Hydrochemistry and nutrients dynamic in the Suquía River urban catchment’s,Córdoba,Argentina

Suquía River is a medium-sized hydrological system (basin area of ~7,700 km²) that supplies fresh water to Córdoba city, a town of ~1,500,000 inhabitants in central Argentina. This paper examines the present-day hydrochemistry of Suquía River urban catchment analyzing its major and minor dissolved components, and the nutrients variability by means of QUAL-2K modeling software. The Suquía River has bicarbonate-type waters upstream the city and sulfate-type waters right downstream, whereas they exhibit a mixed-to-alkali-type cationic composition. The seasonal analysis of its major dissolved constituents clearly showed a dilution process during the wet season (i.e. austral summer). In the last 20 years, the Suquía River has modified its anionic composition, now showing higher relative concentrations of SO₄ ²⁻ as a consequence of urban activities. However, trace elements dissolved concentrations do not evidence a strong pollution effect. Nutrients [nitrogen species, total phosphorous (TP)] and related parameters, such as biochemical oxygen demand (BOD), and dissolved oxygen (DO), evidence a clear influence of human activities. The QUAL-2K model was used to evaluate the spatial behavior of selected nutrients and associated variables, (i.e. TP, N–NH₄ ⁺, N–NO₃ ⁻, DO, BOD). Nutrient concentrations are affected by point sources of contaminants, particularly domestic waste and sewage, as well as by diffuse agricultural pollution. A calibrated QUAL-2K modeling exercise clearly shows the impact of the Córdoba city’s municipal wastewater treatment plant on the Suquía River water quality.     

Genetic implications of a retransported loess profile near Córdoba,Argentina

This paper deals with a loess profile located southeast of Córdoba (64° 05′ 30 W to 31°30′ S) that was dated in Beijing University using the OSL method according to Simple Aliquot Regeneration Protocol. This study provides some inferences regarding climatic and environmental features, such as transport agents and probable sources of the materials.The profile, located inside Llanura Pampeana, is approximately 6.80 m in depth and comprises ages between 22.4 ± 3.2 and 9.9 ± 0.3 ka. Throughout the profile, and for all grain sizes, major minerals are quartz and feldspar, with micas, and opaques as subordinates. Illite and chlorite appear as traces, though the last one was not confirmed in the finest fraction analysis. Calcite is abundant in the uppermost sample and decreases downwards. In the base of the profile, and in the clay fraction, XRD showed illite, swellable clay minerals (smectite + mixed layers) and kaolinite traces. It was concluded that the profile would have been derived from the accumulation of sediments, along several events very similar in transport conditions, even though there are some indications that about 21 ka BP, water availability was slightly smaller than for the rest of the profile. This change was also established in some other places, allowing some regional correlations. According to the analyzed data, about 19 ka BP, water availability again increased.     

Asbestiform and non-asbestiform morphologies in a talc and vermiculite mine from the province of Córdoba (Argentina): a case study

In this work, a talc and vermiculite mine from the province of Córdoba (Argentina) was investigated with special emphasis on the occurrence of asbestiform and non-asbestiform phases. The meta-ultramafic rock was studied by a multimethodological approach, complementing field studies with petrographic-mineralogical, compositional and morphological analyses. Samples were examined by stereomicroscopy, polarizing light microscopy, SEM–EDS, XRD, DSC-TGA and FTIR. Complementary, compositional and textural analyses were performed with FE-SEM–EDS and EPMA. Talc-rich veins with a laminar and fibrous appearance were at first recognized. However, the fibrous morphology observed both in the field and by microscopy is due to an apparent habit because of the sample orientation. To avoid erroneous interpretations, studies by secondary electron images (SEM) are fundamental to carrying out this type of analysis. Tremolite was identified in different zones of the outcrop; however, only ~40% of the crystals located in the vermiculite zone have dimensions to be considered as asbestiform fibres in the range of respirable particles. In these types of complex deposits affected by superimposed metamorphic, igneous and deformational events, multimethodological approaches are necessary to develop models of occurrence of asbestiform morphologies that may be applicable to other with similar characteristics.     

