scholarly journals An Estimate of Production and Consumption Rates in the Spiny Lobster Panulirus homarus on a Shallow Littoral Reef off the Natal Coast, South Africa

1980 ◽  
Vol 2 ◽  
pp. 337-343 ◽  
Author(s):  
PF Berry ◽  
MJ Smale
2020 ◽  
Author(s):  
Xin Sun ◽  
Amal Jayakumar ◽  
John C. Tracey ◽  
Elizabeth Wallace ◽  
Colette L. Kelly ◽  
...  

AbstractThe ocean is a net source of N2O, a potent greenhouse gas and ozone-depleting agent. However, the removal of N2O via microbial N2O consumption is poorly constrained and rate measurements have been restricted to anoxic waters. Here we expand N2O consumption measurements from anoxic zones to the sharp oxygen gradient above them, and experimentally determine kinetic parameters in both oxic and anoxic seawater for the first time. We find that the substrate affinity, O2 tolerance, and community composition of N2O-consuming microbes in oxic waters differ from those in the underlying anoxic layers. Kinetic parameters determined here are used to model in situ N2O production and consumption rates. Estimated in situ rates differ from measured rates, confirming the necessity to consider kinetics when predicting N2O cycling. Microbes from the oxic layer consume N2O under anoxic conditions at a much faster rate than microbes from anoxic zones. These experimental results are in keeping with model results which indicate that N2O consumption likely takes place above the oxygen deficient zone (ODZ). Thus, the dynamic layer with steep O2 and N2O gradients right above the ODZ is a previously ignored potential gatekeeper of N2O and should be accounted for in the marine N2O budget.


2017 ◽  
Vol 2017 ◽  
pp. 1-27 ◽  
Author(s):  
Declan T. Waugh ◽  
Michael Godfrey ◽  
Hardy Limeback ◽  
William Potter

In countries with fluoridation of public water, it is imperative to determine other dietary sources of fluoride intake to reduce the public health risk of chronic exposure. New Zealand has one of the highest per capita consumption rates of black tea internationally and is one of the few countries to artificially fluoridate public water; yet no information is available to consumers on the fluoride levels in tea products. In this study, we determined the contribution of black tea as a source of dietary fluoride intake by measuring the fluoride content in 18 brands of commercially available products in New Zealand. Fluoride concentrations were measured by potentiometric method with a fluoride ion-selective electrode and the contribution of black tea to Adequate Intake (AI) and Tolerable Upper Intake Level (UL) was calculated for a range of consumption scenarios. We examined factors that influence the fluoride content in manufactured tea and tea infusions, as well as temporal changes in fluoride exposure from black tea. We review the international evidence regarding chronic fluoride intake and its association with chronic pain, arthritic disease, and musculoskeletal disorders and provide insights into possible association between fluoride intake and the high prevalence of these disorders in New Zealand.


2017 ◽  
Vol 43 (2) ◽  
pp. 51-63 ◽  
Author(s):  
Morgan Ndlovu

While many of the peoples who exist in the ‘spatio-temporal’ construct known as the postcolonial world today are convinced that they have succeeded – through anticolonial and anti-imperial struggles – to defeat colonial domination, the majority of the people of the same part of the world have not yet reaped the freedoms which they aimed to achieve. The question that emerges out of the failure to realise the objectives of anti-colonial and anti-imperial struggles by the people of the Third World after a number of years of absence of juridical-administrative colonial and apartheid systems is to what extent did the people who sought to dethrone colonial domination understand the complexity of the colonial system? And to what end did the ability and/or inability to master the complexity of the colonial system affect the process of decolonization? Through the case study of the production and consumption of cultural villages in South Africa, this article deploys a de-colonial epistemic perspective to reveal, within the context of tourism studies, the complexity of the colonial system and why a truly decolonized postcolonial world has so far eluded the people of the developing world.


Author(s):  
J C Groenewald ◽  
C L Greengrass ◽  
G M Branch ◽  
S A McCue

2020 ◽  
Vol 2 (1) ◽  
pp. 31
Author(s):  
Dejan Dimkić

The production of water in a drinking water supply system (WSS) comprises all drinking water enter in the net, while the consumption of water generally comprises all billed amounts of water in a WSS. The production and consumption of water in a drinking WSS depend on different factors. Consumption rates depend on the consumer structure and habits, industrial demand, time of year, water pricing, climatic variables, secondary water losses and many other factors. One of the interesting factors is air temperature. It is especially important in the frame of climate change and global warming. Temperature impact on water consumption in a WSS is not uniform temporally (particularly throughout the year) and spatially (different climate regions and countries, different habits and different conditions in each WSS). Obtained correlations for the two biggest cities in Serbia (Belgrade and Niš) are presented in the paper and compared with some examples worldwide.


