Evaluation of the e ectiveness of horizontal subsurface flow constructed wetlands for di erent media

Two media bed (gravel and Filtralite NR) were tested in a mesocosm to evaluate the removal of organic matter (as chemical oxygen demand (COD)), ammonia (NH4-N), nitrite, nitrate and solid matter (as total suspended solids (TSS)) for a synthetic wastewater (acetate-based) and a domestic wastewater. The use of Filtralite allowed average removal rates (6–16.8 g COD/(m2 day), 0.8–1.1 g NH4-N/(m2 day) and 3.1 g TSS/(m2 day)) and removal e ciencies (65%–93%, 57%–85% and 78% for COD, NH4-N and TSS, respectively), higher than that observed in the experiments with gravel. The applied loads of COD, ammonia, nitrate and TSS seem to influence the respective removal rates but only for the treatment of domestic wastewater with higher correlation coe cients for Filtralite. Regardless the type of media bed and the type of wastewater, nitrate was completely removed for nitrogen loading rates up to 1.3 g NO3-N/(m2 day). There was no evidence of the influence of nitrate loads on the removal of organic matter.     

Origin of compartmentalization in food webs

The response of an ecosystem to perturbations is mediated by both antagonistic and facilitative interactions between species. It is thought that a community's resilience depends crucially on the food web--the network of trophic interactions--and on the food web's degree of compartmentalization. Despite its ecological importance, compartmentalization and the mechanisms that give rise to it remain poorly understood. Here we investigate several definitions of compartments, propose ways to understand the ecological meaning of these definitions, and quantify the degree of compartmentalization of empirical food webs. We find that the compartmentalization observed in empirical food webs can be accounted for solely by the niche organization of species and their diets. By uncovering connections between compartmentalization and species' diet contiguity, our findings help us understand which perturbations can result in fragmentation of the food web and which can lead to catastrophic effects. Additionally, we show that the composition of compartments can be used to address the long-standing question of what determines the ecological niche of a species.     

The reproductive cycle of <Emphasis Type="Italic">Scolelepis goodbodyi</Emphasis> (Polychaeta,Spionidae)

The aim of this study was to examine the reproductive and gametogenic cycle of the spionid polychaete Scolelepis goodbodyi (Jones). Every 15 days, in the upper level of the intertidal zone on Barequeçaba Beach in southeastern Brazil, a 100 m² area was delimited and within it three points were selected and sampled using a core sampler 0.01 m² in area × 0.2 m long. Each sample was divided into three sub-samples: surface (2 cm) and middle (8 cm), which were sieved through 0.5, 0.25 and 0.125 mm mesh sieves; and lower (10 cm), sieved through 1.0 and 0.5 mm mesh sieves. Males, females and undetermined individuals were separated, and the width of the third setiger was measured. The gonadal development of each individual was classified based on external features of the gametogenic setigers. Ten to 20 adults from each sampling period were classified according to their gonadal development stage and then analyzed histologically for gametogenic studies, for comparison with the former classification. Some of the ripe females were used for fecundity evaluation. The diameters of the oocytes were measured prior to spawning. Eight hundred and twenty-eight females (29.70%), 848 males (30.42%) and 1,112 undetermined individuals (39.89%) were analyzed. The sex ratio did not differ significantly from unity (χ² = 0.24; df = 1; P < 0.05). Males and females were more abundant in May 2002 (ca. 80%) and between November 2002 and May 2003 (between 77 and 90%); the proportion of undetermined individuals did not represent recruitment alone, but also a high incidence of adults with recovering gonads. Fecundity varied from 134 oocytes in a 0.54 mm W3 individual to 289 oocytes in a 0.4 mm W3 individual, with a mean of 220 (SD = 57) oocytes per female and 19 (SD = 5) oocytes per gametogenic setiger. Oocytes were ellipsoid, and ranged in size from 150 × 80 (to 220 × 120 μm (mean ± SD = 173 × 113 ± 15 × 11 μm). Neither a well-defined gametogenic cycle nor synchrony in the reproductive period was observed, because many gonadal development stages occurred in each month. Nevertheless, peaks of maturity were observed between October–December 2002 and April–May 2003.     

Image analysis application for the study of activated sludge floc size during the treatment of synthetic and real fishery wastewaters

Background, aim, and scope  

Fishery wastewater treatment can be compromised due to seasonal production. The use of sequencing batch reactors is not completely successful, despite flexibility being one of the principal advantages. Most research on activated sludge is performed using synthetic wastewater to ensure a stable and constant feed. The current work compared biomass morphology and settling ability using image analysis of synthetic and real fishery wastewaters, with and without NaCl addition.     

