Long-term passive restoration following fluvial deposition of sulphidic copper tailings: nature filters out the solutions

Despite the growing popularity of ecological restoration approach, data on primary succession on toxic post-mining substrates, under site environmental conditions which considerably differ from the surrounding environment, are still scarce. Here, we studied the spontaneous vegetation development on an unusual locality created by long-term and large-scale fluvial deposition of sulphidic tailings from a copper mine in a pronouncedly xerothermic, calcareous surrounding. We performed multivariate analyses of soil samples (20 physical and chemical parameters) and vegetation samples (floristic and structural parameters in three types of occurring forests), collected along the pollution gradients throughout the affected floodplain. The nature can cope with two types of imposed constraints: (a) excessive Cu concentrations and (b) very low pH, combined with nutrient deficiency. The former will still allow convergence to the original vegetation, while the latter will result in novel, depauperate assemblages of species typical for cooler and moister climate. Our results for the first time demonstrate that with the increasing severity of environmental filtering, the relative importance of the surrounding vegetation for primary succession strongly decreases.     

Risk assessment and prioritisation of contaminated sites on the catchment scale

Contaminated sites pose a significant threat to groundwater resources worldwide. Due to limited available resources a risk-based prioritisation of the remediation efforts is essential. Existing risk assessment tools are unsuitable for this purpose, because they consider each contaminated site separately and on a local scale, which makes it difficult to compare the impact from different sites. Hence a modelling tool for risk assessment of contaminated sites on the catchment scale has been developed. The CatchRisk screening tool evaluates the risk associated with each site in terms of its ability to contaminate abstracted groundwater in the catchment. The tool considers both the local scale and the catchment scale. At the local scale, a flexible, site specific leaching model that can be adjusted to the actual data availability is used to estimate the mass flux over time from identified sites. At the catchment scale, a transport model that utilises the source flux and a groundwater model covering the catchment is used to estimate the transient impact on the supply well. The CatchRisk model was tested on a groundwater catchment for a waterworks north of Copenhagen, Denmark. Even though data scarcity limited the application of the model, the sites that most likely caused the observed contamination at the waterworks were identified. The method was found to be valuable as a basis for prioritising point sources according to their impact on groundwater quality. The tool can also be used as a framework for testing hypotheses on the origin of contamination in the catchment and for identification of unknown contaminant sources.     

Is the growth stimulation by low doses of glyphosate sustained over time?

The herbicide, glyphosate, has been shown to stimulate growth in a range of species when applied at doses of 5-60 g a.e. ha⁻¹, corresponding to realistic spray drift events. This study investigates growth of shoot parameters over time to detect whether the glyphosate induced growth increase was sustained and had a final effect on reproduction. The results showed that an actual biomass growth rate increase took place within the first week after spraying with glyphosate doses <60 g a.e. ha⁻¹. This initial growth boost kept treated plants larger than untreated plants for up to six weeks, but at harvest there was no significant difference between control plants and treated plants. Possible effects of glyphosate hormesis on the competitive ability of spray drift affected plants are discussed.     

Trace element levels in adults from the west coast of Canada and associations with age, gender, diet, activities, and levels of other trace elements

The purpose of this study was to assess trace element levels in whole blood, serum and urine of 61 non-smoking adults living on the west coast of Canada and to determine their association with the following variables: age, gender, diet, participation in certain hobby and/or occupational activities, and levels of other trace elements. Participants or their spouses were employed as oyster growers and were originally recruited to study the absorption of cadmium from oyster consumption. Trace elements were measured using inductively-coupled plasma mass spectrometry. A telephone interview was used to assess participant's intake of selected foods and the amount of time they have spent on certain activities over the lifetime. Comparison of results to previous studies revealed that blood lead, blood mercury, serum nickel, serum selenium and urine molybdenum levels were generally higher in this study than have previously been measured, possibly due to higher consumption of seafood in this sample. Men had statistically higher levels of serum iron, blood lead, and serum selenium, while women had statistically higher levels of serum copper and blood manganese. Blood lead levels increased with age. Diet had a statistically significant association with several elements. Consumption of spinach, seaweed, organ meats, and shellfish tended to be positively correlated with trace element concentrations and consumption of various forms of potatoes tended to be negatively correlated. Several statistically significant correlations were also observed between trace elements.     

Pruning waste management and climate change in Sierra Mágina’s olive groves (Andalusia,Spain)

Regional Environmental Change - In the context of climate change, concern is raising about the negative effects of some pruning waste management practices. On the one hand, burning of pruning...     

Mating effort or paternal investment? Incorporation rate and cost of male donations in the wartbiter

Summary Provision of nuptial gifts and incorporation of male-derived substances occurs in several insects. There has been some discussion as to whether these gifts should be regarded as a form of paternal investment or part of mating effort. One assumption of the paternal investment hypothesis is that the donating male is expected to father all, or the majority of, the offspring. The rate of incorporation into developing eggs is therefore assumed to be rapid enough to assure the donating male of paternity of the offspring in which he is investing. Spermatophore production in a paternal investment system is also expected to be costly, since males are providing females with highly nutritious gifts during copulation, thereby increasing female fecundity. Therefore, under conditions of food limitation males are expected to alter either mating frequency or spermatophore size. Experiments on the wartbiter (Decticus verrucivorus), using radioactive isotopes, show that the incorporation rate of male-derived substances is so slow that females become sexually receptive before any material received from the last male have been incorporated into eggs laid by the female. Since sperm mixing occurs in this species and since the label is present in eggs laid up to more than 30 days after mating, males might potentially benefit another male's offspring. The nuptial gift (the spermatophylax) was found, regardless of mating frequency and diet, to have a low protein content. These findings coincide with previous results showing that consumption of the gift had no effect on female fecundity. Instead, wartbiter males keep mating frequency high, are capable of mating every day regardless of food availability, invest the same proportion of the body weight in spermatophore production regardless of size, and produce a spermatophylax that correlates with ampulla size. These results indicate that the nuptial gift mainly functions to increase fertilization success in the wartbiter.     

Antecedents of organizational commitment across occupational groups: A meta-analysis

This meta-analysis examines whether the relationships between organizational commitment (OC) and its antecedents differ across occupational groups. Two models representing different antecedents are proposed: the member model, presented by the personal variables, and the organization model, presented by role related, structural and work experiences variables. The study is based on 98 samples with correlational data for the relationships between OC and its antecedents. The total sample was divided into two main occupational groups: white collar employees, subdivided into professionals and nonprofessionals, and blue collar employees. The findings reveal that in general the relationship between OC and personal antecedents, representing the member model, is stronger for blue collar and nonprofessional white collar employees than for professional employees. For the role-related, structural, and work experiences antecedents, representing the organization model, differences among the occupational groups were found to be less consistent. In general, the findings demonstrate that the member and the organization model operate differently for varying occupational groups. The findings are discussed in terms of the need for elaboration of the existing explanations for the development of OC.