An easily implemented agro-hydrological procedure with dynamic root simulation for water transfer in the crop-soil system: validation and application

Models for water transfer in the crop-soil system are key components of agro-hydrological models for irrigation, fertilizer and pesticide practices. Many of the hydrological models for water transfer in the crop-soil system are either too approximate due to oversimplified algorithms or employ complex numerical schemes. In this paper we developed a simple and sufficiently accurate algorithm which can be easily adopted in agro-hydrological models for the simulation of water dynamics. We used a dual crop coefficient approach proposed by the FAO for estimating potential evaporation and transpiration, and a dynamic model for calculating relative root length distribution on a daily basis. In a small time step of 0.001 d, we implemented algorithms separately for actual evaporation, root water uptake and soil water content redistribution by decoupling these processes. The Richards equation describing soil water movement was solved using an integration strategy over the soil layers instead of complex numerical schemes. This drastically simplified the procedures of modeling soil water and led to much shorter computer codes. The validity of the proposed model was tested against data from field experiments on two contrasting soils cropped with wheat. Good agreement was achieved between measurement and simulation of soil water content in various depths collected at intervals during crop growth. This indicates that the model is satisfactory in simulating water transfer in the crop-soil system, and therefore can reliably be adopted in agro-hydrological models. Finally we demonstrated how the developed model could be used to study the effect of changes in the environment such as lowering the groundwater table caused by the construction of a motorway on crop transpiration. (c) 2009 Elsevier B.V. All rights reserved.

Water transfer from São Francisco river to semiarid northeast of Brazil: technical data, environmental impacts, survey of opinion about the amount to be transferred

The transposition of the São Francisco River is considered one of the greatest engineering works in Brazil of all time since it will cross an extensive agricultural region of continental dimensions, involving environmental impacts, water, soil, irrigation, water payment and other multidisciplinary themes. Taking into account its importance, this subject was incorporated into a discipline of UFSCar (Federal University of São Carlos - Brazil) named "Pollution and Environmental Impacts". It was noted strong reaction against the project, even before the presentation. To allow a critical analysis, the first objective was to compile the main technical data and environmental impacts. The second objective was to detect the three most important aspects that cause reaction, concluding for the following reasons: assumption that the volume of water to be transferred was much greater than it actually is proposed in the project; lack of knowledge about similar project already done in Brazil; the idea that the artificial canal to be built was much broader than that proposed by the project. The participants' opinion about "volume to be transferred" was raised quantitatively four times: 2-undergraduate students; 1-graduate; 1-outside community. The average resulted 14 times larger than that proposed in the project, significant according to t-test. It was concluded that the reaction to water transfer project is due in part to the ignorance combined with a preconceived idea that tend to overestimate the magnitude of environmental impacts.

Incorporation of water vapour transfer in the JULES Land Surface Model: implications for key soil variables and land surface fluxes

This study focuses on the mechanisms underlying water and heat transfer in upper soil layers, and their effects on soil physical prognostic variables and the individual components of the energy balance. The skill of the JULES (Joint UK Land Environment Simulator) land surface model (LSM) to simulate key soil variables, such as soil moisture content and surface temperature, and fluxes such as evaporation, is investigated. The Richards equation for soil water transfer, as used in most LSMs, was updated by incorporating isothermal and thermal water vapour transfer. The model was tested for three sites representative of semi-arid and temperate arid climates: the Jornada site (New Mexico, USA), Griffith site (Australia) and Audubon site (Arizona, USA). Water vapour flux was found to contribute significantly to the water and heat transfer in the upper soil layers. This was mainly due to isothermal vapour diffusion; thermal vapour flux also played a role at the Jornada site just after rainfall events. Inclusion of water vapour flux had an effect on the diurnal evolution of evaporation, soil moisture content and surface temperature. The incorporation of additional processes, such as water vapour flux among others, into LSMs may improve the coupling between the upper soil layers and the atmosphere, which in turn could increase the reliability of weather and climate predictions.

