Methane concentration and isotopic composition (d13C-CH4) in the Nerja Cave system (South Spain)

Air in underground caves often has methane (CH4) concentrations below the atmospheric level, due to methanotrophic or other unkown CH4 consuming processes. Caves are thus considered a potential sink for atmospheric methane. If globally important, this underground CH4 oxidation should be taken into account in the atmospheric methane budget, in addition to the known soil methanotrophy and tropospheric/stratospheric sinks. A large set of data is however necessary to understand how and how much methane from external atmospheric air is consumed in the caves. While methane concentration data are available for several caves worldwide, its isotopic composition and variations in space and time are poorly documented. We measured methane concentration and stable C isotope composition (d13C) in the Nerja cave (Southern Spain) air during two surveys in March and April 2015. CH4 concentration decreases progressively from the more external cave rooms, with atmospheric levels of 1.9 ppmv, to the more internal and isolated rooms down to 0.5 ppmv. d13C increases correspondingly from -47 h to -41 h (VPDB). CH4 is systematically 13C-enriched (d13C > -45 permil) in areas of the cave where the concentration is below 1.4 ppmv. This combination of concentration decrease and 13C-enrichment towards the more internal and isolated zones of the cave confirms the importance of CH4 oxidation, likely driven by methanotrophic bacteria. Further data, including stable H isotope composition of subatmospheric CH4 concentrations, CO2 and microbial analyses, shall be acquired over time to assess the actual role of methanotrophic bacteria and seasonal controls in the CH4 consumption process.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Coronavirus pandemic: An opportunity to study the anthropogenic impact on micro-climate conditions and CaCO3 crystal morphology in the Nerja Cave (SE Spain)

Funding charge open access: University of Malaga / CBUA. It is financed by the Nerja Cave Foundation, co-ordinated by its Research Institute and authorized by the Consejería de Cultura (Junta de Andalucía). This study is also a contribution to the Research Groups RNM-308 and RNM-126 of the Junta de Andalucía and to the Projects PID2021-125619OB-C21, PID2021-125619OB-C22, TED2021-130549B-I00 funded by MCIN/AEI/10.13039/501100011033.Following the declaration of the COVID-19 pandemic, the Spanish Government restricted non-essential movements of all citizens and closed all public spaces, such as the Nerja Cave, until May 31, 2020. This particular condition of the closure of the cave provided a unique opportunity to study the micro-climate conditions and carbonate precipitation in this tourist cave without the presence of visitors. Our results show the significant effect of visitors on the air isotopic signature of the cave and on the genesis of the extensive dissolution features affecting the carbonate crystals formed in the tourist sector of the cave, alerting us to the possible corrosion of the speleothems located there. The movement of visitors within the cave also favours the mobilisation of aerial fungi and bacterial spores and their subsequent sedimentation simultaneously with the abiotic precipitation of carbonates from the drip water. The traces of these biotic elements could be the origin of the micro-perforations previously described in the carbonate crystals formed in the tourist galleries of the cave, but they are subsequently enlarged due to abiotic dissolution of the carbonates through these weaker zones.University of MalagaNerja Cave FoundationJunta de Andalucia RNM-308, RNM-126PID2021-125619OB-C21, PID2021-125619OB-C22, TED2021-130549B-I00, MCIN/AEI/10.13039/50110001103

Control of Environmental Parameters for Management and Conservation of Nerja Cave (Malaga, Spain)

