Accurate Chart Latticing for Loran-C

Unless the Loran-C lattice has much the same accuracy as any other feature shown, the chart is out of balance. There is not much point in charting hazards with great precision if the mariner must allow a large margin for positioning error in his navaid. The Canadian Hydrographic Service’s calibration program aims eventually to improve our knowledge of radio wave propagation so that we can rely on a calculated lattice with only a very few check points to verify the predictions. While we work towards this, we also map the lattice in the field so that we can put it on the chart accurately now. We calibrated the Canadian West Coast Loran-C chain in the Spring of 1977, using Satnav offshore to give the ± 150 m accuracy needed for latticing small scale charts. We looked for and found the predicted coastal " phase recovery " using Trisponder and sextant fixing. And we made observations on shore by helicopter and calibration van to give propagation data for future predictions

Enhanced phosphorus locking by novel lanthanum/aluminum–hydroxide composite: implications for eutrophication control

Lanthanum (La) bearing materials have been widely used to remove phosphorus (P) in water treatment. However, it remains a challenge to enhance phosphate (PO4) adsorption capacity and La usage efficiency. In this study, La was co-precipitated with aluminum (Al) to obtain a La/Al-hydroxide composite (LAH) for P adsorption. The maximum PO4 adsorption capacities of LAH (5.3% La) were 76.3 and 45.3 mg P g-1 at pH 4.0 and 8.5, which were 8.5 and 5.3 times higher than those of commercially available La-modified bentonite (Phoslock®, 5.6% La), respectively. P K-edge X-ray absorption near edge structure analysis showed that PO4 was preferentially bonded with Al under weakly acid conditions (pH 4.0), while tended to associate with La under alkaline conditions (pH 8.5). La LIII-edge extended X-ray absorption fine structure analysis indicated that PO4 was bonded on La sites by forming inner sphere bidentate-binuclear complexes and oxygen defects exhibited on LAH surfaces, which could be active adsorption sites for PO4. The electrostatic interaction, ligand exchange and oxygen defects on LAH surfaces jointly facilitated PO4 adsorption but with varied contribution under different pH conditions. The combined contribution of two-component of La and Al may be an important direction for the next generation of commercial products for eutrophication mitigation

Understanding the mobilisation of metal pollution associated with historical mining in a carboniferous upland catchment

Point and diffuse pollution from metal mining has led to severe environmental damage worldwide. Mine drainage is a significant problem for riverine ecosystems, it is commonly acidic (AMD), but neutral mine drainage (NMD) can also occur. A representative environment for studying metal pollution from NMD is provided by Carboniferous catchments characterised by a circumneutral pH and high concentrations of carbonates, supporting the formation of secondary metal-minerals as potential sinks of metals. The present study focuses on understanding the mobility of metal pollution associated with historical mining in a Carboniferous upland catchment. In the uplands of the UK, river water, sediments and spoil wastes were collected over a period of fourteen months, samples were chemically analysed to identify the main metal sources and their relationships with geological and hydrological factors. Correlation tests and principal component analysis suggest that the underlying limestone bedrock controls pH and weathering reactions. Significant metal concentrations from mining activities were measured for zinc (4.3mg/l), and lead (0.3 mg/l), attributed to processes such as oxidation of mined ores (e.g. sphalerite, galena) or dissolution of precipitated secondary metal-minerals (e.g. cerussite, smithsonite). Zinc and lead mobility indicated strong dependence on biogeochemistry and hydrological conditions (e.g. pH and flow) at specific locations in the catchment. Annual loads of zinc and lead (2.9 and 0.2 tonnes/year) demonstrate a significant source of both metals to downstream river reaches. Metal pollution results in a large area of catchment having a depleted chemical status with likely effects on the aquatic ecology. This study provides an improved understanding of geological and hydrological processes controlling water chemistry, which is critical to assessing metal sources and mobilization, especially in neutral mine drainage areas

