Soil Cd,Cu, Pb and Zn contaminants around Mount Isa city,Queensland, Australia: Potential sources and risks to human health

This article investigates the relationship between soil Cd, Cu, Pb and Zn contaminants and the location and activities of the Pb–Zn–Ag and Cu mines at Mount Isa, Queensland, Australia. Analysis of the data focuses primarily on soil Pb distributions and concentrations because of their potential impact on children’s health. The Xstrata Mount Isa Mines lease (XMIM) is Australia’s leading emitter of numerous contaminants to the environment, including Cu and Pb, and the mining-related activities have been linked causally to the findings of a 2008 study that showed 11.3% of local children (12–60 months) have blood Pb levels >10 μg/dL. Queensland government authorities and Xstrata Mount Isa Mines Pty Ltd maintain that contaminants within environmental systems around Mount Isa are largely the result of near-surface mineralization. The evidence for whether the contamination is derived from XMIM or other possible sources, such as the natural weathering of ore-rich bedrock, is investigated using data from surface and subsurface soil chemistry, atmospheric modelling of metal contaminants from mining and smelting operations and local geological and associated geochemical studies. Sixty surface soil samples collected from sites adjacent to houses, parks and schools throughout Mount Isa city were analyzed for their total extractable Cd, Cu, Pb and Zn concentrations in the <2 mm to >180 μm (coarser) and <180 μm (finer) grain size fractions. Concentrations in the finer size fraction reveal a range of values: Cd – 0.7–12.5 ppm; Cu – 31–12,100 ppm; Pb – 8–5770 ppm; Zn – 26–11,100 ppm, with several samples exceeding Australian residential health investigation guidelines. Spatial analysis shows that surface soil metal concentrations are significantly higher within 2 km of XMIM compared to more distant samples, and that more than 1000 property lots are at risk of having detrimentally high soil Pb levels. Determination of metal concentrations in 49 samples from eight soil pits shows that surface samples (0–2 cm) are enriched significantly relative to those at depth (10–20 cm), suggesting an atmospheric depositional origin. AUSPLUME air dispersal modelling of Pb originating from the Cu and Pb smelter stacks and mine site fugitive sources confirms that Pb is deposited across the urban area, during periods of the year (∼20%/a) when the wind blows from the direction of XMIM towards the urban area and disperses dusts from the uncovered spoil and road surfaces, as well as from stack emission sources. Although there are some spatially restricted outcrops of Pb close to the surface in parts of the urban area, the Cu-ore body is ∼244 m below the surface. However, enriched and significantly correlated surface soil concentrations of Cu and Pb (Pearson correlation 0.879, p = 0.000) in and around the urban area of Mount Isa can only be explained by atmospheric transport and deposition of metals from the adjoining mining and smelting operations. The results from this study provide unequivocal evidence that both historic and ongoing emissions from XMIM are contaminating the urban environment. Given the ongoing Pb poisoning issues in Mount Isa children, it is clear that remediation, reductions in mine emissions and more stringent regulatory actions are warranted.     

C 1s K-edge near edge X-ray absorption fine structure (NEXAFS) spectroscopy for characterizing functional group chemistry of black carbon

Black carbon (BC) is considered ubiquitous in soil organic matter (OM) and therefore plays an important role in soil biogeochemistry. Its complexity, particularly within environmental matrices, presents a challenge for research, primarily as a result of techniques which may favor detection of certain functional group types rather than capturing total sample C. The objective of this study was to utilize carbon (C) 1s near edge X-ray absorption fine edge structure (NEXAFS) spectroscopy to characterize the C chemistry of a broad range of BC materials. Characteristic resonances in the NEXAFS spectra allowed direct molecular speciation of the total C chemistry of the reference materials, environmental matrices and potentially interfering materials, obtained from an earlier BC ring trial. Spectral deconvolution was used to further identify the functional group distribution of the materials. BC reference materials and soils were characterized by a large aromatic C region comprising around 40% of total absorption intensity. We were able to distinguish shale and melanoidin from BC reference materials on the basis of their unique spectral characteristics. However, bituminous coal shared chemical characteristics with BC reference materials, namely high aromaticity of more than 40% identified by way of a broad peak. Lignite also shared similar spectra and functional group distributions to BC reference materials and bituminous coal. We compared the results of spectral deconvolution with the functional group distributions obtained by way of direct polarization magic angle spinning (DPMAS) ¹³C nuclear magnetic resonance (NMR) spectroscopy. Correlations between aromatic type C values for DPMAS ¹³C NMR and NEXAFS gave r² = 0.633 (p < 0.05) and the values for NEXAFS were around 30–40% lower than for ¹³C NMR. Correlations were also drawn between the aromatic C/O-alkyl C ratio values for the two methods (r² = 0.49, p < 0.05). Overall, NEXAFS was applicable for a wide range of environmental materials, such as those measured, although some limitations for the technique were addressed.     

