Quantifying land use influences on event-based flow frequency,timing, magnitude,and rate of change in an urbanizing watershed of the central USA

There is a need for research that advances understanding of flow alterations in contemporary watersheds where natural and anthropogenic interactions can confound mitigation efforts. Event-based flow frequency, timing, magnitude, and rate of change were quantified at five-site nested gauging sites in a representative mixed-land-use watershed of the central USA. Statistically independent storms were paired by site (n = 111 × 5 sites) to test for significant differences in event-based rainfall and flow response variables (n = 17) between gauging sites. Increased frequency of small peak flow events (i.e., 64 more events less than 4.0 m³ s^?1) was observed at the rural–urban interface of the watershed. Differences in flow response were apparent during drier periods when small rainfall events resulted in increased flow response at urban sites in the lower reaches. Relationships between rainfall and peak flow were stronger with decreased pasture/crop land use and increased urban land use by approximately 20%. Event-based total rainfall explained 40–68% of the variance in peak flow (p < 0.001). Coefficients of determination (r²) were negatively correlated with pasture/crop land use (r² = 0.92; p = 0.007; n = 5) and positively correlated with urban land use (r² = 0.90; p = 0.008; n = 5). Significant differences in flow metrics were observed between rural and urban sites (p < 0.05; n = 111) that were not explained by differences in rainfall variables and drainage area. An urban influence on flow timing was observed using median time lag to peak centroid and time of maximum precipitation to peak flow. Results highlight the need to establish manageable flow targets in rapidly urbanizing mixed-land-use watersheds.     

Potency of constructed wetlands for deportation of pathogens index from rural,urban and industrial wastewater

Pathogen removal is essential for wastewater treatment and its potential reuse in agriculture. Three field-scale wastewater treatment systems consisting of free surface flow were operated around 1.5 years receiving water from urban domestic, rural domestic and industrial sources. The study was conducted to evaluate seasonal performance of constructed wetland systems in removing Escherichia coli, Enterococci and total coliforms under continuous hydraulic flow. Results displayed that all three wetlands gain recognition in removing pathogen load with high removal efficacy till water reaches output ports. Removal efficiencies were even higher, 66–93, 78–92 and 80–94% for E. coli, Enterococci and total coliforms, respectively, within constructed wetlands. Remarkably at shorter temporal scales in CW-A, greater homogeneity of pathogen concentrations was assessed at wetland outlet sites. In outlet ports, results displayed a highly effective removal of E. coli concentration 80–90% (June 2015), 86–92% (October 2015) and 79–92% (February 2016), Enterococci 80–94% (June 2015), 83–94% (October 2015) and 80–94% (February 2016) and total coliforms 85–93% (June 2015), 87–95% (October 2015) and 88–96% (February 2016). Positive correlation was observed between bacterial indicators (E. coli–Enterococci, r = 0.038; p < 0.01 and E. coli–total coliforms, r = 0.142; p < 0.01). Removal of bacterial indicators in constructed wetland was also displayed by PCA in which three-component analysis of variance was 98.39% and showed a clear decrease in measured parameter gradients toward samples from outlet ports. Constructed wetlands provide cost-effective treatment systems for reducing the pathogen load in wastewater in variable agro-climatic conditions and thus improve water quality.     

Sulfate Reduction and Sulfur Cycles at Two Seagrass Beds Inhabited by Cold Affinity <Emphasis Type="Italic">Zostera marina</Emphasis> and Warm Affinity <Emphasis Type="Italic">Halophila nipponica</Emphasis> in Temperate Coastal Waters

