bluuebunny/crossref_metadata_2025 huggingface dataset:
Tufa stromatolite ecosystems on the South African south coast
Authors: Perissinotto Renzo , Bornman Tommy G. , Steyn Paul-Pierre , Miranda Nelson A.F. , Dorrington Rosemary A. , Matcher Gwynneth F. , Strydom Nadine , Peer Nasreen
Published: September 2014

Following the first description of living marine stromatolites along the South African east coast, new investigations along the south coast have revealed the occurrence of extensive fields of actively calcifying stromatolites. These stromatolites have been recorded at regular distances along a 200-km stretch of coastline, from Cape Recife in the east to the Storms River mouth in the west, with the highest density found between Schoenmakerskop and the Maitland River mouth. All active stromatolites are associated with freshwater seepage streams flowing from the dune cordon, which form rimstone dams and other accretions capable of retaining water in the supratidal platform. Resulting pools can reach a maximum depth of about 1 m and constitute a unique ecosystem in which freshwater and marine organisms alternate their dominance in response to vertical mixing and the balance between freshwater versus marine inflow. Although the factors controlling stromatolite growth are yet to be determined, nitrogen appears to be supplied mainly via the dune seeps. The epibenthic algal community within stromatolite pools is generally co-dominated by cyanobacteria and chlorophytes, with minimal diatom contribution.
Tests on timber frame walls under in-plane forces: part 1
Authors: Grossi Paolo , Sartori Tiziano , Tomasi Roberto
Published: September 2014

The mechanical behaviour of timber frame shear walls subjected to in-plane forces has been investigated through full-scale tests. Eleven monotonic and 11 cyclic tests were performed on full-scale shear walls, each 2·5 m high by 2·5 m long. Some variables were changed during the tests as follows; different vertical loads were applied, various angle brackets and hold-downs were used, and different sheathing panels were connected to the timber frame. Also, the influence of openings was investigated. Furthermore two walls with non-structural finishing were tested in order to correlate the inter-storey drift with the level of damage. In part 1 of the paper, the test procedure and test results are presented. A detailed discussion of the test apparatus and how the boundary conditions influence the results are also reported. The theoretical approach used to predict the mechanical behaviour of the presented system is explained.
Weak growth response to nitrogen deposition in an old‐growth boreal forest
Authors: Du Enzai , Fang Jingyun
Published: September 2014

Nitrogen (N) deposition has been enhanced globally due to the dramatic increase in anthropogenic N emissions, but the effects of N deposition on the growth of old‐growth forests remain poorly understood. A three‐year N enrichment experiment (0, 20, 50 and 100 kg N ha−1 yr−1) was conducted in an old‐growth boreal forest in Northeast China to explore its growth response to enhanced N deposition. Nitrogen enrichment significantly increased N availability but caused only a very weak stimulation of growth (<3 kg C/kg N), indicating a minor N limitation. Nitrogen enrichment did not significantly influence the mass production of needle‐leaves but increased the production of woody biomass, leading to a slight improvement in growth efficiency. Nitrogen content increased and phosphorus (P) content decreased in freshly fallen needle‐leaves, leading to an increase of N:P ratios. The failure of P acquisition to match the increased N uptake suggests a limitation of soil P availability. Our results support the hypothesis of progressive N saturation and indicate that N deposition may cause a very weak stimulation of carbon sequestration in old‐growth forests.
Enhanced Fluid Flow: An Improved Method for Estimating Stimulated Reservoir Volume
Authors: Preiksaitis Mike , Bowman Sheri , Urbancic Ted , Baig Adam
Published: September 2014

In hydraulic fracture treatment programs microseismic imaging is often used to determine geometrical dimensions of the fracture network. The geometrical dimensions can be measured using fracture lengths, widths, and heights, or as an estimation of the potential volume that will contribute to production typically referred to as the stimulated reservoir volume (SRV). These SRV values are often used in reservoir models to plan and optimize a completion plan. Most techniques involve simply fitting a volume to these events. However, microseismic events also provide information on the deformation, energy and stress release and other seismic parameters that can possibly be used to constrain and provide realistic SRV estimates. In this paper, we investigate how SRV values vary by comparing standard approaches, with values as calculated based on seismic deformation and by taking into account the source types and fracture orientations derived from Seismic Moment Tensor Inversion (SMTI) to define regions of Enhanced Fluid Flow (EFF), akin to SRV estimates for fracture networks with propped or opening components of failure. By using a representative microseismic dataset from a shale gas play in North America, differences in approach are considered, and we conclude that EFF derived SRV estimates are likely a better reflection and more accurate representation of potential yields and estimates of reservoir volume.
Effect of Formation Stimulation Order in the Marcellus Shale
Authors: Kocon Ken , Urbancic Ted , Baig Adam
Published: September 2014

