The low-temperature geochemical cycle of iron: From continental fluxes to marine sediment deposition

Suspended sediments from 34 major rivers (geographically widespread)and 36 glacial meltwater streams have been examined for their variations in different operationally-defined iron fractions; FeHR (iron oxides soluble in dithionite), FePR (iron soluble in boiling HCl but not in dithionite) and FeU (total iron less that soluble in boiling HCl). River particulates show a close association between FeHR and total iron (FeT), reflecting the effects of chemical weathering which derive oxide iron from, and retain it in close association with, total iron. Consistent with this, continentalscale average FeHR/FeT ratios vary with runoff ratios (average river runoff per unit area/average precipitation per unit area). By contrast, the diminished effects of chemical weathering produce no recognizable association of FeHR with FeT in glacial particulates, and instead both FePR and FeU are closely correlated with FeT, reflecting essentially pristine mineralogy. A comparison of the globally-averaged compositions of riverine particulates and marine sediments reveals that the latter are depleted in FeHR, FePR and FeT but enriched in FeU. The river and glacial particulate data are combined with estimates of authigenic, hydrothermal, atmospheric and coastal erosive iron fluxes from the literature to produce a global budget for FeHR, FePR, FeU and FeT. This budget suggests that the differences between riverine particulates and marine sediments can be explained by; (i) preferentially removing FeHR from the riverine particulate flux by deposition into inner shore reservoirs such as floodplains, salt marshes and estuaries; and (ii) mixing the resulting riverine particulates with FeHRdepleted glacial particulates. Preliminary measurements of inner shore sediments are consistent with (i) above. Phanerozoic and modern normal marine sediments have similar iron speciation characteristics, which implies the existence of a long-term steady state for the iron cycle. This steady state could be maintained by a glacioeustatic feedback, where FeHR-enriched riverine particulates are either more effectively trapped when sealevel is high (small ice masses, diminished glacial erosion), or are mixed with greater masses of FeHR-depleted glacial particulates when sealevel is low (large ice masses, enhanced glacial erosion). Further important controls on the steady state for FeHR operate through the formation of euxinic sediments and ironstones, which also provide sealevel-dependent sinks for FeHR-enriched sediment

An interregional analysis of natural vegetation analogues using ERTS-1 imagery

The identification of ecological analogs of natural vegetation and food crops using ERTS-1 imagery is discussed. Signatures of four natural vegetation analogs have been determined from color photography. Color additive techniques to improve the photointerpretation are examined. Tests were conducted at test sites in Louisiana, California, and Colorado

Plan for the uniform mapping of earth resources and environmental complexes from Skylab imagery. Assessment of natural vegetation, environmental, and crop analogs

The author has identified the following significant results. For interpreting a wide range of natural vegetation analogs, S-190A color infrared and the ERTS-1 color composite were consistently more useful than were conventional color or black and white photos. Color infrared was superior for five vegetation analogs while color was superior for only three. The errors in identification appeared to associate more with black and white single band images than with multiband color. For rice crop analogs, spectral and spatial discriminations both contribute to the usefulness of images for data collection. Tests and subjective analyses conducted in this study indicated that the spectral bands exploited in color infrared film were the most useful for agricultural crop analysis. Accuracy of crop identification on any single date of Skylab images was less than that of multidate analysis due to differences in crop calendar, cultural practices used, rice variety, planting date, planting method, water use, fertilization, disease, or mechanical problems

FES rehabilitation platform with real-time control and performance feedback.

Osteoporosis after spinal cord injury is associated with low-trauma fractures, and consequently with increased risk of morbidity and mortality. The loss of bone mass density (BMD) due to paraplegia can be reduced through cyclical electrically-induced muscle contractions. Here we propose an FES control system based on posture switching, that induces transient loading of the lower limbs during a set of standing postures. This aims to produce an increased, evenly distributed BMD, whilst minimising FES-induced muscle fatigue. Here we describe the design and assessment of the FES exercising platform, comprising a controllable multi-channel electrical stimulator and an instrumented standing frame. The platform supports standing and postural shifting, provides real-time human-in-the-loop FES control with on-line feedback to the user. The platforms is used to investigate the effect of regular exercise on the distribution of BMD in people with paraplegia

Response of three cereal crops in continuous arable or ley-arable rotations to fertiliser nitrogen and soil nitrogen at Rothamsted's Woburn Ley-arable experiment

The concept of improving soil fertility by ley-arable farming, developed in the 1930s in England, was practised on many “mixed” farms that had both arable crops and permanent grass. The practice declined from the 1960s as farms became predominantly arable or grassland. However, there is increasing interest in including leys in arable farming to fix carbon from carbon dioxide in the atmosphere in soil organic matter (SOM). For example, in the United Kingdom a project “Grass and herbal leys in farm network” was launched in 2018 (adas.uk, 2020) and in the European Union (EU) farmers are now required to grow a wider range of crops (ec. europa.eu, 2020. The Woburn Ley-arable experiment started in 1938 has compared six rotations, two with 3-yr leys, two with 8-yr leys and two with continuous arable crops on the yields of two cereal test crops. The effect of these rotations on SOM is given elsewhere (Johnston et al., 2017). Here we give the yields of both test crops in each of the six rotations for 21 years starting in 1981. We discuss the response to four levels of applied fertiliser nitrogen (N), the effect of rotation, the level of SOM and the availability of soil N. Where no fertiliser N was added, crop yields increased as % N in soil increased, but, with sufficient fertiliser N there was little benefit from the extra N in the soil. Yields of winter wheat were larger after the 3-year grass ley than in the all-arable rotations and larger again following the grass/clover ley. Less fertiliser N was needed to achieve the yields after the leys than in the all-arable rotations. Yields of the second cereal crop following 3- or 8-yr leys were also larger than those in all-arable rotations but there was no difference between the leys. However, the extra N available from the leys and the increases in yield were modest. If leys are to be introduced into mainly arable farming systems, they may need to be subsidised to make them financially viable

Natural resources inventory and monitoring in Oregon with ERTS imagery

Multidiscipline team interpretation of ERTS satellite and highflight imagery is providing resource and land use information needed for land use planning in Oregon. A coordinated inventory of geology, soil-landscapes, forest and range vegetation, and land use for Crook County, illustrates the value of this approach for broad area and state planning. Other applications include mapping fault zones, inventory of forest clearcut areas, location of forest insect damage, and monitoring irrigation development. Computer classification is being developed for use in conjunction with visual interpretation