Spatially Explicit Analysis of Metal Transfer to Biota: Influence of Soil Contamination and Landscape

Concepts and developments for a new field in ecotoxicology, referred to as “landscape ecotoxicology,” were proposed in the 1990s; however, to date, few studies have been developed in this emergent field. In fact, there is a strong interest in developing this area, both for renewing the concepts and tools used in ecotoxicology as well as for responding to practical issues, such as risk assessment. The aim of this study was to investigate the spatial heterogeneity of metal bioaccumulation in animals in order to identify the role of spatially explicit factors, such as landscape as well as total and extractable metal concentrations in soils. Over a smelter-impacted area, we studied the accumulation of trace metals (TMs: Cd, Pb and Zn) in invertebrates (the grove snail Cepaea sp and the glass snail Oxychilus draparnaudi) and vertebrates (the bank vole Myodes glareolus and the greater white-toothed shrew Crocidura russula). Total and CaCl2-extractable concentrations of TMs were measured in soils from woody patches where the animals were captured. TM concentrations in animals exhibited a high spatial heterogeneity. They increased with soil pollution and were better explained by total rather than CaCl2-extractable TM concentrations, except in Cepaea sp. TM levels in animals and their variations along the pollution gradient were modulated by the landscape, and this influence was species and metal specific. Median soil metal concentrations (predicted by universal kriging) were calculated in buffers of increasing size and were related to bioaccumulation. The spatial scale at which TM concentrations in animals and soils showed the strongest correlations varied between metals, species and landscapes. The potential underlying mechanisms of landscape influence (community functioning, behaviour, etc.) are discussed. Present results highlight the need for the further development of landscape ecotoxicology and multi-scale approaches, which would enhance our understanding of pollutant transfer and effects in ecosystems

A Hybrid Approach With Artificial Neural Networks, Levenberg-marquardt And Simulated Annealing Methods For The Solution Of Gas-liquid Adsorption Inverse Problems

In the present work the inverse problem of gas-liquid interface adsorption isotherm identification is investigated using a combination of an artificial neural network (ANN), and the Levenberg-Marquardt (LM) and the simulated annealing (SA) methods.1718596Özturk, S.S., Schumpe, A., Deckwer, W.D., Organic liquids in a bubble column: Holdups and mass transfer coefficients (1987) AIChE J, 33, pp. 1473-1480Deckwer, W.-R., Schumpe, A., Improved tools for bubble columns reactor design and scale-up (1993) Chem. Eng. Sc, 48, pp. 889-911Graham, D.E., Phillips, M.C., Proteins at liquid interfaces, II. Adsorption isotherms (1979) J. Colloid Interface Sci, 70, pp. 415-426Santana, C.C., Carbonell, R.G., Waste minimization by flotation: Recovery of proteins and other surface-active compounds (1993) 3rd International Conference Waste Management, , Bahia, BrazilC.C. Santana, and R.G. Carbonell, Adsorplive bubble separation as a means of reducing surface-active contaminants in industrial wastewaters, in Proceedings Int. Symp. on Heat and Mass Transfer, Cancun, Mexico, 1993, pp. 1-11Santana, C.C., Adsorplive bubble separation process as a means of reducing surface-active contaminants in industrial wastewaters (1994) Brazilian J. Eng. -Chem, 94, pp. 1-74Krishna, R., van Baten, J.M., Mass transfer in bubble columns (2003) Catalysis Today, 79-80, pp. 67-75Haut, B., Cartage, T., Mathematical modeling of gas-liquid mass transfer rate in bubble columns operated in the heterogeneous regime (2005) Chem. Eng. Sci, 60, pp. 5937-5944Mouza, A.A., Dalakoglou, G.K., Paras, S.V., Effect of liquid properties on the performance of bubble column reactors with fine pore spargers (2005) Chem. Eng. Sci, 60, pp. 1465-1475Lugon Jr., J., (2005) Gas-liquid interface adsorption and one-dimensional porous media drying inverse problems solution, , D.Sc thesis, Universidade do Estado do Rio de Janeiro in PortugueseForssén, P., Arnell, R., Fornstedt, T., An improved algorithm for solving inverse problems in liquid chromatographv (2006) Comp. Chem. Eng, 30, pp. 1381-1391Gamier, C., Görner, T., Villiéras, F., De Donato, P., Polakovic, M., Bersillon, J.-L., Michot, L.J., Activated carbon surface heterogeneity seen by parallel probing by inverse liquid chromatography at the solid/liquid interface and by gas adsorption analysis at the solid/gas interface (2007) Carbon, 45, pp. 240-247Voelkel, A., Strzemiecka, B., Characterization of fillers used in abrasive articles by means of inverse gas chromatography and principal components analysis (2007) Int. J. Adhesion Adhesives, 27, pp. 188-194Ahmad, T., Guiochon, G., Numerical determination of the adsorption isotherms of tryptophan at different temperatures and mobile phase composition (2007) J. Chromatogr. A, 1142, pp. 148-163Silva Neto, A.J., Soeiro, F.J.C.P., Solution of implicitly formulated inverse heat transfer problems with hybrid methods (2003) Mini-Symposium Inverse Problems from Thermal/Fluids and Solid Mechanics Applications - 2nd MIT Conference on Computational Fluid and Solid Mechanics, , Cambridge, USASilva Neto, A.J., Moura Neto, F.D., (2005) Inverse Problems: Fundamental Concepts and Applications, , EdUERJ, Rio de Janeiro, in PortugueseDowding, K.J., Blackwell, B.F., Cochran, R.J., Applications of sensitivity coefficients for heat conduction problems (1999) Num. Heat Trans, 36 (PART B), pp. 33-55Beck, J.V., Combined parameter and function estimation in heat transfer with application to contact conductance (1988) J. Heat Trans, 110, pp. 1046-1058Haykin, S., (1999) Neural Networks - A Comprehensive Foundation, , Prentice Hall, New JerseySoeiro, F.J.C.P., Soares, P.O., Campos Velho, H.F., Silva Neto, A.J., Using neural networks to obtain initial estimates for the solution of inverse heat transfer problems (2004) Proc. Inverse Prob., Design and Opt. Symp, 1, pp. 358-363. , Rio de Janeiro, BrazilSoeiro, F.J.C.P., Scares, P.O., Silva Neto, A.J., Solution of inverse radiative transfer problems with artificial neural networks and hybrid methods (2004) Proceedings 13th Inverse Problems in Engineering Seminar, pp. 163-169. , Cincinnati, USAMarquardt, D.W., An algorithm for least-squares estimation of nonlinear parameters (1963) J. Soc. Industr. Appl. Math, 11, pp. 431-441Metropolis, N., Rosenbluth, A.W., Rosenbluth, M.N., Teller, A.H., Teller, E., Equation of state calculations by fast computing machines (1953) J. Chem. Phys, 21, pp. 1087-109

