Hg transfer from contaminated soils to plants and animals

Understanding the transfer of mercury (Hg) from soil to crops is crucial due to Hg toxicity and Hg occurrence in terrestrial systems. Previous research has shown that available Hg in soils contributes to plant Hg levels. Plant Hg concentrations are related to soil conditions and plant characteristics. Mechanistic models describing such soil–plant interactions are however difficult to quantify. Here we performed a field study in agricultural, mining and industrial areas in Portugal to evaluate potential food chain risks. The uptake of Hg by Italian ryegrass, ryegrass, orchard grass, collard greens and rye was measured to calculate daily intakes (DI) of Hg for cows and sheep grazing. A total of 136 soil samples and 129 plant samples were analysed. Results show that total Hg concentrations ranged from 0.01 to 98 mg kg⁻¹ in soils; 0.01–5.4 mg kg⁻¹ in shoots and 0.01–42 mg kg⁻¹ in roots. Calculated DI ranged from 0.18 to 132 mg d⁻¹ for cows, and from 0.028 to 23 mg d⁻¹ for sheep. In 27 grassland sites, daily intakes exceeded the acceptable daily intake of both cows and sheep in view of food safety considering Hg in animal kidneys evidencing potential risks to human health. The transfer of Hg from soil to crops was described using empirical Freundlich-type functions. For ryegrass, orchard grass and collard greens, the soil-to-root or soil-to-shoot transfer of Hg appeared to be controlled by the total soil Hg concentration and levels of Al_ox and Fe_ox. Empirical functions allowed us to obtain realistic estimates of Hg levels in crops and can be used as an alternative to mechanistic models when evaluating food chain risks of Hg contamination in agricultural soils.     

Electrochemical detection and degradation of ibuprofen from water on multi-walled carbon nanotubes-epoxy composite electrode

This work describes the electrochemical behaviour of ibuprofen on two types of multi-walled carbon nanotubes based composite electrodes,i.e.,multi-walled carbon nanotubes-epoxy(MWCNT) and silver-modified zeolite-multi-walled carbon nanotubes-epoxy(AgZMWCNT) composites electrodes.The composite electrodes were obtained using two-roll mill procedure.SEM images of surfaces of the composites revealed a homogeneous distribution of the composite components within the epoxy matrix.AgZMWCNT composite electrode exhibited the better electrical conductivity and larger electroactive surface area.The electrochemical determination of ibuprofen(IBP) was achieved using AgZMWCNT by cyclic voltammetry,differential-pulsed voltammetry,square-wave voltammetry and chronoamperometry.The IBP degradation occurred on both composite electrodes under controlled electrolysis at 1.2 and 1.75 V vs.Ag/AgCl,and IBP concentration was determined comparatively by differential-pulsed voltammetry,under optimized conditions using AgZMWCNT electrode and UV-Vis spectrophotometry methods to determine the IBP degradation performance for each electrode.AgZMWCNT electrode exhibited a dual character allowing a double application in IBP degradation process and its control.     

Continuous process applied to degradation of triclosan and 2.8-dichlorodibenzene-p-dioxin

Environmental Science and Pollution Research - This study describes the use of a prototype for the continuous photocatalytic reaction process using Fe/Nb2O5-immobilized catalyst for triclosan and...     

Mercury and selenium in blue shark (Prionace glauca, L. 1758) and swordfish (Xiphias gladius, L. 1758) from two areas of the Atlantic Ocean

Muscle, liver and stomach contents of 64 blue sharks and 52 swordfishes, caught between September 2004 and February 2005 near the Azores (area A) and the Equator (area E), were analysed for mercury and selenium. Levels of mercury were relatively high (blue shark: 0.032-2.5microgg(-1); swordfish: 0.031-9.8microgg(-1)) and comparable to values reported in the literature. However, mercury and organic mercury concentrations in muscle and liver of specimens from E were significantly higher than those from A. A similar trend was registered in stomach contents, suggesting higher uptake of Hg in specimens from E. This difference was also observed in the relationship between concentration in muscle and size, indicating a higher accumulation rate in specimens from E. The accumulation of Se in the liver of both species showed a positive correlation with inorganic mercury concentrations, pointing to a detoxifying mechanism of organic mercury in these species through Se-Hg liasons.     

