6 pages, 5 figures, 4 tables. | [EN] In this paper the water interchange between the Ria of Vigo and the coastal shelf is discussed from the points of view both of salinity and of the fresh water contribution from the drainage basin. In winter the results show a typical estuarine circulation, produced by the great quantity of fresh water running into Ria. This factor causes flows of arount 2 X 106 kg s-1; 2 m day-1 upward movement of sea water, and a speed of 3 km day-1 for the estuarine residual current in the outlet of the Ria. In summer these values decrease to about one sixth of the winter values, although there is an increase in the circulation of up to 1 X 106 kg s-1 , the consequence of upwelling produced by north winds over the shelf. Later the south winds produce the opposite effect, blocking interchange with the shelf. The mixing of water in the Ria is greater in summer, favouring the arrival and recycling of nutrient salts in the area. | [ES] Se calcula el intercambio de agua entre la ría de Vigo y la plataforma continental a partir de la salinidad y de los aportes de agua dulce desde la cuenta hidrológica. Los resultados manifiestan una circulación típicamente estuárica en invierno, que es causada por la alta cantidad de agua dulce vertida a la Ría. La mezcla de agua en la Ría aumenta según avanza la estación favoreciendo el reciclado y la llegada de sales nutrientes a la zona fótica. | Peer reviewed

To optimize Drosophila suzukii rearing and establish mass rearing its local parasitoids, this washing method collects pupae from wheat germ diet. The diet consists of purified water (480 ml), raw wheat germ (100 g), table sugar (45 g), Brewer's yeast (35 g), and maize flour (30 g). Preparation requires stirring and boiling all ingredients for 7 minutes, then cooling to room temperature. Implementation of the method allows collecting clean pupae and compiling them into a smaller space, so it helps mass rearing D. suzukii and its parasitoids. Additionally, it could facilitate execution of other ideas with potential to control the pest, among them, the sterile insect technique and sterile insect technique + entomopathogenic fungi.

Resumen Se presenta un balance de calor del Lago de Zapotlán que fue resuelto numéricamente mediante el método de Runge-Kutta de cuarto orden con un incremento de tiempo de un día. A semejanza de otros lagos tropicales, el presupuesto anual de calor es muy bajo. La temperatura del lago (correlacionada con la radiación atmosférica y la radiación de fondo), la acción del viento (correlacionada con la radiación solar), y los escurrimientos (correlacionados con la radiación atmosférica, la radiación de fondo, la precipitación sobre el lago y la temperatura del lago), producen el mezclado del lago durante las estaciones de invierno, primavera y verano. Pero en el inicio del otoño, al disminuir el flujo neto de calor superficial y terminar las lluvias, el hipolimnión se enfría levemente debido a que esta capa es ocupada por escurrimientos más fríos y más densos. Esta pequeña diferencia térmica provoca que la columna de agua se estratifique de manera inestable. Los episodios alternados de mezclado y estratificado afectan significativamente el ciclo de nutrientes y la dinámica de la cadena alimenticia del lago. | Abstract This paper presents a heat balance for Lake Zapotlán, which was solved numerically using the fourth-order Runge-Kutta method with a step size of one day. Like other tropical lakes, the annual heat budget of Lake Zapotlán is very low. Lake temperature (correlated with both atmospheric longwave radiation and water back radiation), wind strength (correlated with solar shortwave radiation, and runoffs (correlated with atmospheric longwave radiation, water back radiation, precipitation on lake and lake temperature) produce lake mixing during three seasons: winter, spring and summer. When fall begins, as the net surface heat flux diminishes and rainfall ends, the epilimnion is slightly cooled since this layer receives colder, denser runoff. This small difference in temperature causes the water column to stratify in an unstable manner. The alternating episodes of mixing and stratification significantly affect the nutrient cycle and the dynamics of the food chain.

