Compositonal Analysis of Potentially harmful Elements in Soils: Implications for Epidemiology and Kidney Disease

A substantial proportion of aetiological risks for many cancers and chronic diseases remain unexplained. Using geochemical soil and stream water samples collected as part of the Tellus Project studies, current research is investigating naturally occurring background levels of potentially toxic elements (PTEs) in soils and stream sediments and their possible relationship with progressive chronic kidney disease (CKD). The Tellus geological mapping project, Geological Survey Northern Ireland, collected soil sediment and stream water samples on a grid of one sample site every 2 km2 across the rural areas of Northern Ireland resulting in an excess of 6800 soil sampling locations and more than 5800 locations for stream water sampling. Accumulation of several PTEs including arsenic, cadmium, chromium, lead and mercury have been linked with human health and implicated in renal function decline. The hypothesis is that long-term exposure will result in cumulative exposure to PTEs and act as risk factor(s) for cancer and diabetes related CKD and its progression. The ‘bioavailable’ fraction of total PTE soil concentration depends on the ‘bioaccessible’ proportion through an exposure pathway. Recent work has explored this bioaccessible fraction for a range of PTEs across Northern Ireland. In this study the compositional nature of the multivariate geochemical PTE variables and bioaccessible data is explored to augment the investigation into the potential relationship between PTEs, bioaccessibility and disease data.

Magnitude, form and bioavailability of fluvial carbon exports from Irish organic soils under pasture

Organic soils are widespread in Ireland and vulnerable to degradation via drainage for agriculture. The soil-landuse combination of pasture on organic soils may play a disproportionate role in regional C dynamics but is yet to receive study. Fluvial C fluxes and labile organic fractions were determined for two such sites at nested field (c.4 ha) and subcatchment scales (>40 ha); one relatively dry and nutrient rich, the other wetter and nutrient poor. Field scale flux from the nutrient poor site over 2 years was 38.9 ± 6.6 g C m⁻² yr⁻¹ with DIC > DOC > POC at 57, 32 and 11 % respectively, and 72 % DIC was comprised of above equilibrium CO₂. At the nutrient rich site, which overlies limestone geology, field scale export over an individual year was 90.4 g C m⁻² with DIC > DOC > POC at 49, 42 and 9 %, but with 90 % DIC as bicarbonate. By comparison with the nutrient poor site, the magnitude and composition of inorganic C exports from the nutrient rich site implied considerable export of soil-respiratory C as bicarbonate, and lower evasion losses due to carbonate system buffering. Labile DOC determined using dark incubations indicated small fractions (5–10 %) available for remineralisation over typical downstream transit times of days to weeks. These fractions are probably conservative as photolysis in the environment can increase the proportion of labile compounds via photocleavage and directly remineralise organic matter. This study demonstrates that monitoring at soil–water interfaces can aid capture of total landscape fluvial fluxes by precluding the need to incorporate prior C evasion, although rapid runoff responses at field scales can necessitate high resolution flow proportional, and hydrograph sampling to constrain uncertainty of flux estimates.

The Application of Geophysics to a Number of Threats to Irish Soils

In its 2002 Communication "Towards a Thematic Strategy on Soil Protection" (COM 2002, 179), the Commission identified the main threats to which soils in the EU are confronted. More recently, the EU published a Thematic Strategy for Soil Protection (COM 2006, 231) as well as a proposal for a Soil Framework Directive (COM 2006, 232). The proposed directive, if implemented, will require states to identify a number of specific soil degradation processes that have occurred or are likely to occur in the near future. This project applies a number of recent geophysical developments, in addition to a range of traditional approaches, to a number of areas of Irish concern to Thematic Strategy for Soil Protection and the proposed Soil Framework Directive.