For vertically stacked wells undergoing hydraulic fracture stimulation, the order in which wells are stimulated can affect the achieved fracture length, width, height and intensity. We examine the effect of stimulation order for the plug-and-perf completion of two pairs of vertically stacked wells in the Marcellus Shale. Each pair of lateral wells hosts one well targeting the Lower Marcellus Formation, and one well targeting the Upper Marcellus Formation. All stages are completed in one well before moving to the next. For one pair of laterals, the Lower Marcellus is simulated before the Upper Marcellus. In this case, the cumulative seismic moment, and by extension the reservoir deformation, is much greater for the well which is completed second. In the next pair of laterals the stimulation order reverses and the Upper Marcellus Formation is stimulated before the Lower Marcellus. In this case, the cumulative seismic moment, and by extension total reservoir deformation, is again much greater for the well that is completed second. For the wells targeting both the Upper and Lower Marcellus, the achieved fracture length and width is independent of which Formation is simulated first. However, for both formations the kurtosis of the depth distribution is greater for whichever Formation is stimulated second. These observations demonstrate that in situ stress changes induced by hydraulic fracturing effect achieved fracture length and fracture intensity in the Marcellus Formation.
Wettability of the Montney Tight Gas Formation
Authors: Lan Qing , Dehghanpour Hassan , Wood James , Sanei Hamed
Published: September 2014

The abundant hydrocarbon resources in low-permeability formations are now technically accessible due to advances in drilling and completion of multi-lateral/multi-fractured horizontal wells. However, measurement and modeling of petrophysical properties, required for reserve estimation and reservoir-engineering calculations are the remaining challenges for the development of tight formations. In particular, characterizing wettability (wetting affinity) of tight rocks is challenging due to their complex pore structure, which can be either in hydrophobic organic materials or in hydrophilic inorganic materials.

We conduct comparative and systematic imbibition experiments on ten binary core plugs from the Montney tight gas formation, which is an enormous tight gas fairway in the Western Canadian Sedimentary Basin. Both contact angle and imbibition data indicate that the formation has a stronger affinity to oil than to water. However, the ratio between oil and water uptake of these samples is usually higher than what capillary-driven imbibition models predict. This discrepancy can be explained by the strong adsorption of oil on the surface of a well-connected organic pore-network that is partly composed of degraded bitumen. We also define a wettability index based on the equilibrium oil and water uptake of the binary samples. Oil wettability index is positively correlated with Total Organic Carbon (TOC) and clay content of the rocks which increase with depth from the Upper Montney to the Lower Montney.
Adding Value to the Kerrobert, Viking Oil Formation via Emerging Completion Methodologies of Horizontal Multi-Stage Wells – A Case Study
Authors: Toyad G.
Published: September 2014

Horizontal multistage fracture stimulation techniques have strategically advanced the completion and stimulation development in the Viking formation. Conventional Viking plays were vertically drilled, produced and thought to be depleted, but are now resurfacing with new opportunities.

The combination of being able to reach further with wellbore lengths and increase stimulation intensity has contributed to the viability of unconventional resources. As a direct result, various stimulation technologies have emerged and evolved, such as coiled tubing straddle systems, ball drop systems, and sliding sleeves with a resettable frac-isolation tool. These completion technologies have revived and renewed interest in challenging plays and have made it possible to economically stimulate portions of the reservoir that were previously bypassed. Implementing multistage technologies in the Halkirk, Provost and Dodsland fields have created positive and noticeable production results. Operators have begun to explore and revisit areas that may have been overlooked or less obvious. With improvements in technology and techniques for horizontal multistage stimulation treatments, areas like Prairiedale, Kerrobert, Lucky Hills, Plato and Forgan are capturing attention.

This case study seeks to investigate and discuss stimulation treatments, technology, and completion efficiency, which includes a case history describing how an operator completed in excess of 100 wells in the Kerrobert Viking play. It is located in southwest Saskatchewan, Canada, and lies below the Base of Fish Scales and above the Joli Fou. It will highlight key foreseen and unexpected challenges that arose in this play. Despite the challenging average 6 m pay thickness and interbedded layers of sandstone, siltstone and shale, production continues to proliferate within the Kerrobert Viking pool. Contributions of strategic horizontal drilling and multistage stimulations have improved efficiencies and reduced completion cycle time. This play has relatively low completion costs, is predictable, and therefore demonstrates repeatable economic results.
Dependence of Stress-Induced Micro-Seismicity on Natural Fracture Properties and In-Situ Stress
Authors: Garcia-Teijeiro Xavier , Rodriguez-Herrera Adrian
Published: September 2014

