Effects of water-borne copper on metallothionein and lipid peroxidation in the marine amphipod Gammarus locusta

The aim of the current work was to determine over 10 days the effects of water-borne exposure of the marine amphipod Gammarus locusta to 4 microgCu l(-1) on the metallothionein (MT; measured by differential pulse polarography) protection system and lipid peroxidation (LP: thiobarbituric acid-reactive malondialdehyde equivalents) as a measure of oxidative damage. MT levels in exposed animals increased significantly at day 2 (36% > control; P < 0.001) and remained high at days 6 and 10 (55 and 38%, respectively, P < 0.001). The maximum level of MT at day 6 coincided with the highest Cu body-burden. LP increased within I day of exposure, indicative of Cu as an oxidative stressor. However, in contrast to MT, the highest LP level was seen at day 4 (68% > control, P < 0.001) before returning to control values by day 6, indicating a protective role of MT against the pro-oxidant effects of Cu.     

A new design of the LAPS land surface scheme for use over and through heterogeneous and non-heterogeneous surfaces: Numerical simulations and tests

Numerical simulations and tests with the recently redesigned land–air parameterization scheme (LAPS) are presented. In all experiments, supported either by one-point micrometeorological, 1D or 3D simulations, the attention has been directed to: (1) comparison of simulation outputs, expressing the energy transfer over and through heterogeneous and non-heterogeneous surfaces, versus observations and (2) analysis of uncertainties occurring in the solution of the energy balance equation at the land–air interface. To check the proposed method for aggregation of albedo, “propagating hole” sensitivity tests with LAPS over a sandstone rock grid cell have been performed with the forcing meteorological data for July 17, 1999 in Baxter site, Philadelphia (USA). Micrometeorological and biophysical measurements from the surface experiments conducted over crops and apple orchard in Serbia, Poland, Austria and France were used to test the operation of LAPS in calculating surface fluxes and canopy environment temperatures within and above plant covers of different densities. In addition, sensitivity tests with single canopy covers over the Central Europe region and comparison against the observations taken from SYNOP data using 3D simulations were made. Validation of LAPS performances over a solid surface has been done by comparison of 2 m air temperature observations against 5-day simulations over the Sahara Desert rocky ground using 3D model. To examine how realistically the LAPS simulates surface processes over a heterogeneous surface, we compared the air temperature measured at 2 m and that predicted by the 1D model with the LAPS as the surface scheme. Finally, the scheme behaviour over urban surface was tested by runs over different parts of a hypothetical urban area. The corresponding 1D simulations were carried out with an imposed meteorological dataset collected during HAPEX-MOBILHY experiment at Caumont (France). The quantities predicted by the LAPS compare well with the observations and the various subcomponents of the scheme appear to operate realistically.     

High-resolution historical records from Pettaquamscutt River basin sediments: 2. Pb isotopes reveal a potential new stratigraphic marker

A high-resolution record of Pb deposition in Rhode Island over the past 250 yr was constructed using a sediment core from the anoxic Pettaquamscutt River basin. The sedimentary Pb concentration record shows the well-described maximum associated with leaded gasoline usage in the United States. Diminished Pb variability during recorded periods of local industrial activity (1735 to 1847) supports the greater importance of regional atmospheric lead transport vs. local inputs. The Pb isotopic composition at this site shows a clear maximum in anthropogenic ²⁰⁶Pb/²⁰⁷Pb in the mid-1800s. Similar peaks have also been observed in sediments from Chesapeake Bay and the Great Lakes, suggesting a common source. Possible causes for this event include mining and smelting of Pb ores in the Upper Mississippi Valley district, which accounted for almost all Pb production in the United States in that period. The timing of this event can provide an important stratigraphic marker for sediments deposited in the past 200 yr in the Northeastern United States. The downcore profile of anthropogenic ²⁰⁶Pb/²⁰⁷Pb provides a classic example of how changes in the mixture of ores for production of tetraethyl lead caused a regional-scale shift in the sedimentary record, and suggests that coal could have played a secondary role in Pb emissions after 1920.     

