Numerical Modeling of the Impact of a Pumped-Storage Hydroelectric Power Plant on the Reservoirs’ Thermal Stratification Structure: a Case Study in NW Spain

Pumped-storage hydroelectric power plants are generally perceived as an environmentally respectful technology. Nevertheless, the pumping of water from a lower reservoir to an upper impoundment, and the return of that water during power generation, can strongly affect the water quality of the reservoirs. In particular, plant operation can alter their thermal structure, deep water mixing, and water circulation characteristics. The objective of this study is to quantify, through the use of 3D hydrodynamic modeling, the potential impacts of a pumped-storage hydroelectric plant on the thermal stability and mixing of two reservoirs in Galicia, northwest of Spain. To this end, three-dimensional hydrodynamic simulations were conducted using the model Delft3D. Two different coupled models, one for each reservoir, were constructed and subsequently tested for several stratification scenarios, according to measured temperature profiles during the spring and summer season. Several reservoir minimum and maximum operation water levels were also considered. Model simulations demonstrated a high level of mixing in the vicinity of the intake-outlet structures, in particular during startup of the power plant, regardless of the water level in the reservoir. Beyond this area, the results showed a limited overall effect on stratification and mixing in the upper reservoir, owing to the relation between the inflow temperatures and the initial temperature profile of this reservoir. A more significant alteration of the thermal structure is expected in the lower reservoir due to its narrow shape and shallow depth at the structure location, as well as the temperature differences between receiving waters and inflow.     

Greenhouse gases emissions from a closed old landfill cultivated with biomass crops

Closed landfills need after-closure rehabilitation. The chosen option should ensure greenhouse gases release, from the landfill, is not promoted once settled. The objective of this study was to estimate and confront, during different seasons, CH₄, CO₂ and N₂O emissions under three vegetation covers in a closed landfill in Buenos Aires, Argentina. CH₄ (methane), CO₂ (carbon dioxide) and N₂O (nitrous oxide) emissions from landfill’s technosol under spontaneous vegetation (control), Pennisetum purpureum and Miscanthus giganteus (biomass crops), were quantified with non-steady-state non-flow-through chambers, in July 2014 and from February to July 2015. A linear regression analysis was performed to relate the variables “flux of a gas” and “concentration of that gas” from the 3 treatments and 6 dates, separating the 5 sampling times. A high correlation between concentrations and fluxes of CO₂ and N₂O was found, but no correlation was established for CH₄. Mean emissions (2014–2015) varied from: ?2.3 to 639.41 mgCH₄ m^?2 day^?1, 3884 to 46,365 mgCO₂ m^?2 day^?1 and 0.40 to 14.59 mgN₂O m^?2 day^?1. Vegetation covers had no significant effect on CH₄ and N₂O concentration in time, but they had on CO₂ concentration. Season of the year had a significant effect on concentration of the three gases. This is the first study on CH₄, CO₂ and N₂O emissions from a landfill closed 27 years ago covered with biomass crops.     

Mechanical properties and microstructure of cement mortars incorporating Cd-zeolitized fly ash

Journal of Material Cycles and Waste Management - A solid enriched with NaA zeolite was synthesized from a coal fly ash, and the so-obtained zeolitized material was used as ion exchanger for...     

Accumulation of heavy metals in native Andean plants: potential tools for soil phytoremediation in Ancash (Peru)

