The life history responses of the abalone pest,<Emphasis Type="Italic"> Terebrasabella heterouncinata</Emphasis>, under natural and aquaculture conditions

The sabellid, Terebrasabella heterouncinata, is a small (<5 mm) intratubular brooder that lives in burrows within the hosts shell matrix. It is a semi-continuous breeder and despite producing small numbers of large eggs, infestation by this animal has reached epidemic proportions on local abalone farms. The present study compared the morphometrics and reproductive characteristics of worms from farmed and wild abalone, in the Walker Bay area of the south Western Cape Province of South Africa, to gain insights into why this animal has become so successful under aquaculture conditions. The farms designated farm A and farm B each had one on-farm site, and two wild sites, while farm C had two on-farm sites and two wild sites. The wild sites were natural abalone habitats located within 2.5 km of the farms. Our results conclusively showed that environmental conditions prevalent on the farms enhanced the reproductive success of these worms relative to that observed in its natural environment. At farms B and C, worms occurred in significantly higher densities at the on-farm sites than in the corresponding wild samples, but at farm A, density was equally low at the three sites. At all three farms, a greater proportion of the population was reproductively active in the on-farm samples than in the wild samples. Worms on farmed abalone had a higher instantaneous fecundity, brooded more clutches simultaneously and were larger than their conspecifics from the wild. There was a positive correlation between adult size and brood size and the number of clutches brooded simultaneously. Within the three on-farm sites there was a negative correlation between egg volume and brood size, indicating a trade-off between these traits. However, such a trade-off was not apparent between sites, with brood size being higher at the on-farm sites than at the wild sites, irrespective of egg size. This suggests that the stable nutrient-enriched environment on the farm led to an increase in fecundity without compromising the size (and implicitly the quality) of the eggs. Worm density did not have a significant effect on body size or any other reproductive traits at most sites, and the density of T. heterouncinata was unaffected by the density of other shell-infesting polychaetes. The results suggest that the farm environment has selected for larger, more fecund worms that breed rapidly with high recruitment success as a consequence of abundant nutrients, high host density, habitat stability and a possible lack of predation and interspecific competition.Communicated by J.P. Thorpe, Port Erin     

Dental Fluorosis in Wild Deer: Its Use as a Biomarker of Increased Fluoride Exposure

The relationships between age (range: 3 to 14 yr), mandibular bone fluoride level (marker of accumulated internal dose, range: 597 to 4680 mg F^- kg^-1> dry wt) and intensity of dental fluorosis (reflecting fluoride exposure during enamel formation) were studied in a sample of 53 fluorosed red deer from a fluoride-polluted area in the Czech-German border region (Ore mountains and their southern foreland). Assessment of the severity of dental fluorosis was performed for the 3 permanent premolars and 3 molars of one hemimandible per animal by using an ordinal measurement scale. For statistical analysis, the maximum tooth score of fluorosis (MTS) and the dental lesion index of fluorosis (DLI, sum of the six tooth scores per individual) were used. In the sample, both MTS (r_s = 0.850) and DLI (r_s = 0.813) were highly significantly (p <0.00001) correlated with bone fluoride content. A weaker correlation existed between age and bone fluoride content (r_s = 0.322, p <0.05). The results demonstrate that in case of regional, long-term fluoride pollution, dental fluorosis (measured as MTS or DLI) can be used as a sensitive biomarker of fluoride exposure in deer and thus as an indicator of the level of environmental contamination by fluorides. In many countries, skulls and mandibles of wild deer are regularly and continuously collected by hunters. Assessment of the prevalence and severity of dental fluorosis in this material offers the opportunity for an efficient large-scale biomonitoring of environmental pollution by fluorides at very low cost.     

Evaluation of the effect of small organic acids on phytoextraction of Cu and Pb from soil with tobacco Nicotiana tabacum

Phytoremediation, the use of plants to extract contaminants from soils and groundwater, is a promising approach for cleaning up soils contaminated with heavy metals. However its use is limited by the time required for plant growth, the nutrient supply and, moreover, by the limited metal uptake capacity. Synthetic chelators have shown positive effects in enhancing heavy metal extraction, but they have also revealed several negative side-effects. The objective of this study was to investigate the use of three natural low molecular weight organic acids (NLMWOA) (citric, oxalic, and tartaric acid) as an alternative to synthetic chelators. Slurry-, column-, toxicity- and phytoextraction experiments were performed. For the phytoextraction experiment the three NLMWOA were applied to a copper- and a lead-contaminated soil respectively. A significant increase in copper uptake was visible only in the citric acid treatment (67 mg kg-1) in comparison to the EDTA treatment (42 mg kg-1). The NLMWOA application showed no enhanced effect concerning the lead phytoextraction. A possible explanation for this lack of significance could be the rate of the degradation of NLMWOA. This rate might well be too high for these heavy metals with low mobility and bioavailability such as lead. The amounts of NLMWOA applied to the soil were very high (62.5 mmol kg-1 of soil) and the effect was too little. In this respect EDTA, which was applied in very small amounts (0.125 mmol kg-1) was more efficient. Thus making NLMWOA unsuitable to enhance phytoextraction of heavy metals from soil.     

