Decoupling of dissolved organic matter patterns between stream and riparian groundwater in a headwater forested catchment Hydrology and Earth System Sciences DOI 10.5194/hess-22-1897-2018 19 March 2018 Streams are important sources of carbon to the atmosphere, though knowing whether they merely outgas terrestrially derived carbon dioxide or mineralize terrestrial inputs of dissolved organic matter (DOM) is still a big challenge in ecology. Our study highlights that stream DOM is not merely a reflection of riparian groundwater entering the stream and that headwater streams have the capacity to internally produce, transform, and consume DOM. Read more
Ideas and perspectives: hydrothermally driven redistribution and sequestration of early Archaean biomass – the “hydrothermal pump hypothesis” Biogeosciences DOI 10.5194/bg-15-1535-2018 15 March 2018 The origin of organic matter in the oldest rocks on Earth is commonly ambiguous (biotic vs. abiotic). This problem culminates in the case of hydrothermal chert veins that contain abundant organic matter. Here we demonstrate a microbial origin of kerogen embedded in a 3.5 Gyr old hydrothermal chert vein. We explain this finding with the large-scale redistribution of biomass by hydrothermal fluids, emphasizing the interplay between biological and abiological processes on the early Earth. Read more
A systemic approach for modeling soil functions SOIL DOI 10.5194/soil-4-83-2018 15 March 2018 This paper deals with the importance of soil for our terrestrial environment and the need to predict the impact of soil management on the multitude of functions that soil provides. We suggest to consider soil as a self-organized complex system and provide a concept of how this could be achieved. This includes how soil research, currently fragmented into a number of more or less disjunct disciplines, may be integrated to substantially contribute to a science-based evaluation of soil functions. Read more
Thermodynamics of saline and fresh water mixing in estuaries Earth System Dynamics DOI 10.5194/esd-9-241-2018 13 March 2018 This paper presents a new equation for the dispersion of salinity in alluvial estuaries based on the maximum power concept. The new equation is physically based and replaces previous empirical equations. It is very useful for application in practice because in contrast to previous methods it no longer requires a calibration parameter, turning the method into a predictive method. The paper presents successful applications in more than 23 estuaries in different parts of the world. Read more
Evaluation of stratospheric age of air from CF4, C2F6, C3F8, CHF3, HFC-125, HFC-227ea and SF6; implications for the calculations of halocarbon lifetimes, fractional release factors and ozone depletion potentials Atmospheric Chemistry and Physics DOI 10.5194/acp-18-3369-2018 8 March 2018 Chemical species measured in stratospheric air can be used as proxies for stratospheric circulation changes which cannot be measured directly. A range of tracers is important to understand changing stratospheric dynamics. We demonstrate the suitability of PFCs and HFCs as tracers and support recent work that reduces the current stratospheric lifetime of SF6. Updates to policy-relevant parameters (e.g. stratospheric lifetime) linked to this change are provided for O3-depleting substances. HFC-125, HFC-227ea and SF6; implications for the calculations of halocarbon lifetimes, fractional release factors and ozone depletion potentials">Read more
From engineering hydrology to Earth system science: milestones in the transformation of hydrologic science Hydrology and Earth System Sciences DOI 10.5194/hess-22-1665-2018 7 March 2018 The paper presents major milestones in the transformation of hydrologic science over the last 50 years from engineering hydrology to Earth system science. This transformation has involved a transition from a focus on time (empirical) to space (Newtonian mechanics), and to time (Darwinian co-evolution). Hydrology is now well positioned to again return to a focus on space or space–time and a move towards regional process hydrology. Read more
Atmospheric QBO and ENSO indices with high vertical resolution from GNSS radio occultation temperature measurements Atmospheric Measurement Techniques DOI 10.5194/amt-11-1333-2018 6 March 2018 Tropical atmospheric variability is often described using proxy indices of the Quasi-Biennial Oscillation and the El Niño–Southern Oscillation. We introduce new proxies derived from GNSS radio occultation (RO) satellite measurements. Using the high vertical resolution of the RO temperature fields we obtain altitude-resolved indices which can improve the description of atmospheric variability patterns and can be used in climate studies where a detailed knowledge of these patterns is required. QBO and ENSO indices with high vertical resolution from GNSS radio occultation temperature measurements">Read more
Results from the Fourth WMO Filter Radiometer Comparison for aerosol optical depth measurements Atmospheric Chemistry and Physics DOI 10.5194/acp-18-3185-2018 6 March 2018 Aerosol optical depth measured from ground-based sun photometers is the most important parameter for studying the changes in the Earth’s radiation balance due to aerosols. Representatives for various sun photometer types belonging to individual institutions or international aerosol networks gather every 5 years, for 3 weeks, in Davos, Switzerland, in order to compare their aeorosol optical depth retrievals. This work presents the results of the latest (fourth) filter radiometer intercomparison. WMO Filter Radiometer Comparison for aerosol optical depth measurements">Read more
U–Th and 10Be constraints on sediment recycling in proglacial settings, Lago Buenos Aires, Patagonia Earth Surface Dynamics DOI 10.5194/esurf-6-121-2018 5 March 2018 Sediments produced by glaciers are transported by rivers and wind toward the ocean. During their journey, these sediments are weathered, and we know that this has an impact on climate. One key factor is time, but the duration of this journey is largely unknown. We were able to measure the average time that sediment spends only in the glacial area. This time is 100–200 kyr, which is long and allows a lot of processes to act on sediments during their journey. Read more
Using hydraulic head, chloride and electrical conductivity data to distinguish between mountain-front and mountain-block recharge to basin aquifers Hydrology and Earth System Sciences DOI 10.5194/hess-22-1629-2018 2 March 2018 This article tackles the problem of finding the origin of groundwater in basin aquifers adjacent to mountains. In particular, we aim to determine whether the recharge occurs predominantly through stream infiltration along the mountain front or through subsurface flow from the mountain. To this end, we discuss the use of routinely measured variables: hydraulic head, chloride and electrical conductivity. A case study from Australia demonstrates the approach. Read more
