Sulfur, chromium, and selenium accumulated in Chinese cabbage under direct covers

Currently, pollution of our agricultural soils and waters is increasing and is often associated with many human health ailments. Soils contaminated with low levels of heavy metals and other trace elements are frequently used for growing vegetable crops and in such a situation, these toxic contaminants often accumulate in the edible portions of these agricultural plants and thereby enter the human food chain. In 3 consecutive years of field experiments (1994-1996), two different crop-covering treatments--T (50 microm perforated polyethylene), and T2 (17 gm(-2) non-woven polypropylene)--were used to modify the environmental conditions for the growth of Chinese cabbage 'Nagaoka 50' [Brassica rapa L. (Pekinensis group)]. Open-air plots (T(0)) were used as controls. Analytical determinations of chromium (Cr), selenium (Se), two forms of sulfur (total-S and sulfate-S), and amino acids (Isoleucine, leucine, lysine, methionine, serine, threonine, and valine) were performed utilizing plant shoots for analysis. The T1 and T2 treated plants contained concentrations of lysine, methionine, serine, and threonine higher than in T(0). Under T1, the extent of Cr and Se removal in the field was more favorable. Direct covers could be used in contaminated agricultural zones for a variety of plant species, not just for use with those plants previously reported to be efficient at bio-accumulating toxic elements because the thermal effect created by the covers favors phytoextraction processes. However, it is clear that the accumulation of these toxic substances in the plants (Cr) would deem the plant material unsuitable for human consumption and use as animal fodder.     

Sperm removal and ejaculate size correlate with chelae asymmetry in a freshwater crayfish species

Asymmetry in traits of sexual relevance may impair copulation behaviour and sexual performance of males, ultimately resulting in a fitness cost. Freshwater crayfish males use chelae, a sexually selected trait, to secure and position the female prior to and during mating. Thus, a relatively large chelae asymmetry, resulting from accidental loss and regeneration of one cheliped after autotomy, could have great consequences for male sexual behaviour. We studied copulatory behaviour and sperm expenditure of males paired to a mated female in Austropotamobius italicus, a freshwater crayfish species where both male and female mate multiply and where last-mating males are able to actively remove previously deposited sperm. We aimed at assessing whether male sperm removal and expenditure varied according to sperm allocated by first-mating males, and according to copulation behaviour and phenotypic traits (carapace length, chelae length and relative chelae asymmetry) of second-mating males. Second-mating males did not adjust their ejaculate size in relation to first-mating male ejaculate, nor to the first-mating male’s sperm removed. Moreover, the amount of sperm removed by second-mating males increased with increasing first-mating males ejaculate size, and first-mating male sperm remaining after removal did not correlate with the original first-mating male ejaculate size. Interestingly, the amount of sperm removed by second-mating males decreased with increasing relative chelae asymmetry, while increasing with male body size. However, second-mating (but not first-mating) asymmetric-clawed males produced larger ejaculates than symmetric-clawed ones. Importantly, the proportion of second-mating male sperm remaining after the two matings did not vary with relative chelae asymmetry nor with body size of second-mating males. Thus, small, asymmetric-clawed crayfish males appear to adopt sperm allocation tactics that allow them to fully compensate for their inferior sperm removal ability.     

Impact of three different fungicides on fungal epi- and endophytic communities of common bean (Phaseolus vulgaris) and broad bean (Vicia faba)

In this study, the impacts of three different fungicides to fungal phyllosphere communities on broad bean (Vicia faba, Fabaceae) and common bean (Phaseolus vulgaris, Fabaceae) were analyzed. The fungicides included copper, sulfur, and azoxystrobin. The plants were sowed, grown, and treated under conditions occurring in conventional and organic farming. A culture-based approach was used to identify changes in the phyllosphere fungal community after the treatment. Different effects on species richness and growth index of the epiphytic and endophytic communities for common bean and broad bean could be shown. Treatments with sulfur showed the weakest effect, followed by those based on copper and the systemic azoxystrobin, which showed the strongest effect especially on endophytic communities. The epiphytic fungal community took five weeks to recover after treatment with azoxystrobin. However, the effect of azoxystrobin on the endophytic community lasted more than five weeks. Finally, the data suggest that the surface structure of the host leaves have a huge impact on the mode of action that the fungicides exert.     