Persistente Organische Umweltschadstoffe (POPs)

The presence of Persistent Organic Pollutants (POPs) is identified as a global problem for humans and the environment. POPs, in fact, are released by numerous static, mobile and diffuse sources, and are frequently seen to be widespread. Due to the global dimension of the potential environmental impacts, POP related problems can only be handled on the basis of international agreements. Concerning this aspect, some international activities are presented and general requirements are discussed in view of the international POPs management, both for static and diffuse releases     

Single- and dual-porosity modelling of flow in reclaimed mine soil cores with embedded lignitic fragments

Lignitic mine soils represent a typical two-scale dual-porosity medium consisting of a technogenic mixture of overburden sediments that include lignitic components as dust and as porous fragments embedded within a mostly coarse-textured matrix. Flow and transport processes in such soils are not sufficiently understood to predict the course of soil reclamation or of mine drainage. The objective of this contribution is to identify the most appropriate conceptual model for describing small-scale heterogeneity effects on flow on the basis of the physical structure of the system. Multistep flow experiments on soil cores are analyzed using either mobile–immobile or mobile–mobile type 1D dual-porosity models, and a 3D numerical model that considers a local-scale distribution of fragments. Simulations are compared with time series' of upward infiltration and matric potential heads measured at two depths using miniature tensiometers. The 3D and the 1D dual-permeability models yielded comparable results as long as pressure heads are in local equilibrium; however, could describe either the upward infiltration or the matric potential curves but not both at the same time. The mobile–immobile type dual-porosity model failed to describe the data. A simultaneous match with pressure heads and upward infiltration data could only be obtained with the 1D dual-permeability model (i.e., mobile–mobile) by assuming an additional restriction of the inter-domain water transfer. These results indicate that for unsaturated flow conditions at higher matric potential heads (i.e., here >− 40 hPa), water in a restricted part of the fragment domain must be more mobile as compared to water in the sandy matrix domain. Closer inspections of the pore system and first neutron radiographic imaging support the hypothesis that a more continuous pore region exists at these pressure heads in the vicinity of the lignitic fragments possibly formed by fragment contacts and a lignitic dust interface-region between the two domains. The results suggest that the small-scale structure is too complex as to be represented by weighted contributions of individual components alone.     

Critical analysis of the waste management performance of two uranium production units in Brazil--part II: Caetite production center

This paper discusses the environmental waste management of the Heap-Leach Uranium Production Facility of Caetité located in a semi-arid region in Brazil. A comparison is made with the first uranium production site of the country located in Poços de Caldas. It is demonstrated that differences in the operational process along with different environmental conditions can lead to different impacts. In the present case groundwater is the potential most sensitive environmental medium despite the well-established consensus in the literature that radon and aerosol emissions may turn-out to be the most relevant environmental aspects of an installation located at this type of region. Most of the ²²⁶Ra content in the ore remains in the leached ore that is deposited with the waste rock. A lack in appropriate prediction of the hydrological balance has been causing unanticipated emissions of liquid effluents into the environment. Chemical treatment of this effluent may be needed. Contamination of groundwater in the short term by the waste ponds is not to be expected but it can be a relevant issue in the long term. As a consequence, careful closure schemes will need to be put in place. Finally, the overall costs with remediation in the Caetité production center are lower than those observed at the Poços de Caldas mining site.     

Hydrolysed wool: a novel chelating agent for metal chelant-assisted phytoextraction from soil

Phytoextraction has revealed great potential, however it is limited by the fact that plants need time and nutrient supply and have a limited metal uptake capacity. Although the use of synthetic chelators, such as EDTA, enhances heavy metal extraction, it also produces the negative side effects of high phytotoxicity, as well as leaching of essential metals. The aim of this research was to investigate the application of wool, in mobilising metals and in improving the phytoextraction of metals-contaminated soil. We performed column experiments with 14 d and 7 d partially hydrolysed wool as chelating agent on a silty-loamy sand agricultural soil. In the column experiment the 14 d wool hydrolysate mobilised 68% of Cu in soil, whereas in the case of Cd it mobilised 5.5%. The model plant selected for the phytoextraction experiments was tobacco (Nicotiana tabacum). The plant uptake of Cd and Cu, assisted by the application of 6.6 g kg(-1) wool hydrolysate was increased by 30% in comparison to the control plants. The application of 13.3 g kg(-1) wool hydrolysate enhanced the Cu uptake by up to 850%. Moreover, high leaching probability frequently observed when applying chelating agents, such as EDTA or ethylene diamine disuccinate (EDDS), were not detected. The use of hydrolysed wool therefore merits further investigation.