Characterization of a chalcopyrite from Brazil by Mössbauer spectroscopy and other physicochemical techniques

We studied a chalcopyrite from a Cu ore deposit in Rio Grande do Sul, Brazil, by Mössbauer spectroscopy at room temperature and 110 K. Supporting methods to check for sample purity and to characterize further sample properties were slow-scanning X-ray powder diffraction and optical and microprobe analyses of polished sections of selected grains. Chemical analyses obtained using a scanning electron microscope equipped with an energy-dispersive X-ray spectrometer showed the sample to consist of homogeneous and essentially stoichiometric chalcopyrite (CuFeS₂). Mössbauer spectra taken at both the above temperatures consist of asymmetric magnetically ordered patterns with unequal intensities of the line pairs 1–6 and 2–5, pointing to the existence of non-equivalent or multiple Fe sites. Least-squares fittings evidenced that the resonance intensity ratio of subspectrum with lower quadrupole shift (indicative of a more symmetric environment) to that with higher shift is 69:31, at room temperature, and 68:32, at 110 K. Rietveld refinement of the XRD data indicates the existence of tetragonal [a = 0.52855(1) and c = 1.0412(1) nm] and cubic [a ₀ = 0.5273(2) nm] modifications in a proportion of 74:26, in good agreement with the Mössbauer data. The saturation magnetization of the sample was 32.7 J/(T kg), confirming the oxidation state of Fe as trivalent and pointing to little to no spin canting.     

Structural evolution of the contact between two Penninic nappes (Zermatt-Saas zone and Combin zone,Western Alps) and implications for the exhumation mechanism and palaeogeography

The boundary zone between two Penninic nappes, the eclogite-facies to ultrahigh-pressure Zermatt-Saas zone in the footwall and the blueschist-facies Combin zone in the hanging wall, has been interpreted previously as a major normal fault reflecting synorogenic crustal extension. Quartz textures of mylonites from this fault were measured using neutron diffraction. Together with structural field observations, the data allow a refined reconstruction of the kinematic evolution of the Pennine nappes. The main results are: (1) the contact is not a normal fault but a major thrust towards northwest which was only later overprinted by southeast-directed normal faulting; (2) exhumation of the footwall rocks did not occur during crustal extension but during crustal shortening; (3) the Sesia-Dent Blanche nappe system originated from a continental fragment (Cervinia) in the Alpine Tethys ocean, and the Combin zone ophiolites from the ocean basin southeast of Cervinia; (4) out-of-sequence thrusting played a major role in the tectonic evolution of the Penninic nappes. An erratum to this article can be found at     

Research on Relationship Between Fluorine in Tap Water and That in Urine of Chinese Residents

In this study, the relationship between fluorine in drinking water and that in urine of urban residents in China is assessed. Fluorine concentrations in tap water and those in urine show a good correlation with a linear regression coefficient of 0. 9798, indicating that the fluorine concentrations in big cities under investigation are extremely low, and the main source of fluorine is tap water. The weather effect on the intake amount of fluorine is also discussed. When air temperature is above 15℃, people would intake more fluorine through drinking water with the rise of air temperature. When temperature is below 15℃, no remarkable relationship is observed between air temperature and the intake amount of fluorine. This phenomenon indicates that the main source of fluorine in China is tap water instead of foodstuff.     

Phosphorus Sorption Dynamics of Hawaii’s Coastal Wetlands

While phosphorus (P) sorption has been studied in Hawaii’s terrestrial soils, P sorption dynamics have yet to be investigated in coastal wetlands. In other coastal zones, wetlands have been shown to sorb P and act as P sinks at the land–sea interface. Thus, the objectives of this study were to examine variance in the P sorption index (PSI) within wetlands along hydrologic gradients and among wetlands of different types and to identify soil properties that best explain variability in the PSI. Forty wetlands on five islands were sampled and P sorption and related properties were measured. Phosphorus sorption index values ranged from −16.4–1,732.5. Hydrologic zone (within sites) and surface water salinity (among sites) accounted for significant proportions of the variance in the PSI. While texture, pH, and carbon content were found to be important predictors of PSI, the highest correlations were found for oxalate-extractable iron.     

The impact of political transformation on employment in the Transkei bureaucracy and civil service in Umtata,South Africa since 1994

The demise of South African Apartheid Planning in 1994 and subsequent lost of Umtata’s capital status when the Transkei was subsumed into the new Eastern Cape Province resulted in the major political transformation of the Transkei state. Central to the post-apartheid transformation was restructuring of Transkei bureaucracy which at the time of South Africa’s independence in 1994 displayed abnormalities. This paper documents the restructuring of the Transkei bureaucracy focusing on Umtata since 1994. The study has brought to the forefront the following facts: Firstly, that at the time of the Transkei merger into South Africa, employment in the government was ‘booming’ and to greater extent it was affected by Umtata’s role—being the capital city of the pseudo-Transkei state. Secondly, the post 1994-political transformation of the Transkei Bantustan impacted negatively on Umtata’s employment notably the civil service sector by ‘squeezing’ it during the early years of democracy (1994–2000). Thirdly, since 2001, with Umtata serving as the major urban centre of both King Sabata Local Municipality and OR Tambo District Municipality, employment in the civil service and municipality has been revitalized.     