Study of flood quotas in urban channels of small hydrographic basins, close to estuarine areas, under tidal effect

This paper presents the results generated by a hydrodynamic model applied to the Capote Channel in the urban area of Macaé / RJ. It also evaluates the flooding resulting from rainfall peaks in the micro-basin and spring tides in its estuary. The software used in the investigation includes a four-point implicit algorithm to complete resolution of Saint-Venant equations by finite difference method, with approximations to both derivations: time and space, originated from continuity and momentum. The solution to the flow rate and increase of the liquid surface was obtained for times and incremental distances along the channel. From the top-bathymetric information available, a digital terrain model was built and calibrated by measuring the limnimetric variations of the channel and flows, as well as by comparing the observed and simulated data for the conditions of peaks and troughs. The models simulated different scenarios, with special emphasis on those generated under high flow regime as they represent the most critical situation from an environmental approach and aim of this work. Results showed that, for these conditions, important areas close to that channel will be flooded

Mineral metabolism, bone histomorphometry and vascular calcification in alternate night nocturnal haemodialysis

Background: Poor control of bone mineral metabolism (BMM) is associated with renal osteodystrophy and mortality in dialysis-dependent patients. The authors explored the efficacy of alternate nightly home haemodialysis (ANHHD) in controlling BMM parameters and its effects on bone mineral density and histomorphometry. Methods: In this prospective observational study, 26 patients on home haemodialysis (3-5 h, 3.5-4 sessions weekly) were converted to ANHHD (6-9 h, 3.5-4 sessions weekly). Biochemical parameters of BMM at baseline, 6 and 12 months, radiological parameters at baseline and 12 months and bone histomorphometry at 12 months are described. Results: Pre-dialysis serum phosphate fell from 2.13 ± 0.65 to 1.38 ± 0.35 mmol/L; P 1000 ng/L) did not significantly improve parathyroid hormone status. Abnormal bone turnover and mineralization were present in a significant proportion of patients at 12 months but low turnover was uncommon. Vascular calcification was stabilized or improved in the majority. ANHHD compares favourably with every night and short daily therapy in relation to BMM management and may offer lifestyle advantages for patients