The megascopic and mesoscopic structure of La Cocha ultramafic body,Sierra Chica of Córdoba,Argentina

The serpentinized ultramafic body of La Cocha is located in the Sierra Chica of Córdoba (31° 36′ 40″ South and 64° 32′ 40″ West). The body is a spinel harzburgite composed of olivine, enstatite and spinel, almost completely hydrated to associations of serpentine minerals. The rock is dark green, foliated, rich in serpentinized olivine and grains or aggregates of enstatite, partially to totally altered to bastite, with spinel as inclusions and a general porphyritic appearance. The S₂ metamorphic foliation was determined by a compositional layering defined by the lengthening and concentration of irregular pyroxene layers that alternate with olivine layers. This foliation is affected by S₃, composed of serpentine, which is parallel or cut sharply with low angles to S₂. The main structure of La Cocha ultramafic body is a low cylindrical recumbent fold interpreted as an “a”-type domal structure which is part of a major sheath fold, currently cut off by erosion. La Cocha ultramafic body is interpreted as an obducted slice of oceanic mantle, probably part of a basal tectonite of an ophiolitic complex. This slice, after its emplacement, was metamorphosed and deformed together with the country rocks.     

Vertebrate tracks from the Paso Córdoba fossiliferous site (Anacleto and Allen formations,Upper Cretaceous), Northern Patagonia,Argentina: Preservational,environmental and palaeobiological implications

The Paso Córdoba fossiliferous site (Río Negro, Northern Patagonia) is one of the first Mesozoic fossiliferous localities studied in Argentina. There, turtle, crocodile and dinosaur remains as well as dinosaur and bird tracks have been recorded. Recently, a new locality with vertebrate tracks, the Cañadón del Desvío, has been discovered in Paso Córdoba. Six track-bearing layers were located in outcrops belonging to the Anacleto (lower to middle Campanian, Neuquén Group) and Allen (middle Campanian-lower Maastrichtian, Malargüe Group) formations. The Cañadón del Desvío locality reveals that vertebrate trace fossils are distributed in two distinct environments, floodplains of a meandering fluvial to shallow lacustrine system and a wet interdune deposit that is associated to an aeolian setting. Also, in the logged section several soft sediment deformation structures were found. In regard of this, a sedimentary facies analysis is provided in order to assess the palaeoenvironmental implications of this new record. The analysed tracks are preserved in cross-sections, on bedding-planes and as natural casts. When it is possible, the tracking surface, true tracks, undertracks and overtracks/natural casts have been identified and the track preservation and the formation history of the tracksite are discussed. Only two tracks preserve enough anatomical details to relate them with their trackmakers, in this case hadrosaurid dinosaurs. The stratigraphical, facial and palaeoenvironmental data of this study support the idea of a transitional passage between the Anacleto and Allen Formation in Paso Córdoba. The presence of hadrosaurid dinosaur tracks suggests that the upper part of the log, where this kind of tracks were found, likely belong to Allen Formation due to this dinosaurs appear in the Southern Hemisphere in this epoch. The sum of osteological and ichnological remains improve the Paso Córdoba palaeofaunistic knowledge. The presence of six different levels in which the trackmakers walked reflects the abundance of vertebrates in the transition between Anacleto and Allen formations.     

Mercury emission from the indigenous mercury smelting in Wuchuan mercury mining areas, Guizhou Province, China

Mercury smelting is one of the important anthropogenic atmospheric mercury emission sources. Small-scale mercury smelting activities with indigenous method which is considered illegal and forbidden by local government always extensively existed in the Wuchuan area, northeastern Guizhou Province, China. Because of the simple processes without any environmental protection, a large amount of mercury vapor released to the ambient air during the processing of cinnabar roasting. By determining mercury concentrations in mercury ore and smelting slag samples, a mass balance method was used to calculate mercury emission factors and annual mercury emission from indigenous mercury smelting in Wuchuan mercury mining areas, Guizhou Province, China. The mercury emission factors ranged from 6.9% to 32.1% with the recovery from 78.4% to 93.6% and the annual mercury emission was up to 3.7-9.6 metric tons. The results highlighted that the indigenous mercury smelting was one of the most important anthropogenic atmospheric mercury emission sources in this region.     

Methylmercury and total mercury distribution in the sediments of Baihua Reservoir, Guizhou Province, China

Mercury is an important pollutant in lakes. Methylmercury （MeHg）, the most toxic mercury species, which can be formed from inorganic mercury in lakes, can be bioaccumulated into high concentration in food chain and result in a potential threat to human beings. Sediments play an important role for the Hg biogeochemistry in the aquatic systems： Mercury methylation has been shown to be fastest in the surfacial sediments, where the microbial activity is highest. The formation of MeHg in lakes suggests that sediments and/or near-shore wetlands can be the sources of MeHg in aquatic environments. The Baihua Reservoir, located in the suburb of Guiyang, was impounded in 1966. From the 1970s to the 1990s, Guizhou Organic Chemical Plant which used inorganic mercury as catalyst to produce acetic acid, was responsible for the discharge of waste water with high mercury content.     