The opening and propagation of a hydraulic fracture introduces stress and pressure changes around it that could potentially lead to slippages of natural fractures. If detected, the associated microseismicity is commonly used to indirectly measure the geometry of the hydraulic fracture and the stimulated rock volume. One source of microseismicity is the fluid leakoff and pressure increase into the natural fractures. As pressure increases, the effective stress is reduced and shear failure of the natural fractures can be triggered. The natural fractures can also be reactivated in absence of leakoff due to the stress changes induced in the rock due to the opening of the hydraulic fracture itself and due to the inflation of the natural fractures intersected by the main hydraulic fracture. The volume in which stress changes alone can reactivate natural fractures is commonly thought to be small and localized near the hydraulic fracture tips. Yet, this paper shows that when the presence of natural fractures is explicitly taken into account, together with the potential propagation of further stress changes as the natural fractures slip, then such reactivated volume can be substantially larger. The results presented here demonstrate the importance of local stress heterogeneities in the potential generation of microseismicity and highlight how the local stress heterogeneity directly depends on the mechanical properties of the natural fractures.
Back to the Future: Shale 2.0 - Returning Back to Engineering and Modelling Hydraulic Fractures in Unconventionals With New Seismic to Stimulation Workflows
Authors: Ramanathan V. , Boskovic D. , Zhmodik A. , Li Q. , Ansarizadeh M.
Published: September 2014

Stimulating Shale Gas Wells has become a mundane activity with very little or no engineering. The industry has focused heavily on reducing costs and increasing efficiencies of operations that there is seldom any time for engineering. The lack of any horizontal logging information, assumptions that rock quality does not change have led to excel driven spreadsheets doing glorified mass balances which are considered as the fracture designs of today. In addition to this the same fracture treatment is pumped stage after stage well after well. Needless to say the industry's lack of ability to model these complex fractures has also contributed to the exercise of moving away from fundamental fracture design. This trend has resulted in productivities of wells being all over the place that mostly are unexplained. The industry is beginning to realize that a significant % of the wells drilled in unconventionals are not profitable.

Refracturing is also gaining prominence because of a single important factor that primary initial completions are ineffective. Shale 2.0 is all about integrating seismic to stimulation information to provide better answers and ultimately better productivity via simple measurements in the lateral. These measurements are ultimately used to engineer the completion, design and understand the science behind fracturing than just merely pumping the job.

This paper details the planning, design and evaluation processes in the application of a new workflow called the Unconventional Reservoir Optimized Completion workflow. This revolutionary Seismic to Stimulation workflow demonstrates with examples how we have migrated, a dominant well centric process to a reservoir centric process. A significant step change in fracture modelling has been applied using unconventional fracture models which have the ability to model complex fractures using discrete fracture networks. These models can be validated using microseismic and when calibrated with production can become a powerful prediction tool. Experiences and lessons learned in the Canadian Montney will be presented.
Utilizing Fit-For-Purpose Decision Analysis Techniques to Maximize Value From Unconventionals: Case Studies from the Wolfcamp Play, Permian Basin
Authors: Rexilius Jarrad , Prochnow Shane , Morgan Michael , Fields Michael
Published: September 2014

In any petroleum industry application, it is important that sound decision making techniques are applied to maximize value of investments and generate optimal returns from execution of these decisions. This is especially critical for lower margin unconventional resource plays, where cost reduction is of upmost concern. Whilst significant attention is placed on minimizing costs to improve economics for unconventional projects, there are often opportunities with potential to yield substantial incremental value creation, despite some outlay of additional capital. This paper will discuss the application of fit-for-purpose decision analysis (DA) and value of information (VOI) techniques to evaluate various opportunities to enable data driven decisions to be made, and maximize value from unconventionals.

The Wolfcamp Play in Permian Basin is one of the most active unconventional oil plays in North America, and is widely considered a statistical play requiring a manufacturing approach, whereby many wells are drilled and completed in the same fashion to develop the field with optimal operational efficiency. However, this paper will discuss several case studies where more detailed study and analysis have led to opportunities to optimize the development and increase economic viability, by adopting a more scientific and DA based approach. Final results suggest that these opportunities have generated significant value creation and highly favorable economic returns, and should serve as examples for other tight rock plays.

This paper provides a robust workflow of fit-for-purpose DA techniques for application to various decision points for unconventional projects. The paper also presents case studies that convey the complexities and challenges faced in unconventional resource plays, and how making data driven decisions that provide value creation can enhance the value of the assets. Case studies discussed include 1) Open hole logging decisions, 2) Proppant selection for hydraulic fracturing, and 3) The use of mud logs as a completion selection tool. To evaluate these opportunities, a series of VOI and DA techniques were employed, including decision trees, investment efficiency charts, sensitivity to probability calculations, and other net present value (NPV) and profitability analyses.

The subject matter discussed in this paper has relevance and application to other unconventional plays in the industry that seek to maximize value of the resource base and capital investment employed.
A Rock and Fluid Study of Middle Bakken Formation: Key to Enhanced Oil Recovery
Authors: Kurtoglu Basak , Kazemi Hossein , Rosen Richard , Mickelson William , Kosanke Tobi
Published: September 2014

The discovery of significant reserves in the Middle Bakken of the Elm Coulee Field in 2000 changed the development of Bakken Formation in the Williston Basin. In 2006 the Elm Coulee success led to the exploration of other fields in the Williston Basin, such as Parshall and Sanish fields in North Dakota. Thousands of Middle Bakken wells have been drilled and produced in the primary production mode, yet there is likely significant potential for enhanced oil recovery, which prompted this multi-facetted research study.