To evaluate the impact of invading seagrass on biogeochemical processes associated with sulfur cycles, we investigated the geochemical properties and sulfate reduction rates (SRRs) in sediments inhabited by invasive warm affinity Halophila nipponica and indigenous cold affinity Zostera marina. A more positive relationship between SRR and below-ground biomass (BGB) was observed at the H. nipponica bed (SRR = 0.6809 × BGB ? 4.3162, r ² = 0.9878, p = 0.0006) than at the Z. marina bed (SRR = 0.3470 × BGB ? 4.0341, r ² = 0.7082, p = 0.0357). These results suggested that SR was more stimulated by the dissolved organic carbon (DOC) exuded from the roots of H. nipponica than by the DOC released from the roots of Z. marina. Despite the enhanced SR in spring-summer, the relatively lower proportion (average, 20%) of acid-volatile sulfur (AVS) in total reduced sulfur and the strong correlation between total oxalate-extractable Fe (Fe_(oxal)) and chromium-reducible sulfur (CRS = 0.2321 × total Fe_(oxal) + 1.8180, r ² = 0.3344, p = 0.0076) in the sediments suggested the rapid re-oxidation of sulfide and precipitation of sulfide with Fe. The turnover rate of the AVS at the H. nipponica bed (0.13 day^?1) was 2.5 times lower than that at the Z. marina bed (0.33 day^?1). Together with lower AVS turnover, the stronger correlation of SRR to BGB in the H. nipponica bed suggests that the extension of H. nipponica resulting from the warming of seawater might provoke more sulfide accumulation in coastal sediments.     

Assessment of potential sediment contamination using screening methods (XRF,TGA/MS) taking into account principles of green chemistry,Eastern Slovakia

Mining and milling of metal ores coupled with industries have bequeathed many countries the legacy of wide distribution of metal contaminants in sediments. The aim of this study was to assess potential sediment contamination via useful screening methods (XRF, CHNS, TGA/MS). The sediments were collected from the water reservoir Krompachy Eastern Slovakia in April 2015. Within the frame of evaluation it was found that the concentrations of the study elements (Cu, Zn, As, Pb, Cr, Ni, Cd) exceeded some of the MPC, TV and IV values. Sample c was the most polluted by metals, which evident according to it’s the highest CHNS proportion as well as the highest clay and silt proportion. In the samples studied the best correlation was confirmed between weight losses in the temperature range (400–620 °C) and the following metal concentrations: Cu (r = 0.89), Zn (r = 0.88), As (r = 0.93), Hg (r = 0.83), Pb (r = 0.87). The greatest proportions of m/z 44, m/z 18 were detected at temperatures (400–620 °C) associated with decomposition of minerals such as siderite, barite, and exothermic loss of more refractory aromatic C took also place.     

Properties of the aftershocks sequences of the 2000 and 2002 earthquakes in Aksehir-Afyon graben,west-central Anatolia,Turkey

The b-value of the Gutenberg–Richter’s frequency–magnitude relation and the p-value of the modified Omori law, which describes the decay rate of aftershock activity, were investigated for more than 500 aftershocks in the Aksehir-Afyon graben (AAG) following the 15 December 2000 Sultandagi–Aksehir and the 3 February 2002 Çay–Eber and Çobanlar earthquakes. We used the Kandilli Observatory’s catalog, which contains records of aftershocks with magnitudes ≥2.5. For the Çobanlar earthquake, the estimated b-values for three aftershock sequences are in the range 0.34 ≤  b ≤ 2.85, with the exception of the one that occurred during the first hour (4.77), while the obtained p-values are in the range 0.44 ≤ p ≤ 1.77. The aftershocks of the Sultandagi earthquake have a high p-value, indicating fast decay of the aftershock activity. A regular increase of b can be observed, with b < 1.0 after 0.208 days for the Çay–Eber earthquake. A systematic and similar increase and decrease pattern exists for the b- and p-values of the Çobanlar earthquakes during the first 5 days.     