A combined simulation-optimization model was developed to minimize the freshwater footprint at multi-well hydraulic fracturing sites. The model seeks to reduce freshwater use by blending it with brackish groundwater and recovered water. Time-varying water quality and quantity mass balance expressions and drawdown calculations using the Theis solution along with the superposition principle were embedded into the optimization model and solved using genetic algorithms. The model was parameterized for representative conditions in the Permian Basin oil and gas play region with the Dockum Formation serving as the brackish water source (Texas, USA). The results indicate that freshwater use can be reduced by 25–30 % by blending. Recovered water accounted for 2–3 % of the total blend or 10–15 % of total water recovered on-site. The concentration requirements of sulfate and magnesium limited blending. The evaporation in the frac pit constrained the amount blended during summer, while well yield of the brackish (Dockum) aquifer constrained the blending during winter. The Edwards-Trinity aquifer provided the best quality water compared to the Ogallala and Pecos Valley aquifers. However, the aquifer has low diffusivity causing the drawdown impacts to be felt over large areas. Speciation calculations carried out using PHREEQC indicated that precipitation of barium and strontium minerals is unlikely in the blended water. Conversely, the potential for precipitation of iron minerals is high. The developed simulation-optimization modeling framework is flexible and easily adapted for water management at other fracturing sites.

This work focuses on the geochemical processes taking place in the acid drainage in the Ribeira da Água Forte, located in the Aljustrel mining area in the Iberian Pyrite Belt. The approach involved water and stream sediment geochemical analyses, as well as other techniques such as sequential extraction, Mössbauer spectroscopy, and X-ray diffraction. Ribeira da Água Forte is a stream that drains the area of the old mine dumps of the Aljustrel mine, which have for decades been a source of acid waters. This stream flows to the north for a little over than 10km, but mixes with a reduced, organic-rich, high pH waste water from the municipal waste water pools of the village. This water input produces two different results in the chemistry of the stream depending upon the season: (i) in the winter season, effective water mixing takes place, and the flux of acid water from the mine dumps is continuous, resulting in the immediate precipitation of the Fe from the acid waters; (ii) during the summer season, acid drainage is interrupted and only the waste water feeds the stream, resulting in the reductive dissolution of Fe hydroxides and hydroxysulfates in the stream sediments, releasing significant quantities of metals into solution. Throughout the year, water pH stays invariably within 4.0–4.5 for several meters downstream of this mixing zone even when the source waters come from the waste water pools, which have a pH around 8.4. The coupled interplay of dissolution and precipitation of the secondary minerals (hydroxides and sulfates), keeps the system pH between 3.9 and 4.5 all along the stream. In particular, evidence suggests that schwertmannite may be precipitating and later decomposing into Fe hydroxides to sustain the stream water pH at those levels. While Fe content decreases by 50% from solution, the most important trace metals are only slightly attenuated before the solution mixes with the Ribeira do Rôxo stream waters. Concentrations of As are the only ones effectively reduced along the flow path. Partitioning of Cu, Zn and Pb in the contaminated sediments also showed different behavior. Specific/non-specific adsorption is relevant for Cu and Zn in the upstream branch of Ribeira da Água Forte with acid drainage conditions, whereas the mixture with the waste water causes that the association of these metals with oxyhydroxide to be more important. Metals bound to oxyhydroxides are on the order of 60–70% for Pb, 50% for Cu and 30–60% for Zn. Organic matter is only marginally important around the waste water input area showing 2–8% Cu bound to this phase. These results also show that, although the mixing process of both acid and organic-rich waters can suppress and briefly mitigate some adverse effects of acid drainage, the continuing discharge of these waste waters into a dry stream promotes the remobilization of metals fixed in the secondary solid phases in the stream bed back into solution, a situation that can hardly be amended back to its original state.

Complex hydrogeological systems require detailed knowledge of aquifer dynamics to ensure appropriate and sustainable management of the groundwater resource. The Riardo Plain aquifer, southern Italy, is a strategic resource for conjunctive uses; nevertheless, the conceptual model still suffers some uncertainties due to the presence of a deep lateral inflow through the carbonate basement. Therefore, the realisation of a 3D numerical model at catchment scale needs preliminary tests to constrain the possible additional inflow rate, which is at the moment only estimated through the results of the groundwater budget calculation. A 2D section of the mixing area was modelled using FEFLOW in order to test the hypothesis of a combined recharge. Seven versions of the same model were calibrated over an increasing number of adjustable parameters according to their sensitivity. The most efficient model version was identified according to the calculated information criteria and the sum of squared-weighted residuals. In the second phase of the work, nine model scenarios characterised by different deep inflow rates were calibrated and validated according to the same procedure of the first model, in order to identify the range of possible acceptable solutions. The most likely deep inflow rate is 34 ± 4% of the total recharge, corresponding to an estimated deep inflow of 415 ± 50 L/s in the Riardo Plain aquifer through the carbonate basement. This methodological approach will be the basis of following numerical 3D numerical models of the Riardo Plain and can be a valuable tool in conceptualising similar mineral water areas.