First, the physical properties of the reservoir brine, oil, and gas of fluid samples from different Middle Bakken geographic locations are presented to emphasize significant physical property differences across North Dakota. This information is essential to understand the impact of fluid properties on primary production and potential for oil recovery at different locations.

Second, we identified reservoir connectivity by combining petrographic analysis, scanning electron microscopy, and permeability measurements. The permeability measurements included core-based steady-state permeability and unsteady-state water-oil relative permeability. The selected cores were characterized using X-ray diffraction mineralogy, thin section petrology, and scanning electron microscopy (SEM) to correlate flow capacity to the petrophysical properties. The conclusion is that interconnected microfractures make current production possible in successful wells.

Finally, the high salinity formation water compared to the low salinity of fracturing and IOR fluids was investigated by performing spontaneous imbibition using both low and high salinity brines. It was concluded that in the oil-wet environment of the Bakken, the low salinity injection fluids can enter part of the reservoir because of osmotic pressure while high salinity makes the clay surface extremely hydrophobic and causes local oil-wetness.
Bilinear Flow in Shale Gas Wells: Fact or Fiction?
Authors: Kanfar M. S. , Alkouh A. B. , Wattenbarger R. A.
Published: September 2014

Many shale wells undergo a gradual production decline before reaching a linear flow decline. This gradual decline lasts for several days and often matches a quarter-slope. Some authors attribute this gradual decline to bilinear flow, which occurs as a result of simultaneous linear flow in natural fractures and matrix (Al-Ahmadi and Wattenbarger 2011; Tivayanond et al 2012). In this paper, we show that bilinear flow in natural fractures and matrix is short and, therefore, it cannot explain the sustainable gradual decline observed in shale wells. Instead, we provide two alternative explanations. Bilinear flow caused by low-conductive hydraulic fractures is one explanation. Another one is an artificial shift in data caused by ignoring flowback.

First, we use analytical solutions and show that bilinear flow is short unless matrix permeability is extremely low or natural-fracture spacing is very large. Second, we show that analytical solutions are unrealistic when natural fracture spacing is large. Third, we use reservoir simulation to obtain more realistic results and show that bilinear flow in matrix and natural fractures is not sustainable. In conclusion, we show that ignoring flowblack data results in a fictitious quarter-slope and demonstrate the concept with field examples.

This work shows the importance of including flowback data into rate transient analysis. In addition, it describes a procedure to accurately analyze production data and avoid misleading bilinear flows. Several sensitivity studies are also shown to define the geometrical and petrophysical conditions under which the bilinear flow regime is not expected. Concepts presented in this paper provide engineers with better tools for analyzing and forecasting production from shale gas wells.
Soil Organic Carbon Sequestration Rates under Crop Sequence Diversity, Bio‐Covers, and No‐Tillage
Authors: Ashworth Amanda J. , Allen Fred L. , Wight Jason P. , Saxton Arnold M. , Tyler Don D. , Sams Carl E.
Published: September 2014

Climate change may be mitigated through soil organic C (SOC) storage under no‐tillage; however, crop management influences on SOC are not well defined in all systems. Our objective was to compare long‐term C fluxes under two no‐tillage sites at Research and Education Centers in Milan (RECM) on Oxyaquic Fragiudalfs and at Middle Tennessee (MTREC) on a Typic Paleudalf in a split‐block design with four replications. The whole‐block was cropping sequences of corn (Zea mays L.), soybeans [Glycine max (L.) Merr.], and cotton (Gossypium hirsutum L.) with split‐block bio‐cover treatments of winter wheat (Triticum aestivum L.), hairy vetch [Vicia villosa Roth subsp. villosa], poultry litter, and a fallow control. The same sequences were performed at MTREC without cotton. Soil C flux was calculated at surfaces (0–5 cm) and subsurfaces (5–15 cm) during Year 0, 2, 4, and 8. During the first 2 yr, C losses occurred in all treatments and locations (1.40 and 1.20 Mg ha−1 at RECM and MTREC, respectively), with stabilization initiating by Year 4. By Year 8, sequences with high frequencies of soybean and greater temporal complexity gained more surface SOC. Poultry litter bio‐covers gained more surface SOC compared to wheat, vetch, and fallow bio‐covers (P < 0.05). After 8 yr, surface SOC surpassed initial levels (9.20 and 8.79 Mg ha−1), with mean gains of 1.33 and 1.16 Mg C ha−1 at RECM and MTREC, respectively. Losses occurred in subsoils at MTREC and RECM, but by Year 8 several treatments had recovered to near baseline levels. Results suggest surface C storage may be enhanced by crop sequence diversity combined with poultry litter bio‐covers in no‐till systems, whereas subsurface levels may require more time.
Near‐Infrared Calibrations for Organic, Inorganic, and Mineralized Nitrogen from Poultry Litter
Authors: Mowrer Jake , Kissel David , Cabrera Miguel , Hassan Sayed
Published: September 2014

