Micro-spatial variation of soil metal pollution and plant recruitment near a copper smelter in Central Chile

Soil chemical changes produced by metal smelters have mainly been studied on a large scale. In terms of plant survival, determination of small scale variability may be more important because less toxic microhabitats may represent safe sites for successful recruitment and thus for plant survival. Three dominant microhabitats (open spaces and areas below the canopy of Sphaeralcea obtusiloba and Baccharis linearis shrubs) were defined in a heavily polluted area near a copper smelter and characterised in terms of microclimate, general soil chemistry, total and extractable metal concentrations in the soil profile (A0 horizon, 0-5 and 15-20 cm depth), and seedling densities. Results indicated a strong variability in microclimate and soil chemistry not only in the soil profile but also among microhabitats. Air/soil temperatures, radiation and wind speed were much lower under the canopy of shrubs, particularly during the plant growth season. Soil acidification was detected on top layers (0-5 cm depth) of all microhabitats while higher concentrations of N, Cu and Cd were detected on litter and top soil layers below shrubs when compared to open spaces; however, high organic matter content below shrubs decreased bioavailability of metals. Plant recruitment was concentrated under shrub canopies; this may be explained as a result of the nursery effect exerted by shrubs in terms of providing a more favourable microclimate, along with better soil conditions in terms of macronutrients and metal bioavailability.     

Study of fractionation and potential mobility of metal in sludge from pyrite mining and affected river sediments: changes in mobility over time and use of artificial ageing as a tool in environmental impact assessment

Sludge from mining exploitation can be a source of land and water contamination in the adjacent zone. Accidents such as the break of waste mining pools in the Aznalcollar Mine (Seville, Spain) in 1998 produce important ecological disasters. In this work is presented a study of the evolution of aqua regia leachable concentration and mobility of metals in sediment samples of Guadiamar River basin from the accident date up to 2001. The application of BCR standard extraction procedures provides valuable information about the mobility and toxicity of the spill and the metal mobility in Guadiamar River polluted sediments. As a rule, themobility of several metals in the initial sludge (sulphides) is low, except for copper. Otherwise, the results of aqua regia leachable concentration and mobility of metal obtained for sediments samples indicate that the cleaning and inertisation works carried out in the zone have been adequate but insufficient, being the metal levels observed in the zone are higher than natural levels. To establish the initial impact of the spill and the mobility changes with time, mineralogical composition of the pyritic sludge and its evolution after the natural weathering and after the induction, of accelerated ageing processes by light and temperature was studied in the laboratory. Oxidation of initial sulphides to sulphates was observed. Both environmental and laboratory oxidation of the metallic sulphides increase the mobility of all metals, especially of copper, zinc and lead. The proposed laboratory procedure allows to predict the changes in mobility and therefore in toxicity that can occur at short or long term after exposure of sludge at environ-mental conditions. The mobility results in sludge and sediment samples are interpreted in terms of the mineral composition of the samples.     

Heterospecific call recognition and phonotaxis in the orientation behavior of the marbled newt,Triturus marmoratus

The role of acoustic cues as reference cues for orientation by amphibians has been demonstrated in anurans, the only amphibian group that engages in acoustic communication, but not in urodeles. Orientation responses of marbled newts, Triturus marmoratus, were studied to determine whether heterospecific calls elicited positive phonotaxis. The orientation tests consisted in presenting either a familiar acoustic stimulus, the advertisement calls of natterjack toads (Bufo calamita), or a control stimulus, the advertisement calls of European green toads (Bufo viridis) that the newts would not be expected to recognize. Marbled newts and natterjack toads occur in simpatry, but T. marmoratus and B. viridis are allopatric species. Thus, T. marmoratus is distributed over the northern half of the Iberian Peninsula, whereas B. viridis occurs in the Balearic Islands, but not over the Iberian Peninsula. Newts were released in a circular arena while a recorded chorus of natterjack toads or European green toads played outside the arena to determine whether they displayed positive phonotactic orientation. Our results show that marbled newts performed positive phonotaxis when exposed to the breeding calls of natterjack toads, but not to those of European green toads. Newts chose a compass course in the direction of the advertisement calls of B. calamita. Acoustic information might improve orientation accuracy. This study is the first to provide evidence of heterospecific call recognition and positive phonotactic response in urodeles.Communicated by W. Wiltschko     

Superciliums in white-eared hummingbirds as badges of status signaling dominance

The role of badges as indicators of contest ability has been previously described. In hummingbirds, the exhibition of a badge is expected to save energy expenditure in agonistic interactions and to favor energy intake. Here, we investigate whether variable supercilium size in the white-eared hummingbird has a role in dominance status signaling. Firstly, 45 hummingbird males were captured and their superciliums were photographed to investigate variation in size and any possible allometric relationships. Secondly, 42 male birds were used to analyze whether the supercilium has a role in dominance status signaling in a dyadic contest. We found that supercilium size varied continuously but that despite variability between individuals, there was no relationship between supercilium size and body size. However, our dyad experiment indicated that birds with larger badges were able to make more visits to the feeders than individuals with smaller badges. We suggest a status signaling function of the supercilium.     