Estimation of the Specific Energy of TBM Using the Strain Energy of Rock Mass,Case Study: Amir-Kabir Water Transferring Tunnel of Iran

The specific energy (SE) is the most important parameter to estimate the energy consumption in tunnel boring machines (TBMs). It is defined as the amount of required energy to excavate a unit volume of rock mass which used to predict the performance of TBMs. Several models are used to estimate the SE based on different parameters such as the rock mass properties, disc cutter dimensions and cutting geometry. The aim of this work is to propose new relations between the SE and the strain energy of rock mass (W) using the geological mappings of rock mass and TBM operational parameters from Amir-Kabir Water Transferring Tunnel of Iran. W is an appropriate criterion to estimate SE because it is a function of different parameters such as rock mass behavior, pre and post failure properties and peak and residual strains. In this study, to increase the correlation coefficient of relation between the mentioned parameters, the rock mass is classified in two methods, in the first method according to the geological strength index (GSI) all data is classified in three classes such as weak, fair and good and in the second method using the drop to deformation modulus ratio (η) the classification of data is performed in three classes such as η < 0.05, 0.05 ≤ η < 10 and η ≥ 10. The results show that there are direct relations between both parameters. It is suggested to estimate SE in all rock mass classes using the proposed relations based on GSI classification.     

Biosorption of heavy metals by organic carbon from spent mushroom substrates and their raw materials

The use of agricultural wastes as biosorbents is gaining importance in bioremediation of heavy metal-polluted water and soils, due to their effectiveness and low cost. This work assesses the Cd, Pb and Cu adsorption capacity of the raw materials used in the production of substrates for mushroom production (Agaricus bisporus and Pleurotus ostreatus) and the spent mushroom composted (SMC), based on the functional groups of their organic carbon. The raw materials studied included agricultural wastes (wheat straw, wheat and rice poultry litter, grape pomace) and inorganic substances (gypsum and calcareous sand). Organic carbon from wastes and their composting products were characterized by CP-MAS ¹³C NMR. Langmuir adsorption isotherms of metals were plotted for each raw material, composting step, spent A. bisporus and P. ostreatus substrates and the final SMC. The maximum adsorption capacities of SMC were 40.43, 15.16 and 36.2 mg g^?1 for Cd, Pb and Cu, respectively. The composting process modified the adsorption properties of raw materials because of the enhanced adsorption of Cd and Cu and decreased adsorption capacity of Pb. CP-MAS ¹³C NMR and potentiometric titration were used to identify the functional groups of the organic carbon responsible for the metal adsorption. The content of cellulose was correlated with Pb adsorption (p < 0.001), alkyl and carboxyl carbon with Cd adsorption (p < 0.001), and N-alkyl (p < 0.001) and carboxyl (p < 0.010) groups with Cu adsorption. These results are valuable to develop new biosorbents based on agricultural wastes and demonstrate the high potential of SMC to adsorb heavy metals from polluted environments.     

The transfer of oxygen isotopic signals from precipitation to drip water and modern calcite on the seasonal time scale in Yongxing Cave,central China

Stable isotope data of precipitation (δ¹⁸O_p and deuterium excess), drip water (δ¹⁸O_d), and modern calcite precipitates (δ¹⁸O_c and δ¹³C_c) from Yongxing Cave, central China, are presented, with monthly sampling intervals from June 2013 to September 2016. Moderate correlations between the monthly variation of δ¹⁸O_p values (from ??11.5 to ??0.7‰) and precipitation amount (r = ??0.59, n?=?34, p?<?0.01) and deuterium excess (r?=?0.39, n?=?31, p?<?0.01) imply a combined effect of changes in precipitation amount and atmospheric circulation. At five drip sites, the δ¹⁸O_d values have a much smaller variability (from ??9.1 to ??7.5‰), without seasonal signals, probably a consequence of the mixing in the karst reservoir with a deep aquifer. The mean δ¹⁸O_d value (??8.4‰) for all drip waters is significantly more negative than the mean δ¹⁸O_p value (??6.9‰) weighted by precipitation amount, but close to the wet season (May to September) mean value (??8.3‰), suggesting that a threshold of precipitation amount must be exceeded to provide recharge. Calculation based on the equilibrium fractionation factor indicates that the δ¹⁸O_c values are not in isotopic equilibrium with their corresponding drip waters, with a range of disequilibrium effects from 0.4 to 1.4‰. The δ¹⁸O_c and δ¹³C_c values generally increase progressively away from the locus of precipitation on glass plates. The disequilibrium effects in the cave are likely caused by progressive calcite precipitation and CO₂ degassing related to a high gradient of CO₂ concentration between drip waters and cave air. Our study provides an important reference to interpret δ¹⁸O_c records from the monsoon region of China.     

