Influence of the Active Layer Thickness of Permafrost in Eastern Siberia on the River Discharge of Nutrients into the Arctic Ocean

Large rivers are important links between continents and oceans for material flows that have a global impact on marine biogeochemistry. Processes in the catchment areas of large rivers can affect the flow of solutes into the global ocean. The goal was to determine how the concentration of individual components of nutrients in the rivers of Eastern Siberia changes depending on the active layer thickness of the permafrost (ALT) and to elucidate whether the ALT is a factor that can control nutrient flux to the Arctic Ocean. The method of canonical correlation analysis was applied to the data on the concentration of nutrients in the 12 largest rivers of Eastern Siberia and the active layer thickness in their catchments. We found that the concentration of nutrients such as ammonium ion (NH4) and total phosphorus (Ptotal) in river waters is higher in catchments with a deeper active layer. The waters of the mountain rivers in the south of the region (the Chara and Vitim rivers) are the richest in nutrients. Arctic rivers such as the Indigirka and Anabar were low in nutrients. The permeability of soils also affects the discharge of nutrients into rivers with surface runoff. We conclude that in the future, in the context of global climatic changes and the projected deepening of the active layer throughout the permafrost zone of the Northern Hemisphere, an increase in the supply of nutrients to the Arctic Ocean is possible.

DETERMINATION OF CHEMICAL AND TOXICOLOGICAL CHARACTERISTICS OF WATER QUALITY IN RECREATIONAL AREAS ON THE MATYRA RIVER

В работе приведены и проанализированы данные химических и токсикологических исследований воды р. Матыра Липецкой области. Отмечены превышения допустимых значений по органолептическим показателям, а также по сульфатам, аммоний-иону и нитритам. Кроме того, было проведено определение относительной токсичности с помощью метода, основанного на регистрации изменений оптической плотности культуры водоросли хлорелла ( Chlorella vulgaris ). В результате биотестирования показано, что все пробы воды проявили токсичность, которая проявляется в стимуляции роста культуры хлорелла. Такая стимуляция роста свидетельствует о том, что исследованные пробы содержат легкоусвояемые органические и неорганические соединения. При сравнении полученных значений концентраций с предыдущими исследованиями отмечена отрицательная динамика по всем определяемым загрязняющим веществам, что свидетельствует о снижении качества воды. The paper presents and analyzes the data of chemical and toxicological studies of the water of the Matyra river of the Lipetsk region. Excess of permissible values for organoleptic parameters, as well as for sulfates, ammonium ion and nitrites were noted. In addition, the relative toxicity was determined using a method based on the registration of changes in the optical density of the Chlorella (Chlorella vulgaris) algae culture. The results of the bioassay showed that all water samples demonstrated toxicity, which manifests itself in stimulating the growth of chlorella culture. Such growth stimulation indicates that the samples studied contain easily digestible organic and inorganic compounds. When comparing the obtained concentration values with previous studies, negative dynamics was noted for all identified pollutants, which indicates a decrease in water quality.

An ultrafast-response and flexible humidity sensor for human respiration monitoring and noncontact safety warning

The humidity sensor is an essential sensing node in medical diagnosis and industrial processing control. To date, most of the reported relative humidity sensors have a long response time of several seconds or even hundreds of seconds, which would limit their real application for certain critical areas with fast-varying signals. In this paper, we propose a flexible and low-cost humidity sensor using vertically aligned carbon nanotubes (VACNTs) as electrodes, a PDMS-Parylene C double layer as the flexible substrate, and graphene oxide as the sensing material. The humidity sensor has an ultrafast response of ~20 ms, which is more than two orders faster than most of the previously reported flexible humidity sensors. Moreover, the sensor has a high sensitivity (16.7 pF/% RH), low hysteresis (<0.44%), high repeatability (2.7%), good long-term stability, and outstanding flexibility. Benefiting from these advantages, especially the fast response, the device has been demonstrated in precise human respiration monitoring (fast breathing, normal breathing, deep breathing, asthma, choking, and apnea), noncontact electrical safety warning for bare hand and wet gloves, and noncontact pipe leakage detection. In addition, the facile fabrication of the flexible platform with the PDMS-Parylene C double layer can be easily integrated with multisensing functions such as pH sensing, ammonium ion sensing, and temperature sensing, all of which are useful for more pattern recognition of human activity.