V povprečju obišče jamo Nerja ve~ kot 500.000 ljudi letno. Od leta 1993 je v jami instalirana mreža monitoringa, ki vsako uro meri številne parametre, da bi ugotovili vplive obiskovalcev na podzemno okolje. Od 1991 izvršujejo hidrokemične meritve vode v curkih v jami in pri naravnih iztokih iz karbonatnega vodonosnika. Zvezna merjenja fizikalno kemijskih parametrov prenikajoče vode, dnevni odtok, kakor tudi temperatura in relativna vlažnost zraka, koncentracija CO2 in temperatura skale kažejo človekov vpliv. Glavne spremembe okoljskih parametrov so naslednje: 1. zračna temperatura zraste za 0,2 °C na vsakih 1000 obiskovalcev na dan; 2. relativni porast relativne zračne vlage med 2 in 3 %, ki v poletnih dneh doseže nasičenost; 3. koncentracija CO2 v zraku narase do vrednosti med 500 in 700 ppm v obdobju manjšega obiska in za desetkratno izhodiščno vrednost ob času velikega obiska (2.800 ppm); 4. temperatura skale narase med 0,02 °C do 0,15 °C na dan in 5. PCO2 prenikajo~e vode izkazuje spremembe, naraščajoče med velikim obiskom in padajoči indeks nasičenosti karbonatnih mineralov. The Nerja Cave receives on average more than 500,000 visitors per year. In order to know the possible impact in the underground environment by human visits, a monitoring network was installed since 1993, to control hourly several parameters. Also, since 1991 a hydrochemical control has been carried out in the drip water points of the cave and in the natural discharge points of the carbonate aquifer. This continuous record of physical-chemical parameters of drip water, its daily outflow, as well as temperature and relative humidity in the air, CO2 concentration and rock temperature shows the human influence. The main changes in environmental parameters are the following: 1. cave air temperature rises 0.2 °C by 1000 visitors/day; 2. a daily increase between 2 and 3 % in relative air humidity, reaching saturation on summer days; 3. CO2 concentration in air increases up to values between 500 and 700 ppm during low visitability periods and 10 times the background value during high visitability periods (2.800 ppm); 4. temperature of the rock rises between 0.02 °C and 0.15 °C/day, and (5) PCO2 of drip water also presents variations, increasing during the big influx of visits and decreasing the saturation index of carbonated minerals

Vadose zone air as a biogenic source of methane in Nerja Cave system (South of Spain)

Subterranean air in karst cavities has often low methane contents in comparison to atmosphere and so karst systems have been considered a sink of atmospheric methane. Methane-oxidizing bacteria have been hypothesized as responsible for CH4 depletion in many caves around the world, although ionization radiation was also proposed as possible mechanism for this process. We measured CO2 and CH4 concentration and their C isotopic composition (d13C-CO2 and d13C-CH4) over 2 years within the Nerja cave system (South Spain) and in 9 boreholes drilled into the vadose zone (Triassic carbonate aquifer) surrounding the cave. According to d13C-CO2 and d13C-CH4 vadose zone of this karst system is a source of biogenic methane, produced both by acetate fermentation and CO2 reduction. Biogenic and atmospheric methane flows (along fractures from the vadose zone, and through ventilation, respectively) into the cave, where it is oxidized by methanotrophic bacteria that we detected on soil samples into the cave.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Формализованное описание цифрового устройства и его модель

Дано формализованное описание цифрового устройства в виде асинхронной модели, на основании которой разработан алгоритм моделирования произвольной логической сети. Алгоритм представлен на языке ЛЯПАС-71. Разработаны и отлажены на ЭВМ «М-220» соответствующие программы анализа цифровых устройств различной сложности

New hydrochemical and isotopic data in the karstic spring of Maro (Nerja, Málaga). Considerations on the origin of solutes and on the influence of the vadose zone ventilation

The previously stated model concerning the behaviour of the karstic spring of Maro is corroborated with new data from the 2004-2014 period. Sulphate isotopes allow linking the origin of solutes with the dissolution of Mesozoic gypsum. Other hydrochemical data (pH, DO) suggest the association of the spring with relatively large and well-ventilated karstic conduits in the vadose zone of the carbonate aquifer drained by the spring. During the winter season, such conduits could be affected by pressure or temperaturedriven high-PCO2 airflows that may be responsible for local decreases in the pH of the spring waterEl modelo de funcionamiento del manantial kárstico de Maro propuesto en estudios previos se corrobora con nuevos datos del periodo 2004-2014. Los isótopos del sulfato precisan el origen de solutos por disolución de yesos mesozoicos. Otros datos hidroquímicos (pH, OD) sugieren la asociación del manantial con conductos kársticos relativamente grandes y bien ventilados dentro de la zona vadosa del acuífero carbonático triásico al que drena. En el periodo invernal, por diferencias de presión o temperatura entre el interior y el exterior de estos conductos, se pueden producir flujos de aire con PCO2 relativamente elevada hacia los mismos, con el resultado de inducir disminuciones locales del pH del agua del manantia