Near‐infrared reflectance (NIR) spectroscopy was evaluated for use in predicting the plant‐available N (PAN = NH4–N + NO3–N) and mineralizable N (MN) from poultry litter (PL) samples on an “as received” water content basis. Near‐infrared reflectance scans were collected on 118 PL samples of variable water content without drying. The samples were not fresh but had been stacked or otherwise stored for various lengths of time and were closely representative of the PL applied to crop and pasture soils in Georgia (United States). Average PAN for the samples studied was 6.3 g kg−1PL (dry weight). One‐hundred‐day soil incubations with a loamy fine sand and a sandy clay loam were used to determine MN. An average of 19% of the organic N was mineralized after 100 d. Total PAN after 100 d (PAN100= PANinitial+ MN) averaged 33% of the total N for these samples. Near‐infrared reflectance calibration models were developed with a modified partial least squares procedure. The results show that NIR calibration models can be developed on PL with variable water contents for total N (r2= 0.896, ratio of performance to deviation [RPD] = 3.5), NH4–N (r2= 0.795, RPD = 3.2), NO3–N (r2= 0.926, RPD = 2.7), uric acid N (r2= 0.909, RPD = 4.0), organic N (r2= 0.821, RPD = 3.6), water‐soluble organic N (r2= 0.897, RPD = 4.0), MN (r2= 0.842, RPD = 2.6), initial PAN + MN (r2= 0.888, RPD = 2.6), total C (r2= 0.926, RPD = 3.7), and water content (r2= 0.996, RPD = 15.6). We conclude that drying is not necessary to develop highly successful NIR calibrations for N forms from PL.
Real-time flood forecast using the coupling support vector machine and data assimilation method
Authors: Li Xiao-Li , Lü Haishen , Horton Robert , An Tianqing , Yu Zhongbo
Published: September 2014

An accurate and real-time flood forecast is a crucial nonstructural step to flood mitigation. A support vector machine (SVM) is based on the principle of structural risk minimization and has a good generalization capability. The ensemble Kalman filter (EnKF) is a proven method with the capability of handling nonlinearity in a computationally efficient manner. In this paper, a type of SVM model is established to simulate the rainfall–runoff (RR) process. Then, a coupling model of SVM and EnKF (SVM + EnKF) is used for RR simulation. The impact of the assimilation time scale on the SVM + EnKF model is also studied. A total of four different combinations of the SVM and EnKF models are studied in the paper. The Xinanjiang RR model is employed to evaluate the SVM and the SVM + EnKF models. The study area is located in the Luo River Basin, Guangdong Province, China, during a nine-year period from 1994 to 2002. Compared to SVM, the SVM + EnKF model substantially improves the accuracy of flood prediction, and the Xinanjiang RR model also performs better than the SVM model. The simulated result for the assimilation time scale of 5 days is better than the results for the other cases.
Signal analysis and anomaly detection for flood early warning systems
Authors: Pyayt A. L. , Kozionov A. P. , Kusherbaeva V. T. , Mokhov I. I. , Krzhizhanovskaya V. V. , Broekhuijsen B. J. , Meijer R. J. , Sloot P. M. A.
Published: September 2014

We describe the detection methods and the results of anomalous conditions in dikes (earthen dams/levees) based on a simultaneous processing of several data streams originating from sensors installed in these dikes. Applied methods are especially valuable in cases where lack of information or computational resources prohibit computing the state of the dike with finite element and other mathematical models. The data-driven methods are part of the artificial intelligence (AI) component of the ‘Urbanflood’ early warning system. This AI component includes pre-processing (e.g., gap filling and measurements synchronization procedures) of data streams, feature extraction and anomaly detection by one-side (also known as one-class) classification methods. Our approach has been successfully validated during a non-destructive piping experiment at the Zeeland dike (The Netherlands).
Testing linear solvers for global gradient algorithm
Authors: Giustolisi Orazio , Moosavian Naser
Published: September 2014

Steady-state Water Distribution Network models compute pipe flows and nodal heads for assumed nodal demands, pipe hydraulic resistances, etc. The nonlinear mathematical problem is based on energy and mass conservation laws which is solved by using global linearization techniques, such as global gradient algorithm (GGA). The matrix of coefficients of the linear system inside GGA belongs to the class of sparse, symmetric and positive definite. Therefore a fast solver for the linear system is important in order to achieve the computational efficiency, especially when multiple runs are required. This work aims at testing three main strategies for the solution of linear systems inside GGA. The tests are performed on eight real networks by sampling nodal demands, considering the pressure-driven and demand-driven modelling to evaluate the robustness of solvers. The results show that there exists a robust specialized direct method which is superior to all the other alternatives. Furthermore, it is found that the number of times the linear system is solved inside the GGA does not depend on the specific solver, if a small regularization to the linear problem is applied, and that pressure-driven modelling requires a greater number which depends on the size and topology of the network and not only on the level of pressure deficiency.
Water quality and microbial diversity in cisterns from semiarid areas in Brazil
Authors: Alves Fellipe , Köchling Thorsten , Luz Julio , Santos Sylvana Melo , Gavazza Savia
Published: September 2014

