Quantification of ventilation on distribution of gaseous pollutants emitted from stored swine manure

Abstract

This paper describes the quantification of the effects of ventilation on distribution of gaseous pollutants as a result of mass transfer from stored manure to ventilation air in a swine confinement building. A multiple airflow regions model is developed and used to simulate the dynamics of gaseous pollutants in any airspace within a ventilated slotted‐inlet enclosure. The model predictions compared favorably with the measured results adapted from a literature research at ventilation rates between 443 and 932 m³/hr (deviations of 5.1 ‐ 14.68%) for carbon dioxide and ammonia concentrations. A comparison between predictions and measured carbon dioxide concentrations derived from an environmental chamber test found deviations ranged from 3.1 ‐ 5.6% at ventilation rates between 281 and 995 m³/hr. The results suggest that the model can be experimentally applied between ventilation rates of 443 and 995 m³/hr. The model also capable of predicting air exchange rate required to maintain acceptable levels of gaseous pollutants in swine confinement buildings based on gas emission rates.     

Fate and residues of 14C‐chloramphenicol in laying chickens 1

Abstract

Studies were conducted to determine the metabolic fate of chloramphenicol (CAP) in White Leghorn using the ^l4C‐labelled compound. In one experiment birds were administered orally via intra‐crop, a single dose of 100 mg (equivalent to 66 mg kg^‐1 body weight) of CAP containing 14 μCi ¹⁴C‐CAP, and its absorption, elimination and distribution in plasma were recorded. Orally dosed ¹⁴C‐compound was rapidly absorbed, efficiently distributed in plasma and eliminated in excreta (>70% in 5 hr). After 5 h, CAP equivalent residues in tissues were lower than 15 μg g^‐1 for this treatment. In a second experiment birds were given intra‐crop dose of either 0.5 or 5 mg of CAP (each dose contained 2.5 μCi ¹⁴C‐CAP) daily for five consecutive days followed by a seven day withdrawal period and elimination of ¹⁴C in excreta and eggs was monitored. More than 95% of the administered ¹⁴C was eliminated within the first 24 h after dosing. Radiocarbon (¹⁴C) was deposited preferentially in yolks compared to albumen or other tissues. Residues declined when feeding was stopped. Various metabolites were isolated and identified by a combination of TLC, LC, and LC‐MS. The main metabolic route of CAP in laying hens appears to be the glucuronidation. Cleavage of the dichloroacetate moiety was only a minor route.     

VELOCITY AND CONCENTRATION DISTRIBUTIONS OF SEDIMENT‐LADEN OPEN CHANNEL FLOW1

ABSTRACT: A mathematical model to predict both velocity and concentration distributions for sediment‐laden open channel flow is developed. Velocity profiles are derived by theoretical analysis and numerical method. Logarithmic law and semi‐empirical wake function concept are not adopted. An empirical equation for the ratio of sediment exchange and fluid diffusion coefficients is considered to solve the diffusion equation for suspended‐sediment concentration profiles. Four sets of experimental data from previous researchers are compared to numerical calculation. In the engineering applications, velocity and concentration profiles of sediment‐laden flow can be predicted simultaneously by the present model with the measured velocity and sediment‐concentration at reference level.     

EFFECTS OF LAND COVER AND GEOLOGY ON STREAM CHEMISTRY IN WATERSHEDS OF CHESAPEAKE BAY1

ABSTRACT: We measured the base‐flow stream chemistry in all the major physiographic provinces of the Chesapeake Bay drainage basin. The spatial variation of stream chemistry was closely related to differences in geology and land cover among the sampled watersheds. Some stream chemistry variables were strongly affected by geological settings in the watersheds while others were more influenced by land cover. The effects of land cover differed among chemical constituents and regions. Concentrations of Ca²⁺, Mg²⁺, pH, total alkalinity, and conductivity were mainly functions of carbonate bedrock, especially in the Great Valley. Nitrate‐N and total dissolved N were closely related to cropland and increased as the percentage of cropland increased. The rate of increase varied from region to region with the highest in the Piedmont. Na⁺ and Cl^? were mainly affected by the percentage of developed area in a watershed, especially in the Coastal Plain and Piedmont. We observed no significant effects of region or land cover on species of phosphorus because samples were collected under base flow conditions and only dissolved forms were measured. Dissolved silicate (DSi) was not related to any other water chemistry variables. DSi increased as developed area decreased and cropland increased in the Coastal Plain, but these patterns were reversed in the Piedmont. There was no consistent pattern in the spatial variation of land cover effects on the reduced forms of N, dissolved organic P, dissolved organic matter, and K⁺.     