Transparent Exopolymer Particles (TEP) in a River-Dominated Estuary: Spatial–Temporal Distributions and an Assessment of Controls upon TEP Formation

Transparent exopolymer particle (TEP) distributions were examined in North Carolina’s Neuse River Estuary (NRE) over a 1-year period, and experiments were conducted to examine controls upon TEP formation. TEP-carbon averaged 16% of the total organic carbon pool in the NRE. From May to early August 2007, TEP ranged from 805 to 1,801 μg xanthan gum (XG) L⁻¹. A large phytoplankton bloom peaked in early August and then subsequently declined. Within 2 weeks of the bloom’s peak, TEP concentrations increased to >3,500 μg XG L⁻¹ and remained elevated through mid-December. Decreasing water temperatures and enhanced retention due to drought conditions in Fall 2007 likely aided in the persistence of TEP concentrations during this timeframe. Thereafter, TEP decreased coincident with increased river flow and flushing of the estuary that began in January 2008, and TEP remained low (ranging from 991 to 1,712 μg XG L⁻¹) until the end of April 2008. TEP was positively correlated with salinity, suggesting that cation availability (which co-varies with salinity and stabilizes the structural integrity of TEP) may play a role in estuarine TEP formation. In two cation addition experiments using water from the mesohaline region, TEP concentrations tended to be higher in treatments with vs. without cations added. Statistically significant relationships were also found between in situ TEP concentrations and pH, mixing, and temperature, suggesting that a complex suite of environmental parameters affect TEP formation and its distribution in estuaries.     

Mineralogy and geochemistry of banded iron formation and iron ores from eastern India with implications on their genesis

The geological complexities of banded iron formation (BIF) and associated iron ores of Jilling-Langalata iron ore deposits, Singhbhum-North Orissa Craton, belonging to Iron Ore Group (IOG) eastern India have been studied in detail along with the geochemical evaluation of different iron ores. The geochemical and mineralogical characterization suggests that the massive, hard laminated, soft laminated ore and blue dust had a genetic lineage from BIFs aided with certain input from hydrothermal activity. The PAAS normalized REE pattern of Jilling BIF striking positive Eu anomaly, resembling those of modern hydrothermal solutions from mid-oceanic ridge (MOR). Major part of the iron could have been added to the bottom sea water by hydrothermal solutions derived from hydrothermally active anoxic marine environments. The ubiquitous presence of intercalated tuffaceous shales indicates the volcanic signature in BIF. Mineralogical studies reveal that magnetite was the principal iron oxide mineral, whose depositional history is preserved in BHJ, where it remains in the form of martite and the platy hematite is mainly the product of martite. The different types of iron ores are intricately related with the BHJ. Removal of silica from BIF and successive precipitation of iron by hydrothermal fluids of possible meteoric origin resulted in the formation of martite-goethite ore. The hard laminated ore has been formed in the second phase of supergene processes, where the deep burial upgrades the hydrous iron oxides to hematite. The massive ore is syngenetic in origin with BHJ. Soft laminated ores and biscuity ores were formed where further precipitation of iron was partial or absent.     

Comparison of the Salinity Structure of the Chesapeake Bay,the Delaware Bay and Long Island Sound Using a Linearly Tapered Advection-Dispersion Model

Long records of monthly salinity observations along the axis of Chesapeake Bay, Delaware Bay, and Long Island Sound are used to test a simple advection–dispersion model of the salt distribution in linearly tapered estuaries developed in a previous paper. We subdivide each estuary into three to five segments, each with linear taper allowing a distributed input of fresh water, and evaluate the dispersion in each segment. While Delaware Bay has weak dispersion and a classical sigmoidal salinity structure, Long Island Sound and Chesapeake Bay are more dispersive and have relatively small gradients in the central stretches. Long Island Sound is distinguished by having a net volume and salt flux out of its low-salinity end resulting in a smaller range of salinity and increasing axial gradients at its head rather than the usual asymptotic approach to zero salinity. Estimates of residence times based on model transport coefficients show that Long Island Sound has the most rapid response to fresh-water flux variations. It also has the largest amplitude cycle in river discharge fluctuation. In combination, these cause the large seasonal variation in the salinity structure relative to interannual variability in Long Island Sound as compared with Chesapeake Bay and Delaware Bay.     

Short-Term Effects of an Oil Spill on Marsh-Edge Fishes and Decapod Crustaceans

On 19 April 2005, an oil spill occurred in southeastern Louisiana’s Barataria Bay estuary. We used a drop sampler to characterize the marsh-edge nekton community. Thirty-six locations were sampled in pre- and post-spill time frames from March through May 2005. Before–after control–impact (BACI) analyses of the total number of individuals (fishes + decapod crustaceans), total fishes, and sensitive species found significant interactions between the temporal (before/after) and spatial (control/impact) treatments and indicated an effect of the oil spill. Nonparametric analyses detected varied faunal assemblages across temporal treatments, but were similar in species composition among spatial treatments. While the BACI analyses showed event effects, differences were not strongly detected in nonparametric analyses of community structure. Fish are mobile and left the spill area after the disturbance, whereas the less mobile but more numerous benthic decapod crustaceans remained. The overall community structure appears to be robust and quickly recovered from the localized spill event.