Evaluation of genotoxicity and toxicity of water and sediment samples from a Brazilian stream influenced by tannery industries

This paper reports results of genotoxicity and toxicity studies of water and sediment samples collected from the Estancia Velha stream of southern Brazil, a stream transporting both domestic sewage and effluents from regional factories working in the leather industry. Three sites were selected: in the stream headwaters (Site 1), located downstream of an urban area (Site 2), and near the basin outfall (Site 3). Results obtained with Allium cepa showed no evidence of chromosomal mutation, either in water or in sediment, during winter or summer seasons, but samples collected below Site 1 showed high toxicity. Physical and chemical analyses showed high concentrations of pollutants at these sites. Ecotoxicity tests with Daphnia magna and Ceriodaphnia dubia measured toxicity in water from Sites 2 and 3 in summer 2004. A toxic effect on Hyalella azteca was only found in sediment from Site 3 during winter 2003 and summer 2004. The results suggest that the synergy among different compounds in domestic and industrial sewage discharges can make it difficult to maintain system stability.     

Modifying sorbents in controlled release formulations to prevent herbicides pollution

The herbicides chloridazon and metribuzin, identified as groundwater pollutants, were incorporated in alginate-based granules to obtain controlled release properties. In this research the effect of incorporation of sorbents such as bentonite, anthracite and activated carbon in alginate basic formulation were not only studied on encapsulation efficiency but also on the release rate of herbicides which was studied using water release kinetic tests. In addition, sorption studies of herbicides with bentonite, anthracite and activated carbon were made. The kinetic experiments of chloridazon and metribuzin release in water have shown that the release rate is higher in metribuzin systems than in those prepared with chloridazon, which has lower water solubility. Besides, it can be deduced that the use of sorbents reduces the release rate of the chloridazon and metribuzin in comparison to the technical product and to the alginate formulation without sorbents. The highest decrease in release rate corresponds to the formulations prepared with activated carbon as a sorbent. The water uptake, permeability, and time taken for 50% of the active ingredient to be released into water, T(50), were calculated to compare the formulations. On the basis of a parameter of an empirical equation used to fit the herbicide release data, the release of chloridazon and metribuzin from the various formulations into water is controlled by a diffusion mechanism. Sorption capacity of the sorbents for chloridazon and metribuzin, ranging from 0.53mgkg(-1) for the metribuzin sorption on bentonite to 2.03x10(5)mgkg(-1) for the sorption of chloridazon on the activated carbon, was the most important factor modulating the herbicide release.     

Biochemical mechanisms of resistance in Daphnia magna exposed to the insecticide fenitrothion

Resistance to fenitrothion and enzyme activities associated with the toxicity and metabolism of organophosphorus insecticides were measured in three genetically unique Daphnia magna clones collected from rice fields of Delta del Ebro (NE Spain) during the growing season and a lab sensitive clone. The studied clones showed up to sixfold differences in resistance to fenitrothion. The lack of correlation between in vitro sensitivity of acetylcholinesterase (AChE) to fenitrooxon and resistance to fenitrothion indicated that insensitivity of AChE to the most active oxon metabolite was not involved in the observed differences in resistance. Inhibition of mixed- function oxidases (MFOs) by piperonyl butoxide (PBO) increased the tolerance to fenitrothion by almost 20-fold in all clones without altering their relative ranking of resistance. Conversely, when exposed to fenitrooxon, the studied clones showed similar levels of tolerance, thus indicating that clonal differences in the conversion of fenitrothion to fenitrooxon by MFOs were involved in the observed resistance patterns. Despite that resistant clones showed over 1.5 higher activities of carboxilesterase (CbE) than sensitive ones, toxicity tests with 2-(O-cresyl)-4H-1,3,2-benzodioxaphosphorin-2 oxide, which is a specific inhibitor of these enzymes, evidenced that this system only contributed marginally to the observed clonal differences in tolerance. Glutathione-S-transferases activity (GST) varied across clones but not under exposure to fenitrothion, and was only related with tolerance levels in the field clones. In summary, our results indicate that MFO mediated differences on the bio-activation of the phosphorotionate OP pesticide to its active oxon metabolite contributed mostly in explaining the observed moderate levels of resistance, whereas the activities of CbE and GST had only a marginal role.     

