Calculating the global contribution of coralline algae to carbon burial

The ongoing increase in anthropogenic carbon dioxide (CO2) emissions is changing the global marine environment and is causing warming and acidification of the oceans. Reduction of CO2 to a sustainable level is required to avoid further marine change. Many studies investigate the potential of marine carbon sinks (e.g. seagrass) to mitigate anthropogenic emissions, however, information on storage by coralline algae and the beds they create is scant. Calcifying photosynthetic organisms, including coralline algae, can act as a CO2 sink via photosynthesis and CaCO3 dissolution and act as a CO2 source during respiration and CaCO3 production on short-term time scales. Long-term carbon storage potential might come from the accumulation of coralline algae deposits over geological time scales. Here, the carbon storage potential of coralline algae is assessed using meta-analysis of their global organic and inorganic carbon production and the processes involved in this metabolism. Organic and inorganic production were estimated at 330 g C m−2 yr−1 and 880 g CaCO3 m−2 yr−1 respectively giving global organic/inorganic C production of 0.7/1.8 × 109 t C yr−1. Calcium carbonate production by free-living/crustose coralline algae (CCA) corresponded to a sediment accretion of 70/450 mm kyr−1. Using this potential carbon storage by coralline algae, the global production of free-living algae/CCA was 0.4/1.2 × 109 t C yr−1 suggesting a total potential carbon sink of 1.6 × 109 t C yr−1. Coralline algae therefore have production rates similar to mangroves, saltmarshes and seagrasses representing an as yet unquantified but significant carbon store, however, further empirical investigations are needed to determine the dynamics and stability of that store

Biased statistical ensembles for developable ribbons

Letter to the edito

Moisture transport in concrete during fire: an NMR study

The question how concrete responds to a fire is one of the main questions in fire safety. During a fire, a building material can suddenly be heated up to temperatures well above 1000 oC. At temperatures above 100 oC, water inside the pores will start to boil. Simultaneously, in concrete, but also for example in gypsum, chemically bound water will be released by dehydration of the porous matrix. If the concrete has a low permeability, the vapour pressure inside will increase which can give rise to a sudden (explosive) failure of a material. Numerous heat and mass transfer models have been used to predict the moisture transport and its consequences on the strength and permeability of the concrete. However, these models are only of use if they can be validated. For model validation, quantitative measurements of the evolution of moisture, temperature, and possibly pressure distributions in time are needed. For this purpose, we have developed an NMR setup to measure the moisture transport in heated building materials. This setup makes used of the 1.5 T magnet of a medical MRI scanner, while dedicated gradient coils are used to image the moisture profiles in 1D. The sample is heated with the help of four 100 W halogen lamps, capable of generating a heat flux of 12 kW/m2. The measured combined moisture content and temperature profiles give a unique insight in the moisture transport and dehydration kinetics inside concrete during fire. These measurements give the first quantitative proof for the build-up of a moisture peak due to the vapour pressure build-up. While many moisture transport models predicted the existence of such a peak, these predictions had never been validated with moisture profile measurements during fire tests

Septemberwerk

Inwinteren of te wel, de bijenvolken klaarmaken voor de winter. Dit houdt in: bepalen welke volken de winter ingaan, de ruimte geven die het voor de winter nodig heeft, de varroa bestrijden (als dat nog niet is gedaan) en zorgen voor voldoende voer in de kast

Giant cell tumor of bone and tenosynovial tissue : surgical outcome

Giant cell tumor of bone (GCTB) is an intermediate, locally aggressive but rarely metastasizing tumor. Radiologically, GCTB shows typical lytic lesions. MR imaging is required to evaluate extent of GCTB for surgical planning. Preferred treatment for GCTB is extended curettage with local adjuvants, with comparable recurrence rates for different local adjuvants (27-31%). Resection can be performed when joint salvage is not feasible. Denosumab (RANKL-inhibitor) blocks and zoledronic acid (bisphosphonate) inhibits GCTB-derived osteoclast resorption. With zoledronic acid, stabilization of local and metastatic disease has been reported. Denosumab has been studied to a larger extent and seems to be effective in enabling less invasive forms of surgery. Moderate dose radiotherapy should be restricted to rare cases of unresectable or recurrent GCTB when surgery would lead to unacceptable morbidity. Tenosynovial GCT are classified into localized GCT of tendon sheath (GCTTS; nodular tenosynovitis) and diffuse-type GCT (Dt-GCT; pigmented villonodular synovitis, PVNS). Although arthroscopic synovectomy has been advocated as alternative to open synovectomy, there is a significant risk of inadequate excision. For GCT-TS, arthroscopic synovectomy may be sufficient. For Dt-GCT, open synovectomy is advised. For recurrent and extra-articular disease, moderate dose radiotherapy or systemic targeted therapy (M-CSFR-targeted tyrosine kinase inhibitors, e.g. imatinib) can be considered.UBL - phd migration 201

Leegstand bijenhotels

Op de website www.bijenhotels.nl staat een opvallende link met de tekst “grote leegstand bijenhotels”. Volgens deze website van Arie Koster worden veel bijenhotels geplaatst op plekken waar geen wilde (ofwel solitaire) bijen voorkomen. De hotels blijven dan leeg. Hoe zit dat eigenlijk? Leo van der Heijden vroeg bij Koster naar de precieze redenen

Alles over voeren

Wat was het afgelopen voorjaar koud en wat konden de bijen weinig vlieguren maken. Ook geven bloemen bij zulke lage temperaturen minder of helemaal geen nectar en de voedselvoorziening, vooral de honingvoorraad, kan dan te kort gaan schieten. Voeren vereist trouwens het hele jaar door aandacht van elke imker. Als imker hebben we de beschikking over verschillende producten om tekorten aan te vullen

Kunstzwerm in soorten

We maken allemaal wel eens een kunstzwerm, maar de reden kan heel verschillend zijn. Een beginnend imker leert een kunstzwerm maken om het aantal volken te vermeerderen of om volkejes te hebben voor de koninginnenteelt. De grootte van de verschillende kunstzwermen zal daardoor verschillende kunstzwermen zal daardoor verschillen, maar de 'basisingrediënten' moeten aanwezig zijn, wil een kunstzwerm levensvatbaar zijn

Zwermbeheersing met een broedloze koninginnenaflegger

De meeste imkers die de afgelopen jaren de basiscursus volgden, hebben een kunstzwerm gemaakt, meestal aangeduid met 'veger'. Om de kennis nog even op te frissen, vóór het maken van de kunstzwermen, hierbij een beschrijving van het maken van een broedloze koninginnenaflegger. Broedloos, om gelijktijdig de varroa te kunnen bestrijden