Arsenic and Antimony in Groundwater Flow Systems: A Comparative Study

Arsenic (As) and antimony (Sb) concentrations and speciation were determined along flow paths in three groundwater flow systems, the Carrizo Sand aquifer in southeastern Texas, the Upper Floridan aquifer in south-central Florida, and the Aquia aquifer of coastal Maryland, and subsequently compared and contrasted. Previously reported hydrogeochemical parameters for all three aquifer were used to demonstrate how changes in oxidation–reduction conditions and solution chemistry along the flow paths in each of the aquifers affected the concentrations of As and Sb. Total Sb concentrations (Sb_T) of groundwaters from the Carrizo Sand aquifer range from 16 to 198 pmol kg⁻¹; in the Upper Floridan aquifer, Sb_T concentrations range from 8.1 to 1,462 pmol kg⁻¹; and for the Aquia aquifer, Sb_T concentrations range between 23 and 512 pmol kg⁻¹. In each aquifer, As and Sb (except for the Carrizo Sand aquifer) concentrations are highest in the regions where Fe(III) reduction predominates and lower where SO₄ reduction buffers redox conditions. Groundwater data and sequential analysis of the aquifer sediments indicate that reductive dissolution of Fe(III) oxides/oxyhydroxides and subsequent release of sorbed As and Sb are the principal mechanism by which these metalloids are mobilized. Increases in pH along the flow path in the Carrizo Sand and Aquia aquifer also likely promote desorption of As and Sb from mineral surfaces, whereas pyrite oxidation mobilizes As and Sb within oxic groundwaters from the recharge zone of the Upper Floridan aquifer. Both metalloids are subsequently removed from solution by readsorption and/or coprecipitation onto Fe(III) oxides/oxyhydroxides and mixed Fe(II)/Fe(III) oxides, clay minerals, and pyrite. Speciation modeling using measured and computed Eh values predicts that Sb(III) predominate in Carrizo Sand and Upper Floridan aquifer groundwaters, occurring as the Sb(OH)₃⁰ species in solution. In oxic groundwaters from the recharge zones of these aquifers, the speciation model suggests that Sb(V) occurs as the negatively charged Sb(OH)₆⁻ species, whereas in sufidic groundwaters from both aquifers, the thioantimonite species, HSb₂S₄ ⁻ and Sb₂S₄ ²⁻, are predicted to be important dissolved forms of Sb. The measured As and Sb speciation in the Aquia aquifer indicates that As(III) and Sb(III) predominate. Comparison of the speciation model results based on measured Eh values, and those computed with the Fe(II)/Fe(III), S(-II)/SO₄, As(III)/As(V), and Sb(III)/Sb(V) couples, to the analytically determined As and Sb speciation suggests that the Fe(II)/Fe(III), S(-II)/SO₄ couples exert more control on the in situ redox condition of these groundwaters than either metalloid redox couple.     

High-temperature hydrothermal alteration of the Boehls Butte anorthosite: origin of a bimodal plagioclase assemblage

The Boehls Butte anorthosite consists predominantly of an unusual bimodal assemblage of andesine and bytownite–anorthite. Oxygen isotope compositions of the anorthosite were profoundly altered by high temperature, retrograde interaction with meteoric-hydrothermal fluids that varied in composition from isotopically evolved to nearly pristine meteoric water. Oxygen isotope ratios of bulk plagioclase separates are in the range +7.0 to −6.2‰ V-SMOW, however, secondary ion mass spectrometry indicates spot-sized isotope values as low as −16‰. Typical inter- and intra-plagioclase grain variability is 3–6‰, and extreme heterogeneity of up to 20‰ is noted in a few samples. High-temperature hydrothermal alteration of intermediate plagioclase is proposed to explain the origin of bytownite–anorthite in the anorthosite and creation of its unusual bimodal plagioclase assemblage. The anorthite-forming reaction created retrograde reaction-enhanced permeability which, together with rapid decompression, extension, and unroofing of the anorthosite complex, helped to accommodated influx of significant volumes of meteoric-hydrothermal fluids into the anorthosite.     

