bluuebunny/crossref_metadata_2025 huggingface dataset:
Developing a Mini Core Collection of Sorghum for Diversified Utilization of Germplasm
Authors: Upadhyaya H. D. , Pundir R. P. S. , Dwivedi S. L. , Gowda C. L.L. , Reddy V. G. , Singh S.
Published: August 2009

The sorghum [Sorghum bicolor (L.) Moench] germplasm collection at the ICRISAT gene bank exceeds 37,000 accessions. A core collection of 2247 accessions was developed in 2001 to enable researchers to have access to a smaller set of germplasm. However, this core collection was found to be too large. To overcome this, a sorghum mini core (10% accessions of the core or 1% of the entire collection) was developed from the existing core collection. The core collection was evaluated for 11 qualitative and 10 quantitative traits in an augmented design using three control cultivars in the 2004–2005 post‐rainy season. The hierarchical cluster analysis of data using phenotypic distances resulted in 21 clusters. From each cluster, about 10% or a minimum of one accession was selected to form a mini core that comprised 242 accessions. The data in the mini core and core collections were compared using statistical parameters such as homogeneity of distribution for geographical origin, biological races, qualitative traits, means, variances, phenotypic diversity indices, and phenotypic correlations. These tests revealed that the mini core collection represented the core collection, which can be evaluated extensively for agronomic traits including resistance to biotic and abiotic stresses to identify accessions with desirable characteristics for use in crop improvement research and genomic studies.
Interactions between 2‐Aminobenzothiazole and Natural Organic Matter as Evidenced by CPMAS Nitrogen‐15 NMR Spectroscopy
Authors: Berns A. E. , Conte P. , Philipp H. , Witte E. G. , Lewandowski H.
Published: August 2009

Cross‐polarization magic angle spinning (CPMAS) 15N nuclear magnetic resonance (NMR) spectroscopy was used to study the interactions between 2‐aminobenzothiazole (ABT) and natural organic matter in the presence of the natural enzyme laccase and synthetic air. Through the use of synthesized model compounds, we were able to confirm previous findings by CPMAS 13C NMR spectroscopy that showed the formation of covalent amide bonds. We also provide evidence of the presence of two additional H bonds between ABT and the natural organic matter. Both H bonds involved the amino and thiazole groups of ABT.
Noninvasive 3‐D Transport Characterization in a Sandy Soil Using ERT: 1. Investigating the Validity of ERT‐derived Transport Parameters
Authors: Koestel J. , Vanderborght J. , Javaux M. , Kemna A. , Binley A. , Vereecken H.
Published: August 2009

We used time‐lapse electrical resistivity tomography (ERT) and time‐domain reflectometry (TDR) probes to noninvasively capture three‐dimensional solute transport during four tracer experiments under different steady‐state irrigation rates in a large unsaturated undisturbed soil column (140 cm length and 116 cm inner diameter). The transport was characterized by means of apparent convection–dispersion parameters that were derived from breakthrough curves (BTCs) at different lateral scales: the ERT voxel scale, the sampling volume of TDR, and the cross‐section of the column. We validated the ERT‐derived data by means of mass balance, TDR probes, and the effluent BTC. We observed an excellent mass recovery by ERT. The ERT‐derived transport velocities exhibited minimal bias and high precision at the scale of the TDR measurements. On average the ERT‐derived column‐scale transport velocities were also not biased; however, the spatial variability of the voxel‐scale velocities within the column's cross‐sections underestimated the true velocity variability. In contrast to the transport velocities, the ERT‐derived dispersivities exhibited a large bias and low precision and were sensitive to temporal smoothing. Unlike previous studies, we did not find evidence that the ERT‐derived voxel‐scale dispersivities increase with decreasing ERT sensitivity. Although ERT provided unprecedented information about transport processes, resolution and uncertainty analyses remain important issues requiring further investigation.
Inverse Modeling of Pesticide Leaching in Lysimeters: Local versus Global and Sequential Single‐Objective versus Multiobjective Approaches
Authors: Mertens Jan , Kahl Gunnar , Gottesbüren Bernhard , Vanderborght Jan
Published: August 2009

This study used field lysimeter leachate and pesticide concentration data within an inverse modeling framework to estimate pesticide degradation and sorption parameters. Experimental data comprising four pesticide applications during 3 yr were used to compare a local parameter estimation algorithm (Levenberg–Marquardt, LM) with a global algorithm (Shuffled Complex Evolution Metropolis, SCEM). Good model fits (only marginally better model fits using SCEM) with respect to both the observed leachate volumes and corresponding pesticide concentrations were obtained using both algorithms. Parameter optima found with LM and SCEM were very similar, thus suggesting that LM correctly located the global optimum for our experimental data. Equally as important as the optimal parameter values, however, are the estimated parameter uncertainties. This study revealed that LM (using a Jacobian‐based approach) provided too large parameter uncertainties. A logarithmic transformation of the parameter tended to decrease the uncertainty in most cases. The overestimation of parameter uncertainty by LM suggests that model sensitivity close to the optimal parameter set was relatively small and underestimated the sensitivity to large parameter changes. A multiobjective Pareto analysis was subsequently compared with a sequential single‐objective approach to reveal the capability of the multiobjective approach to verify model structure and model concept. Our results indicate that a multiobjective SCEM approach is recommended when the objective is to estimate pesticide degradation and sorption parameters and their uncertainty.
A Fast Field Cycling Nuclear Magnetic Resonance Relaxometry Study of Natural Soils
Authors: Pohlmeier A. , Haber-Pohlmeier S. , Stapf S.
Published: August 2009

