Changes in heat wave characteristics over Extremadura (SW Spain)

Theoretical and Applied Climatology - Heat wave (HW) events are becoming more frequent, and they have important consequences because of the negative effects they can have not only on the human...     

Ozone structure over the equatorial Andes from balloon-borne observations and zonal connection with two tropical sea level sites

In this paper we present first-time measurements of ozone profiles from a high altitude station in Quito, Ecuador (0.19°S, 78.4°W, and 2391 masl) taken from June 2014 to September 2015. We interpret ozone observations in the troposphere, tropopause, and stratosphere through a zonal comparison with data from stations in the Atlantic and Pacific (Natal and San Cristobal from the SHADOZ network). Tropospheric ozone concentrations above the Andes are lower than ozone over San Cristobal and Natal for similar time periods. Ozone variability and pollution layers are also reduced in the troposphere above the Andes. We explain these differences in terms of reduced contributions from the boundary layer and from horizontal transport. In the tropical tropopause layer, ozone is well-mixed up to near the cold point tropopause level. In this regard, our profiles do not show constraints to deep mixing above 14 km, as has been consistently observed at other tropical stations. Total column ozone and stratospheric column ozone are comparable among the three sites. However, the contribution of tropospheric column ozone to total column ozone is significantly lower above the Andes. Our comparisons provide a connection between observations from tropical stations in equatorial South America separated by the wide continental mass. Identified differences in ozone throughout the atmospheric column demonstrate the global benefit of having an ozone sounding station at the equatorial Andes in support of global monitoring networks.     

Long-term simulations of thermal and hydraulic characteristics in a mountain massif: The Mont Blanc case study, French and Italian Alps

 The use of hydrothermal simulation models to improve the prediction of water inflows in underground works during drilling is tested in the Mont Blanc tunnel, French and Italian Alps. The negative thermal anomaly that was observed during the drilling of this tunnel in 1960 is reproduced by long-term, transient hydrothermal simulations. Sensitivity analysis shows the great inertia of thermal phenomena at the massif scale. At the time of tunnel drilling, the massif had not reached thermal equilibrium. Therefore, a set of simulation scenarios, beginning at the end of the last glacial period, was designed to explain the anomaly encountered in the tunnel in 1960. The continuous cooling of alpine massifs due to infiltration of waters from the surface has occurred for 12,000 years and is expected to continue for about 100,000 years. Comparisons of water-discharge rates simulated in the tunnel with those observed indicate that this hydrothermal method is a useful tool for predicting water inflows in underground works. Received, May 1998 · Revised, March 1999 · Accepted, April 1999     

Large-Scale and Mesoscale Distribution of Plankton Biomass and Metabolic Activity in the Northeastern Central Atlantic

Plankton biomass and indices of metabolism and growth [electron transport system (ETS), glutamate dehydrogenase (GDH) and aspartate transcarbamylase (ATC) activities] were studied over a 2,800 km east-west section of the tropical North Atlantic Ocean (21°N) in <200, 200–500 and >;500 µm size classes. On the large-scale, zooplankton (>;200 µm) enzymatic activities increased westward in the study section, where large cyanobacteria chains (Trichodesmium spp.) were observed. Parallel to it, an increase in medium calanoids (1–2 mm length) was observed towards the western part of the transect, whereas small calanoids (<1 mm) were dominant throughout the boundary area of the subtropical gyre. Microplankton ETS and mesoplankton ETS and ATC activities seemed to match the wave length of low frequency waves. Our results suggest that such waves are related to the observed enhancement of metabolic activity of micro- and mesoplankton. The large-scale and mesoscale variability observed give evidence of the inadequacy of assuming a steady-state picture of the euphotic zone of tropical and subtropical waters.     

