Transport processes at quartz–water interfaces: constraints from hydrothermal grooving experiments

We performed hydrothermal annealing experiments on quartzite samples at temperatures of 392 to 568 °C and fluid pressures of 63 to 399 MPa for up to 120 h, during which hydrothermal grooves developed on the free surfaces of the samples. An analysis of surface topology and groove characteristics with an atomic force microscope revealed a range of surface features associated with the simultaneous and successive operation of several processes partly depending on crystal orientation during the various stages of an experiment. Initially, dissolution at the quartzite-sample surface occurs to saturate the fluid in the capsule with SiO2. Subsequently, grooving controlled by diffusion processes takes place parallel to dissolution and precipitation due to local differences in solubility. Finally, quench products develop on grain surfaces during the termination of experiments. The average groove-root angle amounts to about 160°, varying systematically with misorientation between neighboring grains and depending slightly on temperature and run duration. The grooving is thermally activated, i.e., groove depth ranging from 5 nm to several micrometers for the entire suite of experiments generally increases with temperature and/or run time. We use Mullins' classical theories to constrain kinetic parameters for the transport processes controlling the grooving. In the light of previous measurements of various diffusion coefficients in the system SiO2–H2O, interface diffusion of Si is identified as the most plausible rate-controlling process. Grooving could potentially proceed faster by diffusion through the liquid if the fluid were not convecting in the capsule. Characteristic times of healing of microfractures in hydrous environments constrained from these kinetic parameters are consistent with the order of magnitude of timescales over which postseismic healing occurs in situ according to geophysical surveys and recurrence intervals of earthquakes

Актуальные вопросы внедрения системы природно-экономического учета

The article outlines the international standard, System of Environmental-Economic Accounting (SEEA) – Central Framework, adopted by the UN in 2015 as the basis for developing 23 indicators of the Sustainable Development Goals. Statistical data from SEEA accounts provide the comprehensive assessment of environment, help identify trends and consequences of human impact on nature, serve as a tool for the formation and implementation of environmental policy in general, and help in monitoring the implementation of international obligations and recommendations including sustainable development areas.A separate section of the article covers specific features of SEEA implementation in selected countries of the world. There is an elaborate reflection of the work on the introduction of this standard to the Russian Federation, carried out by the Federal State Statistics Service. The authors believe that the need for a certain sequence of actions associated with the development and implementation of SEEA accounts gives impetus (in the short term) for the application of priority accounts, guided by the roadmap for the SEEA priority accounts implementation, approved by the order of the Government of the Russian Federation. The information base built using these accounts is necessary for conducting international comparisons, calculations of SDG indicators and green economy indicators.В статье дается общая характеристика международного стандарта «Центральная основа Системы природно-экономического учета» (Центральная основа СПЭУ), признанного ООН в 2015 г. в качестве основы для формирования 23 индикаторов Целей в области устойчивого развития государства. Статистические данные, получаемые из СПЭУ, позволяют проводить комплексную оценку состояния окружающей среды, способствуют выявлению тенденций и последствий влияния человека на природу, служат инструментом формирования и реализации природоохранной политики в целом, а также позволяют отслеживать выполнение принятых международных обязательств и рекомендаций, в том числе в области устойчивого развития.В качестве самостоятельного раздела публикации дается изложение особенностей внедрения СПЭУ в отдельных странах мира. Более развернуто отражена работа по освоению указанного стандарта в Российской Федерации, проводимая Федеральной службой государственной статистики. Авторы считают, что с учетом определенной последовательности разработки и внедрения счетов СПЭУ, в первоочередном порядке (в краткосрочной перспективе) следует сосредоточиться на приоритетных счетах, руководствуясь «дорожной картой» внедрения приоритетных счетов СПЭУ, утвержденной распоряжением Правительства Российской Федерации. Информационная база, построенная с помощью рассматриваемых счетов, необходима для международных сопоставлений, расчетов индикаторов ЦУР и показателей «зеленой» экономики