Sub-micrometer distribution of Fe oxides and organic matter in Podzol horizons

The spatial distribution of soil constituents at the micrometer scale is of great importance to understand processes controlling the formation of micro-aggregates and the stabilization of organic carbon. Here, the spatial distribution of organic and mineral constituents in Podzol horizons is studied by concerted measurements of (i) the content of various forms of Fe, Al, Si and C determined by selective extraction in the fine earth fraction of soil (f < 2 mm); (ii) the elemental composition of the clay fraction (f < 2 um) with lateral resolution using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and with surface selectivity using X-ray photoelectron spectroscopy (XPS); (iii) the specific surface area (SSA) of fine earth and clay fractions by krypton physisorption. The SSA of the fine earth in illuvial horizons is predominantly due to finely divided Fe oxides, including goethite, characterized by an equivalent particle size of about 10 mu m. Kaolinite platelets of about 2 gm size account for a large volume proportion in the clay fraction but have a minor contribution to SSA. Fe oxides and organic matter (OM) are intimately associated. Heterogeneity at the um scale is created by local variations in the relative amounts of kaolinite and Fe-OM associations. These two kinds of physical entities are in random mixture. Moreover, variation of C/Fe atomic ratios reveals sub-mu m scale heterogeneity. The latter is due to variation in the relative proportion of organic compounds and Fe oxides, indicating that aggregation of nanoparticles, and not only mere adsorption or pore filling, plays a role in these associations. In this regard, our results highlight that OM associated with Fe protects Fe oxides against physical displacement and that part of this associated OM is oxidizable by NaOCl treatment. These findings demonstrate that the concept of OM stabilization through association with Fe must be revisited when considering the sub-mu m scale level because fine Fe oxide particles can be easily dispersed during oxidation of associated carbon. Combination of physical fractionation and microanalysis (e.g. SEM-EDS, vibrational spectroscopy) offer promising perspectives to clarify the relationship between chemical composition and sub-inn scale architecture, and to better understand soil processes

Tracing the origin of dissolved silicon transferred from various soil-plant systems towards rivers: a review

Silicon (Si) released as H4SiO4 by weathering of Si-containing solid phases is partly recycled through vegetation before its land-to-rivers transfer. By accumulating in terrestrial plants to a similar extent as some major macronutrients (0.1–10% Si dry weight), Si becomes largely mobile in the soil-plant system. Litter-fall leads to a substantial reactive biogenic silica pool in soil, which contributes to the release of dissolved Si (DSi) in soil solution. Understanding the biogeochemical cycle of silicon in surface environments and the DSi export from soils into rivers is crucial given that the marine primary bio-productivity depends on the availability of H4SiO4 for phytoplankton that requires Si. Continental fluxes of DSi seem to be deeply influenced by climate (temperature and runoff) as well as soil-vegetation systems. Therefore, continental areas can be characterized by various abilities to transfer DSi from soil-plant systems towards rivers. Here we pay special attention to those processes taking place in soil-plant systems and controlling the Si transfer towards rivers. We aim at identifying relevant geochemical tracers of Si pathways within the soil-plant system to obtain a better understanding of the origin of DSi exported towards rivers. In this review, we compare different soil-plant systems (weathering-unlimited and weathering-limited environments) and the variations of the geochemical tracers (Ge/Si ratios and d30Si) in DSi outputs. We recommend the use of biogeochemical tracers in combination with Si mass-balances and detailed physico-chemical characterization of soil-plant systems to allow better insight in the sources and fate of Si in these biogeochemical systems

Understanding Root Uptake of Nutrients, Toxic and Polluting Elements in Hydroponic Culture

peer reviewe

Force budget: III, Application to three-dimensional flow of Byrd Glacier, Antarctica

This is the published version, also available here: http://dx.doi.org/10.3189/002214389793701554.Stresses at the surface and at depth are calculated for a stretch of Byrd Glacier, Antarctica. The calculations are based on photogrammetrically determined velocities and elevations, and on radio-echo-determined ice thicknesses. The results are maps of drags from each valley wall, of normal forces laterally and longitudinally. and of basal drag. Special challenges in the calculation are the numerical gridding of velocity, ensuring that unreasonable short-wavelength features do not develop in the calculation, and inference of ice thickness where there are no data. The results show important variations in basal drag. For the floating part, basal drag is near zero, as expected. Within the grounded part. longitudinal components of basal drag are very variable, reaching 300 kPa with a dominant wavelength of 13 km. Generally. these drag maxima correlate with maxima in driving stress. Usually the across-glacier component of basal drag is small. An important exception occurs in the center of the grounded part of the glacier where the flow shows major deviations from the axis of the valley. Other results are that side drag is roughly constant at 250 kPa along both margins of the glacier, tension from the ice shelf is about 100 kPa, and tension in the grounded part cycles between 250 and 150 kPa. Calculated deep velocities are too large and this is attributed to deficiencies in the conventional isotropic flow law used

