36 research outputs found
John Francis Talling. 23 March 1929 — 20 June 2017
No full textJohn (Jack) Francis Talling was a master limnologist who pioneered much of our understanding of the River Nile, the great lakes of the African Rift Valley and those of the English Lake District. He was one of the world's leading authorities on the ecophysiology of freshwater phytoplankton and specialized in the control of their productivity by light and carbon dioxide. His perspectives were formed by interaction with leading scientists of the day, mainly at the Freshwater Biological Association, Cumbria, but also at laboratories in Africa and at the Scripps Institution of Oceanography, California. Jack's work on the effects of light on phytoplankton productivity was based on detailed measurements of the underwater light climate in lakes and oceans as well as laboratory and field measurements of the response of phytoplankton photosynthesis to light, involving the development of new or improved measurement methods. Calculation procedures were developed to estimate how light controls primary productivity. He devised the widely used characteristic ‘Ik’ to quantify the onset of light saturation in the curve that defines the response of photosynthesis to light quantity. Experiences in extremely productive African soda lakes stimulated an interest in the possibility of CO2 being a limiting factor controlling phytoplankton productivity and, more generally, Jack had the ecological insight to recognize that ecological dynamics resulted from interactions among factors rather than a response to a single variable
A brief history of the scientific study of tropical African inland waters
No full textAn account is given of a study of African tropical waters, drawing on the personal experiences of the author. Reviewing developments since 1900, the author examines the way in which research has developed and the influence the changes in the policitcal map of Africa, in particular the change from colonial rule, has had on research
A brief history of the scientific study of tropical African inland waters
No full textAn account is given of a study of African tropical waters, drawing on the personal experiences of the author. Reviewing developments since 1900, the author examines the way in which research has developed and the influence the changes in the policitcal map of Africa, in particular the change from colonial rule, has had on research
The development of freshwater science in Britain, and British contributions abroad, 1900-2000
No full textThis article outlines the development of freshwater science between 1900 and 2000 and in particular traces British contributions, both to a deepened knowledge of specifics and to their interrelation as environmental and ecological science. The author provides a selected bibliography of important publications relevant to the topic of the article
The development of freshwater science in Britain, and British contributions abroad, 1900-2000
No full textThis article outlines the development of freshwater science between 1900 and 2000 and in particular traces British contributions, both to a deepened knowledge of specifics and to their interrelation as environmental and ecological science. The author provides a selected bibliography of important publications relevant to the topic of the article
Efficient preservation of young terrestrial organic carbon in sandy turbidity-current deposits
No full text© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Hage, S., Galy, V. V., Cartigny, M. J. B., Acikalin, S., Clare, M. A., Grocke, D. R., Hilton, R. G., Hunt, J. E., Lintern, D. G., McGhee, C. A., Parsons, D. R., Stacey, C. D., Sumner, E. J., & Talling, P. J. Efficient preservation of young terrestrial organic carbon in sandy turbidity-current deposits. Geology, 48(9), (2020): 882-887, doi:10.1130/G47320.1.Burial of terrestrial biospheric particulate organic carbon in marine sediments removes CO2 from the atmosphere, regulating climate over geologic time scales. Rivers deliver terrestrial organic carbon to the sea, while turbidity currents transport river sediment further offshore. Previous studies have suggested that most organic carbon resides in muddy marine sediment. However, turbidity currents can carry a significant component of coarser sediment, which is commonly assumed to be organic carbon poor. Here, using data from a Canadian fjord, we show that young woody debris can be rapidly buried in sandy layers of turbidity current deposits (turbidites). These layers have organic carbon contents 10× higher than the overlying mud layer, and overall, woody debris makes up >70% of the organic carbon preserved in the deposits. Burial of woody debris in sands overlain by mud caps reduces their exposure to oxygen, increasing organic carbon burial efficiency. Sandy turbidity current channels are common in fjords and the deep sea; hence we suggest that previous global organic carbon burial budgets may have been underestimated.We thank C. Johnson, M. Lardie, A. Gagnon, A. McNichol, and the NOSAMS (National Ocean Sciences Accelerator Mass Spectrometry) team (Woods Hole Oceanographic Institution [WHOI], Massachusetts, USA) for