A hydrogeochemical approach to the characterization of low-enthalpy geothermal systems: the Scordia – Lentini graben (Sicily, Italy)

We describe the geochemical characteristics of groundwater samples collected in 23 water wells located on the northern margin of the Hyblean plateau (East Sicily). This area, mostly made of highly permeable carbonate rocks, is rich in low temperature (T < 50° C) hydrothermal groundwaters, distributed in an active sismogenetic zone, with several ENE-WSW-directed tectonic structures that drove magma to the surface during Upper Pliocene and Pleistocene. The chemical features suggest complex mixing between rainwater, CO2-rich groundwater, steam-heated groundwater and geothermal brines, as highlighted by Principal Component Analysis (PCA). Some parameters, however, indicate widespread pollution of the aquifers from human activities. Stable isotopes analysis confirms the meteoric origin of groundwater and supports the origin of dissolved CO2 mostly from mantle degassing through deep tectonic faults. Geothermometric estimates, mostly based on quartz and Saturation Indexes geothermometers, suggest minimum reservoir temperature between 100 and 120° C.

Regional Hydrogeochemical Evolution of Groundwater in the Ring of Cenotes, Yucatán (Mexico): An Inverse Modelling Approach

The Ring of Cenotes (RC) extends along the edge of the Chicxulub crater, in the limestone platform of the Yucatan Peninsula (YP), where groundwater shows two preferential flow paths toward the coast near Celestun and Dzilam Bravo towns. The objectives of this study were to describe the regional hydrogeochemical evolution of the groundwater in the RC, and its association with the dissolution/precipitation of the minerals present along its pathway to the ocean. These objectives results were obtained by: (a) characterizing groundwater hydrogeochemistry; (b) calculating calcite, dolomite, and gypsum saturation indexes in the study area; and (c) developing a hydrogeochemical model using PHREEQC (U. S. Geological Survey) inverse modelling approach. The model predictions confirmed that there are two evolution pathways of the groundwater consistent with the preferential flow paths suggested in a previous regionalization of the RC. On the western path, where groundwater flows towards Celestun, marine intrusion influences the hydrogeochemical processes and represents a risk for the freshwater. On the eastern path, where groundwater flows toward Dzilam Bravo, rainfall has an important effect on the hydrogeochemical processes, evidenced by a higher concentration in sulfates during droughts than during rainy periods. Then, monitoring of marine intrusion and phases dissolution in the RC is highly recommended.

Groundwater Quality Evolution Model in the Ring of Cenotes, Yucatan, Mexico

Karst aquifers show dissolution/precipitation processes of the minerals present in the carbonate rocks. The Ring of Cenotes (RC) extends along the edge of the Chicxulub crater, in the limestone platform of the Yucatan Peninsula (YP), where groundwater shows preferential flow paths toward the coast near Celestun and Dzilam Bravo towns. This study aimed to describe the regional hydrogeochemical evolution of groundwater of the RC, and its association with the dissolution/precipitation of the minerals present along its path to the ocean. To achieve this aim, we: a) characterized groundwater's hydrogeochemistry; b) determined the calcite, dolomite, and gypsum saturation indexes (reaction phases with the groundwater) in the study area; c) proposed a hydrogeochemical model developed through PHREEQC using an inverse modelling approach. The model predictions confirmed that there are two evolution pathways of the groundwater consistent with the preferential flow paths suggested in a previous regionalization of the RC. On the western path, where groundwater flows towards Celestun, an important marine intrusion influences the hydrogeochemical processes and represents a risk for the prevalence of freshwater. On the eastern path, where groundwater flows toward Dzilam Bravo, the hydrogeochemistry in the sinkholes correlates well with rainfall, suggesting a higher vulnerability during droughts than during rainy periods.