Petrogenetic links between lepidolite-subtype aplite-pegmatite,aplite veins and associated granites at Segura (central Portugal)

In the Segura area, Variscan S-type granites, aplite veins and lepidolite-subtype granitic aplite-pegmatite veins intruded the Cambrian schist-metagraywacke complex. The granites are syn D3. Aplite veins also intruded the granites. Two-mica granite and muscovite granite have similar ages of 311.0 ± 0.5 Ma and 312.9 ± 2.0 Ma but are not genetically related, as indicated by their geochemical characteristics and (⁸⁷Sr/⁸⁶Sr)₃₁₁ values. They correspond to distinct pulses of magma derived by partial melting of heterogeneous metapelitic rocks. Major and trace elements suggest fractionation trends for: (a) muscovite granite and aplite veins; (b) two-mica granite and lepidolite-subtype aplite-pegmatite veins, but with a gap in most of these trends. Least square analysis for major elements, and modeling of trace elements, indicate that the aplite veins were derived from the muscovite granite magma by fractional crystallization of quartz, plagioclase, K-feldspar and ilmenite. This is supported by the similar (⁸⁷Sr/⁸⁶Sr)₃₁₁ and δ¹⁸O values and the behavior of P₂O₅ in K-feldspar and albite. The decrease in (⁸⁷Sr/⁸⁶Sr)₃₁₁ and strong increase (1.6‰) in δ¹⁸O from two-mica granite to lepidolite-subtype aplite-pegmatite veins, and the behaviors of Ca, Mn and F of hydroxylapatite indicate that these veins are not related to the two-mica granite.     

Nutrient dynamics in Mediterranean temporary streams: A case study in Pardiela catchment (Degebe River, Portugal)

Most of the streams in the Mediterranean region are temporary, following predictable seasonal of flooding and drying, with a transition from lotic conditions to shallow lentic conditions. The goal of our study was to assess the nitrogen and phosphorus dynamics in channel-bed processes of temporary streams between floods. Results show that, during winter, temperatures ranged between 9.5 and 11.2 °C and oxygen concentration ranged from 8.0 to 9.5 mg L⁻¹, whereas, during summer, temperatures varied between 21.2 and 26.8 °C and oxygen between 1.2 and 5.3 mg L⁻¹, with oxygen depletion in the pools during the night. The nitrate concentrations were far more abundant during winter (February), while ammonium concentration increased after stream fragmentation into pools (especially in July when oxygen depletion conditions favoured ammonification). Results on sediment profiles showed that the most active sediment layers for NH₄-N are the top 2–3 cm, corresponding to the sediment depositional sites of the stream. Phosphate concentrations had larger variability, yet concentrations decreased from winter to spring and increased again in summer, when the shallow water pools were formed. Sediment profiles at the sediment depositional sites showed that PO₄-P was more dynamic in the first 6 cm.

In Mediterranean temporary streams, nutrient dynamics vary seasonally, as the system transits from lotic conditions to shallow lentic conditions, evidencing the regeneration of nutrients from organic and inorganic matter during the flow cessation period.     

Temporal dynamics of soil water balance components in a karst range in southeastern Spain: estimation of potential recharge

Abstract

This paper analyses the temporal dynamics of soil water balance components in a representative recharge area of the Sierra de Gádor (Almeria, southeastern Spain) in two hydrological years. Two approaches are used to estimate daily potential recharge (PR): Approach 1 based on deriving PR from the water balance as the difference between measurements of rainfall (P) and actual evapotranspiration (E) obtained by eddy covariance; and Approach 2 with PR obtained from the dynamic pattern of the soil moisture (θ) recorded at two depths in the site's thin soil (average 0.35 m thickess). For the hydrological year 2003/04, which was slightly drier than the 30-year average, E accounted for 64% of rainfall and occurred mainly in late spring and early summer. The PR estimated by Approach 1 was 181 ± 18 mm year^-1 (36% of rainfall), suggesting an effective groundwater recharge in the study area. In the unusually dry hydrological year 2004/05, E was about 215 mm year^-1, close to the annual rainfall input, and allowing very little (8 ± 12 mm year^-1) PR according to Approach 1. Estimation of PR based on Approach 2 resulted in PR rates lower than those found by Approach 1, because Approach 2 does not take into account the recharge that occurs through preferential flow pathways (cracks, joints and fissures) which were not monitored with the θ probes. Moreover, using Approach 2, the PR estimates differed widely depending on the time scale considered: with daily mean θ data, PR estimation was lower, especially in late spring, while θ data at 30 min resolution yielded a more reliable prediction of the fraction of total PR resulting from the downward movement of soil water by gravity.

Citation Cantón, Y., Villagarcía, L., Moro, M. J., Serrano-Ortíz, P., Were, A., Alcalá, F. J., Kowalski, A. S., Solé-Benet, A., Lázaro, R. & Domingo, F. (2010) Temporal dynamics of soil water balance components in a karst range in southeastern Spain: estimation of potential recharge. Hydrol. Sci. J. 55(5), 737–753.     

