Levels of plasma B-esterases and glutathione-S-transferase activities in three South American toad species

We determined the normal levels of butyrylcholinesterase (BChE), carboxylesterase (CbE), and glutathione S-transferases (GST) activities in three South American toad species in order to establish reference values for field pesticide monitoring purposes. Interspecies variations in B-esterase and GST activities were examined according to body mass. In addition, comparative inhibition of BChE and CbE activities using malaoxon, and chemical reactivation of malaoxon-inhibited BChE activity using pyridine-2-aldoxime methochloride (2-PAM) were investigated. Bufo fernandezae had average activity values for BChE: 17.31 mmol min^?1 ml^?1; CbE: 621.49 nmol min^?1 ml^?1 and GST: 1.94 mmol min^?1 ml^?1 while B. arenarum enzymatic average activities were BChE: 9.51 mmol min^?1 ml^?1; CbE: 270.07 nmol min^?1 ml^?1, and GST: 1.59 mmol min^?1 ml^?1; finally Bufo schneideri had enzymatic mean values of BChE: 2.08 mmol min^?1 ml^?1; CbE: 301.95 nmol min^?1 ml^?1, and GST: 1.60 mmol min^?1 ml^?1. Moreover, we found an allometric relationship between plasma BChE and CbE activities and body size for the three toad species. We suggest that B. fernandezae would be the species with a higher tolerance capacity to organophosphorous insecticides compared to the other toad species, while B. schneideri may be the most vulnerable toad species to field pesticide exposure, although some other factors (e.g., brain AChE sensitivity or pesticide metabolism by phosphotriesterases) should be also taken into account. The malaoxon-inhibited BChE activity of the three toad species was reactivated in the presence of 2-PAM, and it is recommended as a specific and sensitive methodology in the assessment of field exposure to OP insecticides together to compare BChE activity levels between OP-exposed and nonexposed individuals.     

Automated indirect fluoride determination by ICP-OES using discontinuous-flow analysis

An automated method for the indirect determination of fluoride by inductively coupled plasma atomic emission spectrometry using discontinuous-flow analysis has been developed. A modified flow injection analysis system was used for sample preparation. The method is based on the determination of excess cerium(III) ion after precipitation of CeF₃. Separation of the precipitate is performed online on a syringe membrane filter that is cleaned each analysis cycle by 1 M nitric acid, ensuring a long life-time for the filter. As a result of the short reaction time, a detection limit of 9.5 mg L^?1 was obtained. The precision (RSD) of the proposed method is 1.02% at fluoride concentration of 28 mg L^?1. The applicability of the technique for groundwater monitoring of fluoride-contaminated area is demonstrated.     

Cadmium accumulation by green algae Cladophora glomerata (L.) Kutz. (Chlorophyta) in presence of Nile tilapia Oreochromis niloticus (L.)

Accumulation of metals by aquatic organisms is mostly affected by other biological components in environments. In this study, cadmium (Cd) accumulation in green algae, Cladophora glomerata (L.) Kutz., exposed to 0.1 and 1.0 mg L^?1 of Cd for 15 and 30 days was examined in laboratory conditions in the presence of Nile tilapia Oreochromis niloticus (L.). The green algae C. glomerata accumulated Cd concentrations as 690 ± 70 and 3430 ± 470 mg kg^?1 on day 15, and 1130 ± 180 and 6830 ± 1540 mg kg^?1 on day 30. There were significant increases (p < 0.05) in metal accumulation by green algae as the exposure time and metal concentration increased. The results also indicated that the presence of Nile tilapia in the medium led to a significant Cd accumulation in the green algae compared to control (p < 0.05).     

Presence of metals in drinking water distribution networks due to pipe material leaching: a review

Drinking water quality should remain constant from the drinking water treatment plant to the consumer's tap. However, water quality characteristics might be affected by interactions with pipe materials. This review describes the iron, copper, lead, zinc, aluminum, chromium, and cadmium in drinking water leached from the pipe material present in drinking water, as well as the factors and mechanisms that affect leaching processes. Data analysis suggests that monitoring the water quality in distribution systems is important for their proper management; however, the low measured concentrations highlight the need for sensitive sensors. In addition, further research is necessary to anticipate possible future effects before the installation of new materials/infrastructure or changes in water source/treatment.     

Rainwater composition as a function of the cloud type

The influence of the type of clouds that produce precipitation in the rainwater composition was analyzed. Logroño, a remote station in the North of Spain was chosen for the analyses. Results prove that the rainwater composition from Cumulonimbus is different to the composition of the rainwater from the other clouds. In addition, the source of NO₃ ^? and SO₄ ^2? is studied in the different types of clouds. It is shown that the source is the soil except Stratocumulus formed from Cumulus in which the source is the gas‐particle conversion.     

