Improved procedures for extraction of water-extractable carbohydrates from particulate organic matter

The present work presents improvements to the existing methods for extraction of carbohydrates with water. In order to test the effects of extraction factors on the yield of carbohydrates, extractions of water-soluble carbohydrates were performed with two contrasting samples (suspended particulate organic matter from the high turbidity zone of the Gironde estuary and sedimentary organic matter from the Arcachon lagoon) under different experimental conditions. Results show that: (i) boiling water applied for 30 min yielded the best result for water-soluble carbohydrates in both samples; (ii) sonic disruption had a strong influence on the recovery rate of water-soluble carbohydrates - a steady yield was reached after a 3-min treatment; (iii) almost all the water-extractable carbohydrates are removed after the third extraction. Consequently, a general method is proposed to improve the extraction of water-extractable carbohydrates from particulate matter.Sur la base de deux échantillons organiques de nature opposée (matières en suspension de la zone de maximum de turbidité de l'estuaire de la Gironde et sédiments du bassin d'Arcachon), on a pu évaluer les effets de différents facteurs d'extraction sur la méthode d'extraction des sucres par l'eau. Ainsi, le rendement d'extraction des sucres solubles devient optimum (i) lorsque l'extraction est conduite à 100 °C et dans une période minimale de 30 min ; (ii) lors de l'application d'un traitement aux ultrasons de 3 min ; (iii) après trois extractions successives. Une optimisation de l'extraction des sucres solubles est alors proposée en vue de l'harmonisation des méthodes d'extraction

Egg production of the copepod Acartia bifilosa in two contrasting European estuaries in relation to seston composition

The egg production of the copepod Acartia bifilosa was measured and related to environmental variables and food availability in two estuaries located in the same biogeographic region (Bay of Biscay) but showing very strong differences in abiotic and biotic features: the Gironde estuary (France) and the estuary of Mundaka (Spain). The study was conducted during the spring-summer-autumn period of 1994, Food availability was evaluated by analysing the chlorophyll a (Chi a), the particulate organic carbon (POC) and the easily extractable macromolecular compounds such as proteins, carbohydrates and lipids of the seston. The egg production of copepods was estimated from field incubations with natural water, and phytoplankton feeding of adult females was estimated by means of the gut fluorescence method. The nutritional environment of the Gironde was characterised by high amounts of suspended particulate matter (SPM) with low food value, emphasising the mainly detrital origin of the organic matter (OM). In Mundaka, the higher contribution of phytoplankton to the seston led to marked increase, in particulate food value accounting for up to 35% of organic matter. The weight-specific egg production was found to be sharply higher in Mundaka (ranging from 0.2 to 0.63 x 10(-3) day(-1)) than in the Gironde (ranging from 0 to 0.13 x 10(-3) day(-1)), but the seasonal trend of variations was similar, the highest weight-specific egg production rates occurring in early summer and the lowest in autumn in both estuaries. Egg production was not correlated linearly with temperature since maximal egg production occurred at intermediate temperatures. In Mundaka, the egg production showed a significant positive con-elation with the chlorophyll and the Chl/SPM and the POC/SPM ratios. This coupled with higher values of algal food availability (Chi a/SPM: 10 to 1870 mug g(-1)) and gut fluorescence (between 0, 12 and 0,38 ng Chi a Eq ind(-1)) indicate that a herbivorous diet could cover the energy requirements of A. bifilosa and support egg production. In the Gironde, the algal food availability and the gut fluorescence were lower (Chi a/SPM: 10 to 80 mug g(-1) GF: 0.09 and 0.25 ng Chi a Eq ind(-1)), and the egg production showed significant positive correlation with the particulate food value, suggesting that other sources of carbon rather than phytoplankton ere responsible for the observed changes in egg production, Results indicate that the particular seston properties of each system may be responsible for the noticeable differences in A. bifilosa fertility among estuaries. (C) 2002 Elsevier Science B.V All rights reserved

Accelerated Systematic Investigation of Solvents Suitability for Type II/III Porous Liquids

Porous liquids offer clear advantages in several fields over solid adsorbents and physical solvents. The inherent pores of a well-designed system could be capable of molecular recognition thus combining the material advantages of both liquid and solid phases. Indeed, solid porous systems can have shape and size selectivity toward different gas moieties gas, but the liquid’s ease of use with facile transportation and processing provide significant opportunities. A liquid passes over surfaces to generate a thin film, and even the rapid mass transfer and fluidity of liquids may give porous liquids rapid gas solubility and diffusion. Nowadays, improving existing technologies for gas capture is crucial for an application like pollution removal, storage, or catalysis. Many of these technologies used in these applications rely on the porosity of solids like zeolites or more nascent materials such as metal–organic frameworks (MOFs). In this work, we examine the suitability of 60 various solvents for use in Type II/III porous liquids by looking at their respective molecular dimensions and shape. Six rapid screening modeling methodologies to assess the various dimensions of the solvent molecules have been assessed. Several assessments are performed between solvents, gases, and MOFs’ properties to support the design and generation of novel porous liquids

Comparative spring distribution of zooplankton in three macrotidal European estuaries

The zooplankton of three european estuaries (Ems, Gironde and Westerschelde) was investigated during spring 1992 by means of samples taken along the salinity gradient. The three estuaries are comparable in terms of total area, flushing time and salinity gradient but differ by their level of eutrophication (highest in the Westerschelde), suspended matter concentration (highest in the Gironde) and potential phytoplankton production (highest in the Ems). Copepods and meroplankton dominated the zooplankton in the three estuaries. The dominant copepod species were Eurytemora affinis and Acartia bifilosa. The distribution of E. affinis along the salinity gradient differed between the estuaries. Peaks of abundance were observed at 0 PSU in the Gironde, 6 PSU in the Ems and 9 PSU in the Westerschelde. The downstream shift of the population in the Westerschelde was likely due to anoxic conditions occurring in the oligohaline zone. In the Gironde the downstream distribution of E. affinis was limited by the very high suspended matter concentration found in the maximum turbidity zone. Whatever the estuary, the parameters of the population of E. affinis and maximum abundance values were similar. However, the influence of the better quality of the available food was suggested in the Ems where individual dry weights and egg production were higher than in the two other estuaries. The influence of a good quality of food in the Ems was confirmed by the development of a large population of Acartia bifilosa (as abundant as E. affinis) and highest values of adult individual weights.The meroplankton (essentially Polychaete and cirripede larvae) was much more developed in the Ems than in the Westerschelde and Gironde. This was likely due to the large extent of mudflats and hard substrates in the Ems favouring adult settlement and hence the number of larvae locally produced