Harvesting rainwater is a common practice worldwide, particularly in areas with no access to a public water supply or insufficient groundwater reserves. More than two million people living in semiarid regions of Brazil consume rainwater stored in cisterns, and little information is available regarding the water quality. Despite the initial good quality of the rainwater, its harvest and storage can introduce contaminants that must be eliminated before consumption. To evaluate the influence of handling, cistern age and precipitation on the quality of harvested rainwater, we monitored seven cisterns in the semiarid Brazilian Northeast over 4 years. Microbial and physicochemical parameters were monitored once a month, and denaturant gradient gel electrophoresis (DGGE) was performed at the end of the monitoring period. Coliform bacteria were detected in 100% of samples, while Escherichia coli were observed in 73.8%. The alkalinity and conductivity were the highest for the recently built cisterns due to the dissolution of construction materials. The DGGE of the 16S r DNA did not reveal the presence of E. coli. Instead, DGGE bands sequencing indicated that species primarily affiliated with Alphaproteobacteria were present in all cisterns, indicating the presence of microbial ecosystems capable of purifying and stabilizing the stored rainwater.
A waterborne outbreak of campylobacteriosis in the South Island of New Zealand due to a failure to implement a multi-barrier approach
Authors: Bartholomew Nadia , Brunton Cheryl , Mitchell Peter , Williamson Judy , Gilpin Brent
Published: September 2014

Outbreaks of waterborne gastroenteritis continue to occur in developed countries. Darfield, a rural town in the South Island of New Zealand experienced an outbreak of campylobacteriosis following a transgression of Escherichia coli on 16 August 2012. A descriptive outbreak investigation was performed. As a result, 29 cases had a laboratory-confirmed diagnosis of campylobacteriosis and 138 were identified as probable cases. Heavy rains, contamination of water with animal effluent from nearby paddocks and failures in the treatment of drinking water led to pathogens being distributed through the town's water supply. A multi-barrier approach is advocated to ensure the quality of water and many countries have legislation or programmes to address this. Although legislation for water safety plans based on a multi-barrier approach is in place in New Zealand, at the time of the outbreak it was not a requirement for the Darfield water supply. In addition, despite the awareness of the importance of a multi-barrier approach, competing interests, including those from the agricultural industry and financial restraints on water suppliers, can prevent it from being implemented. Governments need to be more willing to enforce legislation and standards to protect the public from waterborne disease.
Degradation of atrazine by microbial consortium in an anaerobic submerged biological filter
Authors: Nasseri Simin , Baghapour Mohammad Ali , Derakhshan Zahra , Faramarzian Mohammad
Published: September 2014

Atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) (ATZ) is one of the components of S-triazine. Due to its certain characteristics, ATZ causes pollution in various ecosystems and has been of concern for its probable carcinogenic effects on humans. Researchers have used chemical and physical methods for removing ATZ from the environment. Although these methods are quick, they have not been capable of complete mineralization. Therefore, researchers are looking for methods with lower energy consumption and cost and higher efficiency. In this study, biodegradation of ATZ by microbial consortium was evaluated in the aquatic environment. The present study aimed to evaluate the efficiency of ATZ removal from aqueous environments by using an anaerobic submerged biological filter in four concentration levels of atrazine and three hydraulic retention times. The maximum efficiencies of ATZ and soluble chemical oxygen demand (SCOD) were 51.1 and 45.6%, respectively. There was no accumulation of ATZ in the biofilm and the loss of ATZ in the control reactor was negligible. This shows that ATZ removal in this system was due to biodegradation. Furthermore, the results of modeling showed that the Stover–Kincannon model had desirable fitness (R2 > 99%) in loading ATZ in this biofilter.
Direct injection ion chromatography for the control of chlorinated drinking water: simultaneous estimation of nine haloacetic acids and quantitation of bromate, chlorite and chlorate along with the major inorganic anions
Authors: Garcia-Villanova Rafael J. , Raposo Funcia César , Oliveira Dantas Leite M. Vilani , Toruño Fonseca Ivania M. , Espinosa Nieto Miguel , Espuelas India Javier
Published: September 2014

Most methods for the analysis of haloacetic acids published in recent years are based on ion chromatography with direct injection, employing a gradient elution with potassium hydroxide (KOH). This work reports the exploration of an alternative eluent, a buffer of sodium carbonate/sodium hydrogen carbonate, aimed at the simultaneous analysis of nine haloacetic acids along with bromate, chlorite and chlorate. The alternative of both a less alkaline eluent and a lower temperature of operation may prevent the partial decomposition of some of the haloacetic acids during the analytical process, especially the more vulnerable brominated ones. Gradient elution at temperature of 7 °C yielded the best results, with an acceptable separation of 17 analytes (which includes the major natural inorganic anions) and a good linearity. Precision ranges from 0.3 to 23.4 (% V.C.), and detection limits are within units of μg L−1, except for tribromoacetic acid – somewhat high in comparison with those of the official methods. Nonetheless, with the basic instrumentation setup herein described, this method may be suitable for monitoring when the drinking water treatments are to be optimized. This is especially interesting for small communities or for developing/developed countries in which regulations on disinfection by-products others than trihalomethanes are being addressed.
Urban water reuse: microbial pathogens control by direct filtration and ultraviolet disinfection
Authors: de Lima Isaac Ricardo , dos Santos Luciana Urbano , Tosetto Mariana S. , Franco Regina Maura Bueno , Guimarães José Roberto
Published: September 2014

