Showing papers by "University of East Anglia published in 1982"

Organic matter and the surface charge of suspended particles in estuarine waters1

Abstract: The surface electrical charge on suspended particles in four estuaries of the U.K. has been measured as a function of salinity by the technique of particle microelectrophoresis. Two characteristic types of behavior were found. In rivers low in dissolved cations, especially Caz+ (Conwy, Beaulieu), the electrophoretic mobility uE was negative in sign at all salinities, increasing slightly in magnitude from the seawater end member to lower salinities of 5-10%0, with a more pronounced increase toward the river water end member. In rivers draining calcareous terrain and having relatively high concentrations of Ca2’ (Alde, Orwell) uE showed a similar dependence on salinity above 5-l% but no marked increase in magnitude at lower salinities. Ionic composition of the water appears to be the major factor controlling changes in ug with salinity. Positively charged particles were entirely absent. The charge distribution of all samples was highly unifoml, in spite of the mixed nature of the suspended matter, indicating a dominant control of surface properties by adsorbed organic matter, metallic oxides, or both. This implies that differential flocculation of different suspended minerals is largely suppressed in the estuarine zone. Measurements of dissolved organic carbon (DOC) and surface-active substances (by suppression of polarographic maximum) in the same estuaries indicate a sufficient supply of organic matter for the adsorption process. No evidence for nonconservative removal of DOC or surface-active substances was found. Sewage inputs into some of the estuaries are clearly seen by the measurements of surface-active substances. Significant quantities of surface-active materials are injected into the Alde estuary through tidal flushing of a salt marsh area.

Variations in Surface Air Temperatures: Part 1. Northern Hemisphere, 1881–1980

Abstract: We have produced, using objective techniques, a long-term series of average Northern Hemisphere temperatures based on monthly mean station data gridded on a 5° latitude by 10° longitude grid. Difficulties in the estimation of this parameter are discussed, deficiencies in the currently available data base and possible effects on the estimated average are described, and monthly mean data are presented. Long-term trends and extremes are identified in the annual and seasonal data. All seasons show similar long-term trends, but there are noticeable differences on time scales of 10 years and less. For example, for winter temperature, the early 20th century warming peaked during the 1940's whereas the maximum in the other seasons was in the previous decade. Both the magnitude of the long-term trends and the year-to-year variability has been greatest in winter. There is evidence that the long-term cooling that characterized the 1940's, 1950's and 1960's has ended. Warming began in the mid to late 1960's ...

θ-S relationships and water masses in the eastern North Atlantic

Abstract: Observations of temperature and salinity from IGY and Erika Dan sections in the eastern North Atlantic have been re-examined to identify the θ-S relationships of the water masses and the fronts which separate them, using charts of salinity at potential temperature surfaces and sections of salinity at potential temperature levels. In the Deep Water (θ ⪕ 4.0°C) four water masses are identified: Mediterranean Water, Labrador Sea Water, Iceland-Scotland Overflow Water, and Bottom Water. In the Intermediate Water (4.0°C < θ < 12.0°C) ee water masses are identified: Sub-Arctic Intermediate Water, Eastern North Atlantic Water (ENAW), and Mediterranean Water; the first two are separated by the Polar Front, whilst a fairly marked sub-surface front separates the latter two. A standard θ-S relationship is presented for ENAW, together with salinity anomalies from this for four zonal sections to illustrate the distributions of the intermediate water masses. The formation of ENAW is considered in relation to winter temperatures and salinities at the surface in the eastern North Atlantic.

Variations in Surface Air Temperatures: Part 2. Arctic Regions, 1881–1980

Abstract: We describe annual and seasonal changes in air temperatures over high latitudes of the Northern Hemisphere during the period 1881–1980. Trends (that is, fluctuations on time scales greater than 20 years) in the average temperature of the Arctic are compared with those of the Northern Hemisphere. Seasonal and regional departures from the long-term trends in the average temperature of the Arctic are identified. Spatial patterns of variation in the Arctic temperature field are determined by principal component analysis and the major characteristics of the time series of the dominant patterns are summarized. Trends in Arctic temperatures have been broadly similar to those for the Northern Hemisphere during the study period. The Arctic variations were, however, greater in magnitude and more rapid. The spatial pattern of change associated with the trend in Arctic temperatures is clearly identified by principal component analysis. It shows that the trends have, in general, been Arctic-wide, but that cer...