Pessoas e classe: a identidade operária na propaganda do Partido Comunista do Equador (1975-1990)

Para el marxismo, la cuestión del sujeto es fundamental. Quién debía hacer la revolución y, sobre todo, por qué, produjo una intensa literatura que fue interrumpida cuando ciertas lecturas de la obra de Vladímir Lenin se convirtieron en discurso oficial del comunismo internacional: la clase trabajadora, como elemento objetivo dentro de las relaciones de producción, debía liderar la revolución hacia el socialismo en alianza con otras clases. Para el caso ecuatoriano, la organización llamada a defender esta tesis fue el Partido Comunista del Ecuador (PCE), enmarcado dentro de la órbita soviética. Sin embargo, el estudio de su propaganda nos ofrece una disputa discursiva al interior mismo del Partido entre la visión clasista tradicional y una populista de latinoamericano. Un concepto, el pueblo, que amplía los márgenes de la ortodoxia, pero cuyo uso extendido revela una posición ambigua sobre la posición del PCE respecto al sujeto revolucionario.For Marxism, the question of the subject is fundamental. Who should make the revolution and, above all, why, produced an intense literature that was interrupted when certain readings of Vladimir Lenin's work became the official discourse of international communism: the working class, as an objective element in the relations of production, had to lead the revolution towards socialism in alliance with other classes. In the Ecuadorian case, the organization called to defend this thesis was the Communist Party of Ecuador (PCE), framed within the Soviet orbit. However, the study of its propaganda offers us a discursive dispute within the Party itself between the traditional classist vision and a populist one of Latin America. A concept, the people, which widens the margins of orthodoxy, but whose widespread use reveals an ambiguous position on the position of the PCE with respect to the revolutionary subject.Para o marxismo, a questão do sujeito é fundamental. Quem deve fazer a revolução e, acima de tudo, por que, produziu uma literatura intensa que foi interrompida quando certas leituras da obra de Vladimir Lenin se tornaram o discurso oficial do comunismo internacional: a classe trabalhadora, como elemento objetivo nas relações de produção, teve que liderar a revolução para o socialismo em aliança com outras classes. No caso equatoriano, a entidade convocada para defender essa tese foi o Partido Comunista do Equador (PCE), enquadrado na órbita soviética. Porém, o estudo de sua propaganda nos oferece uma disputa discursiva dentro do próprio Partido entre a visão classista tradicional e uma visão populista da América Latina. Um conceito, o povo, que amplia as margens da ortodoxia, mas cujo uso difundido revela uma posição ambígua sobre a posição do PCE em relação ao sujeito revolucionário

Hydrogeological characteristics of the Prieta-Bonela-Alcaparaín aquifer system (Yunquera-Nieves Hydrogeological Unit, Andalusia, province of Málaga)

The analysis of the natural answers of the principal springs (Río Jorox, Fuente Quebrada and Carratraca) of the Prieta-Bonela-Alcaparaín aquifer system has allowed to determine the hydrogeological characteristics and the different degree of karstification existing in the same one. In the sector of aquifer that is drained by the Río Jorox spring (Sierra Prieta) exists a developed karstic net, across which there is produced a rapid flow of the rainwater. In the sector of aquifer that is drained by the Fuente Quebrada spring (Sierra Bonela), the degree of karstification is less developed. The sector drained by the Carratraca spring (Sierra Alcaparaín) presents a behaviour pattern that is typical of a diffuse flow aquife