Transport at basin scales: 1. Theoretical framework

The paper describes the theoretical framework for a class of general continuous models of the hydrologic response including both flow and transport of reactive solutes. The approach orders theoretical results appeared in disparate fields into a coherent theoretical framework for both hydrologic flow and transport. In this paper we focus on the Lagrangian description of the carrier hydrologic runoff and of the processes embedding catchment-scale generation and transport of matter carried by runoff. The former defines travel time distributions, while the latter defines lifetime distributions, here thought of as contact times between mobile and immobile phases. Contact times are assumed to control mass transfer in a well-mixed approximation, appropriate in cases, like in basin-scale transport phenomena, where the characteristic size of the injection areas is much larger than that of heterogeneous features. As a result, we define general mass-response functions of catchments which extend to transport of matter geomorphologic theories of the hydrologic response. A set of examples is provided to clarify the theoretical results towards a computational framework for generalized applications, described in a companion paper. © 2006 Author(s). This work is licensed under a Creative Commons License

Transport at basin scales: 2. Applications

In this paper, the second of a series, we apply the models discussed in Part 1 to a significant case study. The nature of the catchment under study, the transport phenomena investigated (i.e. nitrates moving as solutes within runoff waters) and the scales involved in space and time, provide an elaborate test for theory and applications. Comparison of modeling predictions with field data (i.e. fluxes of carrier flow and solute nitrates) suggests that the framework proposed for geomorphic transport models is capable to describe well large-scale transport phenomena driven and/or controlled by spatially distributed hydrologic fields (e.g. rainfall patterns in space and time, drainage pathways, soil coverage and type, matter stored in immobile phases). A sample MonteCarlo mode of application of the model is also discussed where hydrologic forcings and external nitrate applications (through fertilization) are treated as random processes. © 2006 Author(s). This work is licensed under a Creative Commons License

ACE I/D Gene Polymorphism Can't Predict the Steroid Responsiveness in Asian Children with Idiopathic Nephrotic Syndrome: A Meta-Analysis

The results from the published studies on the association between angiotensin-converting enzyme (ACE) insertion/deletion (I/D) gene polymorphism and the treatment response to steroid in Asian children with idiopathic nephrotic syndrome (INS) is still conflicting. This meta-analysis was performed to evaluate the relation between ACE I/D gene polymorphism and treatment response to steroid in Asian children and to explore whether ACE D allele or DD genotype could become a predictive marker for steroid responsiveness. = 0.85; respectively), however, the result for the association of II genotype with SRNS risk was not stable.Our results indicate that D allele or DD homozygous can't become a significant genetic molecular marker to predict the treatment response to steroid in Asian children with INS

TNFA and IL10 Gene Polymorphisms are not Associated with Periodontitis in Brazilians

IL-10 and TNF-α are cytokines that have complex and opposing roles in the inflammatory responses. G/A polymorphisms at position –1082 of IL10 and –308 of TNFA genes have been reported to influence the expression of IL-10 and TNF-α, respectively. The aim of this study was to investigate the association between the IL10 (-1082) and TNFA (- 308) gene polymorphisms with different clinical forms or severity of periodontitis in a sample of Brazilian individuals. DNA was obtained from oral swabs of 165 Brazilian individuals, which were divided into three groups: individuals with chronic periodontitis, aggressive periodontitis and individuals without clinical evidence of periodontitis. Evaluation of IL10 and TNFA polymorphisms was performed by RFLP analysis. Statistical analysis of data was performed using the χ2 likelihood ratio and Fisher`s exact test. No significant differences in the genotype and allele distribution of either IL10 or TNFA were observed among individuals with different clinical forms or with different degrees of severity of periodontitis. Moreover, combined analysis of IL10 and TNFA polymorphisms did not show any association with periodontal status. As conclusion, the IL10 and TNFA gene promoter polymorphisms investigated are not associated with different clinical forms of periodontitis or with severity of the disease in the Brazilian population polymorphisms

A stochastic model of nitrate transport and cycling at basin scale

A stochastic framework for modelling catchment-scale hydrologic and nitrate responses (as a byproduct of transport processes and of a biogeochemical model of nitrogen cycling and transformations in heterogeneous soils) is proposed and applied to a 53 km2 basin in northeastern Italy, where observational data and complex land-use distribution and geomorphology demand suitable descriptions. The model is based on a geomorphological scheme of the hydrologic response coupled with suitable Lagrangian transport models (mass-response functions) applied in a Montecarlo framework which explicitly addresses the random character of the processes controlling nitrate generation to the hydrologic cycle, and its transformations and transport. This is obtained by coupling the stochastic generation of climatic and rainfall series with the hydrologic and biogeochemical models. Special attention is devoted to the spatial and temporal variability of nitrogen sources of agricultural origin and to the effects of the relative timing and intensity of the forcing rainfall fields on the ensuing nitrate leaching. The influence of random climatic variables on biogeochemical processes affecting the nitrogen cycle in the soil-water system (e.g., plant uptake, nitrification and denitrification, mineralization) is also considered. Besides its conceptual interest, the relevance of the model stems from the capabilities of estimating the return period of nitrate loads to the receiving water body and the probability distribution of the variables computed. We found that the modes of nitrogen injection through fertilization significantly affect the form of probability distribution of nitrate contained in soil moisture even when the total amount is fixed. As a result, the return period of the water volumes discharged and of the nitrate loads released ( in this case into the Venice lagoon) can be linked directly to the ongoing climatic and agricultural regimes, with implications for sustainable management practices. Copyright 2006 by the American Geophysical Union

Transport at basin scales: 1. Theoretical framework

International audienceThe paper describes the theoretical framework for a class of general continuous models of the hydrologic response including both flow and transport of reactive solutes. The approach orders theoretical results appeared in disparate fields into a coherent theoretical framework for both hydrologic flow and transport. In this paper we focus on the Lagrangian description of the carrier hydrologic runoff and of the processes embedding catchment-scale generation and transport of matter carried by runoff. The former defines travel time distributions, while the latter defines lifetime distributions, here thought of as contact times between mobile and immobile phases. Contact times are assumed to control mass transfer in a well-mixed approximation, appropriate in cases, like in basin-scale transport phenomena, where the characteristic size of the injection areas is much larger than that of heterogeneous features. As a result, we define general mass-response functions of catchments which extend to transport of matter geomorphologic theories of the hydrologic response. A set of examples is provided to clarify the theoretical results towards a computational framework for generalized applications, described in a companion paper