This study used nuclear magnetic resonance (NMR) relaxometry at different Larmor frequencies to investigate water dynamics in the pore space of natural porous media. Spin‐lattice NMR relaxation times (T1) were determined in purified fine sand and two natural soils, Kaldenkirchen sandy loam and Merzenhausen silt loam, by means of fast field cycling relaxometry. This technique investigates relaxation processes as a function of the Larmor frequency ν in the range between 0.005 and 20 MHz, yielding so‐called relaxation dispersion curves (1/T1vs. log ν). The data were further analyzed by means of inverse Laplace transformation to calculate theT1relaxation time distribution functions. Only the fine sand was characterized by monomodal distribution withT1of about 1 s at 20 MHz, whereas the natural soil samples showed multimodal distribution functions in the range between 2 and 70 ms. With decreasing Larmor frequency, all distribution functions kept their shapes but were shifted to faster relaxation times. The corresponding relaxation dispersion curves indicate predominance of two‐dimensional diffusion of water in the soils, whereas in the macroporous sand, diffusion behaved like unrestricted three‐dimensional diffusion. In terms of the Brownstein–Tarr model, the decrease in theT1relaxation times with increasing silt and clay content can be explained by an increase of the surface/volume ratios (S/V) of these porous media, i.e., by a decrease in the pore sizes. Finally, distribution functions of the pore size parameterV/Swere obtained from the spin‐lattice relaxation time distributions by normalizing on the specific surface area. They ranged from submicrometers in the Merzenhausen soil to micrometers and submillimeters in the Kaldenkirchen soil and fine sand, respectively.
Multistep Outflow Experiments to Determine Soil Physical and Carbon Dioxide Production Parameters
Authors: Weihermüller L. , Huisman J. A. , Graf A. , Herbst M. , Sequaris J.-M.
Published: August 2009

Soil water content (SWC) plays a crucial role in the production and transport of CO2 in soils. Classical approaches estimating the effects of SWC on soil respiration are incubation experiments, where soil structure is disturbed and transport processes are neglected. Nevertheless, such data govern the water reduction function of C turnover models. In our approach, the water reduction control parameters (WRCP) of a water reduction function were estimated from column experiments using inverse modeling. Therefore, we used the SOILCO2–RothC model in combination with multistep outflow (MSO) experiments. First, the effective hydraulic properties were estimated and then used in a second experiment to estimate the WRCP and rate constants of the resistant plant material (RPM) C pool. The results showed that the estimated hydraulic parameters can be used for the prediction of CO2 production and transport of a second MSO experiment only if the WRCP and the C turnover rate of the RPM pool of RothC will also be optimized. Optimizing only the WRCP matched the CO2 efflux fairly well but the WRCP at the highest matric potential, which determines the start of reduction, was too low at −1.61 cm and (water‐filled pore space [WFPS] = 99.9%). Calibrating both WRCP and the RPM rate constant matched the efflux again fairly well and the results indicate a reduction of optimal CO2 production at water contents of 0.224 m3 m−3 or 53.3% WFPS. Also, the estimated RPM rate constant seems to be in a reasonable range at kRPM = 2.5791 × 10−7 cm−1.
Characterization and Understanding of Bare Soil Respiration Spatial Variability at Plot Scale
Authors: Herbst M. , Prolingheuer N. , Graf A. , Huisman J. A. , Weihermüller L. , Vanderborght J.
Published: August 2009

Soil respiration is known to be highly variable with time. Less is known, however, about the spatial variability of heterotrophic soil respiration at the plot scale. We simultaneously measured soil heterotrophic respiration, soil temperature, and soil water content at 48 locations with a nested sampling design and at 76 locations with a regular grid plus refinement within a 13‐ by 14‐m bare soil plot for 15 measurement dates. Soil respiration was measured with a closed chamber covering a surface area of 0.032 m2 A geostatistical data analyses indicated a mean range of 2.7 m for heterotrophic soil respiration. We detected rather high coefficients of variation of CO2 respiration between 0.13 and 0.80, with an average of 0.33. The number of observations required to estimate average respiration fluxes at a 5% error level ranged between 5 and 123. The analysis of the temporal persistence revealed that a subset of 17 sampling locations is sufficient to estimate average respiration fluxes at a tolerable root mean square error of 0.15 g C m−2 d−1 Statistical analysis revealed that the spatiotemporal variability of heterotrophic soil respiration could be explained by the state variables soil temperature and water content. The spatial variability of respiration was mainly driven by variability in soil water content; the variability in the soil water content was almost an order of magnitude higher than the variability in soil temperature.
Implementation of a Microscopic Soil–Root Hydraulic Conductivity Drop Function in a Three‐Dimensional Soil–Root Architecture Water Transfer Model
Authors: Schröder Tom , Javaux Mathieu , Vanderborght Jan , Körfgen Bernd , Vereecken Harry
Published: August 2009