Metal contamination is a recurring problem in Peru, caused mainly by mine tailings from a past active mining activity. The Ancash region has the largest number of environmental liabilities, which mobilizes high levels of metals and acid drainages into soils and freshwater sources, posing a standing risk on human and environmental health. Native plant species spontaneously growing on naturally acidified soils and acid mine tailings show a unique tolerance to high metal concentrations and are thus potential candidates for soil phytoremediation. However, little is known about their propagation capacity and metal accumulation under controlled conditions. In this study, we aimed at characterizing nine native plant species, previously identified as potential hyperaccumulators, from areas impacted by mine tailings in the Ancash region. Plants were grown on mine soils under greenhouse conditions during 5 months, after which the concentration of Cd, Cu, Ni, Pb, and Zn was analyzed in roots, shoots, and soils. The bioaccumulation (BAF) and translocation factor (TF) were calculated to determine the amount of each metal accumulated in the roots and shoots and to identify which species could be better suited for phytoremediation purposes. Soil samples contained high Cd (6.50–49.80 mg/kg), Cu (159.50–1187.00 mg/kg), Ni (3.50–8.70 mg/kg), Pb (1707.00–4243.00 mg/kg), and Zn (909.00–7100.00 mg/kg) concentrations exceeding national environmental quality standards. After exposure to mine tailings, concentrations of metals in shoots were highest in Werneria nubigena (Cd, 16.68 mg/kg; Cu, 41.36 mg/kg; Ni, 26.85 mg/kg; Zn, 1691.03 mg/kg), Pennisetum clandestinum (Pb, 236.86 mg/kg), and Medicago lupulina (Zn, 1078.10 mg/kg). Metal concentrations in the roots were highest in Juncus bufonius (Cd, 34.34 mg/kg; Cu, 251.07 mg/kg; Ni, 6.60 mg/kg; Pb, 718.44 mg/kg) and M. lupulina (Zn, 2415.73 mg/kg). The greatest BAF was calculated for W. nubigena (Cd, 1.92; Cu, 1.20; Ni, 6.50; Zn, 3.50) and J. bufonius (Ni, 3.02; Zn, 1.30); BCF for Calamagrostis recta (Cd, 1.09; Cu, 1.80; Ni, 1.09), J. bufonius (Cd, 3.91; Cu, 1.79; Ni, 18.36), and Achyrocline alata (Ni, 137; Zn, 1.85); and TF for W. nubigena (Cd, 2.36; Cu, 1.70; Ni, 2.42; Pb, 1.17; Zn, 1.43), A. alata (Cd, 1.14; Pb, 1.94), J. bufonius (Ni, 2.72; Zn, 1.63), and P. clandestinum (Zn, 1.14). Our results suggest that these plant species have a great potential for soil phytoremediation, given their capability to accumulate and transfer metals and their tolerance to highly metal-polluted environments in the Andean region.     

Matrix effect in case of purification of oily waters by membrane separation combined with pre-ozonation

In the present study, oil in water emulsions (c_oil?=?100 ppm; d_{oil droplets}?<?2 μm) was purified with ozonation followed by microfiltration using polyethersulfone (PES) membrane (d_pore?=?0.2 μm). The effects of pre-ozonation on membrane microfiltration were investigated in detail both in case of ultrapure and model groundwater matrices, applying different durations (0, 5, 10, and 20 min) of pre-ozonation. Simultaneously, the effects of added inorganic water components on the combined method were investigated. Size distribution of oil droplets, zeta potentials, fluxes, and purification efficiencies were measured and fouling mechanisms were described in all cases. It was found that the matrix significantly affected the size distribution and adherence ability of oil droplets onto the membrane surface, therefore fouling mechanisms also were strongly dependent on the matrix. In case of low salt concentration, the total resistance was caused mainly by reversible resistance, which could be significantly reduced (eliminated) by pre-ozonation. In case of model groundwater matrix, nearly twice higher total resistance was measured, and irreversible resistance was dominant, because of the higher adhesion ability of the oil droplets onto the membrane surface. In this case, pre-ozonation resulted in much lower irreversible, but higher reversible resistance. Increased duration of pre-ozonation raised the total resistance and reduced the elimination efficiency (due to fragmented oil droplets and water soluble oxidation by-products) in both cases, therefore short pre-ozonation can be recommended both from economic and performance aspects.     

Changes of the phytoplankton community as symptoms of deterioration of water quality in a shallow lake

Covering more than 60% of the lake surface, macrophytes determined the taxonomic composition of phytoplankton. We have found numerous indications of ecological deterioration and an increased trophic level year to year: an increased total number of taxa; a significantly increased number of species of Chlorophyta, Bacillariophyceae and Cyanoprokaryota; a decreased number of Chrysophyceae; increased Nygaard index, and high diversity and variability of phytoplankton functional groups. Within 2 years (2002 and 2003) algal biomass doubled: from 3.616 to 7.968 mg l^?1. An increased contribution of Chlorococcales and Cyanoprokaryota indicates progressive eutrophication of the lake. The average size of planktonic algae increased, particularly Cyanoprokaryota, where small-celled decreased dramatically and were replaced by large colonies. Cyanoprokaryota remained the dominant group of phytoplankton after 10 years, and the ecosystem of the lake remained in the turbid state. This group of algae had the average biomass 9.734 mg l^?1, which constituted almost 92% of the total biomass.     

