopone) marginata: colony founding,group-raiding and migratory patterns

This study provides the first detailed field account of colony founding, group-raiding and migratory habits in the neotropical termite-hunting ant rPachycondyla marginata, in a semi-deciduous forest in south-east Brazil. New colonies can originate by haplometrosis, pleometrosis, or colony fission. Incipient colonies with multiple foundresses persisted longer in the field, and most excavated nests contained more than one dealated female. A total of 202 group raids by P. marginata were registered, and in all cases the raided termite species was Neocapritermes opacus. Nearly 20% of the workers within a colony engage with raiding activity. Colonies of P. marginata hunt for termites approximately every 2–3 weeks, and group-raids may last for more than 24 h. Target termite nests are up to 38 m from the ant colony, and occasionally two nests are simultaneously raided by one ant colony. Raiding ants carry 1 or 2 paralysed prey, and nearly 1600 termites can be captured during a 9-h raid. Migration by P. marginata colonies lasted over 2 days and covered distances of 2-97 m (n = 48). Average residence time at a given location was 150 days. Three basic migratory patterns were noted: colony fission (only part of the colony moves), long-distance migrations, and short-distance migrations. Both raiding and migratory activities appeared to be strongly affected by seasonal factors. The group raiding and migratory patterns of P. marginata are compared with other ant taxa with similar habits. It is concluded that P. marginata presents a rudimentary form of the so-called army ant behavior, which is highly developed in the subfamilies Dorylinae and Ecitoninae. The extremely specialized diet of P. marginata and the associated high costs of migration are features likely to prevent it from evolving a full army ant life pattern.     

Sorption kinetics of atrazine and diuron in soils from southern Brazil

Sorption kinetics of atrazine and diuron was evaluated in soil samples from a typical landscape in Paraná. Samples were collected (0-20 cm) in a no-tillage area from Mamborê, PR, which has been cultivated under a crop rotation for the last six years. Six sampling points of the slope were selected to represent a wide range of soil chemical and physical properties found in this area. Radiolabeled tracers (14C-atrazine and 14C-diuron) were used and the radioactivity was detected by liquid scintillation counting (LSC). Sorption was accomplished for increasing equilibration periods (0.5, 1.5, 3, 6, 12, 24, and 48 h). Kinetics data fitted adequately well to Elovich equation, providing evidences that soil reaction occurs in two distinct stages: a fast, initial one followed by a slower one. During the fast phase, 34-42 and 71-79% of total atrazine and diuron applied were sorbed to soil samples. No important differences were found among combinations of soil and herbicide sorption during the slow phase. The unrealistic conditions under batch experiments should be overestimating sorption in the fast phase and underestimating diffusion in the slow phase. Sorption of both herbicides was positively correlated to organic carbon and clay contents of soils, but atrazine was much less sorbed than diuron, showing its higher potential to contaminate groundwater, specially in sandy, low organic carbon soils.     

The use of Microtox to assess toxicity removal of industrial effluents from the industrial district of Camaçari (BA, Brazil)

The treatment efficiency, as toxicity removal, of complex effluents from the Industrial District of Cama?ari (BA, Brazil), after biological treatment with activated sludge was evaluated using Microtox. Samples of the equalised effluent (EE) were collected prior to treatment together with samples of the treated effluent (TE), which remained 24 h in the treatment plant. Rehydrated colonies of Vibrio fischeri were exposed to sequential dilutions of EE and TE to assess luminosity interference. Values for EC50 were calculated, together with the respective toxicity units. In all, twenty assays of each effluent type were carried out and the mean toxicity removal was 92.71%, while the chemical oxygen demand (COD) presented mean reduction of 83.04%. There was a variability of an order of magnitude between the Microtox results for the two types of effluents. The mean EC50 values were 2.12 for EE and 47.78% for TE. In spite of its weakness in some conditions, the Microtox system demonstrated to work adequately in assessing effluent toxicity removal in this treatment plant and therefore can be used for further toxicity removal programs.     

Sugarcane straw management for bioenergy: effects of global warming on greenhouse gas emissions and soil carbon storage

Mitigation and Adaptation Strategies for Global Change - Global warming can intensify the soil organic matter (SOM) turnover, damaging soil health. Crop residues left on the soil are important to...