Corrigendum: Historical evidence for a dramatic increase in the nitrate component of acid rain

Abstract: The concentrations of nitrate and ammonium ion in rainfall have an important effect on precipitation pH. We have collected sets of rainfall analyses from non-urban sites in North America and western Europe, which start from last century, and we show here that there is a marked increase in the annual deposit of nitrate ion compared with relatively stable levels of ammonium ion deposit. The increase apparent in the data from the US parallels the increases in nitrogen oxide emissions from combustion processes and is large enough for the nitrate ion to contribute almost as much to the acidity of rainfall as the sulphate ion.

Preferential elution of strong acids from a Norwegian ice cap

Abstract: The release of strong acids by melting snows during the early thaw has a serious effect on the ecology of many sensitive areas of the world1–3. The run off is a product of both the input (wet and dry deposition) and of processes occurring within the snow-pack and the firn during the melt season. Temperate glacial ice is very pure4, having lost most of its annual input of original solutes during each melt season, and the analyses reported here of the ionic concentrations in the snow, firn and ice of the top 20 m of an ice cap, indicate that the ions are eluted differentially and in a manner which initially accentuates the loss of sulphuric and nitric acid. Almost all the annual deposits of ions on a glacier or ice cap may be lost during a single year.

A Taxonomy of Current Approaches to Systems Analysis

Abstract: The discipline of systems analysis is still very young and in common with most other emerging disciplines it occasionally enters periods of radical self examination and re-thinking. The authors feel that we are in the midst of such a phase at present; new ideas abound, arguments rage, and the development of technology is a powerful impetus to the re-examination of ideas. The reason for the current turmoil in systems analysis is the emergence over the past few years of a number of new approaches or methodologies. These approaches have generally originated as academic ideas and been taken up and modified in the practising world of systems analysis. Thus there exists a confusing array of approaches. It is the purpose of this paper to examine some of the more fundamental approaches and to attempt to classify them. It is the authors' view that the approaches are not simple alternatives, but that they seek to do different things. The authors have identified six major approaches to systems analysis: (i) General Systems Theory Approach; (ii) Human Activity Systems Approach; (iii) Participative (Socio technical) Approach; (iv) Traditional (NCC, etc.) Approach; (v) Data Analysis Approach; (vi) Structured Systems (Functional) Approach. Except for the General Systems Theory Approach they are all used to some extent in the industry today. General Systems Theory is included as an approach because of its important influence on systems thinking in general and because of the contribution it has made to almost all the other identified approaches.

Light and self-thinning

Abstract: SUMMARY Monocultures of Lolium perenne were grown at high densities under various shade regimes to investigate the effects of shade on self-thinning. Unshaded populations conformed to the minus 3/2 power law when dead matter was taken into account in the calculation of mean weight per plant. In a plot of live weight per plant, populations reached a common minus 3/2 line but then deflected from it. Adherence to the minus 3/2 power law is a characteristic of shoots but not of whole plants of L. perenne. Populations increased in shoot:root ratio as they developed so that the thinning line for shoot plus root weight per plant was shallower than the thinning line for shoot weight per plant. Shoot: root ratios were generally higher in shaded than in unshaded populations. Tiller weights and numbers in experimental populations of L. perenne also conformed to the minus 3/2 power law. Populations grown in deep shade thinned along a line of slope minus 1 when sown at ‘low’ densities but those sown at very high densities underwent an initial period of thinning along a slope of minus 3/2, followed by a switch to a slope of minus 1. Populations at intermediate levels of shade showed a decrease in the intercept of the thinning line with increasing shade but no change in gradient. A schematic diagram is presented to help explain the effects of shade on self-thinning.

A glacio-isostatic facies model and amino acid stratigraphy for late Quaternary events in Spitsbergen and the Arctic

Abstract: Strong early Holocene crustal uplift over the Spitsbergen archipelago reflects disappearance of an ice mass centred just north-east of the archipelago and which decayed rapidly just after 10,000 BP after a maximum extension between 12,600 and 10,000 BP. From the lithofacies distributions associated with these events a glacio-isostatic facies model can be defined which, combined with analyses of amino acid racemization, provides a valuable stratigraphic method for correlating pre-Holocene glacio-isostatic events. These are correlated with events in Greenland, and both are contrasted with Weichselian glacial events at the southern margins of the two great Northern Hemisphere ice sheets and with contemporary water mass changes in the North Atlantic and Norwegian Sea. The geographical variation in glacier response through time is explained by three principal climatic circulation patterns.