In coastal-zone fields with a high groundwater level and sufficient rainfall, freshwater lenses are formed on top of saline or brackish groundwater. The fresh and the saline water meet at shallow depth, where a transition zone is found. This study investigates the mixing zone that is characterized by this salinity change, as well as by cation exchange processes, and which is forced by seepage and by rainfall which varies as a function of time. The processes are first investigated for a one-dimensional (1D) stream tube perpendicular to the interface concerning salt and major cation composition changes. The complex sequence of changes is explained with basic cation exchange theory. It is also possible to show that the sequence of changes is maintained when a two-dimensional field is considered where the upward saline seepage flows to drains. This illustrates that for cation exchange, the horizontal component (dominant for flow of water) has a small impact on the chemical changes in the vertical direction. The flow’s horizontal orientation, parallel to the interface, leads to changes in concentration that are insignificant compared with those that are found perpendicular to the interface, and are accounted for in the 1D flow tube. Near the drains, differences with the 1D considerations are visible, especially in the longer term, exceeding 100 years. The simulations are compared with field data from the Netherlands which reveal similar patterns.

Land subsidence is common in some regions of China. Various eco-environmental problems have arisen due to changes in water–rock interactions in these subsided areas, for which a comprehensive understanding of the hydrogeological setting is needed. This paper presents the general status of land subsidence in three typical subsided areas of China through the compilation of relevant data, and reviews some typical changes in the water–rock interactions in subsided areas along with related eco-environmental issues. It is found that the subsidence development and distribution are controlled by the groundwater-withdrawal intensity externally, and by the thickness and compressibility of unconsolidated sediments internally. The physical changes and related effects of water–rock interactions in subsided areas include: (1) the decreased ground elevation that caused floods, waterlogged farmland, etc.; (2) the differential subsidence that caused ground fissures; and (3) the change of seepage field that caused substantial reduction of the water resource. Chemically, the changes and related effects of water–rock interactions include: (1) the change to the chemical environment or processes due to the hydrogeologic structure alteration, which caused groundwater pollution; and (2) hydrologic mixing (seawater intrusion, artificial recharge; exchange with adjacent aquifers or aquitards), which degraded the groundwater quality. Further research on the subsided areas in China is suggested to reveal the mechanisms regarding biological and gaseous (meteorological) changes from the perspective of interacting systems among water, rocks, biological agents and gases.

Groundwater in upland floodplains has an important function in regulating river flows and controlling the coupling of hillslope runoff with rivers, with complex interaction between surface waters and groundwaters throughout floodplain width and depth. Heterogeneity is a key feature of upland floodplain hydrogeology and influences catchment water flows, but it is difficult to characterise and therefore is often simplified or overlooked. An upland floodplain and adjacent hillslope in the Eddleston catchment, southern Scotland (UK), has been studied through detailed three-dimensional geological characterisation, the monitoring of ten carefully sited piezometers, and analysis of locally collected rainfall and river data. Lateral aquifer heterogeneity produces different patterns of groundwater level fluctuation across the floodplain. Much of the aquifer is strongly hydraulically connected to the river, with rapid groundwater level rise and recession over hours. Near the floodplain edge, however, the aquifer is more strongly coupled with subsurface hillslope inflows, facilitated by highly permeable solifluction deposits in the hillslope–floodplain transition zone. Here, groundwater level rise is slower but high heads can be maintained for weeks, sometimes with artesian conditions, with important implications for drainage and infrastructure development. Vertical heterogeneity in floodplain aquifer properties, to depths of at least 12 m, can create local aquifer compartmentalisation with upward hydraulic gradients, influencing groundwater mixing and hydrogeochemical evolution. Understanding the geological processes controlling aquifer heterogeneity, which are common to formerly glaciated valleys across northern latitudes, provides key insights into the hydrogeology and wider hydrological behaviour of upland floodplains.