To understand how water uptake locally affects and is affected by the soil water distribution, three‐dimensional soil–root models need to be developed. Nowadays, fully coupled three‐dimensional soil–root flow models at the plant scale are available that simulate water flow along water potential gradients in the soil–root continuum, but the problems that arise by the coupling of soil and root have not been investigated thoroughly. In a previous work, we introduced and numerically validated a microscopic model to be used on a coarse numerical soil grid, describing the hydraulic conductivity drop between the bulk soil and the soil–root interface within a voxel of a three‐dimensional soil–root model. In this study, the impact of the local hydraulic conductivity drop on denser root architectures and in drier soil regions was assessed. When a coarse discretization of the soil grid is used, the local hydraulic conductivity drop has a significant effect on the water potential distribution at the soil–root interface and in the xylem, especially under conditions near plant stress where the local soil conductivity is lower than the radial root conductivity regulating root water uptake. As a consequence, plant stress conditions will be reached earlier than if the local conductivity drop within a soil voxel is neglected. In comparison with a fine soil discretization, the soil water potential gradient calculated by including the local conductivity drop at a coarser discretization does not fit the soil water potential gradient resulting from the fine soil discretization. Estimation of accurate water potential gradients throughout the soil requires a fine soil discretization.
Transport of Manure‐Based Applied Sulfadiazine and Its Main Transformation Products in Soil Columns
Authors: Unold M. , Šimůnek J. , Kasteel R. , Groeneweg J. , Vereecken H.
Published: August 2009

Solute displacement experiments with the antibiotic sulfadiazine (SDZ) and its main transformation products in pig manure were performed to investigate the influence of manure on SDZ transport. Either pig manure containing 14C‐sulfadiazine (4‐amino‐N‐2‐pyrimidinyl‐benzenesulfonamide), and its main transformation products 14C‐4‐OH‐SDZ and 14C‐N‐Ac‐SDZ, or a 14C‐SDZ solution was incorporated in the first centimeter of undisturbed and repacked soil columns, which were then irrigated. Breakthrough curves (BTCs) of 14C, SDZ, 4‐OH‐SDZ, N‐Ac‐SDZ and 4‐[2‐iminopyrimidine‐1(2H)‐yl]‐anilin were measured. The 14C distributions vs. depths were determined after the conclusion of the leaching experiments. An application of SDZ together with manure resulted in lower peak values of the 14C BTCs and a slightly lower amount of eluted mass. In the experiments with manure, the 14C concentrations in the uppermost layers of the soil columns were higher, probably due to the filtration of manure particles onto which SDZ or its transformation products were sorbed. The transformation products showed a relatively high leaching potential similar to SDZ. Cotransport with organic particles seemed to be of minor relevance for the eluted amounts of solutes. All BTCs were modeled using a numerical model that considered degradation chains from N‐Ac‐SDZ into SDZ and from SDZ into 4‐OH‐SDZ, as well as one reversible and one irreversible kinetic sorption site for each solute. The applied model fitted the BTCs of SDZ and its transformation products reasonably well. The fitting process revealed a high mobility of both SDZ and its transformation products. While N‐Ac‐SDZ degradation into SDZ was fast and no extended tailing of N‐Ac‐SDZ was observed, the transport behavior of 4‐OH‐SDZ was similar to that of SDZ.
Development of an Automated Tension Infiltrometer for Field Use
Authors: Špongrová Kamila , Kechavarzi Cedric , Dresser Marc , Matula Svatopluk , Godwin Richard J.
Published: August 2009

Tension infiltrometry is a useful in situ technique that is commonly used to determine hydraulic conductivity of the soil near saturation; however, the measurements are time consuming and costly. The aim of this study was to develop a fully automated tension infiltrometer for field use based on already existing designs. Differential pressure transducers were used to automate water level measurements, and the tension settings were automated by a set of solenoid valves. The effects of different design parameters on water level measurement fluctuations created by bubble disturbances (noise) were studied in the laboratory. The differential transducer provided less noisy measurements than the single transducer. The measurement noise was significantly smaller when a large‐diameter reservoir was used. The measurement noise was further reduced by using a reservoir system made of two tubes of different diameters slotted into each other. The effect of an increasing flow rate on the water level fluctuations was also investigated. Based on the design parameters tested, three identical tension infiltrometers connected to a single Mariotte bottle were built and tested under laboratory and field conditions. The pressure‐dependent hydraulic conductivity, K(h), values for all three replicates applied in the laboratory did not significantly differ from each other. In the field, the infiltration experiments were performed on a sandy loam soil on sites with and without wheel tracks. A significant reduction of K(h) values for most of the applied pressure heads was observed in the wheel track. The improved automated tension infiltrometer requires only a little operator intervention.
Hybrid Wireless Underground Sensor Networks: Quantification of Signal Attenuation in Soil
Authors: Bogena H. R. , Huisman J. A. , Meier H. , Rosenbaum U. , Weuthen A.
Published: August 2009