Influence of testing on permeability of compacted fine soils

The British standard constant-head triaxial test for measuring the permeability of fine-grained soils takes a relatively long time. A quicker test could provide savings to the construction industry, particularly for checking the quality of landfill clay liners. An accelerated permeability test has been developed, but the method often underestimates the permeability values compared owing to structural changes in the soil sample. This paper reports on an investigation
into the accelerated test to discover if the changes can be limited by using a revised procedure. The accelerated test is assessed and compared with the standard test and a ramp-accelerated permeability test. Four different finegrained materials are compacted at various water contents to produce analogous samples for testing using the three different methods. Fabric analysis is carried out on specimens derived from post-test samples using mercury intrusion porosimetry and scanning electron microscopy to assess the effects of testing on soil structure. The results show that accelerated testing in general underestimates permeability compared with values derived from the standard test, owing to changes in soil structure caused by testing. The ramp-accelerated test is shown to provide an improvement in terms of these structural changes.

High Resolution measurement and mapping of tungstate in waters, soils and sediments using the low-disturbance DGT sampling technique.

Increasing tungsten (W) use for industrial and military applications has resulted in greater W discharge into natural waters, soils and sediments. Risk modeling of W transport and fate in the environment relies on measurement of the release/mobilization flux of W in the bulk media and the interfaces between matrix compartments. Diffusive gradients in thin-films (DGT) is a promising passive sampling technique to acquire such information. DGT devices equipped with the newly developed high-resolution binding gels (precipitated zirconia, PZ, or ferrihydrite, PF, gels) or classic/conventional ferrihydrite slurry gel were comprehensively assessed for measuring W in waters. FerrihydriteDGT can measure W at various ionic strengths (0.001–0.5 mol L−1 NaNO3) and pH (4–8), while PZDGT can operate across slightly wider environmental conditions. The three DGT configurations gave comparable results for soil W measurement, showing that typically W resupply is relatively poorly sustained. 1D and 2D high-resolution W profiling across sediment—water and hotspot—bulk media interfaces from Lake Taihu were obtained using PZDGT coupled with laser ablation ICP–MS measurement, and the apparent diffusion fluxes across the interfaces were calculated using a numerical model.

Evaluation of the contamination level and proposal of remediation of soils in the basin of a processing plant of heavy metals, under a tropical climate, in Minas Gerais, Brazil

Indústrias metalúrgicas de produção de ligas metálicas podem por em risco toda a área envolvente, nomeadamente a qualidade das águas (superficiais e subterrâneas), dos solos e do ar, sempre que não existam infraestruturas e planos adequados de gestão destes resíduos. No caso em estudo, a unidade industrial situa-se na bacia do rio São Francisco, no estado brasileiro de Minas Gerais, e nos mais de quarenta anos de funcionamento tem produzido inúmeros problemas ambientais. Este estudo baseia-se nos primeiros resultados referentes aos solos da envolvente, tendo como objetivos a identificação dos principais contaminantes e a definição da área contaminada, de forma a avaliar a eficácia de projetos futuros de recuperação.

Alkali-free bioactive glasses for bone regeneration

Bioactive glasses and glass-ceramics are a class of third generation biomaterials which elicit a special response on their surface when in contact with biological fluids, leading to strong bonding to living tissues. The purpose of the present study was to develop diopside based alkali-free bioactive glasses in order to achieve good sintering behaviour, high bioactivity, and a dissolution/ degradation rates compatible with the target applications in bone regeneration and tissue engineering. Another aim was to understand the structure-property relationships in the investigated bioactive glasses. In this quest, various glass compositions within the Diopside (CaMgSi2O6) – Fluorapatite (Ca5(PO4)3F) – Tricalcium phosphate (3CaO•P2O5) system have been investigated. All the glasses were prepared by melt-quenching technique and characterized by a wide array of complementary characterization techniques. The glass-ceramics were produced by sintering of glass powders compacts followed by a suitable heat treatment to promote the nucleation and crystallization phenomena. Furthermore, selected parent glass compositions were doped with several functional ions and an attempt to understand their effects on the glass structure, sintering ability and on the in vitro bio-degradation and biomineralization behaviours of the glasses was made. The effects of the same variables on the devitrification (nucleation and crystallization) behaviour of glasses to form bioactive glass-ceramics were also investigated. Some of the glasses exhibited high bio-mineralization rates, expressed by the formation of a surface hydroxyapatite layer within 1–12 h of immersion in a simulated body fluid (SBF) solution. All the glasses showed relatively lower degradation rates in comparison to that of 45S5 Bioglass®. Some of the glasses showed very good in vitro behaviour and the glasses co-doped with zinc and strontium showed an in vitro dose dependent behaviour. The as-designed bioactive glasses and glass–ceramic materials are excellent candidates for applications in bone regeneration and for the fabrication of scaffolds for tissue engineering.