Atlas of susceptibility to pollution in marinas. Application to the Spanish coast

An atlas of susceptibility to pollution of 320 Spanish marinas is provided. Susceptibility is assessed through a simple, fast and low cost empirical method estimating the flushing capacity of marinas. The Complexity Tidal Range Index (CTRI) was selected among eleven empirical methods. The CTRI method was selected by means of statistical analyses because: it contributes to explain the system's variance; it is highly correlated to numerical model results; and, it is sensitive to marinas' location and typology. The process of implementation to the Spanish coast confirmed its usefulness, versatility and adaptability as a tool for the environmental management of marinas worldwide. The atlas of susceptibility, assessed through CTRI values, is an appropriate instrument to prioritize environmental and planning strategies at a regional scale.     

On the significance of the climate-dataset time resolution in characterising wind-driven rain and simultaneous wind pressure. Part I: scalar approach

Stochastic Environmental Research and Risk Assessment - The joint action of wind-driven rain and wind pressure is the main cause of water penetration in building facades, which causes various...     

Lagged rejuvenation of groundwater indicates internal flow structures and hydrological connectivity

Large proportions of rainwater and snowmelt infiltrate into the subsurface before contributing to stream flow and stream water quality. Subsurface flow dynamics steer the transport and transformation of contaminants, carbon, weathering products and other biogeochemistry. The distribution of groundwater ages with depth is a key feature of these flow dynamics. Predicting these ages are a strong test of hypotheses about subsurface structures and time-varying processes. Chlorofluorocarbon (CFC)-based groundwater ages revealed an unexpected groundwater age stratification in a 0.47 km² forested catchment called Svartberget in northern Sweden. An overall groundwater age stratification, representative for the Svartberget site, was derived by measuring CFCs from nine different wells with depths of 2–18 m close to the stream network. Immediately below the water table, CFC-based groundwater ages of already 30 years that increased with depth were found. Using complementary groundwater flow models, we could reproduce the observed groundwater age stratification and show that the 30 year lag in rejuvenation comes from return flow of groundwater at a subsurface discharge zone that evolves along the interface between two soil types. By comparing the observed groundwater age stratification with a simple analytical approximation, we show that the observed lag in rejuvenation can be a powerful indicator of the extent and structure of the subsurface discharge zone, while the vertical gradient of the age-depth-relationship can still be used as a proxy of the overall aquifer recharge even when sampled in the discharge zone. The single age stratification profile measured in the discharge zone, close to the aquifer outlet, can reveal the main structure of the groundwater flow pattern from recharge to discharge. This groundwater flow pattern provides information on the participation of groundwater in the hydrological cycle and indicates the lower boundary of hydrological connectivity.     

Accumulation of Heavy Metals by Amur Bay Sediments (the Sea of Japan) under the Effect of Biochemical Factors

Water Resources - The average concentrations of elements Fe, Mn, Zn, Pb, Cu, Cr, V, Co, Cd, Ni, As, and Mo in the subcolloidal fraction of bottom sediments were determined in the northern and...     

Evaluation of the removal of heavy metals in a natural wetland impacted by mining activities in Mexico

This research is focused on evaluating heavy metals (Cd, Cu, Fe, Mn, Pb, and Zn) uptake and removal by Eleocharis ovata, Cyperus manimae, Typha dominguensis, and Pteridium aquilinum in a natural wetland impacted by mining activities. We analyzed heavy metals content and distribution in native plants, soils, and water of a semipermanent natural wetland in Taxco de Alarcón, Guerrero, and we also determined the physicochemical characteristics of the water. Translocation factor (TF) and bioconcentration factor (BCF) were evaluated. Results showed that physical and chemical conditions are favorable for plants development. Correlation analysis showed a good and positive relation (0.95) between Cu and Pb in soils and plants. In the analyzed matrices: Zn (0.62–2.20 mg/L) exceeded the permissible limits in water, high concentrations of Pb and Zn (26.57–525.67 and 266.67–983.33 mg/kg, respectively) were detected in the studied soils, and Pb exceeded the normal range for E. ovata and P. aquilinum in the analyzed plants. Uptake of heavy metals in the tissues of different species was found in the following order: root > leaf. Data of TF and BCF showed that E. ovata is a tolerant plant with respect to heavy metals exposure since TF value was greater than 1. This study showed that E. ovata could be considered as a bioaccumulator of heavy metals in contaminated soils.