their help with ramped oxidation system and isotopes. We thank the captain and crew of CCGS Vector. Support was provided by UK Natural Environment Research Council (NERC) grants NE/M007138/1 (to Cartigny) and NE/L013142/1 (to Talling), NE/P005780/1 and NE/P009190/1 (to Clare); a Royal Society Research Fellowship (to Cartigny); an International Association of Sedimentologists Postgraduate Grant and National Oceanography Centre Southampton–WHOI exchange program funds (to Hage); an independent study award from WHOI (to Galy); the Climate Linked Atlantic Sector Science (CLASS) program (NERC grant NE/R015953/1); and the European Research Council under the European Union’s Horizon 2020 research and innovation program (Grant 725955, to Parsons). We thank François Baudin, Xingqian Cui, editor James Schmitt, and three anonymous reviewers
Electrical conductance – a versatile guide in freshwater science
No full textAttention is directed to the many potential uses of specific electrical conductance (‘conductivity’) in the study of inland waters. Its measurement is capable of a precision useful in the detection of differences in a standing or flowing water-mass, but cannot be translated into measures of chemical concentration with equivalent absolute accuracy. Reasons – not infrequently neglected – include approximations in temperature correction, in allowance for a depression effect at higher ionic strength (salinity), and especially in the differences of specific conductance of chemically different ions. The last can be reduced by treating ionic concentration in chemical equivalents (e.g. meq l-1) rather than the usual units of mass (e.g. mg l-1) or molarity (e.g. mmol l-1); also by making allowance for the exceptionally high equivalent conductance of H+ and OH- ions in markedly acid and alkaline waters.Measurement in the field has been helped by the development of small portable instruments with inbuilt temperature compensation, flow-through electrode systems and electrical output. Examples of both field and laboratory measurements, for the charting and interpretation of various field situations, are illustrated chiefly from the author’s experience. They include broad chemical surveys; interrelation with normal chemical analysis; longitudinal change, water travel and nutrient uptake in river and stream systems; ionic ↔ particulate conversion; horizontal and vertical differentiation in lakes; and ionic changes induced by photosynthesis
Preconditioning and triggering of offshore slope failures and turbidity currents revealed by most detailed monitoring yet at a fjord-head delta
No full textRivers and turbidity currents are the two most important sediment transport processes by volume on Earth. Various hypotheses have been proposed for triggering of turbidity currents offshore from river mouths, including direct plunging of river discharge, delta mouth bar flushing or slope failure caused by low tides and gas expansion, earthquakes and rapid sedimentation. During 2011, 106 turbidity currents were monitored at Squamish Delta, British Columbia. This enables statistical analysis of timing, frequency and triggers. The largest peaks in river discharge did not create hyperpycnal flows. Instead, delayed delta-lip failures occurred 8–11 h after flood peaks, due to cumulative delta top sedimentation and tidally-induced pore pressure changes. Elevated river discharge is thus a significant control on the timing and rate of turbidity currents but not directly due to plunging river water. Elevated river discharge and focusing of river discharge at low tides cause increased sediment transport across the delta-lip, which is the most significant of all controls on flow timing in this setting
The development of freshwater science in Britain, and British contributions abroad, 1900-2000
No full textThe nineteenth century was a period in which the framework of sciencedeveloped rapidly and internationally. At its close there were, in Britain,the background and many active ingredients of future freshwater science.Geology and natural history had prospered. Organic evolution wasestablished on a Darwinian foundation. The form of river basins and lakeshad been shown to be influenced by Pleistocene glaciations; the flow of ariver could be related to terms of a water budget; the dissolved mineralcontent of surface waters was broadly characterized. Freshwater organisms- at least many of them - were named and classified. They attracted muchinterest in local societies of naturalists, whose largely amateur enthusiasmcomplemented the work of the fewer professionals in the field - such asL.C. Miall at the Yorkshire College, later University of Leeds. Fishes,amphibians, birds and flowering plants had never been neglected by thewider public. The schoolboy caught and reared tadpoles, his father cast'flies' for trout, his aunt pressed flowers of the water crowfoot andbogbean. There was the conspicuous spread in waterways of the introducedCanadian pondweed. However, naturalists became aware of a newmicrobial assembly - with often bizarre forms - when 'evenings at themicroscope' and books on microscopy became not infrequent in theirVictorian homes