Physicochemical treatment efficiency for unrestricted urban water reuse was evaluated at a conventional activated-sludge wastewater treatment plant (WWTP). Pilot plant set-up consisted of an alum coagulation step, granular media upflow flocculation and direct downflow dual-media filtration followed by ultraviolet disinfection (dose of 95 mJ cm−2). Optimum aluminum sulfate dosage of 10 mg L−1 and coagulation pH 7.0 were preset based on bench scale tests. Under WWTP stable operation, water quality met United States Environmental Protection Agency (USEPA) suggested guidelines for unrestricted urban reuse regarding turbidity (mean value 1.3 NTU) and suspended solids (mean value 2.1 mg L−1). When WWTP overall plant performance dropped from 90 to 80% (although BOD value stayed below 6 mg O2 L−1, suggesting unrestricted reuse), solids breakthrough in filtrate was observed. Microorganism removal rates were: total coliforms 60.0%, Escherichia coli 63.0%, Giardia spp. 81.0%, and helminth eggs 62.5%; thus organisms still remained in filtrate. Ultraviolet (UV) disinfection efficiency was 4.1- and 3.8-log for total coliforms and E. coli, respectively. Considering low UV efficiency obtained for helminths and the survival of protozoa and helminths in the environment, effluent quality presents risk to public health if destined for unrestricted urban reuse.
Removal of micropollutants from treated domestic wastewater by addition of powdered activated carbon to rapid filtration
Authors: Altmann J. , Bruebach H. , Sperlich A. , Jekel M.
Published: September 2014

Advanced treatment of wastewater is currently being discussed throughout Europe in an effort to reduce emissions to surface waters and protect drinking water resources. In this study the combination of adsorption onto powdered activated carbon (PAC) and coagulation/filtration was investigated as a single advanced treatment step for simultaneous removal of organic micropollutants (OMPs) and phosphorus from domestic secondary effluent. Two pilot-scale dual-media filters were operated in parallel for a period of 4 months to investigate the influence of PAC addition on filtration parameters and determine removal of 14 selected OMPs. OMP abatement in the PAC filter was compared to batch tests and correlated with relative removal of UV254 absorption (UVA254). Stable operation with an average PAC dose of 8 mg/L and a removal >90% of total suspended solids was possible for filtration cycles of 24 h. The results show that PAC dosing does not negatively affect either filtration resistance or removal of phosphorus by precipitation. Concentrations of benzotriazole and carbamazepine were reduced by >70%, while sulfamethoxazole and diclofenac were removed to the extent of 40–60% (median values). Relative OMP removal showed only minor fluctuations despite occasionally strong changes of influent concentrations. Moreover, the results indicate that contact times were not sufficient for complete PAC exhaustion before separation and that further adsorption onto embedded PAC in the filter significantly contributes to overall OMP removal.
Estimating the reliable residential water substitution from household rainwater tanks
Authors: Mukheibir P. , Boyle T. , Moy C. , White S.
Published: September 2014

In Australia, household rainwater tanks have come to be considered as one of the broad potential supply options for meeting household water demands. It has been viewed as an effective way of reducing the supply requirements by water businesses and can potentially defer future capital supply investments. With likely variability of future supplies and demands due to climate change impacts, rainwater tanks also have an important role in building future resilience to shifts in historical trends, and also can potentially play a role in mitigating stormwater damage.

The substitution of mains supplied water by rainwater can vary significantly, with the major factors influencing yields being the roof size to capture the rain, water usage regime (having some level of internal water use) and tank size. Tank performance, with respect to reduced substitution as a result of functionality failure, is seldom included in yield calculations however. A review of a number of studies in Australia has illustrated that the vast majority of field studies have produced qualitative responses on the perceptions of the use of rainwater, the structural integrity of their rainwater capture infrastructure and the end-uses connected to the system.