Project tocoen. The fate of selected organic pollutants in the environment—iv. soil,earthworms and vegetation 1988

The samples of soils, earthworms and vegetation (needles, lichens, mosses) were collected for the realization of Project TOCOEN (Toxic Organic Compounds in the ENvironment). The samples were collected from three TOCOEN model areas in Czechoslovakia—one city and two rural areas. The samples were analyzed for polycyclic aromatic hydrocarbons (PAHs), chlorinated pesticides (C1‐PEST) and polychlorinated biphenyls (PCBs).     

Charge‐transfer chromatographic study of the interaction of commercial pesticides with hydroxypropyl‐β‐cyclodextrin

The interaction between 33 commercial pesticides with hydroxypropyI‐β‐cyclodextrin (HPBCD) was studied by charge‐transfer reversed‐phase thin‐layer chromatography using aqueous sodium chloride solutions as eluents. Each pesticide interacted with HPBCD, their lipophilicity linearly decreased with increasing HPBCD concentration, the pesticide ‐ HPBCD complex (probably inclusion complex) always being more hydrophilic than the uncomplexed pesticide. In many cases the retention of pesticide increased with increasing concentration of salt in the eluent. This effect can be tentatively explained by the suppression of the dissociation of the polar groups in the solute molecules resulting in increased apparent lipophilicity. No significant correlation was found between lipophilicity and complex stability or between salting‐out effect and lipophilicity, that is other than hydrophobic forces are involved in the pesticide ‐ HPBCD interaction.     

Ground water pollution by pesticides at the watershed‐soil catena scale: Lindane at the lower Colorado river basin (Argentina)

The movement of Lindane from application points at the surface soil towards the underground water and further transport within this compartment at the watershed‐soil catena scale, was inspected by measurements of the pesticide concentration in soil water at a controlled experiment where it was applied at a usual label dose. The concentrations of Lindane in soil water and the upper phreatic level were also measured at successive dates in samples obtained from a net of phreatimeter probes distributed over the area (1,500 km²) of the lower Colorado River basin (Bs. Aires, Argentina). The location of cultivated‐irrigated areas within the watershed was inferred from NDVI (Normalized Difference Vegetation Index)‐1 km‐10 day AVHRR images obtained at successive dates during the irrigation season. Feasible paths of underground gravitational water flows were computed by means of a GIS‐simulation model on the basis of local terrain slopes and aspects. The pattern of Lindane distribution over the basin was explained on the basis of the distribution of diffuse sources, the patterns of percolation and groundwater flows and the thermodynamic characteristics of the pesticide.     

Natal dispersal in two mice species with contrasting social systems

We compared the natal dispersal behaviour of two mice species under laboratory conditions. Natal dispersal is a movement of an animal from its birthplace to its breeding area. This behaviour is known to be influenced by the mating system. In polygamous species, males are more likely to disperse, while in most of the monogamous species, both sexes disperse. Our subjects, the house mouse (Mus musculus) and the mound-building mouse (Mus spicilegus) are two sympatric species of the genus Mus. Both are native in Hungary, but they differ in their habitat type mating system and overwintering strategy. The house mouse is a polygynous species and adapted to human environment, known for mature and reproduce early. On the contrary, the mound-building mice are monogamous, and they inhabit extensively used agricultural fields, where they spend the unfavourable winter period in nest chambers under mounds, which they construct from soil and plant material. Successful overwintering for this species demands delayed maturity and reduced dispersion during the winter. Our results showed that the natal dispersal of these two species differ; both sexes of the mound-building mice dispersed later than the house mice, where a difference between sexes also occurs; house mice males dispersed earlier than females. The mound-building mice showed no sexual dimorphism in this behaviour.     

Dealing with urban noise: vermilion flycatchers sing longer songs in noisier territories

In noisy conditions, several avian species modulate their songs in amplitude and in the temporal or frequency domains, presumably to improve communication. Most studies on how passerine birds perform such adjustments have been carried out in oscines, a group well known for the importance of learning in the development of their songs. On the other hand, suboscines, in which learning appears to have little influence on the development of their songs, have been largely neglected. We evaluated song adjustment to noise in the vermilion flycatcher (Pyrocephalus rubinus), a suboscine bird. We conducted song recordings and noise measurements at several territories within Mexico City during the length of the dawn chorus. Males living in noisier places sang long songs, while those males inhabiting quieter places sang both short and long songs. We also found evidence of individual song plasticity, as males sang less versatile songs (i.e., songs with more introductory elements) later in the morning when noise levels were higher. This individual shift in song seems to be more associated to time of the day rather than to the observed rise in noise. However, we cannot discard an effect of noise, which should be evaluated with an experiment. We discuss our results in the context of other studies with oscine passerines and other taxa and consider implications for signaling in intra- and intersexual contexts.