The use of a lacertid lizard as a model for reptile ecotoxicology studies: part 2--biomarkers of exposure and toxicity among pesticide exposed lizards

As part of a wider study examining the impacts of corn pesticides on lacertid lizards in north-western Portugal, we examined various physiological, biochemical, and histological biomarkers of exposure and effect among field populations of Podarcis bocagei. Biomarkers included body condition index, standard metabolic rate, locomotor performance, parasitization, glutathione oxidative pathways and related enzyme activity, lipid peroxidation and liver and testis histology. Few of the various biomarkers investigated provided statistically significant evidence of toxic effect. However, using a weight of evidence approach, we conclude that pesticides are affecting lizards living in the vicinity of pesticide exposed corn agriculture sites. Lizards from these locations present a profile of animals under metabolic stress with reduced condition indices, increased standard metabolic rate, lower incidence of hepatocyte vacuolation, altered iron metabolism, increased activation of GSH oxidation pathways, and even increased prevalence of hemoparasites.     

Evaluation of the 226Ra transport by river sediments surrounding the Brazilian uranium mining and milling facilities

A study of the (226)Ra contamination of the river sediments surrounding the Brazilian uranium mining and milling facilities was carried out. The nondetrital (226)Ra concentrations were determined performing a 0.5 N HCl leaching. Some preliminary speciations experiments using Tessier's sequential extraction procedure were also carried out. (228)Ra was used as a monitor of the natural variations. In general one could not observe increase in the non-detrital (226)Ra fraction between the pre-operational and operational data. Additionally, speciations experiments have shown the exchangeable fraction to be the main one responsible for (226)Ra content. Although the results indicate that the sediment is an important means of radium downstream transport, its availability suggests the soluble form to be the main path through the main foodchain. Attention must be paid to the release of (226)Ra bound to barium sulphate from the chemical processing effluent since increments of that fraction were observed in bottom sediments.     

Mean sea-level rise impacts on Santos Bay, Southeastern Brazil – physical modelling study

The greenhouse effect and resulting increase in the Earth’s temperature may accelerate the mean sea-level rise. The natural response of bays and estuaries to this rise, such as this case study of Santos Bay (Brazil), will include change in shoreline position, land flooding and wetlands impacts. The main impacts of this scenario were studied in a physical model built in the Coastal and Harbour Division of Hydraulic Laboratory, University of São Paulo, and the main conclusions are presented in this paper. The model reproduces near 1,000 km² of the study area, including Santos, São Vicente, Praia Grande, Cubatão, Guarujá and Bertioga cities.     

Assessing the transformation of chlorinated ethenes in aquifers with limited potential for natural attenuation: added values of compound-specific carbon isotope analysis and groundwater dating

The evaluation of biotransformation of chlorinated ethenes (CEs) in contaminated aquifers is challenging when variable redox conditions and groundwater flow regime are limiting factors. By using compound-specific stable carbon isotope analysis (C-CSIA) and ³H-³He based groundwater dating, we assessed three CE-contaminated field sites that differed in groundwater flow velocities, redox conditions, and level of contamination. CE isotopic signatures and carbon isotopic mass balances were applied to quantify CE transformation, whereas groundwater dating allowed determining degradation timescales and assessing hydrodynamic regimes. The combination of these techniques enabled at all field sites to indicate zones within the aquifers where CE dechlorination preferably occurred, sometimes even to metabolites of no toxic concern. However, the natural transformation processes were insufficient to mitigate the entire CE contamination at the studied sites. Such situations of limited transformation are worldwide far more common than sites where optimal natural (mainly redox) conditions are enabling complete CEs degradation. Despite such constraints for natural transformation, this study showed that even under non-favorable biogeochemical CEs degradation, the combination of CSIA and groundwater dating provide valuable information to the understanding of the fate of the CEs, thus, being an important contribution in the definition of efficient remediation measures at any given biogeochemical conditions.     

Bioavailable metals and cellular effects in the digestive gland of marine limpets living close to shallow water hydrothermal vents

The pressure exerted by shallow water hydrothermal vents on edible gastropods and their cellular responses triggered by these stresses are almost unknown. The aims of this study were to evaluate the bioavailability of metals in the Macaronesian endemic limpet Patella candei gomesii living close to shallow water hydrothermal vents, and the structural differences in their digestive gland as well as the levels of apoptosis in that organ. Limpets were sampled in four sites, two with the presence of hydrothermalism and the other two without it. Whole body concentrations of several metals (Ca, Cd, Cs, Co, Cu, Fe, Hg, Mg, Mn, Pb, Rb, Se, Sr, and Zn) were obtained, morphometry analysis of the digestive gland and TUNEL test for apoptosis were also performed. Results revealed that the presence of shallow water hydrothermal vents is a source of chronic metal stress to limpets, imposing modifications in the morphometry and cell composition of the digestive gland of those limpets that may constitute cell and tissue adaptations to the environment they live in. This study sets up new baseline data for further research on the influence of shallow water hydrothermal vents over communities living in these habitats.