Determination of environmental flows in rivers using an integrated hydrological-hydrodynamic-habitat modelling approach.

We propose the novel integrated modelling procedure 3H-EMC for the determination of the environmental flow in rivers and streams; 3H-EMC combines Hydrological, Hydrodynamic and Habitat modelling with the use of the Environmental Management Classes (EMCs) that are defined by the Global Environmental Flow Calculator. We apply 3H-EMC in the Sperchios River in Central Greece, in which water abstractions for irrigation cause significant environmental impacts. Calculations of the hydrodynamic-habitat model, in which the large and the small chub are the main fish species, suggest discharge values that range from 1.0 m3/s to 4.0 m3/s. However, hydrological modelling indicates that it is practically difficult to achieve discharges that are higher than approximately 1.0-1.5 m3/s. Furthermore, legislation suggests significantly lower values (0.4-0.5 m3/s) that are unacceptable from the ecological point of view. This behaviour shows that a non-integrated approach, which is based only on hydrodynamic-habitat modelling does not necessarily result in realistic environmental flows, and thus an integrated approach is required. We propose the value of 1.0 m3/s as the "optimum" environmental flow for Sperchios River, because (a) it satisfies the habitat requirements, as expressed by the values of weighted useable area that are equal to 2180 and 1964 m2 for the large and small chub, respectively, and correspond to 82 and 95% of their respective maximum values, (b) it is consistent with the requirements of Environmental Classes A and B, whose percentiles are higher than 75% for discharge (77.2%) and for habitat availability (>83.5% for the large chub and >85.0% for the small chub), (c) it is practically achievable from the hydrological point of view, and (d) it is higher than the value proposed by the Greek legislation. The proposed modelling approach can be applied to any river or stream using the same or similar modelling tools, which should be linked via suitable coupling algorithms.

Use of ionic liquids as media for the biocatalytic preparation of flavonoid derivatives with antioxidant potency.

Biocatalytic preparation of acylated derivatives of flavonoid glycosides was performed using various immobilized lipases in two different ionic liquids, namely 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF(4)) and 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF(6)). The influence of various reaction parameters on the performance and the regioselectivity of the biocatalytic process was pointed out, using as model reaction the acylation of naringin and rutin with vinyl butyrate, catalyzed by immobilized Candida antarctica lipase at 60 degrees C. The biocatalytic modification of flavonoids strongly depended on the ionic liquid used, the molar ratio of substrates, as well as the acyl donor chain length. The highest conversion yield (about 65% after 96 h of incubation) was obtained with short chain acyl donors (up to four carbon atoms), at a relatively high molar ratio (10-15) in both ionic liquids used. The amount of monoacylated flavonoid derivatives produced in a single-step biocatalytic process in [bmim]BF(4) was up to 5.5 g/L for monoacylated rutin and 30 g/L for monoacylated naringin. The regioselectivity of the process was higher in [bmim]BF(4) than in [bmim]PF(6) or organic solvents. Reaction rates observed in ionic liquids were up to four times higher than those reported for organic media. The acylation of sugar moiety of rutin with various acyl donors affected its antioxidant potential towards both isolated LDL and total serum model in vitro. A significant increase of antioxidant activity was observed for rutin-4'''-O-oleate.