A study of osteological and molecular differences in populations of Aphanius fasciatus Nardo 1827, from the central Mediterranean (Teleostei, Cyprinodontidae)

Nine populations of Aphanius fasciatus Nardo, 1827 from the central Mediterranean were analysed by examining the mitochondrial control region and the morphology of the bony elements of the skull and vertebral column, to study the degree of intraspecific differentiation of A. fasciatus considering the level of isolation of the different populations and the palaeogeographic history of the central Mediterranean area. Both the molecular and morphological analyses differentiate between the populations, even if the topologies of the two trees are different. Molecular and osteological investigations have consistently demonstrated a well-supported differentiation of the south-eastern Sicilian populations both within the same group (Tigano et al. in Ital J Zool 71:1124–1133, 2004a; Tigano et al. in Abstract volume XI European Congress of Ichthyology, Tallin, Estonia, 2004b), and from the populations from western Sicily, Tunisia and the island of Malta. The molecular results show that the nine populations are characterised by haplotypes that are well defined in relation to a probably limited gene flow; while, as regards the morphological data the differentiation found could be explained in terms of the geographic isolation of the various populations, although the influence of environmental factors, which differ greatly between the various sites where the populations live, cannot be ruled out.     

Influence of atmospheric stability on the mass concentration and chemical composition of atmospheric particles: a case study in Rome, Italy

PM(10) concentration and chemical composition (ions and carbon compounds) at three sampling stations in Rome and in its surroundings was determined daily during a one-month field study, carried out during December 2003. PM concentration at the traffic station was considerably higher than at the urban background and semi-rural stations; elemental carbon was detected as one of the chemical components responsible for this increase. The difference in the concentration of sulphate and ammonium was negligible, as it was expected for secondary pollutants. A negative artefact in the determination of ammonium nitrate by means of heated automatic monitors was highlighted. The dilution properties of the lower atmosphere were traced by means of a natural radioactivity monitor. This parameter has been found to play an essential role in pollution buildup. A considerable increase in PM concentration was observed to coincide with periods of atmospheric stability. The main difference in PM composition between periods of high concentration and periods of "clean" air was found to be in the increase of ammonium nitrate concentration.     

Validation of Ucides cordatus as a bioindicator of oil contamination and bioavailability in mangroves by evaluating sediment and crab PAH records

This study is aimed at verifying the relevance of Ucides cordatus as a bioindicator of oil contamination and PAH bioavailability in mangrove sediments. For this, crabs and sediment cores were sampled from five mangroves, including an area suspected of contamination derived from an MF380 oil spillage, and analyzed for the 16 PAH in the USEPA priority list as well as for the five series of alkylated homologues. Concentrations in sediments varied from 35 microg kg-1 in the lower core layer of the control area to 33,000 microg kg-1 in the upper layer of the most contaminated area. Total PAH contents in crabs varied from 206 to 62,000 microg kg-1 and were closely correlated to that in sediments. In general, individual PAH profiles in both matrices were in good agreement. Phenanthrenes, however, were more predominant in crabs making up to 30-46% of the Total PAH. Accumulation factors found in the range of 0.7 to 35 were highly variable even after normalizing concentrations for organic carbon and lipid content. Survival in highly contaminated environment and reliable record of environmental contamination in the tissue provide evidence that U. cordatus is an excellent bioindicator for oil in mangroves.     

Contributions of green infrastructure to enhancing urban resilience

After briefly reviewing key resilience engineering perspectives and summarising some green infrastructure (GI) tools, we present the contributions that GI can make to enhancing urban resilience and maintaining critical system functionality across complex integrated social–ecological and technical systems. We then examine five key challenges for the effective implementation of GI that include (1) standards; (2) regulation; (3) socio-economic factors; (4) financeability; and (5) innovation. We highlight ways in which these challenges are being dealt with around the world, particularly through the use of approaches that are both context appropriate and socially inclusive. Although progress surmounting these challenges has been made, more needs to be done to ensure that GI approaches are inclusive and appropriate and feature equally alongside more traditional ‘grey’ infrastructure in the future of urban resilience planning. This research was undertaken for the Resilience Shift initiative to shift the approach to resilience in practice for critical infrastructure sectors. The programme aims to help practitioners involved in critical infrastructure to make decisions differently, contributing to a safer and better world.