Seasonal distribution of total mercury and methylmercury in sediments of the Wujiangdu Reservoir, Guizhou, China

The concentrations of total mercury and methylmercury in sediments were determined at the dam of the Wujiangdu Reservoir in different seasons. Total mercury (HgT) levels in the whole sediment profile were 254.2±47.0 ng/g in winter, 254.2±31.6 ng/g in spring, and 256.7±60.8 ng/g in summer, without significant variations in different seasons or at different depths. In contrast, the methylmercury (MeHg) compounds were most abundant at the sediment-water interface and decreased progressively with depth. MeHg contents of the sediments during different seasons are highly dependent on microbial activity, and seem to be higher when Hg (II)-methylating microorganisms are active. Thus, MeHg levels tend to rise in the loci where nutrient supplies and biological productivity are favorable. The percentage of HgT that is present as MeHg in the sediments increased gradually from December 2003 to April 2004 and to July 2004.     

Southern Hemisphere Westerly Winds have modulated the formation of laminations in sediments in Lago Fagnano (Tierra del Fuego,Argentina) over the past 6.3 ka

Tierra del Fuego in Argentina is a unique location to examine past Holocene wind variability since it intersects the core of the Southern Hemisphere Westerly Winds (SHWW). The SHWW are the most powerful prevailing winds on Earth. Their variation plays a role in regulating atmospheric CO₂ levels and rainfall amounts and distribution, both today and in the past. We obtained a piston core (LF06-PC8) from Bahía Grande, a protected sub-basin at the southern margin of Lago Fagnano, the largest lake in Tierra del Fuego. This article focuses on the uppermost 185 cm of this core, corresponding to laminated sediment from the last ~6.3 ka. Laminations consist of millimetre-scale paired dark and light layers. Previous studies and new geochemical analysis show that the dark and light layers are characterized by differing concentrations of Mn and Fe. We attribute the distribution of Mn and Fe to episodic hypolimnic oxic–anoxic variations. The age model suggests an approximately bidecadal timescale for the formation of each layer pair. We propose a new model of these redox changes with the SHWW variations. The most likely phenomenon to produce complete water-column mixing is thermobaric instability, which occurs in colder winters with low-intensity SHWW (El Niño-like conditions). In contrast, windier winters are characterized by higher temperatures and reduced mixing in the water column, facilitating a decline in oxygen concentration. Laminations, and the inferred presence of periodic hypolimnion redox changes, are common features of the past ~6.3 ka. Geochemical proxy variability is compatible with an intensification of El Niño/Southern Oscillation activity during the past ~2 ka.     

Distribution of mercury species in water and sediments in Caohai Lake, Guizhou Province

Caohai Lake which is situated in Guizhou Province, has suffered drain project many times since 1958.The main mercury contamination includes industry waste water, litter and waste residue from refine zinc furnace and so on. The water and sediment samples which were collected from Caohai Lake in different seasons using metal clean protocols. Study sites were selected at the upper and down reaches and the tributaries of this lake, respectively. Total mercury （THg）, reactive mercury （RHg） and dissolved mercury （DHg） concentrations were measured by trap pre-concentration and CVAFS detection methods, and the concentrations of particulate mercury （PHg） are equal to difference of THg and DHg. Total methylmercury （MeH） and dissolved methylmercury （DMeHg） concentrations were measured by GC-CVAFS detection method. Mercury in sediment was measured by AAS method. The results in autumn were obtained as follows： the average concentrations of total mercury, reactive mercury,     

Morphotectonic study of two regions in the Centre-South Segment of Spain: Córdoba and Granada

The morphotectonics of Córdoba and Granada are differentiated using the Rantsman method [53]. Over 40 quantitative geomorphologic indicators are used in the systemic classification. Both areas are included in what are known as the macroblocks no. 1 (Southern) and no. 2 (Sub-Western 2A) of the Iberian Peninsula megablock. The qua ntities of the four lowest order Territorial Units defined for Córdoba/Granada are: mesoblocks (4/4), blocks (9/9), microblocks (15/35) and nanoblocks (64/83). The main lineaments/intersections determined in Córdoba total 16/1041 and in Granada 25/633, A series of seven morphostructural scarps is found in both areas, along with important modifications (inflections) in some river beds. Some of the structures described are seismicity-related. Córdoba displays less activity than Granada. Between the towns of Loja, Beas de Granada, and Lentejí a seismoactive sector (～820 km²) with blocks B2, B3, B5, and B6 forms the area where the deep earthquakes are concentrated.     