Organic contaminants in urban soils: major inputs and potential risks

Urban soil quality may be severely affected by hydrophobic organic contaminants (HOCs), impairing environmental quality and human health. A comprehensive study was conducted in two contrasting Portuguese urban areas (Lisbon and Viseu) in order to assess the levels and potential risks of these contaminants, to identify sources and study their behaviour in soils. The concentrations of HOCs were related to the size of the city, with much higher contamination levels observed in Lisbon urban area. Source apportionment was performed by studying the HOCs profiles, their relationship with potentially toxic elements and general characteristics of soil using multivariate statistical methods. Lisbon seems to be affected by nearby sources (traffic, industry and incineration processes) whereas in Viseu the atmospheric transport may be playing an important role. In a first tier of risk assessment (RA) it was possible to identify polycyclic aromatic hydrocarbons (PAHs) in Lisbon soils as a potential hazard. The levels of PAHs in street dusts were further studied and allowed to clarify that traffic, tire and pavement debris can be an important source of PAHs to urban soils. Street dusts were also identified as being a potential concern regarding human and environmental health, especially if reaching the nearby aquatic bodies. Geostatistical tools were also used and their usefulness in a RA analysis and urban planning was discussed. In order to obtain a more realistic assessment of risks of HOCs to environment and human health it is important to evaluate their available fraction, which is also the most accessible for organisms. Therefore, a review of the processes involved on the availability of PAHs was performed and the outputs produced by the different chemical methods were evaluated. The suitability of chemical methods to predict bioavailability of PAHs in dissimilar naturally contaminated soils has not been demonstrated, being especially difficult for high molecular weight compounds. No clear relationship between chemical and biological availability was found in this work. Yet, in spite of the very high total concentrations found in some Lisbon soils, both the water soluble fraction and the body residues resulting from bioaccumulation assays were generally very low, which may be due to aging phenomena. It was observed that the percentage of soluble fraction of PAHs in soils was found to be different among compounds and mostly regulated by soil properties. Regarding bioaccumulation assays, although no significant relationship was found between soil properties and bioavailability, it was verified that biota-to-soil bioaccumulation factors were sample dependent rather than compound dependent. In conclusion, once the compounds of potential concern are targeted, then performing a chemical screening as a first tier can be a simple and effective approach to start a RA. However, reliable data is still required to improve the existing models for risk characterization.

Sequential application of soil vapor extraction and bioremediation processes for the remediation of ethylbenzene-contaminated soils

Soil vapor extraction (SVE) is an efficient, well-known and widely applied soil remediation technology. However, under certain conditions it cannot achieve the defined cleanup goals, requiring further treatment, for example, through bioremediation (BR). The sequential application of these technologies is presented as a valid option but is not yet entirely studied. This work presents the study of the remediation of ethylbenzene (EB)-contaminated soils, with different soil water and natural organic matter (NOMC) contents, using sequential SVE and BR. The obtained results allow the conclusion that: (1) SVE was sufficient to reach the cleanup goals in 63% of the experiments (all the soils with NOMC below 4%), (2) higher NOMCs led to longer SVE remediation times, (3) BR showed to be a possible and cost-effective option when EB concentrations were lower than 335 mg kgsoil −1, and (4) concentrations of EB above 438 mg kgsoil −1 showed to be inhibitory for microbial activity.