Quantification of karst aquifer discharge components during storm events through end-member mixing analysis using natural chemistry and stable isotopes as tracers

Karst aquifer components that contribute to the discharge of a water supply well in the Classical Karst (Kras) region (Italy/Slovenia) were quantitatively estimated during storm events. Results show that water released from storage within the epikarst may comprise as much as two-thirds of conduit flow in a karst aquifer following rainfall. Principal components analysis (PCA) and end-member mixing analysis (EMMA) were performed using major ion chemistry and the stable isotopes of water (δ¹⁸O, δ²H) and of dissolved inorganic carbon (δ¹³C_DIC) to estimate mixing proportions among three sources: (1) allogenic river recharge, (2) autogenic recharge, and (3) an anthropogenic component stored within the epikarst. The sinking river most influences the chemical composition of the water-supply well under low-flow conditions; however, this proportion changes rapidly during recharge events. Autogenic recharge water, released from shallow storage in the epikarst, displaces the river water and is observed at the well within hours after the onset of precipitation. The autogenic recharge end member is the second largest component of the well chemistry, and its contribution increases with higher flow. An anthropogenic component derived from epikarstic storage also impacts the well under conditions of elevated hydraulic head, accounting for the majority of the chemical response at the well during the wettest conditions.     

Vertical distribution and water solubility of phosphorus and heavy metals in sediments of the St. Lucie Estuary, South Florida, USA

Accumulation and distribution of heavy metals and phosphorus in sediments impact water quality. There has been an increasing concern regarding fish health in the St. Lucie Estuary, which is related to increased inputs of nutrients and metals in recent decades. To investigate vertical changes of contaminants (P, Cd, Cr, Co, Cu, Ni, Pb, Zn, and Mn) in sediments of the St. Lucie Estuary in South Florida, 117 layer samples from six of the 210 to 420 cm depth cores were analyzed for their total and water-soluble P and heavy metals, clay, total Fe, Al, K, Ca, Mg, Na, and pH. Principal component analysis (PCA) was used in two sets of analytical data (total and water-soluble contaminant concentrations) to document changes of contaminants in each core of sediments. The PCA of total contaminants and minerals resulted in two factors (principal components). The first and second factors accounted for 61.7 and 17.2 % of the total variation in all variables, and contrast indicators associated with contaminants of P, Cd, Co, Cr, Ni, Pb, Zn, and Mn and accumulation of Fe and Al oxides, respectively. The first factor could be used for overall assessment of P and heavy metal contamination, and was higher in the upper 45–90 cm than the lower depths of each core. The concentrations of P and heavy metals in the surface layers of sediments significantly increased, as compared with those in the sediments deeper than 45–90 cm. The PCA of water-soluble contaminants developed two factors. The second factor (Cu–P) was higher in the upper than the lower depths of the sediment, whereas the highest score of the first factor (Cd–Co–Cr–Ni–Pb–Zn–Mn) occurred below 100 cm. The water-soluble Cu and P concentrations were mainly dependent on their total concentrations in the sediments, whereas the water-soluble Cd, Co, Cr, Ni, Pb, Zn, and Mn concentrations were mainly controlled by pH.     

3D behaviour of contamination in landfill sites using 2D resistivity/IP imaging: case studies in Portugal

Aiming at defining a valid spatial contamination model, resistivity and induced polarization (IP) measurements were used to investigate contamination plumes in the vicinity of two municipal landfills (Ovar and ílhavo). Previous geophysical surveys and underground water samples confirmed the contamination. However 2D resistivity/IP surveys enabled in obtaining a more accurate spatial model. The Ovar survey consisted of two profiles with nine Wenner soundings each; the ílhavo survey was carried out along two individual lines using a Wenner standard pseudo-section. In both situations, negative IP values were found associated with positive IP values, which can be explained mainly by 2D or 3D geometric effects caused by the presence of the conductive plumes. The data were modelled using a 2D inversion program (RES2DINV) and the resulting resistivity and chargeability distributions were displayed as pseudo-sections. The resistivity and chargeability pseudo-sections define the contamination plumes and the sedimentary structure. These case studies illustrate the advantages of 2D resistivity/IP surveys for the mapping of shape and dimension of contamination associated with landfills.     

Zr-in-rutile thermometry in blueschists from Sifnos, Greece

Zr-in-rutile thermometry on samples of blueschist from Sifnos, Greece, yields temperatures that reflect progressive crystallization of rutile from ca. 445 to 505°C with an analytical precision of + 18/−27 and ± 10°C using the electron microprobe and ± 1.5–3.5°C using the ion microprobe. Individual grains are generally homogeneous within analytical uncertainty. Different grains within a single sample record temperature differences as large 55°, although in most samples the range of temperatures is on the order of 25°. In several samples, Zr-in-rutile temperatures from grains within garnet are lower than temperatures from matrix grains, reflecting growth of rutile with increasing temperature of metamorphism. Although the specific rutile-producing reactions have not been identified, it is inferred that rutile grows from either continuous reaction involving the breakdown of lower grade phases (possibly ilmenite), or from pseudomorph reactions involving the breakdown of relic igneous precursors at blueschist-facies conditions. No systematic variation in rutile temperatures was observed across the blueschist belt of northern Sifnos, consistent with the belt having behaved as a coherent block during subduction.     