ARX modeling approach to leak detection and diagnosis

This work presents a time series strategy for detection, location and quantification of leaks in large pipeline systems. The technology has two active components, which operate sequentially: the Detector and the Localizer. The Detector continuously screens real-time data, searching for any anomalies such as leaks, which are detected (or not) depending on their size and position. The Detector is based on auto-regressive multi-input/multi-output (MIMO) ARX predictors with one input filter. Subsequent to successful leak detection, the Localizer is launched to diagnose the leak via estimation of its parameters – diameter and location – using recorded data on a Search Time Window that includes information in the neighborhood of the instant of detection. The Localizer is also an ARX predictor, but with two input processors, the first is a filter for dynamic plant inputs and the second filter processes “parameter signals” of active leaks. The Localizer is developed beforehand via model identification with plant data under the action of known, artificially simulated, leaks. It is, therefore, able to recognize an active pattern of leak parameters, by maximizing the adherence of its predictions to data in the Search Time Window. The proposed detection and location methods were successfully tested in simulated leak scenarios for an industrial naphtha pipeline.     

Virological Characterization of Roof-Harvested Rainwater of Densely Urbanized Low-Income Region

Food and Environmental Virology - Roof-harvested rainwater (RHRW) is considered relatively clean water, even though the possible presence of pathogens in the water may pose human health risks. In...     

Conserving the species-rich meadows of Europe

Owing to changes in agricultural practices throughout Europe, with greater emphasis on intensification, traditionally managed hay meadows have become scarce. Their loss has also meant the loss of species diversity. One of the few areas of Europe where traditional management is still practised is in Northern Spain.The hay meadows of Northern Spain can be defined as semi-natural, species-rich communities that are maintained by one or more factors which are under the direct control of man. The traditional management to which they are subjected has led to a high species diversity. For centuries the meadows have been important to man in supporting cattle during the winter. There is now little need for further increase of production. However, the importance of the need for conservation of species diversity and protection of ecologically sensitive areas is now recognised. Although the biological richness of the hay meadows is well known, few studies have been made of the effects of different traditional management regimes on the diversity and floristic composition of these grasslands.A survey was carried out to examine the effects of traditional management on the floristic composition, diversity and production of these meadows. The area studied is situated in the Valdeón valley, northwestern Spain (Cantabrian Mountains) and consists of a deep valley in which arboreal vegetation is represented by beech (Fagus sylvatica) forests. The survival of semi-natural habitats and traditional forms of management and also the low use of chemical fertilisers compared with Northern Europe are the most important reasons for the richness of these habitats. In this study, cutting for hay once per year, non-irrigation non-manuring and grazing in autumn was correlated with high species diversity. The future conservation of these habitats will depend on the formulation of support to continue with traditional management practices.     

Comparison of mass concentrations of SO2 determined in air by two different methods

Mass concentrations of sulphur dioxide were determined in parallel 24-hour samples of ambient air at a measuring site in Zagreb during a period of eight years. The methods used were the West-Gaeke's tetrachloromercurate-pararosaniline method (TCM) and the Standard British Method (SBM). Total results for the annual intervals of measuring were analyzed statistically and also discussed separately for winter and summer periods, in order to see whether they are influenced by seasonal rhythm.     

Rapid molecular prenatal diagnosis of ataxia-telangiectasia by direct mutational analysis

Mutations of the ataxia-telangiectasia-mutated (ATM) gene are responsible for the autosomal recessive disorder ataxia-telangiectasia (A-T). This study reports the first A-T prenatal diagnosis performed in Spain by direct molecular analysis. The pregnant woman had a previous child suffering from A-T due to a deletion in the ATM gene. The ATM coding region was sequenced in the A-T patient and her parents. Then, a specific polymerase chain reaction (PCR) to detect the deletion was performed for prenatal diagnosis. Additionally, polymorphic HLA loci were examined in order to exclude the possible contamination by maternal DNA. In this family of Gypsy origin, we carried out a rapid molecular diagnosis of A-T. Then, a prenatal diagnosis was carried out, identifying the deletion in the fetal DNA. Additionally, we performed a population study in unrelated Spanish Gypsies and in unrelated controls, showing that the deletion described could be a hotspot in the Spanish Gypsy population. The size of the coding region and the genomic structure, together with the absence of hotspots, make the mutation screening of the ATM gene difficult. The ability to identify ATM mutations provides a tool that can be applied in confirmatory diagnosis, genetic counselling, carrier prediction and prenatal diagnosis. Copyright © 2007 John Wiley & Sons, Ltd.