A model of flow and nutrient absorption in artificial wetland systems

An analysis is presented of nutrient absorption controlled by a simple growth law in an artificial wetland system. The distribution of transit times for fluid particles to pass through the wetland is described by a function determined from experimental dye data, and the model includes a constant diffusion term, which is important at slow flow rates. The nutrient absorption efficiency is determined as a function of the flow rate and size of the system. Conditions for maximum absorption are derived from the model for a fixed rate of nutrient input to the wetland using an assumption of nonoverlapping paths. Diffusion within the wetland tends to decrease the absorption efficiency, but this effect may be negligible, provided that the optimum flow rate lies well above a certain minimum value, which is derived from the analysis

Coastal lagoon ecosystem modelling

We explore the use of mathematical modelling as a tool for understanding the functioning of lagoons, and address a range of models from those for individual processes through to complex models of ecosystem function. The models have evolved from work on the lagoons of southwestern Australia. We have attempted to understand the influence of man-made changes on the ecology of the natural systems

Copper(II) complexes of three isomeric bis(tacn) ligands: syntheses, structures and properties

Abstract not availableCampbell J. Coghlan, Eva M. Campi, Stuart R. Batten, W. Roy Jackson, Milton T.W. Hear

Efeitos da sacarose e do nitrogénio inorgânico sobre a multiplicação "in vitro" de brotações de porta-enxerto de citros Effects of sucrose and inorganic nitrogen on multiplication of "in vitro" culture of poncirus trifoliata

O presente trabalho objetivou estudar os efeitos da sacarose e do nitrogênio inorgânico (NH4NO3 e KNO3) sobre a multiplicação "in vitro" de Poncirus trifoliata (L.) Raf. Brotos apicais obtidos através de sucessivas repicagens em meio Murashige & Skoog (MS) acrescido de BAP 1,0 mg/l e ANA 1,0 mg/l, foram transferidos para novo meio MS suplementado com as combinações de sacarose (0; 7,5; 15; 30; 45 e 60 g/l) e nitrogênio inorgânico (0; 1/4; 1/2; 1 e 2 MS) dos níveis presentes no meio MS. Os brotos foram mantidos a 2.500 Lux por 16 horas diárias, com temperatura de 27 ± 2°C. Após 45 dias de cultivo, avaliaram-se o número total de brotos e o número de brotos com medidas superiores a 1 cm de comprimento. Observou-se que as doses da sacarose e do nitrogênio inorgânico afetaram as carac-terísticas avaliadas, sendo as melhores respostas obtidas quando se utilizaram concen-trações entre 30 e 45 g/1 da sacarose associadas ao dobro da dose (2 MS) do nitrogênio inorgânico presente no meio MS.<br>It was studied the effects of sucrose and inorganic nitrogen on multiplication of (NH4NO3 and KNO3) "in vitro" culture of Poncirus trifoliata (L.) Raf. Apex buddings from successive multiplications in MS medium added with BAP l.0 mg/l and ANA l.0 mg/l were placed into new MS media where different tested combinations of sucrose (0; 7.5; 15; 30; 45 and 60 g/l) and inorganic nitrogen levels (0 MS; 1/4 MS; 1/2 MS; 1 MS and 2 MS) present in MS medium were tested. The buddings were maintained under the 2,500 lux for 16 daily hours at 27 ± 2°C. After 45 days they were evaluated according characteristics of total number of buds and number of buds higher than 1 cm long. The sucrose and inorganic nitrogen doses affected the rated characteristics. The best responses observed were between 30 to 45 g/l of sucrose associated with double (2 MS) dose of inorganic nitrogen