Investigation of young water inflow in karst aquifers using SF6–CFC–3H/He–85Kr–39Ar and stable isotope components

Karst aquifers are known for their wide distribution of water transfer velocities. From this observation, a multiple geochemical tracer approach seems to be particularly well suited to provide a significant assessment of groundwater flows, but the choice of adapted tracers is essential. In this study, several common tracers in karst aquifers such as physicochemical parameters, major ions, stable isotopes, and d13C to more specific tracers such as dating tracers – 14C, 3H, 3H–3He, CFC-12, SF6 and 85Kr, and 39Ar – were used, in a fractured karstic carbonated aquifer located in Burgundy (France). The information carried by each tracer and the best sampling strategy are compared on the basis of geochemical monitoring done during several recharge events and over longer time periods (months to years). This study’s results demonstrate that at the seasonal and recharge event time scale, the variability of concentrations is low for most tracers due to the broad spectrum of groundwater mixings. The tracers used traditionally for the study of karst aquifers, i.e., physicochemical parameters and major ions, efficiently describe hydrological processes such as the direct and differed recharge, but require being monitored at short time steps during recharge events to be maximized. From stable isotopes, tritium, and Cl� contents, the proportion of the fast direct recharge by the largest porosity was estimated using a binary mixing model. The use of tracers such as CFC-12, SF6, and 85Kr in karst aquifers provides additional information, notably an estimation of apparent age, but they require good preliminary knowledge of the karst system to interpret the results suitably. The CFC-12 and SF6 methods efficiently determine the apparent age of baseflow, but it is preferable to sample the groundwater during the recharge event. Furthermore, these methods are based on different assumptions such as regional enrichment in atmospheric SF6, excess air, and flow models among others. 85Kr and 39Ar concentrations can potentially provide a more direct estimation of groundwater residence time. Conversely, the 3H–3He method is inefficient in the karst aquifer for dating due to 3He degassing.

How federal policies affect the allocation of water /

"August 2006."

Nebraska water service extension : report (to accompany S. 891).

"October 27, 2005."

Barriers to Temporary Inter‐District Water Transfers in the Yakima River Basin: Irrigation District Perspective

Water marketing, or mechanisms to acquire and redistribute water such as temporary water transfers, can represent a valuable response to drought for irrigation districts. The Department of Ecology, the US Bureau of Reclamation, and a workgroup composed of members from various entities collaborated to develop the Yakima River Basin Integrated Water Resource Management Plan (Integrated Plan) to better manage water resources and address ecosystem issues in the Yakima River Basin. The Integrated Plan addresses water marketing but it does not provide specifics on how barriers to inter‐district water transfers will be eliminated. This study asks irrigation district managers in the Yakima River basin about the factors they consider when deciding whether to engage in a temporary inter‐district water transfer or not. Results show that institutional barriers are the most common barrier to inter‐district water transfers. This topic requires further research on fallowing and irrigation district behavior in relation to the other water supply efforts outlined in the Integrated Plan. Finally, the water market in the Yakima basin can benefit from education and outreach to senior water rights holders, shortening the time frame to process expedited transfers, and documentation from irrigation districts reporting denial reasons for temporary inter‐district water transfers.

(Table 1) Water column silicic acid concentrations and Si isotopic composition during Marion Dufresne cruise MD166 off South Africa