Fatty acid profile of muscles and adipose tissues of fat-tail Barbarine lambs as affected by rosemary residue intake

The rosemary distillation industry produces a considerable amount of rosemary distillation residues (RRs), which can be an alternative for feeding animals in harsh conditions and could enhance animal product quality. Given the meat quality is largely influenced by its fat content and fatty acid composition, the fatty acid (FA) profiles of longissimus thoracis et lumborum (LTL), semi-membranous (SM) muscles, and caudal (CFs) and omental fats (OFs) were determined using 21 Barbarine lambs fed with or without RRs. Diets contained 600 g of concentrate plus 600 g of forage. Forage represented oat hay, RR87 and RR60 pellets containing 87 % or 60 % of RR, respectively. At the end of the study, all lambs were slaughtered, and the fatty acid profile was studied. The inclusion of RR increased the polyunsaturated fatty acid (PUFA) contents and reduced saturated fatty acids (SFAs), and the thrombogenic and saturation indexes in all tissues. The SM muscle was the richest tissue in PUFAs, n-3 and n-6; however, both adipose tissues contained the highest proportions of SFAs. Especially the OF was the richest tissue in oleic acid and SFAs. Feeding RR to lambs enhanced meat quality.

Hydrochemical Evolution in Ciliwung River – Java, Indonesia: Study of Sea Water Mixture and Mineral Dissolution

The chemical characteristics of the Ciliwung River were analyzed to understand hydrochemical evolution. A fraction of sea water mixture and kinds of mineral controlling for chemicals were also determined. During three year investigations in 2015, 2016, and 2018, electrical conductivity increased with decreasing elevations. Two hydrochemical facies had been identified for the Ciliwung river water; those were Ca-Mg-HCO3 and Ca-Na-HCO3. The river water mixing with seawater was recognized in the Mangga Dua site in which its water type had shifted to Na-Ca-HCO3-Cl. Based on Na-Cl contents, the fraction of sea water into the Ciliwung River reached 2% in the Mangga Dua site during the dry season and decreased to 0.7% during the rainy season in 2015. The much higher monthly rainfall during the dry season in 2016 and 2018 had washed out invading seawater from the Mangga Dua site; its fraction of sea water was less than 0.4%. Saturation indexes with respect to calcite, dolomite, and gypsum minerals showed an increasing trend related to the decreasing elevations. All water samples were undersaturated with respect to gypsum. Meanwhile, saturation indexes with respect to calcite and dolomite mostly indicated undersaturated, except in the Mangga Dua site that was saturated (during the rainy season in 2015 and dry season in 2018) and supersaturated during the dry season in 2015.

The inhibitory effect of inorganic carbon on phosphate recovery from upflow anaerobic sludge blanket reactor (UASB) effluent as calcium phosphate

After treatment of the wastewater from the potato processing industry in an upflow anaerobic sludge blanket reactor (UASB) the effluent is rich in phosphate and dissolved inorganic carbon (IC). Increasing the pH of the UASB effluent with NaOH to precipitate phosphate as calcium phosphate leads to contamination with magnesium phosphate. Increasing the pH with Ca(OH)2 had a positive effect on phosphate precipitation, but after increasing the pH with Na2CO3 no precipitate was formed. After prior nitrification of the UASB effluent to remove IC, less NaOH was needed to increase the pH and the ions precipitated in a ratio that agreed with calcium phosphate formation. When the pH of the nitrified effluent was increased with Na2CO3 neither calcium nor phosphate precipitated. This inhibitory effect of IC on phosphate precipitation as calcium phosphate could not be derived from the saturation indexes calculated by the geochemical modelling program PHREEQC.

Chemistry of Groundwater from Two Aquifers in Liuyi Coal Mine, Northern Anhui Province, China: a Comparative Study

Major ion concentrations of twenty groundwater samples from two deep seated aquifers (coal bearing-GC and limestone-LC) are analyzed for identify the differences between them and the source of ions. The results suggest that they are moderate to highly mineralized water with their average TDS values are 2444 (GC) and 1178 (LC) mg/L. LCs show lower Na but much higher Ca and Mg concentrations relative to GCs. Saturation indexes and principle component analysis, as well as mole ratios between Na and Cl, Ca and SO4, Ca and HCO3 indicate that they have multi sources with incorporation of halite and albite for Na, calcite, dolomite and gypsum for Ca, pyrite and gypsum for SO4.