2013 ◽  
Vol 69 (5) ◽  
pp. 909-914 ◽  
Author(s):  
Shuying Tan ◽  
Tong Yu ◽  
Han-chang Shi

Microsensor techniques were used to investigate in situ the simultaneous occurrence of sulfate reduction and nitrogen removal in a membrane aerated biofilm reactor. H2S, O2, pH, ORP, NH4+ and NO3− microsensors were fabricated and used to measure the profiles inside the membrane aerated biofilm. Production and consumption rates of H2S, O2, NH4+ and NO3− were estimated using corresponding concentration profiles. The results showed that in anoxic zone, located from the interface between biofilm and bulk liquid to about 550 μm below the interface, both sulfate reduction and denitrification occurred. Highest H2S production rates (around 0.27 mg L−1s−1) were found about 400 to 450 μm below the interface. Below the anoxic zone, an aerobic zone was present. High H2S oxidation activity occurred at around 550–700 μm below the interface. High oxygen consumption rates (0.34 mg L−1s−1) occurred at around 750–900 μm below the interface. Nitrification activity occurred at about 500–650 μm below the interface. Along the entire biofilm depth, pH changed slightly (within 0.2 unit). Near the interface of the aerobic and anoxic zone, there was a drastic redox potential change. These results demonstrated simultaneous sulfate reduction and nitrogen removal in a piece of membrane aerated biofilm.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Fortune Nwaiwu

Abstract Background Digital technologies have unique characteristics for achieving radically disruptive transitions within the energy sector. They provide opportunities for new production and consumption models between micro-producers and consumers of electricity within communities in a way that transforms the traditional energy generation and consumption model. The study critically assessed the digitalisation of energy systems in Africa within the context of existing policy frameworks in the quest to achieve sustainable energy transitions in Africa. It investigated how digital technologies such as blockchain, digital platforms and smart grids were adopted and implemented within the energy sector to achieve new energy production and consumption models that are both environmentally sustainable and socially inclusive. This assessment was done within the context of existing policy and regulatory frameworks of the society where the use cases were domiciled. Methods The aim of the research was to investigate how sustainable energy transitions are being achieved in Nigeria and South Africa through the digitalisation of energy systems. A qualitative methodological approach was done in three stages—a document analysis that reviewed relevant literature on the energy sector policies in Nigeria and South Africa; the next step involved a comparative case study conducted to assess the characteristics of digital technology deployment in each country’s energy transition. Finally, outcomes of the comparative case studies were then situated within the context of existing policies within the countries covered by the study. Results Results from the research indicate that Africa is still in the early stages of adoption and application of digital technologies such as blockchain and smart grids within the energy sector. The results also showed a disconnect between the policy environment and industry efforts at achieving this. The current applications as exemplified in the use cases by the three companies covered in this study indicates that Africa's sustainable energy transition is in a rudimentary or early adoption stage, and they are not currently aided by the policy environments in which such projects are domiciled. Conclusions The research provides deep insights into the current state and developments within the energy sector especially in relation to how digital technologies are being adopted and implemented in solving the energy poverty prevalent across sub-Saharan Africa.


2020 ◽  
Vol 84 ◽  
pp. 121-126
Author(s):  
AY Tsai ◽  
GC Gong ◽  
KP Chiang

The northwestern Pacific Ocean and East China Sea (ECS) are frequently affected by typhoons during the summer period. To identify changes in production and consumption rates of phytoplankton (<20 and 20~200 µm) affected by Typhoon Maria (9-10 July 2018), 2 sampling periods were compared: a pre-typhoon cruise (4-9 July 2018) and a post-typhoon cruise (13-17 July 2018). Results showed that <20 and 20~200 µm phytoplankton production was 14- and 1.8-fold higher, respectively, in the post-typhoon period compared to the pre-typhoon. Accompanying this post-typhoon shift from pico- and nanophytoplankton to microphytoplankton, the consumption rate of microzooplankton on <20 µm phytoplankton was 11.6 mgC m-3 d-1 in the pre-typhoon period, and increased to 203.3 mgC m-3 d-1 after the typhoon. Furthermore, the ingestion fluxes were 4.9 and 8.0 mgC m-3 d-1 through mesozooplankton grazing on microzooplankton (ciliates and dinoflagellates) pre- and post-typhoon, respectively. Our findings show that organisms from the microbial food web (i.e. ciliates and dinoflagellates) may control the phytoplankton assemblage during the post-typhoon period of increased productivity, and thus represent an important trophic link between the classical and microbial food webs in the southern ECS.


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