Silicon isotopic signatures (d30Si) of water column silicic acid (Si(OH)4) were measured in the Southern Ocean, along a meridional transect from South Africa (Subtropical Zone) down to 57° S (northern Weddell Gyre). This provides the first reported data of a summer transect across the whole Antarctic Circumpolar Current (ACC). d30Si variations are large in the upper 1000 m, reflecting the effect of the silica pump superimposed upon meridional water transfer across the ACC: the transport of Antarctic surface waters northward by a net Ekman drift and their convergence and mixing with warmer upper-ocean Si-depleted waters to the north. Using Si isotopic signatures, we determine different mixing interfaces: the Antarctic Surface Water (AASW), the Antarctic Intermediate Water (AAIW), and thermoclines in the low latitude areas. The residual silicic acid concentrations of end-members control the d30Si alteration of the mixing products and with the exception of AASW, all mixing interfaces have a highly Si-depleted mixed layer end-member. These processes deplete the silicic acid AASW concentration northward, across the different interfaces, without significantly changing the AASW d30Si composition. By comparing our new results with a previous study in the Australian sector we show that during the circumpolar transport of the ACC eastward, the d30Si composition of the silicic acid pools is getting slightly, but significantly lighter from the Atlantic to the Australian sectors. This results either from the dissolution of biogenic silica in the deeper layers and/or from an isopycnal mixing with the deep water masses in the different oceanic basins: North Atlantic Deep Water in the Atlantic, and Indian Ocean deep water in the Indo-Australian sector. This isotopic trend is further transmitted to the subsurface waters, representing mixing interfaces between the surface and deeper layers. Through the use of d30Si constraints, net biogenic silica production (representative of annual export), at the Greenwich Meridian is estimated to be 5.2 ± 1.3 and 1.1 ± 0.3 mol Si/m**2 for the Antarctic Zone and Polar Front Zone, respectively. This is in good agreement with previous estimations. Furthermore, summertime Si-supply into the mixed layer of both zones, via vertical mixing, is estimated to be 1.6 ± 0.4 and 0.1 ± 0.5 mol Si/m**2, respectively.

An engineering model of the human colon

The development and performance of a three-stage tubular model of the large human intestine is outlined. Each stage comprises a membrane fermenter where flow of an aqueous polyethylene glycol solution on the outside of the tubular membrane is used to control the removal of water and metabolites (principally short chain fatty acids) from, and thus the pH of, the flowing contents on the fermenter side. The three stage system gave a fair representation of conditions in the human gut. Numbers of the main bacterial groups were consistently higher than in an existing three-chemostat gut model system, suggesting the advantages of the new design in providing an environment for bacterial growth to represent the actual colonic microflora. Concentrations of short chain fatty acids and Ph levels throughout the system were similar to those associated with corresponding sections of the human colon. The model was able to achieve considerable water transfer across the membrane, although the values were not as high as those in the colon. The model thus goes some way towards a realistic simulation of the colon, although it makes no pretence to simulate the pulsating nature of the real flow. The flow conditions in each section are characterized by low Reynolds numbers: mixing due to Taylor dispersion is significant, and the implications of Taylor mixing and biofilm development for the stability, that is the ability to operate without washout, of the system are briefly analysed and discussed. It is concluded that both phenomena are important for stabilizing the model and the human colon.

Trophallaxis in Dehydrated Leaf Cutting Colonies of Atta sexdens rubropilosa (Hymenoptera: Formicidae)

Trophallaxis, the transfer of liquid among individuals by oral regurgitation or anal deposition, occurs in many insect groups including ants. The first indication that trophallaxis could occur in leaf cutting ants (Atta sexdens rubropilosa) was made by Autuori in 1942. He reported water collection by this ant species, and highlighted what in those days was an undescribed behavior for this species. In 2005, Da-Silva and Ribeiro presented preliminary results suggesting the existence of trophallaxis in A. sexdens rubropilosa. Here we report on a formal test of the hypothesis of trophallaxis in that species. Our approach was to test ant pairs in which only one individual (Group I) had access to blue-dyed water and the other individual (Group II), a nest-mate, came from a colony dehydrated by offering dry crushed corn for fungal growth. Positive results for trophallaxis were obtained in ants from four colonies and accounted for 33%-46% of all tests in which ants from Group I drank dyed water. These results indicate that trophallaxis occurs in this species.