Elemental abundances for Nova LMC 1990#1

We present our analysis of the UV spectra of the fast ONeMg Nova LMC 1990#1. Observations with the IUE began on 1990 January 18 and continued through to 1990 March 15. We have analysed these spectra, and determined line fluxes and physical parameters as a function of time. Using both He  ii lines and the Balmer decrement, we find the reddening for the nova to be E ( B − V )≃0.22. Using the photoionization code cloudy 90.03b and the minimization routine minuit , we derive elemental abundances for the ejecta. We find the following abundances, relative to solar material: He=1, C=8, N=109, O=20, Ne=62, Mg=16, Al=257 and Si=41. These results are based on independent fits to different data sets acquired three weeks apart. These abundances are extremely similar to those found for V693 Corona Austrinae 1981. Given the position of V693 CrA in the Galaxy and the range of distances found for it, the similar abundances imply that the V693 CrA outburst took place on an older population white dwarf. The high N/O ratio implies an outburst on a massive white dwarf.     

Paleoecology and geochronology of glacial Lake Hind during the Pleistocene–Holocene transition: A context for Folsom surface finds on the Canadian Prairies

Stratigraphic and paleoecologic (palynomorph, macrobotanical) data obtained from a cutbank of the Souris River in southwestern Manitoba establish some fundamental parameters of Folsom land‐use in association with a proglacial lake on the Canadian Prairies. By dating the regression of glacial Lake Hind, we observed that recorded Folsom sites are restricted to areas of the Hind basin drained shortly before 10,400 yr B.P. This pattern may therefore record the interception of seasonal resources on recently‐drained proglacial lake surfaces. Based on paleovegetation reconstructions, we note that these surfaces were rapidly colonized by emergent and aquatic vegetation following regression, generating a viable resource base for Folsom hunter‐gatherers. However, low plant productivity and diversity may have greatly limited the extent to which this locale was exploited, in contrast to nonperiglacial regions on the Plains. We also suggest that wetland plant succession during the Pleistocene‐Holocene transition was due, at least locally, to climate‐forced fluctuations in groundwater levels. © 2003 Wiley Periodicals, Inc.     

Bio-gentrification: vulnerability bio-value chains in gentrifying neighbourhoods†

In this paper, I develop the concept of “bio-gentrification” as a way to broaden critical theoretical debates on the relationship between gentrification and “social mixing” policies. Bio-gentrification weds urban Marxist political economic insights to the neo-Foucauldian notion of biopower. The former stresses spatial tactics of removal and displacement and value generated through land and property. The latter assesses a wider terrain of spatial tactics, their relationship to knowledge produced about humans as living beings, and their alignment with capitalist urbanization. The Vancouver example illuminates how social mixing “truths” and practices to which they are tied generate value by naturalizing human insecurity in situ and transforming the biological existence of disadvantaged peoples into raw material for profit through a process that can be conceptualized as a “vulnerability bio-value chain.” Bio-gentrification refers to the tension between removal and embedding of disadvantaged peoples and points to the need for a bio-gentrification politics to confront this dynamic.     

The use of chemical dispersants to combat oil spills at sea: A review of practice and research needs in Europe

In order to better understand the practice of dispersant use, a review has been undertaken of marine oil spills over a 10 year period (1995-2005), looking in particular at variations between different regions and oil-types. This viewpoint presents and analyses the review data and examines a range of dispersant use policies. The paper also discusses the need for a reasoned approach to dispersant use and introduces past cases and studies to highlight lessons learned over the past ten years, focussing on dispersant effectiveness and monitoring; toxicity and environmental effects; the use of dispersants in low salinity waters; response planning and future research needs.     

