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Metal-mining exploitation has caused ecosystem degradation worldwide. Legacy wastes are often concentrated around former mines where monitoring and research works are mostly focused. Geochemical and physical weathering can affect metal-enriched sediment locations and their capacity to release metals at a catchment scale. This study investigated how fluvial geomorphology and soil geochemistry drive zinc and lead dispersion along the Nant Cwmnewyddion (Wales, UK). Sediments from different locations were sampled for geochemical and mineralogical investigations (portable X-ray fluorescence, scanning electron microscope, X-ray diffraction, and electron microprobe analysis). The suspended sediment fluxes in the streamwater were estimated at different streamflows to quantify the metal dispersion. Topographical and slope analysis allowed us to link sediment erosion with the exposure of primary sulphide minerals in the headwater. Zinc and lead entered the streamwater as aqueous phases or as suspended sediments. Secondary sources were localised in depositional stream areas due to topographical obstruction and a decrease in stream gradient. Sediment zinc and lead concentrations were lower in depositional areas and associated with Fe-oxide or phyllosilicates. Streamwater zinc and lead fluxes highlighted their mobility under high-flow conditions. This multi-disciplinary approach stressed the impact of the headwater mining work on the downstream catchment and provided a low-cost strategy to target sediment sampling via geomorphological observations.

Exceptionally low river flows are predicted to become more frequent and more severe across many global regions as a consequence of climate change. Investigations of trace metal transport dynamics across streamflows reveal stark changes in water chemistry, metal transformation processes, and remediation effectiveness under exceptionally low-flow conditions. High spatial resolution hydrological and water quality datasets indicate that metal-rich groundwater will exert a greater control on stream water chemistry and metal concentrations because of climate change. This is because the proportion of stream water sourced from mined areas and mineralized strata will increase under predicted future low-flow scenarios (from 25% under Q45 flow to 66% under Q99 flow in this study). However, mineral speciation modelling indicates that changes in stream pH and hydraulic conditions at low flow will decrease aqueous metal transport and increase sediment metal concentrations by enhancing metal sorption directly to streambed sediments. Solute transport modelling further demonstrates how increases in the importance of metal-rich diffuse groundwater sources at low flow could minimize the benefits of point source metal contamination treatment. Understanding metal transport dynamics under exceptionally low flows, as well as under high flows, is crucial to evaluate ecosystem service provision and remediation effectiveness in watersheds under future climate change scenarios.

The production of iron and steel has generated substantial volumes of slag as waste, with estimates of up to 384 million tonnes (Mt) of iron slag and 280 Mt of steel slag produced globally, to date. Whilst the majority of these by-products (approximately 70 %) have seen bulk re-use in a number of applications (e.g. as ballast in construction applications), a significant volume of slag has been disposed of in environmental settings, where the release of metal-rich alkaline leachates can cause enduring pollution. However, the mineralogical and physical properties of slags also offer opportunity for environmental benefits, namely; through sequestration of atmospheric carbon dioxide, by acting as stockpiles of critical raw materials, and in certain situations performing as incidental coastal defences.Findings are presented from national-scale field investigations, laboratory experiments, and spatial data analyses, which aim to explore the resource potential of iron and steel slags in the United Kingdom (UK). Within the 236 Mt of slags disposed of in the UK environment, projected carbonation rates revealed a potential for uptake of 138 Mt CO2 under enhanced weathering conditions. Notable masses of technologically-critical elements were also estimated within UK slags, with reserves in the region of 1.55 Mt of V2O5, 1.58 Mt of TiO2, and 1.26 Mt of Cr2O3 estimated. Further to acting as a resource, in areas of coastal deposition, slag banks were observed to offer tidal protection. At a number of sites this allowed the development of nationally-significant ecological communities, whilst laboratory leaching experiments reveal a very low risk of chemical leaching in saline conditions. The integration of spatial analyses with chemical composition and leaching data can help to inform decisions on maximising resource potential whilst minimising the potential environmental risks associated with slag reworking.

Hydrologic tracer techniques were applied to Rio Irvi (SW Sardinia), a stream affected by mine drainage, allowing the calculation of stream discharge and metal loads and comparison to other streams. The calculated discharge showed a continuous increase from near 21.2 L/s to 29.1 L/s. Cumulative loads of mine-related constituents, including the Casargiu adit inflow, were large, with more than 9900 kg/day of SO42−, 2370 kg/day of Zn, 550 kg/day of Fe and 172 kg/day of Mn. The greatest measurable inflow source of metals, other than the Casargiu adit, was an acidic tributary (L4), but most sources of instream metal load were related to dispersed groundwater inflows. Some of those groundwater inflows were related to non-flowing tributaries. Calculations of the cumulative instream metal load, excluding the Casargiu adit inflow, indicated increases of 1250 kg/day for SO42, 858 kg/day for Zn-, 137 kg/day gain for Fe and 60 kg/day for Mn. Rio Irvi Zn load was extreme for a stream of this size and discharge. A comparison with two other mine-affected rivers in Sardinia indicated the loading in Rio Irvi was two to three orders of magnitude greater. This difference was attributed to different geochemical conditions, but also to a lack of a biogeochemical barrier like that seen to be acting along and below the riverbed in Rio San Giorgio. Several years of intense vegetation growth in the river bed of Rio San Giorgio created a biogeochemical barrier to metal loading, and the cumulative Zn load there was near 8 kg/day, despite being a drainage with a greater mass of mine wastes to contribute to the load.

In southwestern Sardinia, Italy, the Rio Naracauli drains a catchment that includes several abandoned mines. The drainage from the mines and associated waste rocks has led to extreme concentrations of dissolved Zn, but because of the near-neutral pH, concentrations of other metals remain low. In the reach from approximately 2300 to 3000 m downstream from the headwaters area, an amorphous Zn-silicate precipitates from the water. In this reach, concentrations of both Zn and silica remain nearly constant, but the loads (measured in mass/time) of both increase, suggesting that new Zn and silica are supplied to the stream, likely from emerging groundwater. Zinc isotope signatures of the solid are heavier than the dissolved Zn by about 0.5 permil in 66/64 Zn, suggesting that an extracellular biologically mediated adsorption process may be involved in the formation of the Zn-silicate.

Juvenile myelo-monocytic leukemia (JMML) is a severe malignant stem cell disorder of childhood. A proportion of cells from JMML mononuclear cells (MNC) spontaneously diAerentiate in vitro into dendritic cells (DC). We have studied MNC from 14 JMML patients, and characterized their functional activity as antigen presenting cells (APC). Large cells, diAerentiated after seven days of culture, expressed high levels of MHC II molecules and Mannose Receptor, variable levels of CD80 and CD86, and low levels of CD1a. Similar to immature DC, cells from JMML had high levels of dextran endocytosis, and were able to elicit proliferation of allogeneic T lymphocytes in mixed leukocyte reaction (MLR). CD40Lmatured DC from JMML was associated with relevant increase of CD80, CD86 and CD83, increased APC activity, responded in chemotaxis assays to MIP-3b and secreted increased amounts of macrophage derived chemokine (MDC). Immature DC and CD40L-matured DC from JMML produced very low amounts of IL-12, whereas the production of IL-10 was higher than normal DC. In line with these findings, they showed defective capacity to polarize naive T cells to diAerentiate into Th1 eAectors. These results indicate that MNC from JMML are committed to spontaneously diAerentiate into DC with morphological and phenotypical characteristics similar to normal DC. The cytokine profile produced by these APC is likely to suppress and not to elicit a protective immune response. The Hematology Journal (2002) 3, 302‐310. doi:10.1038/sj.thj.6200192