Sistemática integrativa de Cichlasoma orientale Kullander 1983 e Crenicichla menezesi Ploeg 1991 (Teleostei: Cichlidae) das bacias hidrográficas do Nordeste do Brasil

Understanding the historical and ecological relationships which are influent in current biological diversity is one of the most challenging tasks of evolutionary biology. Recent systematics emphasizes the need of integrative approaches to delimit different lineages and species. The northeastern Brazil, mostly placed in Caatinga biome, is characterized by a semi-arid weather, low precipitation and seasonal behavior of rivers. This region is regarded lacking as ichthyological knowledge and one of the most threatened by anthropic activities. Further, will be affected by a massive water diverpsion work that will transfer waters from São Francisco basin, to other major four basins: Jaguaribe, Apodi-Mossoró, Piranhas-Açu and Paraiba do Norte. Loss of diversity and richness, hibridizitation, community interactions changes, population homogenization, changes in water quality and flow regime, are examples of environmental impacts already related with similar works. The present study aims to investigate morphological and molecular variation of Cichlasoma orientale Kullander 1983 and Crenicichla menezesi Ploeg 1991, two cichlid species present in northeastern Brazil basins. Further, the study aims to evaluate the influence of geomorphological and climatic processes in this variation, and point some possible impacts of the artificial connectivity which can be brought by São Francisco interbasin water transfer to their population dynamics. Geometric morphometrics and phylogeographical analysis were used to investigate the populations from three different hydrological regions. Our results showed a significant morphological variation of populations from basins that are involved in the São Franscisco s diversion project, not related to an ancient separation between populations, emphasizing morphological variation which could represent a set of plastic responses to the variable hydrological regime in Northeastern Brazil. The role of plastical responses in naturally variable habitats as well as the potential disturbs that could be brought by the interbasin water transfer works are discussed here. Further, our molecular data allowed us to make inferences about species distribution and their taxonomy, and identification of a potential new species of Crenicichla for São Francisco river basin. Our data also allowed to identify some shared haplotypes for both species, which could be related to lineage sorting scenarios or recent gene flow between populations. However a strong structure in most of the pairwise comparisons between populations for both species was revealed. Climatic events such as Atlantic forest regression during the Pleistocene, sea level fluctuations and dispersion by paleorivers in the mouth of Apodi-Mossoró river, and neotectonic events regulating the connection between drainages are likely to have had a contribution for the actual lineages distribution in northeastern Brazil. Further, analysis of molecular variation (AMOVA and SAMOVA) showed that the actual basin s isolation is an important factor to molecular variation, in spite of the signal of recent contact between some basins. Different genetic diversity patterns between species could be related to multiple historic events of colonization, basins landscapes or biological differences. The present study represents the first effort of integrative systematics involving fish species of northeastern Brazil, and showed important morphological and molecular patterns which could be irrecoverably affected by the artificial connection that might be caused by the São Francisco interbasin water transfer

Structure of the Lining Epithelium of the Cauda Epididymis of the Golden Hamster

The ductus epididymis has roles in the maturation and storage of spermatozoa. The main function of the cauda epididymis is the storage of spermatozoa; however, this region exerts other morphophysiological roles. So, this study was aimed at investigating structural features of the cauda epididymis epithelium, which could indicate roles other than the storage. The relative percentages of the cell types in the epithelium were 74.9, 6.9, 12.5 and 5.6% of principal, clear, basal and halo cells respectively. Large intercellular spaces were seen among the lateral plasmatic membranes of adjacent principal cells or among these cells and others cell types. These spaces were found to be filled with multivesicular bodies, myelin figures, scrolls and debris of membranes or flocculent dense material. Clear cells had the cytoplasms filled with lysosomes (3/4 of basal cytoplasm), and vacuoles and vesicles (1/4 of apical cytoplasm). The observations allowed us to infer that clear cells could act in the process of endocytosis and also in water transfer from the lumen to the interstitium through the epithelium compartment. Moreover, transcytosis may occur at the cauda epididymis of Golden hamster.

A transposição das águas do rio São Francisco para o nordeste nos jornais do Rio Grande do Norte e São Paulo: um estudo enunciativo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)