The early metamorphic history of the Haast Schists and related rocks of New Zealand

Abstract: Rare but widespread relics of sodic amphibole occur in metabasites and metacherts of the Haast Schists and related Caples Terrane rocks. Present main-stage metamorphic assemblages are frequently chemically equivalent to earlier sodic amphibole bearing assemblages, indicating that these rocks underwent an earlier, higher P/Tmetamorphism prior to formation of the present pumpellyite-actinolite and greenschist facies assemblages. The earlier assemblages were stable during and after early isoclinal folding, but were replaced by the present moderate P/T assemblages prior to the last major fabric-forming deformation. The change in conditions was due to thermal relaxation, probably accompanied by uplift and erosion, and peak metamorphic temperatures were about 350–370° C in the pumpellyite-actinolite zone of the Caples Terrane and near 390° C in the greenschist facies chlorite zone near Queenstown. According to Henley (1975) these greenschist facies rocks attained a pressure of at least 6.4±0.4 kb during their history, but a pressure of 4.6±0.6 kb has been estimated for a chlorite zone rock from Middlemarch, and so the 6.4 kb estimate probably refers to the maximum pressure attained during the earlier, higher P/T metamorphism. Similar changes in ‘metamorphic facies series’ with time occur in some older and more complex metamorphic belts such as the Caledonides, and this study suggests that it may be possible to interpret particular elements in the metamorphic development of such belts in terms of specific circum-Pacific analogues.

Apnoea in Amphibians and Reptiles

Abstract: The amphibian ancestor had two gas exchangers, one working in water and one in air. It also ventilated the aerial exchanger in an intermittent fashion. The functional repercussions of thie ancestry can be seen in all amphibians and reptiles. During periods of apnoea, which almost all amphibians and reptiles show in their breathing patterns, there are variable fluctuations in lung and arterial PO2 and PCO2. Arterial PCO2 and pH show only small fluctuations during apnoea induced by voluntary dives, and blood lactate does not build up. More considerable acidoses and lactate accumulations occur in forced dives which the animals can readily survive, even when the dives are prolonged. Anaerobic metabolism plays an important role in their capacity to survive prolonged apnoea. Amphibians ventilate their lungs with a buccal pump whose pattern of activity differs from species to species. Short periods of apnoea characterize the more terrestrial forms. Long dives punctuated by bursts of lung ventilation, or irregular bouts of breathing with no distinctive pattern occur in more aquatic forms. Similar differences in pattern can be seen in terrestrial and aquatic reptiles. The most striking characteristic of ventilation is its extreme variability, even in a single individual. Responses occur to decreasing oxygen tensions and increasing carbon dioxide tensions in inspired air, alveolar air, and arterial blood, the animals almost always increasing lung ventilation and decreasing the duration of apnoea. However, no simple relationship can be seen between the tensions of respiratory gases in lungs or arterial blood and the beginning or end of an apnoeic period. Periods of apnoea are accompanied by vasoconstriction in the lung vasculature. This has the effect of decreasing blood flow to the lung and increasing right to left shunt in the incompletely divided heart.

Sand waves and sediment transport around the end of a tidal sand bank

Abstract: Two detailed surveys have been made of the north-western end of the Haisborough Sand off the Norfolk coast using echosounder, 3.5 kHz reflection profiler and side-scan sonar. Asymmetrical sand waves indicate north-westerly sand movement on the southern side and south-easterly sand movement on the steeper northern side of the bank. Secondary, superimposed megaripples, which are probably better indicators of sediment movement, give evidence of a cross-bank component. Between the north-westerly and south-easterly facing sand waves on the tip of the bank there is a zone of symmetrical sand waves. These are usually taken to indicate zero net transport, but in this case the oblique orientation of megaripples in their troughs indicates transport parallel to the sand wave crests. This suggests the route by which sand travels around the end of the bank to form a roughly closed circulation. Sediment textural parameters support the notion that sand is winnowed from the foot of the bank on both sides and is transported to the middle with an overall net transport from the south to the north. Analysis of charts dating back to 1886 shows that the bank is stable within the error limits of position fixing, though that could allow more than 0.25 km shift to the north east in 100 years to pass undetected. A box model is drawn up for the estimated sediment fluxes around the end of the bank, and implications for residence times and circulation rates are drawn from it.

The role of coprophagy in the feeding strategies of terrestrial isopods.