Wireless sensor network technology allows real‐time soil water content monitoring with a high spatial and temporal resolution for observing hydrological processes in small watersheds. The novel wireless soil water content network SoilNet uses the low‐cost ZigBee radio network for communication and a hybrid topology with a mixture of underground end devices each wired to several soil sensors and aboveground router devices. Data communication between the end and router devices occurs partially through the soil, and this causes concerns with respect to the feasibility of data communication due to signal attenuation by the soil. In this study, we determined the impact of soil depth, soil water content, and soil electrical conductivity on the signal transmission strength of SoilNet. In a first step, we developed a laboratory experimental setup to measure the impact of soil water content and bulk electrical conductivity on signal transmission strength. The laboratory data were then used to validate a semi‐empirical model that simulates signal attenuation due to soil adsorption and reflection and transmission at the soil boundaries. With the validated model, it was possible to show that in the case of a soil layer of 5 cm, sufficient power will remain to ensure data communication over longer distances for most soil conditions. These calculations are fairly simplified and should be considered as a first approximation of the impact of attenuation. In actual field situations, signal transmission may be more complex. Therefore, a field evaluation of signal attenuation is a crucial next step.
Research at the Agrosphere Institute: From the Process Scale to the Catchment Scale
Authors: Vereecken H. , Burauel P. , Groeneweg J. , Klumpp E. , Mittelstaedt W. , Narres H.-D. , Pütz T. , van der Kruk J. , Vanderborght J. , Wendland F.
Published: August 2009

Global change is increasingly affecting our terrestrial ecosystem, including the filtering and buffering capacity of soils, the supply of clean water, and the production of food, feed, and fiber. This article introduces a portfolio of papers in a special section of Vadose Zone Journal addressing flow, transport and biogeochemical processes of terrestrial ecosystems. The articles document research at the Agrosphere Institute, Forschungszentrum Jülich, Germany. They are organized along three major themes of research at Agrosphere: functional analysis of soils and sediments, development of sensing methods to explore terrestrial systems, and modeling of flow and transport processes of terrestrial systems.
When Roots Lose Contact
Authors: Carminati Andrea , Vetterlein Doris , Weller Ulrich , Vogel Hans-Jörg , Oswald Sascha E.
Published: August 2009

It has been speculated that during periods of water deficit, roots may shrink and lose contact with the soil, with a consequent reduction in root water uptake. Due to the opaque nature of soil, however, this process has never been observed in situ for living plants. Through x‐ray tomography and image analysis, we have demonstrated the formation and dynamics of air gaps around roots. The high spatial resolution required to image the soil–root gaps was achieved by combining tomography of the entire sample (field of view of 16 by 16 cm, pixel side 0.32 mm) with local tomography of the soil region around the roots (field of view of 5 by 5 cm, pixel side 0.09 mm). For a sandy soil, we found that when the soil dries to a water content of 0.025 m3 m−3, gaps occur around the taproot and the lateral roots of lupin (Lupinus albus L.). Gaps were larger for the taproot than the laterals and were caused primarily by root shrinkage rather than by soil shrinkage. When the soil was irrigated again, the roots swelled, partially refilling the gaps; however, large gaps persisted in the more proximal, older part of the taproot. Gaps are expected to reduce water transfers between soil and roots. Opening and closing of gaps may help plants to prevent water loss when the soil dries, and to restore the soil–root continuity when water becomes available. The persistence of gaps in the more proximal parts is one reason why roots preferentially take up water from their more distal parts.
Noninvasive 3‐D Transport Characterization in a Sandy Soil Using ERT: 2. Transport Process Inference
Authors: Koestel J. , Vanderborght J. , Javaux M. , Kemna A. , Binley A. , Vereecken H.
Published: August 2009

In this study, we examined four tracer displacement experiments in a large undisturbed soil column under unsaturated hydraulic steady‐state conditions. Using electrical resistivity tomography (ERT), we were able to investigate the corresponding solute transport processes in unprecedented three‐dimensional (3‐D) spatiotemporally resolved detail. In addition, time‐domain reflectometry (TDR) probes and tensiometers provided hydrologic state variables relevant to solute transport. One important result from the study is that despite considerable differences between soil hydrologic state variables of the low‐ and high‐flux experiments, the 3‐D–resolved transport patterns remained approximately stable and were aligned to a structural feature in the topsoil. Furthermore, the ERT image data indicated that the solute front evolutions were influenced by spatiotemporal heterogeneities of the irrigation system. Another result is that the column‐scale mixing regime was found to be convective–dispersive, although the transport process exhibited considerable heterogeneities at smaller scales. We introduced an upscaling approach that allowed us to predict the column‐scale apparent dispersivity on the basis of the convection–dispersion equation parameters at the scale of the ERT voxels. The approach proved to be useful to evaluate at which scale the apparent dispersivity was generated. We consider the investigation of the relationship between apparent dispersivity and lateral scale as a promising tool for characterizing solute transport in future studies.
Regionalizing rainfall–runoff model parameters to predict the daily streamflow of ungauged catchments in the dry tropics
Authors: Post David A.
Published: August 2009