Longshore drift estimation using fluorescent tracers: New insights from an experiment at Comporta Beach, Portugal

A fluorescent sand-tracer experiment was performed at Comporta Beach (Portugal) with the aim of acquiring longshore sediment transport data on a reflective beach, the optimization of field and laboratory tracer procedures and the improvement of the conceptual model used to support tracer data interpretation.

The field experiment was performed on a mesotidal reflective beach face in low energetic conditions (significant wave height between 0.4 and 0.5 m). Two different colour tracers (orange and blue) were injected at low tide and sampled in the two subsequent low tides using a high resolution 3D grid extending 450 m alongshore and 30 m cross-shore. Marked sand was detected using an automatic digital image processing system developed in the scope of the present experiment.

Results for the two colour tracers show a remarkable coherence, with high recovery rates attesting data validity. Sand tracer displayed a high advection velocity, but with distinct vertical distribution patterns in the two tides: in the first tide there was a clear decrease in tracer advection velocity with depth while in the second tide, the tracer exhibited an almost uniform vertical velocity distribution. This differing behaviour suggests that, in the first tide, the tracer had not reached equilibrium within the transport system, pointing to a considerable time lag between injection and complete mixing. This issue has important implications for the interpretation of tracer data, indicating that short term tracer experiments tend to overestimate transport rates. In this work, therefore, longshore estimates were based on tracer results obtained during the second tide.

The estimated total longshore transport rate at Comporta Beach was 2 × 10^− 3 m³/s, more than four times larger than predicted using standard empirical longshore formulas. This discrepancy, which results from the unusually large active moving layer observed during the experiment, confirms the idea that most common longshore transport equations under-estimate total sediment transport in plunging/surging waves.     

Kinetics of the reactions of Cl atoms with 2-buten-1-ol, 2-methyl-2-propen-1-ol, and 3-methyl-2-buten-1-ol as a function of temperature

The reactions of three structurally similar unsaturated alcohols, 2-buten-1-ol (crotyl alcohol), 2-methyl-2-propen-1-ol (MPO221) and 3-methyl-2-buten-1-ol (MBO321) with Cl atoms, have been investigated for the first time, using a 400 l Teflon reaction chamber coupled with gas chromatograph-coupled with flame-ionization detection (GC-FID). The experiments were performed at atmospheric pressure and at temperatures between 255 and 298 K, in air or nitrogen as the bath gas. The obtained kinetic data were used to derive the Arrhenius expressions , , (in units of cm³ molecule⁻¹ s⁻¹). Finally, atmospheric lifetimes of those unsaturated alcohols with respect to OH, NO₃, O₃ and Cl have been calculated.     

Impact of lightning on organic matter-rich soils: influence of soil grain size and organic matter content on underground fires

A detailed study was carried out on a piece of land that had been struck by lightning during the violent rainstorm that raged over the Island of S?o Miguel (Azores Archipelago) in late October 2006. Temperature and gas measurements (CO₂, CO, H₂S and CH₄) were performed in four study trenches, dug in an area of ∼3 m², where an underground fire had been initiated by the impact with a lightning stroke, followed by the emission of a column of gases and smoke. The soil under study was originally a well-pedogenized about 80 cm thick bed, made of volcanic clayey to silty tephra fallouts and contained 5.5–9.7% of organic matter. The underground fire was monitored for one week and revealed a peak release of 404 ppm CO and 3.4% CO₂ originating from a horizon located about 45 cm under the soil surface. Measurements of temperature, performed one week after the impact, indicated a maximum value of 326°C inside the soil, while 516.5°C were measured on the surface of a lava block interred about 20 cm under the surface. Subsequently, a stratigraphic and sedimentologic study proved the role of the grain-size of the soil and of the organic matter content of the different horizons of the impact area, in determining the ratio between anoxic/oxidised combustion conditions and in the progress of the process itself. It was also noticed that combustion was not total all over in the soil bed and that the process had slightly migrated toward SW during the observation period. The combustion process went on for about ten days, in spite of several other violent rainstorms, until it was artificially extinguished through the excavations made to obtain study trenches. This particular circumstance evidenced the potential natural hazard represented by this kind of atmospheric event, especially in a land where the volcanic nature of the soil may easily mislead inexperienced observers and, consequently, delay proper action.