Effect of episodic rainfall on aqueous metal mobility from historical mine sites

The increasing frequency and magnitude of episodic rainfall events may affect historical metal mining areas by remobilisation and deposition of metal-rich sediments and enhancing metal-rich run off, impacting river water quality. This study assesses the effects of episodic rainfall in a Carboniferous headwater catchment contaminated by historical Pb and Zn mining. Comprehensive hourly water chemistry measurements combined with modelling using PHREEQC, WHAM/Model VII and WHAM-FTOX were used in this assessment. For the episodic event, we measured flow increases from a baseline of 0.05 to 2.12 m3 s−1 at peak flow. Changes in metal concentration were most marked for ephemeral tributary, with Pb increasing from a baseline concentration of 55 μg L−1 to a peak of 576 μg L−1. Behaviour for Pb showed great affinity to form organic complexes or bind to colloidal Al and Fe oxides, whereas for Zn and the tributary flowing subsurface a more complex behaviour was observed. For example, the dissolution of secondary metal carbonate minerals (e.g. smithsonite (ZnCO3)) is likely constrained by higher concentrations of carbonate and bicarbonate derived from increased bedrock weathering under flow conditions induced by episodic rainfall. The abundance of secondary mineral sources and circumneutral pH present during episodic rainfall are important factors controlling the mobilisation of Pb and Zn. Furthermore, episodic rainfall events could enhance metal toxicity but there are aggravating and mitigating factors that depend on site-specific chemical changes. Overall, this study highlighted the complexity of metal mobility and toxicity during these events

Nest site selection by sea turtles

The distribution of 38 nests of loggerhead turtles (Caretta caretta) on beaches on Sanibel and Captiva islands, south-western Florida (26°26\u27N 82°16\u27W), and of 70 first digging attempts by green turtles (Chelonia mydas) on Ascension Island (7°57\u27S 14°22\u27W), was quantified. For loggerhead turtles on Sanibel and Captiva, nests were clumped close to the border between the open sand and the supra-littoral vegetation that backed the beaches. This spatial pattern of nests was closely reproduced by assuming simply that turtles crawled a random distance above the most recent high water line prior to digging. In contrast, green turtles on Ascension Island clumped their first digging attempts on the uneven beach above the springs high water line, crawling up to 80 m to reach this beach zone

The initiation and development of metamorphic foliation in the Otago Schist, Part 2: evidence from quartz grain-shape data

Shape, size and orientation measurements of quartz grains sampled along two transects that cross zones of increasing metamorphic grade in the Otago Schist, New Zealand, reveal the role of quartz in the progressive development of metamorphic foliation. Sedimentary compaction and diagenesis contributed little to the formation of a shape-preferred orientation (SPO) within the analysed samples. Metamorphic foliation was initiated at sub-greenschist facies conditions as part of a composite S1-bedding structure parallel to the axial planes of tight to isoclinal F1 folds. An important component of this foliation is a pronounced quartz SPO that formed dominantly by the effect of dissolution?precipitation creep on detrital grains in association with F1 strain. With increasing grade, the following trends are evident from the SPO data: (i) a progressive increase in the aspect ratio of grains in sections parallel to lineation, and the development of blade-shaped grains; (ii) the early development of a strong shape preferred orientation so that blade lengths define the linear aspect of the foliation (lineation) and the intermediate axes of the blades define a partial girdle about the lineation; (iii) a slight thinning and reduction in volume of grains in the one transect; and (iv) an actual increase in thickness and volume in the survivor grains of the second transect. The highest-grade samples, within the chlorite zone of the greenschist facies, record segregation into quartz- and mica-rich layers. This segregation resulted largely from F2 crenulation and marks a key change in the distribution, deformation and SPO of the quartz grains. The contribution of quartz SPO to defining the foliation lessens as the previously discrete and aligned detrital quartz grains are replaced by aggregates and layers of dynamically recrystallized quartz grains of reduced aspect ratio and reduced alignment. Pressure solution now affects the margins of quartz-rich layers rather than individual grains. In higher-grade samples, therefore, the rock structure is characterized increasingly by segregation layering parallel to a foliation defined predominantly by mica SPO

Using surgical sustainability principles to improve planetary health and optimise surgical services following the COVID-19 pandemic

As the world faces crises instigated by environmental disruption, demands on healthcare require sustainable solutions. In this article, we outline the principles of sustainable surgery, how these can be used to optimise surgical services in light of healthcare crises, and how long-term adoption of these principles can help to reduce the carbon and plastic footprint of surgery in the UK and internationally. We describe how planetary and human health are closely related, including the relationship between environmental disruption and emerging infectious diseases