A methodology has been derived which allows an estimate to be made of the daily streamflow at any point within the Burdekin catchment in the dry tropics of Australia. The input data requirements are daily rainfall (to drive the rainfall–runoff model) and mean average wet season rainfall, total length of streams, percent cropping and percent forest in the catchment (to regionalize the parameters of the rainfall–runoff model). The method is based on the use of a simple, lumped parameter rainfall–runoff model, IHACRES (Identification of unit Hydrographs And Component flows from Rainfall, Evaporation and Streamflow data). Of the five parameters in the model, three have been set to constants to reflect regional conditions while the other two have been related to physio-climatic attributes of the catchment under consideration. The parameter defining total catchment water yield (c) has been estimated based on the mean average wet season rainfall, while the streamflow recession time constant (τ) has been estimated based on the total length of streams, percent cropping and percent forest in the catchment. These relationships have been shown to be applicable over a range of scales from 68–130,146 km2. However, three separate relationships were required to define c in the three major physiographic regions of the Burdekin: the upper Burdekin, Bowen and Suttor/lower Burdekin. The invariance of the relationships with scale indicates that the dominant processes may be similar across a range of scales. The fact that different relationships were required for each of the three major regions indicates the geographic limitations of this regionalization approach. For most of the 24 gauged catchments within the Burdekin the regionalized rainfall–runoff models were nearly as good as or better than the rainfall–runoff models calibrated to the observed streamflow. In addition, models often performed better over the simulation period than the calibration period. This indicates that future improvements in regionalization should focus on improving the quality of input data and rainfall–runoff model conceptualization rather than on the regionalization procedure per se.
Statistical performance indices for a hydropower reservoir
Authors: Jain Sharad K.
Published: August 2009

Commonly employed indices to assess the performance of a storage reservoir include reliability, resilience and vulnerability. Depending upon the way in which resilience and vulnerability are computed, different values and behaviour of these are obtained. This study has examined the behaviour of statistical performance indices for a hydropower reservoir located in a semi-arid region with the aim to identify those indices which give correct and complete insight of the behaviour of the reservoir. A detailed Monte Carlo simulation analysis was carried out using synthetic data to investigate the behaviour of a number of performance measures. Uncertainty of the indices was also assessed using synthetic data. While considering the sensitivity of measures, their monotonic behaviour and uncertainty of estimates, use of time and volume reliabilities and vulnerability were found to give adequate information about the performance of the project.
Similarities and differences in the response to climate warming of two ice caps in Iceland
Authors: Guðmundsson S. , Björnsson H. , Jóhannesson T. , Aðalgeirsdóttir G. , Pálsson F. , Sigurðsson O.
Published: August 2009

The transient response to projected climate change of two ice caps in the central Icelandic highland was simulated with a vertically integrated ice-flow model coupled to a degree-day mass-balance model. The ice caps, Langjökull and Hofsjökull, are of similar size (area ∼900 km2 and volume ∼200 km3) and located only ∼30 km apart. The climate change simulations were started in 1990 from steady states corresponding to the average climate of 1981–2000 and driven with observed weather parameters until 2005. Thereafter, the forcing was according to a Nordic climate change scenario based on the IPCC B2 emission scenario. The simulations during the period 1990–2005 compare reasonably well with observations of mass-balance and glacier extent. Both ice caps are projected to essentially disappear during the next 100 to 200 years. Langjökull, which disappears within the next 150 years, shows larger mass-balance sensitivity to warming than the higher elevated Hofsjökull, where ice on the highest peaks may last over 200 years. A large proportion of the simulated runoff increase with respect to a 1981–2000 average has already taken place within the period 1990–2005. The runoff will increase further during the next 40–60 years and remain considerably higher than at present until the end of the 21st century.
On-line estimation of suspended solids in biological reactors of WWTPs using a Kalman observer
Authors: Beltrán S. , Irizar I. , Monclús H. , Rodríguez-Roda I. , Ayesa E.
Published: August 2009

The total amount of solids in Wastewater Treatment Plants (WWTPs) and their distribution among the different elements and lines play a crucial role in the stability, performance and operational costs of the process. However, an accurate prediction of the evolution of solids concentration in the different elements of a WWTP is not a straightforward task. This paper presents the design, development and validation of a generic Kalman observer for the on-line estimation of solids concentration in the tank reactors of WWTPs. The proposed observer is based on the fact that the information about the evolution of the total amount of solids in the plant can be supplied by the available on-line Suspended Solids (SS) analysers, while their distribution can be simultaneously estimated from the hydraulic pattern of the plant. The proposed observer has been applied to the on-line estimation of SS in the reactors of a pilot-scale Membrane Bio-Reactor (MBR). The results obtained have shown that the experimental information supplied by a sole on-line SS analyser located in the first reactor of the pilot plant, in combination with updated information about internal flow rates data, has been able to give a reasonable estimation of the evolution of the SS concentration in all the tanks.
Analysis and optimization of flocculation activity and turbidity reduction in kaolin suspension using pectin as a biopolymer flocculant
Authors: Ho Y. C. , Norli I. , Alkarkhi Abbas F. M. , Morad N.
Published: August 2009

