[en] The Ogoniland axis of Rivers State, Niger Delta (Nigeria) is a heavily hydrocarbon contaminated region, due to prolonged oil spillages and other oil-related and petrochemical activities on-going in the area. UNEP, 2011 issued an environmental impact assessment report on the state of oil pollution in Ogoniland, which highlighted the severe problem of hydrocarbon-contaminated groundwater and surface waters which in turn heavily impacts regional ecosystems and drinking water resources. Despite the acknowledged severity of surface and groundwater contamination in this area, understanding of hydrocarbon migration and exposure pathways, and practical methods of managing the impact of hydrocarbon-derived contaminants, is currently limited. This research therefore investigates the distribution and concentrations of key hydrocarbon contaminants in groundwater and surface waters around major oil and petrochemical sites in Ogoniland; examines potential contaminant migration pathways between groundwater, surface water, and drinking water resources; and assesses the potential application of practical, more sustainable, water remediation or management methods, with particular emphasis on low-cost adsorption and enhanced natural attenuation approaches. The research discussed in this contribution focuses on assessment of activated carbon and biochar-based methods for pathway management of phenol and other contamination in the Ogoniland area. (author)

[en] Highlights: • Enhanced remediation with cheap, non-toxic additives (KCl) in organic/clayey soils. • Target radionuclides are ¹³⁷Cs (and ⁹⁰Sr) by electrokinetic remediation, EKR. • Remediation efficiencies: high (80+% for Cs, 50%+ for Sr) at low voltage. • Remediation speed is key; longer than months and Cs becomes intractable. • Understanding waste form is vital for removal of Cs in environmental contexts. Electrokinetic remediation, EKR, is technology that circumvents the traditional challenges faced by many existing remediation technologies in low permeability substrates. Cheap, non-toxic additives such as KCl may further help EKR remediation efficiency by increasing electrolyte strength; their use has been reported in concretes, but not soils. Here, we investigate the efficiency of low-energy EKR (with and without electrolyte additives) in the mobilisation of radiostable Cs and Sr in a clayey, organic-rich soil. Soil maturation time and voltage are key factors in determining success of EKR. Although Cs and Sr are effectively mobilised (up to 317 and 330%, respectively) in the electric field in our soils (determined by XRF), maturation time (7 or 45 days) and voltage (15 or 20 V) are key to successful remediation using EKR. We more broadly show that understanding speciation and the local ionic environment of relevant radionuclides within entrained matrices is vital to effective application of this technology.

[en] Highlights: • Historic landfills were constructed prior to modern environmental regulation. • Historic metal-rich leachate plumes have contaminated adjacent fine-grained marine sediments. • This represents a small, but significant source of diffuse pollution in the coastal zone. - Abstract: Prior to modern environmental regulation landfills in low-lying coastal environments were frequently constructed without leachate control, relying on natural attenuation within inter-tidal sediments to dilute and disperse contaminants reducing environmental impact. With sea level rise and coastal erosion these sites may now pose a pollution risk, yet have received little investigation. This work examines the extent of metal contamination in saltmarsh sediments surrounding a historic landfill in the UK. Patterns of sediment metal data suggest typical anthropogenic pollution chronologies for saltmarsh sediments in industrialised nations. However, many metals were also enriched at depth in close proximity to the landfill boundary and are indicative of a historical leachate plume. Though this total metal load is low, e.g., c. 1200 and 1650 kg Pb and Zn respectively, with > 1000 historic landfills on flood risk or eroding coastlines in the UK this could represent a significant, yet under-investigated, source of diffuse pollution.

[en] The use of composite materials based on metal ferrocyanides combined with natural mineral sorbents for treatment of high salinity Cs-containing liquid radioactive waste (LRW) was investigated. The study indicated that among the investigated composites, the best sorption characteristics for Cs were shown by materials based on copper ferrocyanide. Several factors affecting the removal of cesium from LRW, namely total salt content, pH and organic matter content, were also investigated. High concentrations of complexing organic matter significantly reduced the sorption capacity of ferrocyanide sorbents.

[en] Electrokinetic Remediation, EKR, is an environmental remediation technology that uses electricity to remove pollutants from contaminated materials. It is a flexible and low-energy (< 1 V.cm^-1) technique, that operates effectively in low permeability substrates (clayey soils, cements, etc.) which are often difficult to remediate by conventional means (e.g. soil washing, pump-and-treat). It can be combined with renewable power inputs and operate in-situ, providing effective, safe and sustainable solutions in which worker exposure to hazardous materials is minimized while high remediation efficiencies are retained. However, EKR is limited mostly to the laboratory or pilot scale for nuclear industry applications, with reliable, meter plus scale studies in real operating environments still lacking. Here, we discuss EKR and its potential uses at nuclear sites. We begin by summarizing the key advantages offered by EKR over other, conventional remediation methods and, from this, review how EKR, singly or in combination with other technologies, can be or has been applied practically. We illustrate this using real examples at selected nuclear sites of international importance. Finally, we examine perspectives on tools to help the decision-making process for remediation at active nuclear sites, and how these tools could be used to support practical deployment of EKR for nuclear site decommissioning. (authors)

