Monitoring of soil subsidence in urban and coastal areas due to groundwater overexploitation using GPS

The global positioning system (GPS) is widely used for determining the three-dimensional position of points on earth surface. In the last few years, its use has also been increasingly employed for obtaining vertical geometric coordinates, which associated with the orthometrical altitude of the point can be employed in various civil engineering applications, as has been seen in diverse localities throughout the world. The satisfactory performance of this technology for obtaining excellent precision in vertical coordinates demands some conditions, related to the satellites, such as transmission of signals and, principally, in the case of urbanized areas, the presence of obstructions in the proximity of the equipment, which interferes with the quality and quantity of the information collected. GPS is an efficient technique for the detection of small movements, including the monitoring of soil subsidence. The present article describes adequate forms of the use of GPS in such a way as to guarantee good precision of the resulting vertical coordinates, even under unfavorable situations, such as in coastal areas, where the reference networks for monitoring are implanted in only one of the sides of the point?Cobject region, which makes the situation more difficult and requires careful planning so that the use of GPS reaches the desired precision.     

The Imataca Complex, NW Amazonian Craton,Venezuela： Crustal evolution and integration of geochronological and petrological coolinghistories

SHRIMP U/Pb-zircon data and Nd mean crustal residence ages indicate that the lmataca Complex developed from an Archean (≥3.2Ga) continental protolith which has undergone considerable isotopic disturbance plus and juvenile accretion during late-Archean (-2.8Ga) times. Transamazonian granulites experienced peak metamorphic conditions of 750-800℃, 6-8kbar with associated transpressive thrusting and tectonic imbrication. Geochronology on zircon, pyroxene and garnet constrains the timing of peak metamorphism at 1.98-2.05Ga. Diffusion modeling of Fe-Mg exchange between biotite inclusions and host garnet yields (near metamorphic peak) cooling rates of 50-100℃/Ma, with petrological cooling rates being generally consistent with cooling rates determined from geochronology. Combining the retrograde P-T path with cooling rates suggests that after the metamorphic peak, large portions of the lmataca Complex were exhumed from 30 to 17km at a rate of 7-2km/Ma.After this, exhumation rates progressively decreased as the rocks approached the surface. Rapid overall upliftlerosion had ceased when the rocks passed below 600-550℃ at 2.01-1.96 Ga ago. Observed variations in mineral cooling ages are interpreted as to reflect episodic differential tectonic exhumation within major fault systems. Inferred (maximum) ages of fault re-activation generally coincide with major continental accretion events in the Amazonian Craton and reflect long-term thermal evolution of the lmataca terrane, as conditioned by variable response to continued continental convergence during the Proterozoic.     

Reobserving the Extreme-Ultraviolet Emission from Abell 2199: In Situ Measurement of Background Distribution by Offset Pointing

The EUV excess emission from the clusters A2199 and A1795 remains an unexplained astrophysical phenomenon. There has been many unsuccessful attempts to "trivialize" the findings. In this Letter, we present direct evidence proving that the most recent of such attempts, which attributes the detected signals to a background nonuniformity effect, is likewise excluded. We address the issue by a reobservation of A2199 that features a new filter orientation, usage of a more sensitive part of the detector, and, most crucially, the inclusion of a background pointing at approximately 2 degrees offset-the first in situ measurement of its kind. We first demonstrate quantitatively two facts: (1) the offset pointing provides an accurate background template for the cluster observation, while (2) data from other blank fields do not. We then performed a point-to-point subtraction of the in situ background from the cluster field, with an appropriate propagation of errors. The resulting cluster radial profile is consistent with that obtained by our original method of subtracting a flat asymptotic background. The emission now extends to a radius of 20&arcmin;; it confirms the rising prominence of EUV excess beyond approximately 5&arcmin; as previously reported.     

Environmental niche of the smut lizard population on a sandy coastal ecosystem of Southeastern Tenerife (Canary Islands)

Relationships among environmental patterns and population size of the smut lizard Gallotia galloti galloti Oudart, 1839 (Sauria Lacertidae) were examined in the context of longer time-scale variability on a sandy beach and adjacent environments of Southeastern Tenerife. Seasonal and yearly patterns in the population size were likewise analyzed in relation to climatic and anthropic variables. Six sampling plots (coastal, sweet tabaiba, tuff, lava, sandy lava and crater) were selected following a perpendicular transect to the sandy fringe that extends from the beach toward the volcanic interior. Pitfall trapping was conducted from 1984 to 2005, and capture–mark–recapture technique and the Jolly–Seber method were used to estimate population sizes. The highest population size estimates were shown on the sandy lava plot and the neighboring lava plot, reaching values of about 3500 individuals ha⁻¹ during the spring. The population was active almost the whole year, with seasonal patterns of activity from March to October. Seasonal temperature and population size patterns were correlated but the 'calima' episodes produced some disturbance. Gallotia galloti galloti was one of the most abundant lizards of all the species studied and its population size has not remained stable over the study period, probably because of the absence of predation and competition, and because of human interference and environmental instability.     