Elemental composition of otolith growth marks in three geographically separated populations of European hake (Merluccius merluccius)

The composition of the opaque and translucent bands in the otoliths of European hake (Merluccius merluccius) from three different populations (Celtic Sea, Galicia shelf and Cretan Sea) was analysed with wavelength dispersive spectrometry (WDS) and differences in Ca, Sr and Na were compared. The translucent bands (annual marks and checks altogether) were significantly richer in Sr and Ca and significantly poorer in Na than opaque bands. Results support the idea of a more compact arrangement of crystals in translucent bands compared to opaque. Analyses did not help to discriminate between putative annual marks and checks. Clear differences in the range of Sr/Ca variation across the otolith as well as in the composition of the otolith core were observed among the three populations. As a result it was possible to discriminate the natal origin of each fish using the composition of the otolith core in Ca, Sr and Na. Nevertheless, the overall pattern across the otolith was similar among the three populations suggesting the existence of ontogenetic trends. Variation of Na/Ca ratios was largely uninformative. Based on these results, a conceptual model for hake is proposed which integrates the different sources of otolith Sr/Ca variation: ambient Sr/Ca, endogenous cues (ontogeny) and exogenous cues (environment).     

Recovery of Durvillaea antarctica (Durvilleales) inside and outside Las Cruces Marine Reserve, Chile.

We present the results for over two decades of monitoring on intertidal food-gatherers and the population of the low rocky shore dweller kelp Durvillaea antarctica, a short-distance disperser, inside and outside the no-take marine reserve, Estacion Costera de Investigaciones Marinas (ECIM), at Las Cruces, central Chile. It was hypothesized that protection of an initially extremely depleted population would recover by recolonizing first the no-take area and then adjacent non-protected (exploited) areas. We found that recovery of D. antarctica occurred slowly inside ECIM, with increase in density and biomass, of up to three orders of magnitude as compared to an adjacent non-protected area, which showed approximately 2-yr delay. These results suggest that the kelp population inside ECIM was likely regulated via intraspecific competition, which did not occur outside. Results showed no evidence for juvenile vs. adult density dependence other than a weak relationship for the central area of ECIM. These findings also suggest that the population recovery and cross-boundary seeding subsides affected the population dynamics. Understanding these dynamics may enhance management and conservation policies. Our work highlights the critical value of baseline and long-term comparative studies in marine no-take protected and non-protected areas for understanding how population processes respond to human and conservation practices.     

Effectiveness in the use of natural gas for the reduction of atmospheric emissions: case study--industrial sector in the metropolitan region of Santiago,Chile

The purpose of this investigation was to quantify the potential of natural gas to reduce emissions from stationary combustion sources by analyzing the case study of the metropolitan region of Santiago, Chile. For such purposes, referential base scenarios have been defined that represent with and without natural gas settings. The method to be applied is an emission estimate based on emission factors. The results for this case study reveal that stationary combustion sources that replaced their fuel reduced particulate matter (PM) emissions by 61%, sulfur oxides (SOx) by 91%, nitrogen oxides (NOx) by 40%, and volatile organic compounds (VOC) by 10%. Carbon monoxide (CO) emissions were reduced by 1%. As a result of this emission reduction, in addition to reductions caused by other factors, such as a shift to cleaner fuels other than natural gas, technological improvements, and sources which are not operative, emission reduction goals set forth by the environmental authorities were broadly exceeded.     

Effects of customized foot orthoses on manufacturing workers in the metal industry

This 8-week study evaluates the effects of customized foot orthoses on work-related musculoskeletal disorders (WMSDs) of metal industry workers. These WMSDs were evaluated applying the Nordic musculoskeletal questionnaire (NMQ) at three different times (start, 4th week and 8th week) and additional questions were also formulated to obtain information about adaptation, fatigue, comfort and possible improvements. According to the NMQ results, statistical significance was found in the improvements after 4?weeks (p?<?0.05 in two areas, p?<?0.01 in three areas, p?<?0.001 in two areas and no significance in the other two) and after 8?weeks (p?<?0.01 in three areas, p?<?0.001 in four areas and no significance in the other two). The additional questions indicated fatigue reduction (both in general and in lower extremity), comfort level increase (after the adaptation period) and good acceptance, according to workers’ answers, suggesting customized orthoses can be effective in reducing and preventing WMSDs in several body regions.