It was found that the data required to inform the impact of functionality on substitution is currently largely limited to qualitative responses on the perceptions of the use of rainwater tanks, the structural integrity of their rainwater capture infrastructure and the end-uses connected to the system. There is very little in the way of quantitative assessments. This paper offers an interim approach for overcoming this quantitative information gap on the role and extent of functionality failure.
Perceptions of International Female Students toward E-Learning in Resolving High Education and Family Role Strain
Authors: Kibelloh Mboni , Bao Yukun
Published: September 2014

It is a common phenomenon for many mature female international students enrolled in high education overseas to experience strain from managing conflicting roles of student and family, and difficulties of cross-cultural adjustment. The purpose of this study is to examine perceptions and behavioral intentions of international female students toward e-learning as a tool for resolving overseas high education and family strain from a technology acceptance standpoint. To achieve this goal, Davis's (1989) technology acceptance model is used as the study's conceptual framework, to investigate perceived usefulness, ease of use and behavioral intentions toward e-learning. The research draws on face-to-face interviews with 21 female international students enrolled in classroom-taught degree programs at a university in Wuhan, China. The data is analyzed through coding and transcribing. The findings reveal that given its convenience, e-learning is generally perceived as practical in balancing study with family as well as feasible in saving time, money, and energy. However, key concerns were raised over the issues of poor and costly Internet connectivity in developing countries, as well as perceived negative reputation, lack of face-to-face interaction, and lack of motivation in online environment. Important issues and recommendations are raised for consideration when promoting e-learning program. This study emphasizes the need to revisit gender supporting policies and effective marketing to re-position the prevailing image of e-learning as a reputable and reliable education delivery method.
Assessing the Impact of Meta-Cognitive Training on Students' Understanding of Introductory Programming Concepts
Authors: Cetin Ibrahim , Sendurur Emine , Sendurur Polat
Published: September 2014

Students' difficulties in learning computer programming are well documented in the literature and have been studied from different perspectives by the researchers. However, studies that have been conducted from the meta-cognition perspective are rare in the context of programming education. The current study aimed to (i) investigate the effects of a specific metacognitive training on students' programming achievement, retention of programming knowledge, and meta-cognitive awareness; and (ii) explore students' experiences and opinions related to the meta-cognitive training. There were 51 participants (28 male and 23 female) who are 2nd-year students from a public university. In the current study, a mixed methods design, specifically embedded experimental model, was utilized. The experimental group was instructed using the meta-cognitive training, and the control group was taught using traditional instruction. An achievement test, a meta-cognitive awareness inventory, and semi-structured interviews were used to collect data. The results of the study indicated that the intervention based on meta-cognition caused significantly better acquisition of introductory programming concepts. Although there was no significant difference between experimental and control groups in terms of meta-cognitive awareness, qualitative data implied some differences related to students' problem-solving ways and meta-cognitive strategies. Results of retention and post tests revealed that scores of students in experimental and control groups declined at close rates. Moreover, most of the students in the experimental group reported positive feelings toward meta-cognitive instruction. Thus, it might be said that meta-cognitive training was an effective tool to improve students' understanding of introductory programming topics as indicated by post-test scores.
Conditional Conservatism and Audit Fees
Authors: Lee Hye Seung (Grace) , Li Xu , Sami Heibatollah
Published: September 2014

SYNOPSIS

In this study, we examine the impact of conditional conservatism on audit fees and, more importantly, the influence of corporate governance on this relationship. Prior literature presents evidence regarding explanations for the existence and pervasiveness of accounting conservatism such as compensation and debt contracting, shareholder litigation, taxation, and accounting regulation. However, there is very limited evidence or discussion of the potential benefit of accounting conservatism on audit risk and thus audit fees, and how the potential benefit can be attenuated by corporate governance quality. Using a sample of firm-year observations over the period of 2004–2009, we provide evidence consistent with conditional conservatism and firms' commitment to such conservatism reducing their audit fees. However, our evidence shows that this reduction in audit fees is moderated by higher corporate governance quality. These results have implications for auditors, regulators, standard setters, and firms' managers. In addition, our study extends the literature on the determinants of audit fees.

JEL Classifications: M41; M42; D81; D22.
Does Industry Specialist Assurance of Non-Financial Information Matter to Investors?
Authors: Ferguson Andrew , Pündrich Gabriel
Published: September 2014

Previous studies in the financial economics literature highlight the value of non-financial information in Internet and telephony stocks (Amir and Lev 1996; Trueman, Wong, and Zhang 2001). Other studies consider the financial and share price performance implications of assurance of non-financial information such as ISO 9000 certification (Corbett, Montes-Sancho, and Kirsch 2005), Total Quality Management awards (Hendricks and Singhal 1997), and non-financial information disclosure (Coram, Monroe, and Woodliff 2009). However, prior studies have occurred in settings where disclosure and assurance of non-financial information is voluntary. We provide evidence on the value of assurance of non-financial information where the assurance of public resource disclosures made under the JORC Code by Australian Mining Development Stage Entities are mandatory. The assurance role undertaken by Competent Persons reporting under the JORC Code bears many close similarities to the financial reporting assurance role undertaken by auditors. Further, the information environment of MDSEs is characterized by high information asymmetry and the reality that the utility of non-financial technical information supersedes financial statement information in firm valuation. We document very weak evidence of greater abnormal returns evident when reserve disclosures are provided by specialist mining consultants. In supplementary analysis, we test for implications of switching mineral consultant and find that clients experience significant positive abnormal returns when the successor is larger. Overall, our findings support the insurance hypothesis, in that mandatory specialist assurance matters little where litigation risk is low.