Law Enforcement against Illegal Fishing Practices in Sea North Sulawesi Province

The authority enforcing the law against the practice of illegal fishing in the territorial waters of North Sulawesi include the authority handling of cases of violations that occurred in this region. It is based on the provisions of international law which stipulates that coastal states (Coastal states) has a number of interests protected. The Purpose of this study was to determine the enforcement of the law against the practice of illegal fishing in the waters of North Sulawesi, and to know the constraints in law enforcement against illegal fishing practices in the waters of North Sulawesi province. Methods applied research approach is carried out from two sides of the normative research (research literature and field research) to see the reality of the law. normative research is fundamental research in particular to examine aspects of territorial sovereignty and the rule of law, while field research practices in particular saw a case of illegal fishing in the territorial waters of North Sulawesi province. The results showed enforcement of the law against the practice of illegal fishing in the waters of North Sulawesi province carried out by North Sulawesi Police Water Police Directorate and implemented in accordance with the legislation in force through the process of arrest, investigation, investigation, prosecution and examination in court. In many cases the process of resolving the case of minor criminal offenses that have been completed and other cases can not be processed further because of insufficient evidence meets the elements of a crime and some cases temporarily transferred to the North Sulawesi Police for further processing. For administrative violations cruise resolved through guidance and liabilities master and crew to take care of the necessary shipping documents. Constraints in law enforcement, namely the lack of personnel Sulawesi Police Water Police Directorate in comparison with the area of ​​Territorial waters of North Sulawesi to carry out both operational tasks in the field and the lack of facilities owned fleet. Other constraints such as limited operational costs and human resources. In the process of settling disputes lawlessness in North Sulawesi many obstacles, because information about the status of the nationality of the crew requires a relatively long time from other countries of the crew came from. Keywords: Law Enforcement, illegal fishing, sea, north Sulawesi, Indonesi

Flow dynamics of Byrd Glacier, East Antarctica

This is the published version. Copyright 2014Force-balance calculations on Byrd Glacier, East Antarctica, reveal large spatial variations in the along-flow component of driving stress with corresponding sticky spots that are stationary over time. On the large scale, flow resistance is partitioned between basal (∼80%) and lateral (∼20%) drag. Ice flow is due mostly to basal sliding and concentrated vertical shear in the basal ice layers, indicating the bed is at or close to the pressure-melting temperature. There is a significant component of driving stress in the across-flow direction resulting in nonzero basal drag in that direction. This is an unrealistic result and we propose that there are spatial variations of bed features resulting in small-scale flow disturbances. The grounding line of Byrd Glacier is located in a region where the bed slopes upward. Nevertheless, despite a 10% increase in ice discharge between December 2005 and February 2007, following drainage of two subglacial lakes in the catchment area, the position of the grounding line has not retreated significantly and the glacier has decelerated since then. During the speed-up event, partitioning of flow resistance did not change, suggesting the increase in velocity was caused by a temporary decrease in basal effective pressure

Optimal stride frequencies in running at different speeds

During running at a constant speed, the optimal stride frequency (SF) can be derived from the u-shaped relationship between SF and heart rate (HR). Changing SF towards the optimum of this relationship is beneficial for energy expenditure and may positively change biomechanics of running. In the current study, the effects of speed on the optimal SF and the nature of the u-shaped relation were empirically tested using Generalized Estimating Equations. To this end, HR was recorded from twelve healthy (4 males, 8 females) inexperienced runners, who completed runs at three speeds. The three speeds were 90%, 100% and 110% of self-selected speed. A self-selected SF (SFself) was determined for each of the speeds prior to the speed series. The speed series started with a free-chosen SF condition, followed by five imposed SF conditions (SFself, 70, 80, 90, 100 strides·min-1) assigned in random order. The conditions lasted 3 minutes with 2.5 minutes of walking in between. SFself increased significantly (p<0.05) with speed with averages of 77, 79, 80 strides·min-1 at 2.4, 2.6, 2.9 m·s-1, respectively). As expected, the relation between SF and HR could be described by a parabolic curve for all speeds. Speed did not significantly affect the curvature, nor did it affect optimal SF. We conclude that over the speed range tested, inexperienced runners may not need to adapt their SF to running speed. However, since SFself were lower than the SFopt of 83 strides·min-1, the runners could reduce HR by increasing their SFself

The results of using a tendon autograft as a new rotator cable for patients with a massive rotator cuff tear:a technical note and comparative outcome analysis

Background: Several surgical reconstructive options are available to treat massive rotator cuff tears (MRCTs). The rotator cable has an important function and we evaluated the clinical result after arthroscopic reconstruction of the rotator cable with an autograft tendon. Methods: A prospective pilot study was performed with inclusion of four patients, average age of 64 years, with an irreparable MRCT. The patients underwent an arthroscopic reconstruction of the rotator cable with the use of the long head of biceps tendon autograft, except for one which was reconstructed with a hamstring tendon. Pre- and postsurgically, the Constant-Murley Score (CMS), Western Ontario Rotator Cuff Index (WORC), Simple Shoulder Test (SST), visual analog scale (VAS) scores, and an MRI was performed. Clinical results of the study group were compared with clinical results of comparable cohort of patients with a MRCT, treated non-operatively with physiotherapy. Results: The CMS score increased after surgery in three of the four patients. The improvement of CMS score was comparable to the improvement of the CMS score encountered in a comparable cohort. The MRI at 12 months follow-up showed that the reconstructed rotator cable was disintegrated in all patients and the rotator cuff was detached and retracted. Conclusions: In our pilot study, arthroscopic reconstruction of the rotator cable using a tendon autograft failed over time and showed no clinical benefit in comparison to the non-operative treatment with physiotherapy. Trial registration: The regional Medical Ethical Committee (Zwolle) gave approval at 14th of October 2016 and assigned no. 16.06100

Measurements of the SPS transverse impedance in 2000

We report on measurements of coherent tune shifts, head-tail growth rates, and current-dependent betatron phase advances at the CERN SPS in the year 2000. Comparing results obtained at two different energies shows that there is no notable contribution from space charge. Within the measurement resolution the impedance is the same as in 1999, consistent with the expected small effect from changes to ony a small number of pumping ports. In 2000, data were taken over an expanded range of chromaticities, which increases the sensitivity to the impedance frequency distribution. Measuremeents of the current-dependent phase advance around the ring help localizing the most important impedance sources