The link between partial melting,granitization and granulite development in central Ribeira Fold Belt,SE Brazil: New evidence from elemental and Sr–Nd isotopic geochemistry

Elemental and Sr–Nd isotopic data on metatexites, diatexites, orthogneisses and charnockites from the central Ribeira Fold Belt indicate that they are LILE-enriched weakly peraluminous granodiorites. Harker and Th–Hf–La correlation trends suggest that these rocks represent a co-genetic sequence, whereas variations on CaO, MnO, Y and HREE for charnockites can be explained by garnet consumption during granulitic metamorphism.Similar REE patterns and isotopic results of ?_Nd⁵⁶⁵ = ?5.4 to ?7.3 and ⁸⁷Sr/⁸⁶Sr₅₆₅ = 0.706–0.711 for metatexites, diatexites, orthogneisses and charnockites, as well as similar T_DM ages between 2.0 and 1.5 Ga are consistent with evolution from a relatively homogeneous and enriched common crustal (metasedimentary) protolith.Results suggest a genetic link between metatexites, diatexites, orthogneisses and charnockites and a two-step process for charnockite development: (a) generation of the hydrated igneous protoliths by anatexis of metasedimentary rocks; (b) continuous high-grade metamorphism that transformed the “S-type granitoids” (leucosomes and diatexites) into orthogneisses and, as metamorphism and dehydration progressed, into charnockites.     

Mercury bioaccumulation in the spotted dogfish (Scyliorhinus canicula) from the Atlantic Ocean

The annual and life-cycle mercury bioaccumulation pattern in selected tissues of the economically relevant Elasmobranchii species Scyliorhinus canicula was studied, and the risks associated with its consumption evaluated.Preferential mercury bioaccumulation occurred in muscle tissue, and followed the order muscle > heart > liver > gills > pancreas. Total mercury in muscle tissue ranged from 0.13 mg kg⁻¹ (wwt) in 1+ year old males to 0.8 mg kg⁻¹ (wwt) in 8+ year old mature females, with no significant differences found between genders, and no clear lifespan bioaccumulation pattern observed, except for mature females. Organic mercury in the muscle ranged from 0.05 mg kg⁻¹ (wwt) to 0.52 mg kg⁻¹ (wwt), corresponding to an average of 70% of total mercury content. In mature females, a significant correlation (R = 0.99, P = 0.01) was found between size and organic mercury fraction, suggesting reproduction as an important factor controlling organic mercury bioaccumulation in the spotted dogfish.     

Mobility of trace elements between the river water,the sediments,and the pore water of Las Catonas Stream,Buenos Aires Province,Argentina

The composition of river water, sediments, and pore waters (down to 30 cm below the bed) of Las Catonas Stream was studied to analyze the distribution of trace elements in a peri-urban site. The Las Catonas Stream is one of the main tributaries of Reconquista River, a highly polluted water course in the Buenos Aires Province, Argentina. The semi-consolidated Quaternary sediments of the Luján Formation are the main source of sediments for Las Catonas Stream. The coarse-grained fraction in the sediments is mainly composed of tosca (calcretes), intraclasts, bone fragments, glass shards, quartz, and aggregates of fine-grained sediments together with considerably amounts of vegetal remains. The clay minerals are illite, illite–smectite, smectite, and kaolinite. For the clay-sized fraction, the external surface area values are mostly between 70 and 110 m²g^?1, although the fraction at 15 cm below the bottom of the river shows a lower surface area of 12 m²g^?1. The N₂ adsorption–desorption isotherms at 77 K for this sample display a behavior indicative of non-porous or macroporous material, whereas the samples above and below present a typical behavior of mesoporous materials with pores between parallel plates (slit-shaped). As, Cr, Cu, and Cd concentrations increase down to 15 cm depth in the sediments, where the highest trace element and total organic carbon (TOC) concentrations were found, and then decrease toward the bottom of the core. Except for As, the levels of the other heavy metals show higher concentration in surficial waters than in pore waters. Distribution coefficients between the sediments, pore water, and surficial water phases indicate that As is released from the sediments to the pore and surficial waters. Cu content strongly correlates with TOC (mainly from vegetal remains), suggesting that this element is mainly bound to the organic phase.     

Proposal for selection of control,preventive and rehabilitation measures based on degradation land level and geoindicators in the fortaleza metropolitan region,State of Ceará, Brazil

Preventive, controlling, rehabilitative and corrective measures to improve the environmental quality of the hydrographic basins of the Fortaleza metropolitan region in the state of Ceará (Brazil) are presented based on geological and geotechnical data, land degradation rates and sources, and other geoindicators. The region is affected by coastal and stream erosion, gravitational mass movement, dunes, silting, and water pollution, sanitary landfills in inappropriate sites, decommissioned and abandoned aggregate mining, and swamp areas. Geoindicators were used to classify each of the 12 hydrographic basins as possessing low (4), intermediate (3), or high (5) degradation levels. A group of 59 environmental management measures related to ecological, bioengineering, mechanical, policy and administrative, agricultural and clean-up methods was selected. From this general group a set of 31 measures was chosen considering goals, efficacy for specific environmental problems, suitability for large or small areas, behavior under different annual climatic conditions, environmental problems of the region, geological and geotechnical limitations and degradation level of the basins. A set of the more suitable geoindicators was selected for monitoring efficiency of the measures for each basin.     

同位素^131I测西台吉乃尔湖矿区含水层地质参数

盐湖区的水文地质参数特性与淡水区迥然不同。同位素示踪法可以利用西台盐湖区已有的长现井,机动灵活的随时监测含水层水文地质参数;由于介质的特殊性以及卤水性质的垂直差异性,造成水文地质参数的时空可变性;测试结果表明,对于完整井以及深的非完整井,该方法切实有效,但对于很浅的非完整井,测试结果具有很大的随机性。最后,根据测试结果以及有关的水文地质资料,把研究区分成7个渗透系数分区。