Spectral Simulation and Conditioning to Local Continuity Trends in Geologic Modeling

Spectral simulation has gained application in building geologic models due to the advantage of better honoring the spatial continuity of petrophysical properties, such as reservoir porosity and shale volume. Distinct from sequential simulation methods, spectral simulation is a global algorithm in the sense that a global density spectrum is calculated once and the inverse Fourier transform is performed on the Fourier coefficient also only once to generate a simulation realization. The generated realizations honor the spatial continuity structure globally over the whole field instead of only within a search neighborhood, as with sequential simulation algorithms. However, the disadvantage of global spectral simulation is that it traditionally cannot account for the local information such as the local continuity trends, which are often observed in reservoirs and hence are important to be accounted for in geologic models. This disadvantage has limited wider application of spectral simulation in building geologic models. In this paper, we present ways of conditioning geologic models to the relevant local information. To account for the local continuity trends, we first scale different frequency components of the original model with local-amplitude spectrum ratios that are specific to the local trend. The sum of these scaled frequency components renders a new model that displays the desired local continuity trend. The implementation details of this new method are discussed and examples are provided to illustrate the algorithm.     

Ecological characteristics of Vrishabhavathy River in Bangalore (India)

River Vrishabhavathy, a tributary of Cauvery River was studied for 12 physico-chemical parameters at four sites over a distance of 50 km for a period of 2 years (1999–2001) at monthly intervals. Water was faintly alkaline, with pH showing negative correlation with temperature. The dissolved oxygen content increased downstream with negative correlation to biological oxygen demand (BOD), chemical oxygen demand (COD) and turbidity. Bicarbonate alkalinity was very low compared with carbonate alkalinity. Carbonate alkalinity, total hardness, total dissolved solids, total suspended solids, electrical conductivity, BOD and COD decreased downstream, with an upward trend in the middle reaches due to the introduction of raw sewage. The seasonal and yearly trends are also discussed. The river is a sewer collector undergoing self-purification.     

Gzhelian fusulinids first discovered in central Iran

Gzhelian deposits established in Iran for the first time are described. They rest with a considerable hiatus on the Moscovian deposits constituting, along with Asselian strata, an integral carbonate succession of the Zaladu Formation in eastern Iran. The Zaladu Formation is correlative with the Vazhnan Formation of the Abadeh region (central Iran) and the Dorud Formation of the Elburz (Alborz) Mountains. An assemblage of Gzhelian fusulinids from the studied section is well comparable with the assemblage of the Ultradaixina bosbytauensis Zone distinguished in the uppermost Gzhelian of the Darvaz, Fergana, the Southern Urals, Donetsk Basin, and Carnic Alps. Two new species of the genus Schellwienia (Sch. anarakensis and Sch. stocklini) are described. Gzhelian and Asselian fusulinids found in the section are figured in two paleontological plates.     

The influence of ultrahigh-energy cosmic rays on star formation in the early Universe

The presence of ultrahigh-energy (UHE) cosmic rays results in an increase in the degree of ionization in the post-recombination Universe, which stimulates the efficiency of the production of H₂ molecules and the formation of the first stellar objects. As a result, the onset of the formation of the first stars is shifted to higher redshifts, and the masses of the first stellar systems decrease. As a consequence, a sufficient increase in the ionizing radiation providing the reionization of the Universe can occur. We discuss the possible observational manifestations of these effects and their dependence on the parameters of UHE cosmic rays.     

Late Mesozoic collisional granitoids of the upper Amur area: New geochemical data