Characterisation of sulphide-bearing waste-rock dumps using electrical resistivity imaging: the case study of the Rio Marina mining district (Elba Island, Italy)

Sulphide-bearing mine dumps are potential sources of pollution when acid mine drainage (AMD) occurs. Because the generation of AMD depends on the volume and composition of waste materials, their characterisation is crucial for the evaluation of geochemical hazards and for the design of remediation strategies to minimise their environmental impact. In this paper, a cost-effective strategy for the characterisation of an inactive mine dump in the Rio Marina mining district (Elba Island, Italy) using earth resistivity imaging (ERI) is presented. As no information regarding the nature of waste rocks is found in reports for the mine, five ERI profiles were acquired at the top of the waste pile. The results show that waste rocks are heterogeneous with a maximum thickness of 30 m. Due to the large amounts of dispersed sulphide minerals, the waste rocks are characterised by an electrically conductive geophysical signature in comparison to the surrounding resistive metamorphic bedrock. A geostatistical approach was adopted to estimate the elevation of the edges of the mine dump, and the net volume of the waste rocks was computed through a raster analysis of the elevations of the upper and lower boundaries of the mine dump. High-conductivity anomalies were detected within the core of the mine dump. The integration of the hydrogeological, geochemical and geological framework of the Rio Marina mining district suggests that these anomalies could be a geophysical signature of subsurface regions where AMD is currently generated or stored, thus representing sources of environmental pollution.     

An environmental pressure index proposal for urban development planning based on the analytic network process

This paper introduces a new approach to prioritize urban planning projects according to their environmental pressure in an efficient and reliable way. It is based on the combination of three procedures: (i) the use of environmental pressure indicators, (ii) the aggregation of the indicators in an Environmental Pressure Index by means of the Analytic Network Process method (ANP) and (iii) the interpretation of the information obtained from the experts during the decision-making process.The method has been applied to a proposal for urban development of La Carlota airport in Caracas (Venezuela). There are three options which are currently under evaluation. They include a Health Club, a Residential Area and a Theme Park. After a selection process the experts chose the following environmental pressure indicators as ANP criteria for the project life cycle: used land area, population density, energy consumption, water consumption and waste generation. By using goal-oriented questionnaires designed by the authors, the experts determined the importance of the criteria, the relationships among criteria, and the relationships between the criteria and the urban development alternatives.The resulting data showed that water consumption is the most important environmental pressure factor, and the Theme Park project is by far the urban development alternative which exerts the least environmental pressure on the area. The participating experts coincided in appreciating the technique proposed in this paper is useful and, for ranking ordering these alternatives, an improvement from traditional techniques such as environmental impact studies, life-cycle analysis, etc.     

Potential application of 2-(6-ethylamino-3-ethylimino-2,7-dimethyl-3H-xanthen-9-yl) benzoic acid phenyl thiourea for mercury determination

Heavy metal contamination of the environment is a public health problem and research to develop new tools for monitoring the environmental impact of these elements is necessary. This study describes the preparation of a rhodamine-based probe 1 and its potential applications for detecting mercuric ion [Hg(II)] in samples from a nutrition media containing Salvinia auriculata. It was observed that an excess of probe 1 led to quenching in the fluorescence/absorption response, which was evidenced by a decrease in the signal when the stoichiometry differed from 1:1. Consequently, this probe is not suitable for quantitative analysis of Hg(II). Also, probe 1 reacts with methylmercury (MeHg) with different stoichiometry than that observed for Hg(II). These results indicate the potential application of probe 1 for qualitative detection of Hg(II) and MeHg in environmental samples.     

Feeding macroecology of territorial damselfishes (Perciformes: Pomacentridae)

The present study provides the first analysis of the feeding macroecology of territorial damselfishes (Perciformes: Pomacentridae), a circumtropical family whose feeding and behavioral activities are important in structuring tropical and subtropical reef benthic communities. The analyses were conducted from data collected by the authors and from the literature. A strong positive correlation was observed between bite rates and sea surface temperature (SST) for the genus Stegastes. A negative correlation was found between bite rates and mean body size for the genera Stegastes and Pomacentrus, but this relationship was not significant when all territorial pomacentrids were analyzed together. A negative correlation between body size and SST was observed for the whole group and for the genera Stegastes, and Pomacentrus. No relationship was found between territory size and feeding rates. Principal Components Analysis showed that differences in feeding rates accounted for most of the variability in the data. It also suggested that body size may be important in characterizing the different genera. In general, tropical species are smaller and have higher bite rates than subtropical ones. This study extended the validity of Bergmann’s rule, which states that larger species or larger individuals within species occur towards higher latitudes and/or lower temperatures, for an important group of reef fishes. The identification of large-scale, robust ecological patterns in the feeding ecology of pomacentrid fishes may establish a foundation for predicting large-scale changes in reef fish assemblages with expected future changes in global SST.