Geochemistry and origin of Dehoo manganese deposit,south Zahedan,southeastern Iran

Dehoo manganese deposit is located 52 km to the south of Zahedan in Sistan and Baluchestan Province, southeastern Iran. This deposit that lies in the central part of the Iranian Flysch Zone is lenticular in shape and lies above the micritic limestone-radiolarite cherts of the upper Cretaceous ophiolite unit. It is hosted within the reddish to brown radiolarite cherts and in places interlinks with them, so that the radiolarite chert packages play a key role for Mn mineralization in the region. Investigated ore-paragenetic successions and the geochemical characteristics of the Dehoo deposit were studied by means of major oxide, trace, and rare earth element (REE) contents that provide information as to the mineral origin. Strong positive correlations were found between major oxides and trace elements (Al₂O₃-TiO₂, r = 0.95; TiO₂-MgO, r = 0.94; Fe₂O₃-Al₂O₃, r = 0.90; MgO-Al₂O₃, r = 0.84; MgO-Fe₂O₃, r = 0.88; Fe₂O₃-TiO₂, r = 0.91; Fe₂O₃-K₂O, r = 0.74; Al₂O₃-K₂O, r = 0.69; Al₂O₃-V, r = 0.72; TiO₂-V, r = 0.73, and MgO-V, r = 0.69) that testify to the contribution of mafic terrigenous detrital material to the deposit. Chondrite-normalized REE patterns of all ore samples are characterized by negative Ce (0.06–0.15, average 0.10) and slightly positive Eu (0.29–0.45, average 0.36) anomalies. Based on ratios of Mn/Fe (average 56.23), Co/Ni (average 0.33), Co/Zn (average 0.38), U/Th (average 3.40), La/Ce (average 1.45), La_n/Nd_n (average 2.16), Dy_n/Yb_n (average 0.33), and light REE/heavy REE (average 8.40; LREE > HREE), as well as Ba (average 920 ppm) and total REE contents (average 6.96 ppm) negative Ce and positive Eu anomalies, Dehoo could be considered a predominantly submarine hydrothermal Mn deposit complemented by terrigenous detrital mafic material.     

The Influence of Benthic Macrofauna on the Erodibility of Intertidal Sediments with Varying mud Content in Three New Zealand Estuaries

Fine sediment inputs can alter estuarine ecosystem structure and function. However, natural variations in the processes that regulate sediment transport make it difficult to predict their fate. In this study, sediments were sampled at different times (2011–2012) from 45 points across intertidal sandflat transects in three New Zealand estuaries (Whitford, Whangamata, and Kawhia) encompassing a wide range in mud (≤63 μm) content (0–56 %) and macrofaunal community structure. Using a core-based erosion measurement device (EROMES), we calculated three distinct measures of sediment erosion potential: erosion threshold (? _c ; N m^?2), erosion rate (ER; g m^?2 s^?1), and change in erosion rate with increasing bed shear stress (m _e ; g N^?1 s^?1). Collectively, these measures characterized surface (? _c and ER) and sub-surface (m _e ) erosion. Benthic macrofauna were grouped by functional traits (size and motility) and data pooled across estuaries to determine relationships between abiotic (mud content, mean grain size) and biotic (benthic macrofauna, microbial biomass) variables and erosion measures. Results indicated that small bioturbating macrofauna (predominantly freely motile species <5 mm in size) destabilized surface sediments, explaining 23 % of the variation in ? _c (p ≤ 0.01) and 59 % of the variation in ER (p ≤ 0.01). Alternatively, mud content and mean grain size cumulatively explained 61 % of the variation in m _e (p ≤ 0.01), where increasing mud and grain size stabilized sub-surface sediments. These results highlight that the importance of biotic and abiotic predictors vary with erosion stage and that functional group classifications are a useful way to determine the impact of benthic macrofauna on sediment erodibility across communities with different species composition.     