No significant post-Eocene rotation of the Moesian Platform and Rhodope (Bulgaria): Implications for the kinematic evolution of the Carpathian and Aegean arcs

The region located between the Carpathian–Balkan and Aegean arcs, the Moesian Platform and Bulgarian Rhodope, is generally assumed to have been stably attached to the East European craton during the Cenozoic evolution of these arcs. The kinematic evolution of this region is, however, poorly constrained by paleomagnetic analysis. In this paper we provide new paleomagnetic data (800 volcanic and sedimentary samples from 12 localities) showing no significant post-Eocene rotation of the Moesian platform and Rhodope with respect to Eurasia, therefore confirming the stability of this region. We compare this result to a provided review of paleomagnetic data from the South Carpathians (Tisza block) and the Aegean region. The Tisza block underwent 68.4 ± 16.7° of middle Miocene ( 15–10 Ma) clockwise rotation with respect to the Moesian Platform, in line with previous rotation estimates based on structural geology. The stability of the Moesian platform during middle Miocene eastward emplacement of the Tisza block into the Carpathian back-arc supports dextral shear along the Southern Carpathians recorded by 13–6 Ma clockwise strike-slip related rotations in foreland deposits. The new reference direction for the Moesian platform and Rhodope allows accurate quantification of the rotation difference with the west Aegean domain at 38.0 ± 7.2° occurring between 15 and 8 Ma. To accommodate this rotation, we propose that the pivot point of the west-Aegean rotation was located approximately in the middle of the rotating domain rather than at the northern tip as previously proposed. This new scenario predicts less extension southeast of the pivot point, in good agreement with estimates from Aegean structural geology. Northwest of the pivot point, the model requires contraction or extrusion that can be accommodated by the coeval motion of the Tisza Block around the northwestern edge of the Moesian platform.     

Submarine groundwater discharge is an important net source of light and middle REEs to coastal waters of the Indian River Lagoon, Florida, USA

Porewater (i.e., groundwater) samples were collected from multi-level piezometers across the freshwater-saltwater seepage face within the Indian River Lagoon subterranean estuary along Florida’s (USA) Atlantic coast for analysis of the rare earth elements (REE). Surface water samples for REE analysis were also collected from the water column of the Indian River Lagoon as well as two local rivers (Eau Gallie River, Crane Creek) that flow into the lagoon within the study area. Concentrations of REEs in porewaters from the subterranean estuary are 10-100 times higher than typical seawater values (e.g., Nd ranges from 217 to 2409 pmol kg⁻¹), with submarine groundwater discharge (SGD) at the freshwater-saltwater seepage face exhibiting the highest REE concentrations. The elevated REE concentrations for SGD at the seepage face are too high to be the result of simple, binary mixing between a seawater end-member and local terrestrial SGD. Instead, the high REE concentrations indicate that geochemical reactions occurring within the subterranean estuary contribute substantially to the REE cycle. A simple mass balance model is used to investigate the cycling of REEs in the Indian River Lagoon and its underlying subterranean estuary. Mass balance modeling reveals that the Indian River Lagoon is approximately at steady-state with respect to the REE fluxes into and out of the lagoon. However, the subterranean estuary is not at steady-state with respect to the REE fluxes. Specifically, the model suggests that the SGD Nd flux, for example, exported from the subterranean estuary to the overlying lagoon waters exceeds the combined input to the subterranean estuary from terrestrial SGD and recirculating marine SGD by, on average, ∼100 mmol day⁻¹. The mass balance model also reveals that the subterranean estuary is a net source of light REEs (LREE) and middle REEs (MREE) to the overlying lagoon waters, but acts as a sink for the heavy REEs (HREE). Geochemical modeling and statistical analysis further suggests that this fractionation occurs, in part, due to the coupling between REE cycling and iron redox cycling within the Indian River Lagoon subterranean estuary. The net SGD flux of Nd to the Indian River Lagoon is ∼7-fold larger than the local effective river flux to these coastal waters. This previously unrecognized source of Nd to the coastal ocean could conceivably be important to the global oceanic Nd budget, and help to resolve the oceanic “Nd paradox” by accounting for a substantial fraction of the hypothesized missing Nd flux to the ocean.