The performance of pectin in turbidity reduction and the optimum condition were determined using Response Surface Methodology (RSM). The effect of pH, cation's concentration, and pectin's dosage on flocculating activity and turbidity reduction was investigated at three levels and optimized by using Box–Behnken Design (BBD). Coagulation and flocculation process were assessed with a standard jar test procedure with rapid and slow mixing of a kaolin suspension (aluminium silicate), at 150 rpm and 30 rpm, respectively, in which a cation e.g. Al3 + , acts as coagulant, and pectin acts as the flocculant. In this research, all factors exhibited significant effect on flocculating activity and turbidity reduction. The experimental data and model predictions well agreed. From the 3D response surface graph, maximum flocculating activity and turbidity reduction are in the region of pH greater than 3, cation concentration greater than 0.5 mM, and pectin dosage greater than 20 mg/L, using synthetic turbid wastewater within the range. The flocculating activity for pectin and turbidity reduction in wastewater is at 99%.
Controlled operation of a membrane SBR for inhibitory wastewater treatment
Authors: Vargas A. , Sandoval J. L. , Buitrón G.
Published: August 2009

This work presents the design and practical implementation of a control strategy for the operation of a sequencing batch reactor with a submerged membrane. The bioreactor is used for treating wastewater that is inhibitory for sufficiently high concentrations. The strategy combines the use of a robust feeding strategy to ensure biodegradation near an optimal unknown concentration value, using only the dissolved oxygen concentration as feedback signal, and a strategy to minimize membrane fouling based on flux and transmembrane pressure measurements during filtration. The strategy was tested on a 10 L laboratory bioreactor treating synthetic wastewater containing 4-chlorophenol as inhibitory model compound and sole source of carbon. Experimental results show the applicability of the proposed strategy.
Observer-based input estimation in continuous anaerobic wastewater treatment processes
Authors: Jáuregui-Medina E. A. , Alcaraz-González V. , Méndez-Acosta H. O. , González-Álvarez V.
Published: August 2009

In this paper a “virtually controlled observer” (VCO) is proposed to estimate simultaneously the influent substrate concentration and unmeasured state variables in continuous anaerobic digestion processes. The hypothetical (unmeasured) influent substrate concentration is updated by a feedback control, which is regulated by the estimation error of a measured output. The proposed approach is firstly illustrated upon a simple continuous bioprocess. Then, the performance of the observer is tested via numerical simulations in a continuous anaerobic digestion model. Results showed that it is possible to estimate both, the influent substrate concentration and unmeasured states in the digester in the face of parametric uncertainties.
Assessment of rainwater use and greywater reuse in high-rise buildings in a brownfield site
Authors: Zhang Yan , Grant Andrew , Sharma Ashok , Chen Donghui , Chen Liang
Published: August 2009

This study describes the use of rainwater and greywater (originated from bathroom only) for provision of non-contact indoor and outdoor use in high-rise buildings. A brownfield development site in Box Hill suburb of Melbourne was selected as case study site for this investigation. The performance of alternative servicing options was compared with conventional water supply, stormwater and wastewater servicing. A water balance model UVQ (Urban Volume and Quality) was applied to determine storage capacities and to evaluate the percentage reduction in water supplying, stormwater run-off and wastewater disposal, as well as volumes of rainwater use and greywater reuse. In this study, the impact of variation in collection area (600 m2 and 900 m2) and appliance discharge volumes was examined. A number of demand management options were also investigated. The results of this study indicate greywater reuse is more suited than rainwater use for this development because of the steady, constant supply of greywater compared to the highly fluctuating, storm-event supply of rainwater and the high population density creating comparatively large volumes of greywater.
Separate and combined sewer systems: a long-term modelling approach
Authors: Mannina Giorgio , Viviani Gaspare
Published: August 2009

Sewer systems convey mostly dry weather flow, coming from domestic and industrial sanitary sewage as well as infiltration flow, and stormwater due to meteoric precipitations. Traditionally, in urban drainage two types of sewer systems are adopted: separate and combined sewers. The former convey dry and wet weather flow separately into two different networks, while the latter convey dry and wet weather flow together. Which is the best solution in terms of cost-benefit analysis still remains a controversial subject. The present study was aimed at comparing the pollution loads discharged to receiving bodies by Wastewater Treatment Plant (WWTP) and Combined Sewer Overflow (CSO) for different kinds of sewer systems (combined and separate). To accomplish this objective, a comparison between the two systems was carried out using results from simulations of catchments characterised by different dimensions, population densities and water supply rate. The analysis was based on a parsimonious mathematical model able to simulate the sewer system as well as the WWTP during both dry and wet weather. The rain series employed for the simulations was six years long. Several pollutants, both dissolved and particulate, were modelled. The results confirmed the uncertainties in the choice of one system versus the other, emphasising the concept that case-by-case solutions have to be undertaken. Further, the compared systems showed different responses in terms of effectiveness in reducing the discharged mass to the RWB in relation to the particular pollutant taken into account.
Effects of oxidative and physical treatments on inactivation of Cylindrospermopsis raciborskii and removal of cylindrospermopsin
Authors: Cheng Xiaoliang , Shi Honglan , Adams Craig D. , Timmons Terry , Ma Yinfa
Published: August 2009