Abandonment landscapes: user attitudes,alternative futures and land management in Castro Laboreiro,Portugal

Land abandonment is an important process for the European Union, which primarily occurs in less productive, remote and mountainous areas with unfavourable conditions for agriculture. Future management directions of these abandonment areas are under debate, with increasing calls to adjust policies to the local characteristics, including the promotion of rewilding and the management of succession of larger areas of less-productive land. While there is an increase in studies focusing on the environmental impacts of land abandonment, there are few studies that focus on the perceptions of abandonment by different user groups, even though an understanding of local perceptions, opportunities and trade-offs associated with changing land management is crucial for landscape-related policies and planning measures. In a case study in Northern Portugal, we used a combination of statements, photograph rating exercises and open questions to assess the perceptions of local inhabitants, visitors and experts regarding land abandonment and their preferences of different possible trajectories after abandonment. The results show that all user groups have a negative response towards abandonment and associate it mainly with negative emotions and the loss of heritage and traditions. The assessment of the different abandonment stages and outcomes clearly yielded different preferences and explanations, which can be used as input for finding a common ground for landscape management, reducing conflict and as a starting point for a more spatially targeted and nuanced management approach.

     

Land cover effects on water balance partitioning in the Colombian Andes: improved water availability in early stages of natural vegetation recovery

Regional Environmental Change - Vegetation actively affects different components of the water budget in multiple spatial and temporal scales. Changes in vegetation cover and structure—such as...     

Trends in social metabolism and environmental conflicts in four Andean countries from 1970 to 2013

In the global map of environmental injustices (http://www.ejatlas.com), the Andean countries (AC) report many ecological distribution conflicts. Our hypothesis is that the patterns of such conflicts are explained by the structural shifts of the economies and the concomitant changes in their metabolic profiles. Since the 1990s, these countries went through a strong reprimarization process, which changed their social metabolism as well as intensified environmental pressures and conflicts. In monetary terms, in the AC group of countries (Colombia, Ecuador, Peru and Bolivia), the primary sector increased its importance both in exports as well as in GDP. In the metabolic dynamics, the Domestic Extraction of materials (measured in tons) increased by a factor of 3.4 after jumping from 336 to 1145 MT between 1970 and 2012. This was driven by the fossil fuel and mining sectors. This reality was reflected in the environmental conflicts. Mining, fossil fuels, biomass and hydropower plants are the most conflictive sectors. The research in this article relies on a study of material flow analysis for the four AC carried out by the authors as well as 244 environmental conflicts reported in the EJAtlas until August 2016. The shifts in the metabolic–economic patterns help explain the dynamics and characteristics of the environmental conflicts in the AC. Such conflicts produce social mobilizations, which if successful, might help move society towards sustainability and environmental equity.     

Sugar–alcohol industry: quality of its biotreated washing water for reuse in fertigation

All processes in agro-industries consume water and generate large volumes of nutrient-rich effluents. To recycle effluents from a sugar–alcohol industry in the Northeastern Brazil (Coruripe, Alagoas), the effect of a daily application of a microbial formulation (containing five indigenous bacteria and two fungi), at the entrance of the two first facultative ponds (D, E) of its treatment plant formed by seven ponds (A–G), was evaluated in the sugarcane harvests of 2014/2015 and 2015/2016. Fortnightly, the values of 11 physicochemical parameters were checked and statistically compared (one and two-way ANOVA) in untreated (sedimentation pond A) and post-treated effluent (last facultative pond G), during both harvests. The treated effluent presented statistically significant improvements (p > 0.05), even between harvests, with averages of removal of organic matter of ca. 79.21% and 90.62%, and increases of the dissolved oxygen (DO) of ca. 72% and 74%, as well as the average increase of pH was ca. 42% and 50%. This better quality residue generally satisfied the class III level of the Brazilian Resolution 357/2005 (National Council for the Environment (CONAMA)), for water reuse in sugarcane irrigation on the yellow clay latosol soil, since it still is a light source of organic matter, nitrites and phosphorus, reducing the need of fertilizers for maintaining the productivity with low risk of salinization. According to Pearson’s bivariate correlation coefficient, while the DO and pH have positive correlation, they both have general inverse relation with the other physicochemical parameters evaluated and vice versa.