[en] Reactions involving iron play a major role in the environmental cycling of a wide range of important organic, inorganic and radioactive contaminants. Consequently, a range of environmental clean-up technologies have been proposed or developed which utilise iron chemistry to remediate contaminated land and surface and subsurface waters, e.g. the use of injected zero zero-valent iron nanoparticles to remediate organic contaminant plumes; the generation of iron oxyhydroxide-based substrates for arsenic removal from contaminated waters; etc. This paper reviews some of the latest iron-based technologies in contaminated land and groundwater remediation, their current state of development, and their potential applications and limitations

[en] Highlights: • Electrokinetic remediation (EKR) is effective at nuclear sites. • Moving from laboratory to pilot and site-scale. • Site-specific EKR models more applicable than one-size-fits-all. • EKR plus bio-/phyto-remediation and grouting technologies most promising. • Sustainability assessment for EKR at nuclear sites urgently needed. Contamination encountered on nuclear sites includes radionuclides as well as a range of non-radioactive co-contaminants, often in low-permeability substrates such as concretes or clays. However, many commercial remediation techniques are ineffective in these substrates. By contrast, electrokinetic remediation (EKR), where an electric current is applied to remove contaminants from the treated media, retains high removal efficiencies in low permeability substrates. Here, we evaluate recent developments in EKR for the removal of radionuclides in contaminated substrates, including caesium, uranium and others, and the current benefits and limitations of this technology. Further, we assess the present state of EKR for nuclear site applications using real-world examples, and outline key areas for future application.

[en] A facile and rapid assembly of powdered carbon nanotubes (CNTs) into compressible, porous, macroscale monoliths is reported. Despite a Poisson's ratio just above zero, we found that the sample under compression inside a scanning electron microscope (SEM) revealed CNT regions behaving in auxetic and vortex-like rotational modes as well as standard collapse responses. This method is crucial in understanding the macroscale behaviour based on the accumulation of nanoscale responses to an applied force.

[en] The Ensenada de San Simon is the inner part of the Ria de Vigo, one of the major mesotidal rias of the Galician coast, NW Spain. The geochemistry of its bottom sediments can be accounted for in terms of both natural and anthropogenic sources. Mixture-modelling enables much of the Cr, Ni, V, Cu, Pb and Zn concentrations of the bottom and subaqueous sediments to be explained by sediment input from the river systems and faecal matter from manmade mussel rafts. The compositions and relative contributions of additional, unknown, sources of anomalous heavy-metal concentrations are quantified using constrained nonlinear optimization. The pattern of metal enrichment is attributed to: material carried in solution and suspension in marine water entering the Ensenada from the polluted industrial areas of the adjacent Ria de Vigo; wind-borne urban dusts and/or vehicular emissions from the surrounding network of roads and a motorway road-bridge over the Estrecho de Rande; industrial and agricultural pollution from the R. Redondela; and waste from a former ceramics factory near the mouth of the combined R. Oitaben and R. Verdugo. Using ¹³⁷Cs dating, it is suggested that heavy metal build-up in the sediments since the late 1970s followed development of inshore fisheries and introduction of the mussel rafts (ca. 1960) and increasing industrialisation

[en] There is growing concern over the potential detrimental impact of ionizing radiation on natural biota. The mechanistic cause-and-effect impact of ionizing radiation has yet to be characterized in any aquatic species. Adopting an integrated approach, including radiochemical analysis of environmental samples, we evaluate molecular responses to ionizing radiation in the marine mussel, Mytilus edulis. These responses included analyses of RAD51 mRNA expression, a gene involved in the repair of DNA double strand breaks, and induction of DNA strand breaks using the comet assay, in samples collected from a site impacted by low level ionizing radiation discharges. Based on activities of the radionuclides measured in sediment and mussel tissue at the discharge site, external and internal dose rates were low, at ca. 0.61 μGyh⁻¹ and significantly lower than the generic (all species) “no effect” dose rate of 10 uGyh⁻¹, yet DNA strand breakage and RAD51 mRNA expression were both altered. - Highlights: ► We measure radiochemical concentrations and biological effects markers in mussels. ► We develop an assay of RAD51 mRNA expression for ionizing radiation exposure. ► We relate DNA damage in mussels to low-level ionizing radiation exposure. - Apparent detrimental biological effects at the internationally agreed “no effect” chronic radiation dose rate to the natural biota.