Abstract: The hypothesis that faeces recycling in isopods evolved as an adaption to facilitate maintenance of an adequate copper balance in terrestrial environments is examined. Experimental observations on the consumption, absorption and growth rates of Porcellio scaber fed Betula pendula leaf litter varying in copper content and extent of microbial decay are reported. Preventing the isopods from reingesting their faeces caused a reduction in the growth rates of experimental animals fed their natural low copper diet but also of those fed copper enriched diets. When the availability of copper in the primary food was increased consumption of the litter decreased and growth rates were significantly reduced. These results suggest that copper is not normally a critically limiting nutrient for terrestrial isopods. When the primary diet was supplemented with shredded carrot, faeces deprivation did not cause a decrease in growth rates. These experimental animals gained weight significantly faster than controls fed decaying leaf litter alone. Faeces formed a significantly greater proportion of the diet when the animals were fed freshly fallen rather than decayed litter. We conclude a) that enhanced microbial activity in the faeces increases their nutrient status in such a way that some coprophagy is necessary in order to optimize overall nutrient uptake, and b) that theability to vary the extent to which faeces are recycled in response to differences in food quality is important in that it introduces greater flexibility into the feeding strategies of these generalist macro-decomposers.

Developing a simple yet practical method of soil-loss estimation.

Abstract: Soil-loss estimation is a necessary prerequisite in agricultural planning. Current techniques which rely on soil-loss measurement from field plots as their main data base hold many disadvantages for application in developing tropical countries. In order to utilize local experience and a small data base, a new framework for deriving prediction models, the Soil-Loss Estimation Model for Southern Africa (SLEMSA), was developed. The framework has been used to build a prediction model for the Zimbabwean Highveld. The paper outlines the structure of SLEMSA, points out its very significant advantages and describes the development phases of the Highveld Model. SLEMSA's approach and methodology have ready application to other developing countries by those concerned about their rapidly diminishing soil resources.

Factors affecting size in aphids with particular reference to the black bean aphid, aphis fabae

Abstract: Birth weight and food quality had a positive effect on adult weight, while temperature had a negative effect when the aphids were reared on high quality food, but no effect when reared on low quality food. Size was a consequence of the relative effect of birth weight, nutrition and temperature on developmental and growth rates. ZUSAMMENFASSUNG Faktoren, welche die Grosse von Blattlausen beeinflussen, mit besonderer Berucksichtigung der Schwarzen Bohnenlaus, Aphis fabae Das Geburtsgewicht und die Nahrungsqualitat hatte einen positiven Effekt auf das Gewicht der Adulten. Dagegen hatte die Temperatur einen negativen Effekt, wenn die Blattlause auf guter Nahrung und keinen Effekt, wenn sie auf schlechter Nahrung gezogen wurden. Die Grosse der Blattlause war eine Folge der Effekte von Geburtsgewicht. Ernahrung und Temperatur auf die Entwicklung und auf die Wachstumsgeschwindigkeit.

Determining the degree of differencing for time series via the log spectrum

Abstract: . While many time series require differencing before a model may be fitted it has been shown that ‘overdifferencing’ may result in a fitted model with poor long term forecasting properties. This may present real problems when the degree of differencing which is appropriate is fractional. We show that the log spectrum is a natural quantity to consider when attempting to determine the degree of differencing required and outline the distribution theory required. The ideas are shown to extend to the seasonal case and can be used to assess whether seasonal differencing is appropriate.

Towards regional scenarios for a CO2-warmed Earth

Abstract: Measured and projected increases in carbon dioxide content of the atmosphere point towards a significant global warming. The regional effects of such a warming will be of primary importance in determining the social and economic consequences. Four methods of arriving at tentative regional scenarios are discussed and illustrated by application to Australia and New Zealand. Methods used include numerical modelling, extreme warm and cold year ensembles, dynamical/empirical reasoning and palaeoclimatic reconstructions from the Hypsithermal. A surprising degree of consistency is revealed between the various approaches to a scenario for a CO2-warmed Earth and the climatic conditions which prevailed during the Hypsithermal. The best overall analogy to a CO2-warmed Earth seems to be this epoch, especially as recent evidence suggests it to be one of higher CO2 concentrations. High priority should be given to further investigations using numerical models which include an interactive dynamic ocean and hydrologic cycle including variable cloudiness, as well as more detailed reconstruction of climatic conditions during the Hypsithermal in areas sensitive to any circulation changes.

Temperature dependence of the sodium channel gating kinetics in the node of Ranvier.

Abstract: Temperature dependence of the Na+ channel gating kinetics was measured from the ionic and charge displacement currents in the node of Ranvier of Xenopus laevis, m3h kinetics was applied, assuming a delay, delta t, in the activation process. The rate constants for the m- and h-process showed Arrhenius temperature-dependence with Q10 of 2.34 and 2.9 respectively, while delta t exhibited non-Arrhenius temperature-dependence. Q10 for PNa, measured as 1.6, was smaller than for the rate constants and similar to that for a diffusion process. A negative shift and decrease in voltage sensitivity of the steady-state curves, h infinity and m infinity, occurred with decreasing temperature. The maximum time constant obtained from a single exponential fit to the displacement currents during the pulse for times greater than 90 microseconds exhibited Q10 of 2.01, which lies between that for PNa and that for tau m.