Geochemical and isotopic data were used for a comparative analysis of Late Mesozoic (150–120 Ma) granitoids in various geological structures of the upper Amur area. The granitoids are metaluminous high-potassic I-type rocks of the magnetite series. They have variable alkalinity and consist of the monzonite-granite and granosyenite-granite associations. The monzonite-granite association consists of calc-alkaline granitoids of normal alkalinity belonging to the Umlekan-Ogodzhinskaya volcanic-plutonic zone and the Tynda-Bakaran Complex of the Stanovoy terrane. The rocks are characterized by negative anomalies of U, Ta, Nd, Hf, and Ti (in patterns normalized to the primitive mantle), with Eu anomalies pronounced weakly in the granodiorites and quartz and monzodiorites and more clearly in the granites: Eu/Eu* = 0.37–0.95, and (La/Yb)_n = 7–24, Tb_n/Yb_n = 1.4–3.2. The granosyenite-granite association comprises of moderately alkaline rocks, which are subdivided into three groups according to their geochemistry. The first group consists of phase-I granosyenites of the Uskalinskii Massif of the Umlekan-Ogodzhinskaya zone with the highest concentrations of Sc, V, Cr, Co, Ni, Cu, Cs, Rb, Sr, Y, Zr, Yb, and Th; negative anomalies at Ba, Ta, Sr, and Hf; Eu/Eu* = 0.50–0.58, (La/Yb)_n = 15–16, and Tb_n/Yb_n = 1.8. The second group comprises of moderately alkaline granitoids of the Umlekan-Ogodzhinskaya zone and the Khaiktinskii Complex of the Baikal-Vitim superterrane. Geochemically, the granitoids of this group are generally similar to the monzodiorite-granite association and differ from it in having lower concentrations of REE and Y, Eu/Eu* = 6.2–1.0, (La/Yb)_n = 28–63, and Tb_n/Yb_n = 2.1–4.5. The third group consists of granitoids of the Chubachinskii Complex of the Stanovoi terrane, which typically show negative Cs, Rb, Th, U, Ta, Hf, and Ti anomalies; the lowest concentrations of V, Cr, Co, and Ni; and the highest contents of Sr. The granosyenites of the first phase display clearly pronounced negative Eu anomalies (Eu/Eu* = 0.53–0.68), (La/Yb)_n = 7–24, and Tb_n/Yb_n = 0.8–2.0. The granitoids of the second phase have (La/Yb)_n = 51–84, no Eu anomalies, or very weak Eu anomalies (Eu/Eu* = 0.97–1.23). The silica-oversaturated leucogranites of the third phase are characterized by elevated concentrations of REE, clearly pronounced Eu anomalies (Eu/Eu* = 0.48), and flat REE patterns (Tb_n/Yb_n = 1.3). The diversity of the granitoids is demonstrated to have been caused largely by the composition of the Precambrian source, which was isotopically heterogeneous. The rocks of the monzodiorite-granite association and first-group granosyenites of the granosyenite-granite association of the Tynda-Bakaran Complex were supposedly derived from garnet-bearing biotite amphibolites. In contrast to these rocks, the source of the second-group granites of the granosyenite-granite association was of mixed amphibolite-metagraywacke composition. The third-group of granitoids were melted out of Early Proterozoic crustal feldspar-rich granulites of variable basicity, with minor amounts of Archean crustal material. The granitoids were emplaced in a collisional environment, perhaps, during the collision of the Amur superterrane and Siberian craton. This makes it possible to consider these rocks as components of a single continental volcanic-plutonic belt. Original Russian Text ? V.E. Strikha, 2006, published in Geokhimiya, 2006, No. 8, pp. 855–872.     

Dissolved Trace Metal–Organic Complexes in the Lot–Garonne River System Determined Using the C18 Sep-Pak System

An 11-month observation of dissolved and particulate organic matter, chlorophyll a(Chl a), C18 Sep-Pak extractable hydrophobic dissolved organic matter (hDOM) fraction and associated dissolved trace metals (Cd, Cu, V, Co, Ni, Mo, U) was performed in the Lot–Garonne River system. This system includes the Riou Mort, the Lot River and the downstream reaches of the Garonne River and represents the fluvial transport path of trace metals between the major point source of polymetallic pollution, located in the Riou Mort watershed and the Gironde estuary. Spatial and temporal variations of dissolved and particulate organic carbon and Chl areflect the presence of different types of organic matter and their relation with the hDOM fraction. Maximum Chl a/POC ratios (up to 0.03), indicate intense phytoplankton production from March to May. In the Lot River (Temple), DOC and POC concentrations were clearly higher and mean Chl a concentration (2.8 mg g⁻¹) was about three times higher than those of the other sites. High Chl a/POC ratios suggest high phytoplankton activity with maxima in spring and late summer. In the Riou Mort River, very high POC concentrations of up to 40 (mean: 20) occurred, whereas Chl a concentrations were relatively low indicating low phytoplankton activity. High, strongly variable DOC and POC concentrations suggest important natural (Carboniferous soils, forests) or anthropogenic (e.g., former coal mines, waste areas, agriculture, sewage) carbon sources within the small Riou Mort watershed. Despite high DOC concentrations in the Riou Mort River, hDOM metal fractions were generally lower than those at the other sites. The general order of decreasing binding strength between metals and the organic hydrophobic phase (Cu, U > Co, Ni > V, Mo > Cd) at all four sites was in good agreement with the Irving–William series of transition element affinity towards organic ligands. Accordingly, the role of the hydrophobic phase in dissolved Cd transport appeared to be negligible, whereas the hDOM–Cu fraction strongly contributed to dissolved Cu transport.