Study on Water-Rock Interaction in Sea and Freshwater Transitional Zone

Study on water-rock interaction in transitional zone through the mixing of seawater and freshwater in different proportion and water-rock Interaction simulation experiments, In the mixing process of sea and freshwater, mixing is the basis of the mechanical mixing with complex chemical process, Total Alkalinity and pH values significantly increase, while the conductivity decreases significantly, calcite and gypsum saturation index increase significantly, while PCO2 reduces. In the course of water-rock role, the saturation indexes of gypsum elevate from -1.06 ~ -0.71 to -0.86 ~ -0.50 after interactions between mixed solution of various proportion and aqueous, which indicates that gypsum dissolves. The saturation indexes of calcite reduce from 0.69 ~ 1.07 to 0~0.10, which indicates that calcite precipitates in the process of experiment, calcite approaches to equilibrium in the end.

ENTUPIMENTO DE GOTEJADORES CONVENCIONAIS POR PRECIPITADOS QUÍMICOS DE CARBONATO DE CÁLCIO E MAGNÉSIO, COM QUATRO ÍNDICES DE SATURAÇÃO DE LANGELIER

ENTUPIMENTO DE GOTEJADORES CONVENCIONAIS POR PRECIPITADOS QUÍMICOS DE CARBONATO DE CÁLCIO E MAGNÉSIO, COM QUATRO ÍNDICES DE SATURAÇÃO DE LANGELIER Ralini Ferreira de Mélo1; Rubens Duarte Coelho2; Marconi Batista Teixeira21Escola Agrotécnica Federal de Vitória de Santo Antão, Propriedade Terra Preta, Vitória de Santo Antão, PE, [email protected] de Engenharia Rural, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba, SP 1 RESUMO Com o objetivo de avaliar a influência da indução forçada de precipitados químicos à base de carbonatos de cálcio e magnésio no coeficiente de variação e uniformidade de distribuição de água, foi realizado um ensaio no Laboratório de Irrigação da ESALQ/USP, utilizando-se quatro índices de saturação de Langelier (ISL): ISL -2,268; ISL 0,469; ISL 1,156 e ISL 1,439. Em cada ensaio com um determinado ISL, foram utilizados oito tipos de gotejadores convencionais, instalados em uma bancada com11 mde comprimento. As obstruções observadas nos gotejadores, tanto parciais como totais decorrentes do tempo de funcionamento, resultaram em aumento do coeficiente de variação e redução drástica da uniformidade de distribuição de água. Para as condições de ensaio realizado, observou-se que o índice de saturação de Langelier não deve ser usado como único parâmetro para prever a obstrução dos gotejadores. UNITERMOS: irrigação localizada, cálcio e magnésio, Índice de Saturação de Langelier. MÉLO, R. F. de; COELHO, R. D.; TEIXEIRA, M. B. CLOGGING OF A COMMERCIAL DRIPPERS BY CALCIUM AND MAGNESIUM PRECIPITATES USING FOUR LANGELIER SATURARION INDEXES 2 ABSTRACT An essay was carried out in the laboratory of irrigation at ESALQ/USP to evaluate the effect of calcium and magnesium precipitates on the variation and uniformity coefficients in irrigation drippers. Four Langelier saturation indexes (LSI) (-2,268; 0,469; 1,156; 1,439) and eight commercial drippers were used. They were installed on an 11m bench testing apparatus. Both partial and total obstructions of the drippers were observed over the operating time increasing the variation coefficient and reducing the water distribution uniformity. Within the test conditions, LSI should not be used as a single parameter to estimate dripper clogging. KEY WORDS: drip irrigation, calcium and magnesium, Langelier saturation index

Surface and near-bottom water saturation with CaCO3 in the Pomeranian Bay in the vicinity of the Świna Channel mouth

Surface and near-bottom water saturation with CaCOLangmuir and Langelier calcite saturation indexes were calculated for water in the vicinity of the Świna Channel in the Pomeranian Bay. Measurements carried out in April-October of 1994 and 2004 indicated that CaCO