Sequence signal processing of 2012 Ahar–Varzaghan earthquake (<Emphasis Type="Italic">M</Emphasis><Subscript>W</Subscript> 6.4) of NW Iran

Before starting seismic cycle of Ahar–Varzaghan 2012 event, a partial gap in the form of a pre-seismic calm sequence (seismicity rate, r = 0.46 event/year, b = 1.4) with duration of 303 days spatially has dominated over the entire seismogenic area. From April 17, 2012, to May 31, 2012, r significantly increased to 2.16, indicating strong foreshock sequence, and b value changed to 1.9, remarkably. In the last two months before the mainshock, foreshocks have partially migrated toward the earthquake fault (with a decrease in size, b = 2.0). Significantly, high rate of seismicity and low V _P /V _S (1.64) in the foreshocks sequence and also very high seismicity rate (17.3) and high V _P /V _S (1.76) in the aftershocks sequence make substantial differences between the seismic cycle and the background seismicity. Moreover, a significant E–W migration of the microseismicity was confirmed in the study area.     

Effect of Slope on <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">y</Emphasis> Curves for Laterally Loaded Piles in Soft Clay

Pile foundations are often subject to lateral loading due to various forces on a variety of structures like high rise buildings, transmission towers, power stations, offshore structures and highway and railway structures. The present investigation is to study the effect of slopes on p-y curves (where p is the static soil reaction and y is the pile deflection) due to static lateral loading in soft clay (Consistency index I_c = 0.42). A series of laboratory model tests were carried out on the instrumented model pile on sloping ground (slopes of 1V:1H, 1V:1.5H, 1V:2H, 1V:3H and 1V:5H) and with varying embedment length to diameter ratio (L/D) of 20, 25 and 30. From the experimental results, the bending moment curves along the pile shaft are double differentiated to obtain the soil resistance (p) and double integrated to obtain the deflection (y) using curve fitting method. New p-y curves for piles located on crest of soft clay with different sloping ground surface under static lateral loading are developed. Moreover, the effect of sloping angles on proposed p-y curves was studied.     

Temperature induces lead toxicity in <Emphasis Type="Italic">Pangasius hypophthalmus</Emphasis>: an acute test,antioxidative status and cellular metabolic stress

Climate change and pollution are the most vulnerable stressors that are anticipated increasingly to affect all living organisms including fishes. The aquatic ecosystems are the most affected ecosystem due to contamination and global increasing temperature. In view of the above, the present study delineates 96-h median lethal concentration of heavy metal, lead alone and in combination with high temperature (34 °C) by conducting static non-renewable acute toxicity bioassay in Pangasius hypophthalmus (average weight 3.65 ± 0.75 g). Further, the effect of different definitive doses (80, 82, 84, 86, 88 and 90 mg/L) of lead alone and high temperature on cellular metabolic response was probed. The LC₅₀ of lead was found to be 84.93 mg/L, whereas in combination with high temperature it was 83.10 mg/L in P. hypophthalmus. Catalase, superoxide dismutase and glutathione-S-transferase were noticeably higher (p < 0.01) in liver, gill and brain during lead exposure alone and in combination with high temperature. The activities of aspartate aminotransferase and alanine aminotransferase were significantly enhanced (p < 0.01) in muscle, liver and gill in dose- and time-dependent manners in lead-alone-exposed and in combination with high-temperature groups. The brain and liver acetylcholine esterase activities showed noticeable (p < 0.01) inhibition from 80 to 90 mg/L exposure of lead alone and with concurrent exposure to temperature than the control group. Overall results clearly indicate that acute exposure of lead and high temperature led to pronounced deleterious alterations on cellular and metabolic activities of P. hypophthalmus.     