The presence of toxic cyanobacterial blooms (or blue-green algae) in water bodies used either as drinking water or for recreational purposes may present serious health risks for the human population. In this study, the removal of the chemical toxin, cylindrospermopsin, via free chlorine, chlorine dioxide, monochloramine, permanganate, ozone, and UV irradiation was studied. Ozone and free chlorine were found to be highly effective for cylindrospermopsion removal while the other disinfectants were ineffective. Ozone and free chlorine were also determined to be highly effective for the inactivation of the cyanobacteria, Cylindrospermopsis raciborskii, at typical water treatment exposures, chlorine dioxide, monochloramine, and permanganate were only marginally effective at inactivation of Cylindrospermopsis raciborskii.
A game theoretic approach for trading discharge permits in rivers
Authors: Niksokhan Mohammad Hossein , Kerachian Reza , Karamouz Mohammad
Published: August 2009

In this paper, a new Cooperative Trading Discharge Permit (CTDP) methodology is designed for estimating equitable and efficient treatment cost allocation among dischargers in a river system considering their conflicting interests. The methodology consists of two main steps: (1) initial treatment cost allocation and (2) equitable treatment cost reallocation. In the first step, a Pareto front among objectives is developed using a powerful and recently developed multi-objective genetic algorithm known as Nondominated Sorting Genetic Algorithm-II (NSGA-II). The objectives of the optimization model are considered to be the average treatment level of dischargers and a fuzzy risk of violating the water quality standards. The fuzzy risk is evaluated using the Monte Carlo analysis. The best non-dominated solution on the Pareto front, which provides the initial cost allocation to dischargers, is selected using the Young Bargaining Theory (YBT). In the second step, some cooperative game theoretic approaches are utilized to investigate how the maximum saving cost of participating dischargers in a coalition can be fairly allocated to them. The final treatment cost allocation provides the optimal trading discharge permit policies. The practical utility of the proposed methodology for river water quality management is illustrated through a realistic case study of the Zarjub river in the northern part of Iran.
Integrated urban water management for residential areas: a reuse model
Authors: Barton A. B. , Argue J. R.
Published: August 2009

Global concern over growing urban water demand in the face of limited water resources has focussed attention on the need for better management of available water resources. This paper takes the “fit for purpose” concept and applies it in the development of a model aimed at changing current practices with respect to residential planning by integrating reuse systems into the design layout. This residential reuse model provides an approach to the design of residential developments seeking to maximise water reuse. Water balance modelling is used to assess the extent to which local water resources can satisfy residential demands with conditions based on the city of Adelaide, Australia. Physical conditions include a relatively flat topography and a temperate climate, with annual rainfall being around 500 mm. The level of water-self-sufficiency that may be achieved within a reuse development in this environment is estimated at around 60%. A case study is also presented in which a conventional development is re-designed on the basis of the reuse model. Costing of the two developments indicates the reuse scenario is only marginally more expensive. Such costings however do not include the benefit to upstream and downstream environments resulting from reduced demand and discharges. As governments look to developers to recover system augmentation and environmental costs the economics of such approaches will increase.
Hydrology and hydraulics expertise in participatory processes for climate change adaptation in the Dutch Meuse
Authors: Wesselink Anna , de Vriend Huib , Barneveld Hermjan , Krol Maarten , Bijker Wiebe
Published: August 2009

Many scientists feel that scientific outcomes are not sufficiently taken into account in policy-making. The research reported in this paper shows what happens with scientific information during such a process. In 2001 the Dutch Ministry of Transport, Public Works and Water Management commissioned their regional office in Limburg to assess how flood management objectives could be achieved in future in the Dutch Meuse valley, assuming climate change will increase peak discharges. To ensure political support, regional discussion rounds were to help assess the measures previously identified. This paper discusses the ways in which hydrological and hydraulic expertise was input, understood and used in this assessment process. Project participants as a group had no trouble contesting assumptions and outcomes. Nevertheless, water expertise was generally accepted as providing facts, once basic choices such as starting situation had been discussed and agreed. The technical constraints determined that politically unacceptable measures would have to be selected to achieve the legally binding flood management objective. As a result, no additional space will be set aside for future flood management beyond the already reserved floodplain. In this case, political arguments clearly prevail over policy objectives, with hydraulic expertise providing decisive arbitration between the two.
Environmental dissemination of group A rotavirus: P-type, G-type and subgroup characterization
Authors: Ferreira F. F. M. , Guimarães F. R. , Fumian T. M. , Victoria M. , Vieira C. B. , Luz S. , Shubo T. , Leite J. P. G. , Miagostovich M. P.
Published: August 2009

