Performance evaluation of AR5-CMIP5 models for the representation of seasonal and multi-annual variability of precipitation in Brazilian hydropower sector basins under RCP8.5 scenario

ABSTRACT

Representations of precipitation from CMIP5 models over the 1950–1999 period in hydrographic basins that are relevant to the Brazilian electricity sector are evaluated in this study. The majority of ensemble members adequately represented seasonal variability, although they differed about the patterns of high-frequency interannual variation. The models did not adequately represent seasonal-scale precipitation in the southern region of Brazil. Relative to other models, the CNRM_CM5 and HadGEM2-ES models demonstrated good seasonal and interannual representation over most basins, while the global CanESM2, GFDL-ESM2M and IPSL_CM5A-LR models demonstrated relatively poor performance. The models concur on the impact of the RCP8.5 scenario in the Southeast/Midwest and South sectors over the period 2015–2044, suggesting that precipitation will decrease up to 15% in the basin supplying the Furnas hydropower plant and by 12% in the basin supplying the Itaipú plant, which represents 25% of the hydroelectric production in Brazil.     

A DUAL mission for nuclear astrophysics

DUAL will study the origin and evolution of the elements and explores new frontiers of physics: extreme energies that drive powerful stellar explosions and accelerate particles to macroscopic energies; extreme densities that modify the laws of physics around the most compact objects known; and extreme fields that influence matter in a way that is unknown on Earth. The variability of these extreme objects requires continuous all-sky coverage, while detailed study demands an improvement in sensitivity over previous technologies by at least an order of magnitude. The DUAL payload is composed of an All-Sky Compton Imager (ASCI), and two optical modules, the Laue-Lens Optic (LLO) and the Coded-Mask Optic (CMO). The ASCI serves dual roles simultaneously, both as an optimal focal-plane sensor for deep observations with the optical modules and as a sensitive true all-sky telescope in its own right for all-sky surveys and monitoring. While the optical modules are located on the main satellite, the All-Sky Compton Imager is situated on a deployable structure at a distance of 30?m from the satellite. This configuration not only permits to maintain the less massive payload at the focal distance, it also greatly reduces the spacecraft-induced detector background, and, above all it provides ASCI with a continuous all-sky exposure.     

Easily altered minerals and reequilibrated fluid inclusions provide extensive records of fluid and thermal history: gypsum pseudomorphs of the Tera Group, Tithonian-Berriasian, Cameros Basin

This study reports a complex fluid and thermal history using petrography, electron microprobe, isotopic analysis and fluid inclusions in replacement minerals within gypsum pseudomorphs in Tithonian-Berriasian lacustrine deposits in Northern Spain. Limestones and dolostones, formed in the alkaline lakes, contain lenticularly shaped gypsum pseudomorphs, considered to form in an evaporative lake. The gypsum was replaced by quartz and non-ferroan calcite (Ca-2), which partially replaces the quartz. Quartz contains solid inclusions of a preexisting non-ferroan calcite (Ca-1), anhydrite and celestine. High homogenization temperatures (T _h ) values and inconsistent thermometric behaviour within secondary fluid inclusion assemblages in quartz (147?C351°C) and calcite (108?C352°C) indicate high temperatures after precipitation and entrapment of lower temperature FIAs. Th are in the same range as other reequilibrated fluid inclusions from quartz veins in the same area that are related to Cretaceous hydrothermalism. Gypsum was replaced by anhydrite, likely during early burial. Later, anhydrite was partially replaced by Ca-1 associated with intermediate burial temperatures. Afterward, both anhydrite and Ca-1 were partially replaced by quartz and this by Ca-2. All were affected during higher temperature hydrothermalism and a CO₂-H₂O fluid. Progressive heating and hydrothermal pulses, involving a CO₂-H₂O fluid, produce the reequilibration of the FIAs, which was followed by uplift and cooling.     

Total Mercury Distribution and Volatilization in Microcosms with and Without the Aquatic Macrophyte Eichhornia Crassipes

Mercury (Hg) is one of the most toxic pollutants and spreads in the environment according to its affinity to several compartments. Aquatic macrophytes, such as Eichhornia crassipes, are known as sites for accumulation of Hg and methylmercury formation. The objective of this research was to observe Hg distribution among air, water and whole plants of the macrophyte E. crassipes for 17?days. The distribution of a single ²⁰³Hg spike was evaluated by gamma spectrometry. Two experiments, with and without macrophytes, were made, and the compartments analyzed for the presence of Hg were air, 0.2-μm filtered water, suspended and settled particles, roots, leafs, petioles and adsorption on the desiccators walls. ²⁰³Hg was detected in all analyzed compartments, and the highest total Hg concentrations were found in the roots and particles of the incubations with and without macrophytes that retained in average 68 and 34?% of added Hg, respectively. On the other hand, the lowest concentrations were found in air for both incubations, with higher volatilization (up to 2.5?% of added Hg) in the absence of macrophytes. The lower Hg values in leafs and petioles suggest this plant has mechanisms of Hg retention in the roots. Results suggest this macrophyte promotes changes in the Hg cycle since it attracts most Hg present in water and particulate to its roots and settled particles underneath and also reduces Hg volatilization.     

Assessing the inconsistency between groundwater vulnerability and groundwater quality: the case of Chapala Marsh, Mexico

Aquifer systems present intrinsic properties such as vulnerability, which is identified as the potential risk of groundwater pollution by contaminants generated by human activity. When there are surface sources of pollution, usually there is a direct relationship between high vulnerability and decreased water quality. Nevertheless, this relationship is not observed in all aquifers and so the causative circumstances of inconsistencies between aquifer vulnerability and water quality have been investigated. This work addresses the vulnerability assessment of the Chapala Marsh area, Mexico, using SINTACS analysis. The Chapala Marsh aquifer is characterized by a granular structure and a fractured recharge zone; there are natural and anthropogenic sources of pollution. The results show discrepancies between the vulnerability indices and groundwater quality, as indicated by the existence of vulnerable areas with good water quality and vice versa. This is because the SINTACS method works well when contaminants have only vertical movement. For scenarios with lateral movement of contaminants, the method of geographic weighted regression (GWR) is used to model the influence of potential sources of contaminants on the water quality.     

Integration of GIS and remote sensing for estimation of soil loss and prioritization of critical sub-catchments: a case study of Tapacurá catchment

Mapping of erosion risk areas is an important tool for the planning of natural resources management, allowing researchers to propose the modification of land use properly and implement more sustainable long-term management strategies. The objective of this study was to assess and identify critical sub-catchments for soil conservation management using the USLE, GIS, and remote sensing techniques. The Tapacurá catchment is one of the planning units for water resource management of the Recife Metropolitan Region. Maps of the erosivity (R), erodibility (K), slope (LS), cover-management (C), and support practice (P) factors were derived from the climate database, digital elevation model, and soil and land-use maps. In order to validate the simulation process, total sediment delivery ratio was estimated. The results showed a mean sediment delivery ratio (SDR) of around 11.5?% and a calculated mean sediment yield of 0.108?t?ha^?1?year^?1, which is close to the observed one, 0.169?t?ha^?1?year^?1. The obtained soil loss map could be considered as a useful tool for environmental monitoring and water resources management. The methodology applied showed acceptable precision and allowed the identification of the most susceptible areas to soil erosion by water, constituting an important predictive tool for soil and environmental management in this region, which is highly relevant for the prediction of varying development scenarios for Tapacurá catchment. This approach can be applied to other areas for simple and reliable identification of critical areas of soil erosion in catchments.