Geometrical characteristics of earthquake-induced landslides and correlations with control factors: a case study of the 2013 Minxian,Gansu, China, <Emphasis Type="Italic">Mw</Emphasis> 5.9 event

Geometric parameters are useful for characterizing earthquake-triggered landslides. This paper presents a detailed statistical analysis on this issue using the landslide inventory of the 2013, Minxian, China Mw 5.9 earthquake. Based on GIS software and a 5-m resolution DEM, geometric parameters of 635 coseismic landslides (with areas larger than 500 m²) were obtained, including height, length, width, reach angle (arc tangent of the height-length ratio), and aspect ratio (length-width ratio). The fitting relationship of height and length from these data is H = 0.6164L + 0.4589, with an average reach angle of 31.65°. The landslide aspect ratios concentrate in the range of 1.4～2.6, with an average of 2.11. According to the plane geometric shapes and aspect ratios, the landslides are classified into four categories: transverse landslide (LA1, L/W ≤ 0.8), isometric landslide (LA2, 0.8 < L/W ≤ 1.2), longitudinal landslide (LA3, 1.2 < L/W ≤ 3), and elongated landslide (LA4, L/W > 3). Statistics of these four types of landslides versus ten classified control factors (elevation, slope angle, slope aspect, curvature, slope position, distance to drainages, lithology, seismic intensity, peak ground acceleration, and distance to seismogenic fault) are used to examine their possible correlations and the landslide-prone areas, which would be helpful to the landslide disaster mitigation in the affected area.     

Rogue events in spatiotemporal numerical simulations of unidirectional waves in basins of different depth

The evolution of unidirectional nonlinear sea surface waves is calculated numerically by means of solution of the Euler equations. The wave dynamics corresponds to quasi-equilibrium states characterized by JONSWAP spectra. The spatiotemporal data are collected and processed providing information about the wave height probability and typical appearance of abnormally high waves (rogue waves). The waves are considered at different water depths ranging from deep to relatively shallow cases (k _p h > 0.8, where k _p is the peak wavenumber, and h is the local depth). The asymmetry between front and rear rogue wave slopes is identified; it becomes apparent for sufficiently high waves in rough sea states at all considered depths k _p h ≥ 1.2. The lifetimes of rogue events may reach up to 30–60 wave periods depending on the water depth. The maximum observed wave has a height of about three significant wave heights. A few randomly chosen in situ time series from the Baltic Sea are in agreement with the general picture of the numerical simulations.     

Elastic behavior of vanadinite,Pb<Subscript>10</Subscript>(VO<Subscript>4</Subscript>)<Subscript>6</Subscript>Cl<Subscript>2</Subscript>, a microporous non-zeolitic mineral

The high-pressure behavior of a vanadinite (Pb₁₀(VO₄)₆Cl₂, a = b = 10.3254(5), c = 7.3450(4) Å, space group P6₃/m), a natural microporous mineral, has been investigated using in-situ HP-synchrotron X-ray powder diffraction up to 7.67 GPa with a diamond anvil cell under hydrostatic conditions. No phase transition has been observed within the pressure range investigated. Axial and volume isothermal Equations of State (EoS) of vanadinite were determined. Fitting the P–V data with a third-order Birch-Murnaghan (BM) EoS, using the data weighted by the uncertainties in P and V, we obtained: V ₀ = 681(1) Å³, K ₀ = 41(5) GPa, and K′ = 12.5(2.5). The evolution of the lattice constants with P shows a strong anisotropic compression pattern. The axial bulk moduli were calculated with a third-order “linearized” BM-EoS. The EoS parameters are: a ₀ = 10.3302(2) Å, K ₀(a) = 35(2) GPa and K′(a) = 10(1) for the a-axis; c ₀ = 7.3520(3) Å, K ₀(c) = 98(4) GPa, and K′(c) = 9(2) for the c-axis (K ₀(a):K ₀(c) = 1:2.80). Axial and volume Eulerian-finite strain (fe) at different normalized stress (Fe) were calculated. The weighted linear regression through the data points yields the following intercept values: Fe _a (0) = 35(2) GPa for the a-axis, Fe _c (0) = 98(4) GPa for the c-axis and Fe _V (0) = 45(2) GPa for the unit-cell volume. The slope of the regression lines gives rise to K′ values of 10(1) for the a-axis, 9(2) for the c-axis and 11(1) for the unit cell-volume. A comparison between the HP-elastic response of vanadinite and the iso-structural apatite is carried out. The possible reasons of the elastic anisotropy are discussed.     