Principal component analysis of the lamb catalogue of daily weather types: Part 1, annual frequencies

Abstract: Principal component analysis is applied to annual weather type frequencies for the British Isles. The results objectively define characteristic relationships between the different types, and are used to determine changes in the atmospheric circulation in the region of the British Isles over the period 1861 to 1980. It is shown that, as far as annual frequencies are concerned, only six (of the 27) weather types are needed to define and monitor changes in the atmospheric circulation. The component amplitudes are correlated with temperature and rainfall data, and physically reasonable relationships are identified. The analysis is extended to the period 1781 to 1785, and similarities are found between the extremes experienced during that period and during the 1970s.

The influence of light level on the functional response of a zooplanktonivorous fish.

Abstract: Light and vision are clearly of significance in foraging behaviour by underyearling common bream [Abramis brama (L.)]. These fish are effective predators at 1.25 Lux but they were also shown to be capable of taking prey, at a reduced rate, at a much lower light intensity (less than 5x10-3 Lux). In the latter case they may have been using sensory modes other than vision, perhaps involving tactile and/or olfactory stimuli.

Decomposition of inequality measures and a comparative analysis

Abstract: The main objectives of the paper are to decompose Atkinson's measure into within-group and between-group inequality and to compare it with decompositions of inequality measures, like the Gini coefficient, variance of logarithms, Theil's entropy index and the square of the coefficient of variation. Atkinson's inequality index is given an interpretation of mean order β and then it is decomposed for population subgroups. Various other measures are considered for decompositions and a variety of decomposition schemes for Gini coefficient and other measures in the literature is reviewed and commented upon. Empirical analysis using U.S.A. and U.K. data are performed on the basis of income distribution data classified by family size. For various decomposition schemes, contribution to between size-group and within size-group inequalities are compared in percentage terms. Comparisons are also made over time for the years 1964 and 1974 both for U.S.A. and U.K. and the result indicates that within size-group income inequality has declined while between size group and total income inequality shows an increase. Three important properties of Atkinson's inequality index are proved in the appendix.

Tabtoxin-induced symptoms are associated with the accumulation of ammonia formed during photorespiration

Abstract: When tabtoxin was injected into Nicotiana tabacum leaves, glutamine synthetase was reduced by over 97% within 28 h, but the chlorotic and necrotic symptoms only occurred in illuminated leaves and were associated with the accumulation of ammonia. This indicated that symptom development was associated with accumulation of the substrate, rather than depletion of the product, of glutamine synthetase. Ammonia production by tabtoxin-treated tissue ceased immediately the tissue was darkened. A high carbon dioxide concentration and 3-(3,4-dichlorophenyl)-1-dimethyl urea (DCMU) also prevented ammonia production by such tissue. The ammonia was not derived from free pools of ammonia, amino acids or nitrate in the tissue, but was quantitatively accounted for by depletion of a fraction which would contain protein and polynucleotides. These results are consistent with the hypothesis that inhibition of glutamine synthetase by tabtoxin interrupts the photorespiratory-N cycle and the symptoms are associated with accumulation of an intermediate of this cycle, which is probably ammonia.

Secondary host preferences and reproductive activity of the bird cherry‐oat aphid, Rhopalosiphum padi

Abstract: SUMMARY Of 15 species of grass, including cereals, alate exules and emigrants of Rhopalosiphum padi preferred to colonise Lolium perenne. Emigrants colonised cereals twice as readily as alate exules. Apterous exules also preferred L. perenne to cereals. Although small when reared on L. perenne, R. padi was more fecund per unit weight than on any of the other grasses tested. On the later growth stages of Dactylis glomerata and L. perenne, R. padi developed faster and were more fecund than on Phleum pratense at the same growth stages. At low temperatures R. padi were more fecund on P. pratense than on L. perenne and D. glomerata and vice versa at high temperatures. The secondary host preferences and reproductive activity of R. padi are discussed in relation to possible suitable hosts for viviparous overwintering and the pest status of this aphid in Britain.

Instrumentation for NMR spin-warp imaging

Abstract: Implementation of a new NMR imaging technique has lead to the introduction of new instrumentation in imaging machines. The authors describe magnetic field gradient drivers and microprocessor control circuits which have increased the versatility of the system. The performance of the imaging method and improved resolution whole body images are discussed.