Foraging Behavior, Direct Interference and Habitat Use in Three Species of Flamingos (Phoenicopterus Chilensis, Phoenicoparrus Andinus and Phoenicoparrus Jamesi) in Mar Chiquita Lagoon, Córdoba, Argentina

正The Laguna Mar Chiquita,located northeast of the province of Córdoba in Argentina,is the only non-Andean place where three flamingo species regularly coexist in the southern part of South America.Two of these species,     

Contrasting magmatic structures between small plutons and batholiths emplaced at shallow crustal level (Sierras de Córdoba,Argentina)

Processes like injection, magma flow and differentiation and influence of the regional strain field are here described and contrasted to shed light on their role in the formation of small plutons and large batholiths their magmatic structures. The final geometric and compositional arrangement of magma bodies are a complex record of their construction and internal flow history. Magma injection, flow and differentiation, as well as regional stresses, all control the internal nature of magma bodies. Large magma bodies emplaced at shallow crustal levels result from the intrusion of multiple magma batches that interact in a variety of ways, depending on internal and external dynamics, and where the early magmatic, growth-related structures are commonly overprinted by subsequent history. In contrast, small plutons emplaced in the brittle-ductile transition more likely preserve growth-related structures, having a relatively simple cooling history and limited internal magma flow. Outcrop-scale magmatic structures in both cases record a rich set of complementary information that can help elucidate their evolution. Large and small granitic bodies of the Sierra Pampeanas preserve excellent exposures of magmatic structures that formed as magmas stepped through different rheological states during pluton growth and solidification. These structures reveal not only the flow pattern inside magma chambers, but also the rheological evolution of magmas in response to temperature evolution.     

Total gaseous mercury emissions from mercury-enriched soil in Guizhou, China

Guizhou is located in the Circum-Pacific Global Mercuriferous Belt, and mercury concentrations in soil in this area are enriched. In-situ total gaseous mercury （TGM） exchange fluxes between air and soil surface were intensively measured at four sampling sites in Guiyang from 21 May to 16 June, 2003, and five sites in the Lanmuchang mercury mining area in December 2002 and May 2003, respectively. The in-situ Hg flux measurement was conducted with a dynamic flux chamber （DFC） of quartz. Overall, net emissions were obtained from all sampling sites. Soil mercury concentration and solar radiation have been proved to be the two most important parameters to control mercury emissions from soil. Meanwhile, rain events can enhance mercury emission rate significantly.     

Coalification in Carboniferous sediments from the Lötschberg base tunnel

Vitrinite reflectance (Rr), proximate analysis and carbon isotope composition (δ¹³C) have been used to characterise coal samples from two zones of Late Carboniferous sediments (Gastern and Ferden) in the Aar massif where they are penetrated by the Lötschberg base tunnel (constructed between 1999 and 2005). Samples are characterised by variable ash yields (21.7–93.9%; dry basis); those with ash yields of less than ~50% and with volatile matter content (V;dry ash-free basis) within the limits 2 < V% ≤ 8 are anthracite. Values of Rr range from 3.89% to 5.17% and indicate coalification to the rank of anthracite and meta-anthracite in both Gastern and Ferden Carboniferous zones. Samples of anthracite and shale from the Gastern Carboniferous exhibit a relatively small range in δ¹³C values (–24.52‰ to –23.38‰; mean: –23.86‰) and are lighter than anthracite samples from the Ferden Carboniferous (mean: –22.20‰). The degree of coalification in the Gastern and Ferden Carboniferous zones primarily depends on the maximum rock temperature (T) attained as a result of burial heating. Vitrinite reflectance based estimates of T range from ~290° –360 °C. For a proposed palaeogeothemal gradient of 25 ° C/km at the time of maximum coalification the required overburden is attributable to relatively thin autochtonous Mesozoic/Cenozoic sedimentary cover of the Aar massif and Gastern granite and deep tectonic burial beneath advancing Helvetic, Ultrahelvetic and Prealpine (Penninic) nappes in Early Oligocene to Miocene.     

Forms of phosphorus in sediments from the Goczałkowice Reservoir

The occurrence of Total P (P-Tot) and the mineral forms of P (P-Min) in sediments from Goczałkowice Reservoir were investigated using inductively coupled plasma-optical emission spectrometer (ICP-OES). The method is based on sequential extractions of the sediment samples, each releasing four forms of inorganic P: loosely bound P, P bound to Al (P-Al), P bound to Fe (P-Fe) and P bound to Ca (P-Ca). Sediment samples for studies presented in this work were collected in April, August and November of 2009 from four sites of the Goczałkowice Reservoir. Significant variations in the P forms with sediment grain size were observed. The most abundant form of inorganic P in the bottom sediment was P-Fe. Other P forms were as follows: P-Ca > P-Al > loosely bound-P. Moreover, P compounds were studied using ³¹P NMR. It was found that the predominant form was inorganic orthophosphate.