Rotaviruses A (RV-A) infection is the most common cause of acute diarrheal diseases in infants and the dissemination of these viruses in the environment represents a public health hazard. The present study aims to evaluate reverse transcription-polymerase chain reaction (RT-PCR) based protocols for the detection of RV-A genes in different types of environmental samples. RV-A were concentrated by the adsorption-elution method using negatively charged membranes associated with a Centriprep Concentrator 50. The RV-A VP4, VP7 and VP6 genes were detected using RT-PCR in river water from the Amazon Hydrographic basin (Northern region) and from wastewater in a sewage treatment plant in Rio de Janeiro (Southeast region), Brazil. RV-A were successfully detected in water environmental samples by the methods used. The detection of the VP6 gene by RT-PCR was the most sensitive for detecting RV-A in environmental samples (44.0%), when compared to the detection of the VP4 (33.3%) and VP7 (25.3%) genes. Based on nucleotide sequence and phylogenetic analysis of the partial VP6 gene, 22 environmental samples were determined to be subgroup II (Wa-like). These results indicate that analysis of environmental samples could possibly make a valuable contribution to studies on the epidemiology of RV-A.
Analysis of parameter uncertainty of a flow and quality stormwater model
Authors: Dotto C. B. S. , Deletic A. , Fletcher T. D.
Published: August 2009

Uncertainty is intrinsic to all monitoring programs and all models. It cannot realistically be eliminated, but it is necessary to understand the sources of uncertainty, and their consequences on models and decisions. The aim of this paper is to evaluate uncertainty in a flow and water quality stormwater model, due to the model parameters and the availability of data for calibration and validation of the flow model. The MUSIC model, widely used in Australian stormwater practice, has been investigated. Frequentist and Bayesian methods were used for calibration and sensitivity analysis, respectively. It was found that out of 13 calibration parameters of the rainfall/runoff model, only two matter (the model results were not sensitive to the other 11). This suggests that the model can be simplified without losing its accuracy. The evaluation of the water quality models proved to be much more difficult. For the specific catchment and model tested, we argue that for rainfall/runoff, 6 months of data for calibration and 6 months of data for validation are required to produce reliable predictions. Further work is needed to make similar recommendations for modelling water quality.
Effect of fish farming on the water quality of rivers in northeast Spain
Authors: Ruiz-Zarzuela I. , Halaihel N. , Balcázar J. L. , Ortega C. , Vendrell D. , Pérez T. , Alonso J. L. , de Blas I.
Published: August 2009

The effects of fish farming activities on the aquatic environment were evaluated by studying the water quality of twelve rivers located in northeast Spain. Two sampling sites were used for each river: the first sampling point was located just upstream from the fish farming facilities and the second one was downstream from fish farm effluent discharge point. In order to avoid any misinterpretation due to watershed location and seasonality, a stratified statistical analysis was performed. The results show significant decreases in pH and dissolved oxygen, in contrast to chemical oxygen demand, ammonia, phosphates and microbiological parameters, which significantly increased downstream from the fish farm discharges. Other significant variations were also found for conductivity and temperature. According to the European and local regulations concerning to support fish populations, our results fell within the allowable limits for salmonid waters. Nevertheless, we suggest that further investigations should be carried out to study the ecological interactions between farmed and wild fish populations.
The water sensitive city: principles for practice
Authors: Wong T. H. F. , Brown R. R.
Published: August 2009

With the widespread realisation of the significance of climate change, urban communities are increasingly seeking to ensure resilience to future uncertainties in urban water supplies, yet change seems slow with many cities facing ongoing investment in the conventional approach. This is because transforming cities to more sustainable urban water cities, or to Water Sensitive Cities, requires a major overhaul of the hydro-social contract that underpins conventional approaches. This paper provides an overview of the emerging research and practice focused on system resilience and principles of sustainable urban water management Three key pillars that need to underpin the development and practice of a Water Sensitive City are proposed: (i) access to a diversity of water sources underpinned by a diversity of centralised and decentralised infrastructure; (ii) provision of ecosystem services for the built and natural environment; and (iii) socio-political capital for sustainability and water sensitive behaviours. While there is not one example in the world of a Water Sensitive City, there are cities that lead on distinct and varying attributes of the water sensitive approach and examples from Australia and Singapore are presented.
Characterisation of microbial flocs formed from raw textile wastewater in aerobic biofilm reactor (ABR)
Authors: Ibrahim Zaharah , Amin Mohamad Faiz Mohd , Yahya Adibah , Aris Azmi , Umor Noor Azrimi , Muda Khalida , Sofian Nur Shalena
Published: August 2009

Microbial flocs formed from raw textile wastewater in a prototype Aerobic Biofilm Reactor (ABR) system were characterised and studied for their potential use in the treatment of textile wastewater. After 90–100 days of operation, microbial flocs of loose irregular structures were obtained from the reactor with good settling velocity of 33 m/h and sludge volume index (SVI) of 48.2 mL/g. Molecular analysis of the flocs using PCR-amplified 16S rDNA sequence showed 98% homology to those of Bacillus sp, Paenibacillus sp and Acromobacter sp. Detection of Ca2 + (131 mg/g) and Fe2 + (131 mg/g) using atomic absorption spectrometer might be implicated with the flocs formation. In addition, presence of Co2 +  and Ni2 +  were indicative of the flocs ability to accumulate at least a fraction of the metals' present in the wastewater. When the flocs were used for the treatment of raw textile wastewater, they showed good removal of COD and colour about 55% and 70% respectively, indicating their potential application.