High-pressure phase transitions of CaRhO<Subscript>3</Subscript> perovskite

High-pressure phase transitions of CaRhO₃ perovskite were examined at pressures of 6–27 GPa and temperatures of 1,000–1,930°C, using a multi-anvil apparatus. The results indicate that CaRhO₃ perovskite successively transforms to two new high-pressure phases with increasing pressure. Rietveld analysis of powder X-ray diffraction data indicated that, in the two new phases, the phase stable at higher pressure possesses the CaIrO₃-type post-perovskite structure (space group Cmcm) with lattice parameters: a = 3.1013(1) Å, b = 9.8555(2) Å, c = 7.2643(1) Å, V _m  = 33.43(1) cm³/mol. The Rietveld analysis also indicated that CaRhO₃ perovskite has the GdFeO₃-type structure (space group Pnma) with lattice parameters: a = 5.5631(1) Å, b = 7.6308(1) Å, c = 5.3267(1) Å, V _m  = 34.04(1) cm³/mol. The third phase stable in the intermediate P, T conditions between perovskite and post-perovskite has monoclinic symmetry with the cell parameters: a = 12.490(3) Å, b = 3.1233(3) Å, c = 8.8630(7) Å, β = 103.96(1)°, V _m  = 33.66(1) cm³/mol (Z = 6). Molar volume changes from perovskite to the intermediate phase and from the intermediate phase to post-perovskite are –1.1 and –0.7%, respectively. The equilibrium phase relations determined indicate that the boundary slopes are large positive values: 29 ± 2 MPa/K for the perovskite—intermediate phase transition and 62 ± 6 MPa/K for the intermediate phase—post-perovskite transition. The structural features of the CaRhO₃ intermediate phase suggest that the phase has edge-sharing RhO₆ octahedra and may have an intermediate structure between perovskite and post-perovskite.     

Records of organochlorine pesticides in soils and sediments on the southwest of Buenos Aires Province,Argentina

The present study fills a gap in the knowledge in regards to the occurrence of banned pesticides at both coastal and inland locations at the Southwest Buenos Aires region, Argentina. Superficial sediment and soil samples were collected from different sites along the Bahia Blanca Estuary and surrounding sites to assess the concentration levels and spatial distribution of 12 selected organochlorine pesticides (OCs); 13 spatial locations including inland and shore-coast were sampled to evaluate occurrence and concentration levels of hexachlorocyclohexanes α-HCH, β-HCH, δ-HCH, γ-HCH, dichlorodiphenyltrichloroethane and its degradation products (DDXs: p,p′-DDT, o,p′-DDT, p,p′-DDE, o,p′-DDE, p,p′-DDD, o,p′-DDD) and the polychlorobenzenes PeCB (pentachlorobenzene) and HCB (hexachlorobenzene). After cleaning and extractions steps, samples were analyzed by means of gas chromatography/mass spectrometry. ∑OCs (sum of all studied compounds) ranged between 0.206 and 1040 ng g^?1 dw (mean?=?82.4 and SD?=?277 ng g^?1 dw). Total HCHs (sum of α-HCH, β-HCH, γ-HCH and δ-HCH) ranged from 0.0858 to 0.876 ng g^?1 dw (mean?=?0.43 and SD?=?0.23 ng g^?1 dw), DDXs (sum of p,p′and o,p′ isomers) from 0.080 to 1040 ng g^?1 dw (mean?=?81.3 and SD?=?277 ng g^?1 dw). Lower concentrations were found for PeCB (mean?=?0.095 and SD 0.17 ng g^?1 dw) and HCB (mean?=?0.56 and SD 1.7 ng g^?1 dw). Principal component analysis (PCA) permitted the extraction of underlying information about common factors, providing an overview of the distribution of pesticides and allowing the characterization of sites in regards to the major pesticide signature.     

Stability at high-pressure,elastic behaviour and pressure-induced structural evolution of CsAlSi<Subscript>5</Subscript>O<Subscript>12</Subscript>, a potential host for nuclear waste

The elastic and structural behaviour of the synthetic zeolite CsAlSi₅O₁₂ (a = 16.753(4), b = 13.797(3) and c = 5.0235(17) Å, space group Ama2, Z = 2) were investigated up to 8.5 GPa by in situ single-crystal X-ray diffraction with a diamond anvil cell under hydrostatic conditions. No phase-transition occurs within the P-range investigated. Fitting the volume data with a third-order Birch–Murnaghan equation-of-state gives: V ₀ = 1,155(4) ų, K _T0 = 20(1) GPa and K′ = 6.5(7). The “axial moduli” were calculated with a third-order “linearized” BM-EoS, substituting the cube of the individual lattice parameter (a ³, b ³, c ³) for the volume. The refined axial-EoS parameters are: a ₀ = 16.701(44) Å, K _T0a = 14(2) GPa (β_a = 0.024(3) GPa^?1), K′ _a = 6.2(8) for the a-axis; b ₀ = 13.778(20) Å, K _T0b = 21(3) GPa (β_b = 0.016(2) GPa^?1), K′ _b = 10(2) for the b-axis; c ₀ = 5.018(7) Å, K _T0c = 33(3) GPa (β_c = 0.010(1) GPa^?1), K′ _c = 3.2(8) for the c-axis (K _T0a:K _T0b:K _T0c = 1:1.50:2.36). The HP-crystal structure evolution was studied on the basis of several structural refinements at different pressures: 0.0001 GPa (with crystal in DAC without any pressure medium), 1.58(3), 1.75(4), 1.94(6), 3.25(4), 4.69(5), 7.36(6), 8.45(5) and 0.0001 GPa (after decompression). The main deformation mechanisms at high-pressure are basically driven by tetrahedral tilting, the tetrahedra behaving as rigid-units. A change in the compressional mechanisms was observed at P ≤ 2 GPa. The P-induced structural rearrangement up to 8.5 GPa is completely reversible. The high thermo-elastic stability of CsAlSi₅O_12, the immobility of Cs at HT/HP-conditions, the preservation of crystallinity at least up to 8.5 GPa and 1,000°C in elastic regime and the extremely low leaching rate of Cs from CsAlSi₅O₁₂ allow to consider this open-framework silicate as functional material potentially usable for fixation and deposition of Cs radioisotopes.     

Land-use-mediated <Emphasis Type="Italic">Escherichia coli</Emphasis> concentrations in a contemporary Appalachian watershed

A high-spatial resolution study design was used to investigate the relationship between land use practices, stream physicochemistry, hydroclimate, and stream Escherichia (E) coli concentrations in a mixed-land-use watershed in the Appalachian region. Stream samples were collected daily from six monitoring sites and analyzed for total E. coli counts using an enzyme metabolism indicator method. Statistical comparison of E. coli concentration time series showed significant (p?<?0.05) differences between study sites. Although highest average E. coli concentrations were observed at two agricultural sites (534 and 582 colony-forming counts (CFU) per 100 mL, respectively), highest total loadings were observed within the receiving stream, with values increasing downstream (2?×?10¹² and 4.2?×?10¹² study total CFU for bracketed upstream and downstream sites, respectively). No single physical variable displayed a significant correlation (p?<?0.05) with observed E. coli concentration at every site. However, sites displayed different patterns of significant correlations (p?<?0.05) between E. coli concentration and both physicochemical (e.g. pH, dissolved oxygen saturation) and hydroclimate variables (e.g. streamflow and precipitation). Percent agricultural land cover was the only land use category that showed significant (p?<?0.04) correlation with study average E. coli concentrations, thereby emphasizing the importance of land use practices to stream pathogen regimes. Results validate the analytical method and provide high-resolution, detailed, quantitative characterizations of stream E. coli regimes, thereby supplying land and water resource managers with science-based information to advance management decisions and improve public health.