Projecting Canadian Prairie Runoff for 2041–2070 with North American Regional Climate Change Assessment Program (NARCCAP) Data

The South Saskatchewan River Basin (SSRB) of Alberta, Canada, is semiarid and under severe water stress due to increasing human demands. We present the first examination of projected changes in SSRB runoff from a large set of North American Regional Climate Change Assessment Program regional climate models (RCMs) plus one Coordinated Regional Climate Downscaling Experiment RCM. We used six different runoff estimation methods: total surface and subsurface runoff (total runoff), surface runoff, and four estimations based on Budyko functions. Most RCM estimations showed substantial biases and distribution differences when compared to observed data; thus bias correction was necessary. Total runoff was the best of the six variables in modeling observed runoff for each of the four SSRB subbasins. Projected total runoff for 2041–2070 shows a geographic gradient in the SSRB, with possible drying in the southern Oldman River subbasin and possible increased runoff in the northernmost Red Deer River subbasin. A shift to an earlier spring peak in runoff and drier late summer, with a need for increased irrigation, should be expected. In a first examination of the important question of projected changes in interannual variability, we show increasing magnitude. This result further adds to adaptation challenges over the course of this century in this basin, which is already largely closed to further allocation.     

Modes of Variability of Annual and Seasonal Rainfall in Mexico

The aim of this study is to identify temporal and spatial variability patterns of annual and seasonal rainfall in Mexico. A set of 769 weather stations located in Mexico was examined. The country was divided into 12 homogeneous rainfall regions via principal component analysis. A Pettitt test was conducted to perform a homogeneity analysis for detecting abrupt changes in mean rainfall levels, and a Mann‐Kendall test was conducted to examine the presence of monotonically increasing/decreasing patterns in the data. In total, 14.4% of the annual series was deemed nonstationary. Fourteen percent of the samples were nonstationary in the winter and summer, and 9% were nonstationary in the spring and autumn. According to the results, the nonstationarity of some seasonal rainfall series may be associated with the presence of atmospheric phenomena (e.g., El Niño/Southern Oscillation, Pacific Decadal Oscillation, Atlantic Multidecadal Oscillation, and North Atlantic Oscillation). A rainfall frequency analysis was performed for the nonstationary annual series, and significant differences in the return levels can be expected for the scenarios analyzed. The identification of areas that are more susceptible to changes in rainfall levels will improve water resource management plans in the country, and it is expected that these plans will take into account nonstationary theory.     

Who counts,what counts: representation and accountability in water governance in the Upper Comoé sub‐basin,Burkina Faso

This article examines the unfolding of integrated water resource management (IWRM) reforms in southwest Burkina Faso, where water resources are subject to conflicting claims by a diversity of users. We first describe the establishment a local water user committee, showing how choices regarding composition and operations grant varying levels of recognition to different stakeholders. We then discuss the implications for key dimensions of decentralized governance, namely representation and accountability. In particular we focus on: (a) how the interplay of political agendas and policy disconnects shapes the committee's viability and credibility and (b) how tensions between techno‐scientific and local knowledge affect participation and transparency. We argue that in contexts defined by contentious politics and neo‐patrimonial practices, representativeness is better ensured by the direct inclusion of user groups rather than elected officials. Though limited discretionary power, information access, and technical capabilities of committee members inhibit accountability, rural producers uphold their claims through social mobilization and reliance on local knowledge. Recognizing the opportunities offered by the country's recent democratic turn, we formulate recommendations aimed at addressing structural drivers and enabling citizen agency in decentralized water governance. At the same time, further research is needed on local people's understandings of representation and accountability, to ensure that they are involved in institutional design and practices in ways that affirm what they value and what they know.     

Adaptive Water Resource Planning in the South Saskatchewan River Basin: Use of Scenarios of Hydroclimatic Variability and Extremes

The South Saskatchewan River Basin is one of Canada's most threatened watersheds, with water supplies in most subbasins over‐allocated. In 2013, stakeholders representing irrigation districts, the environment, and municipalities collaborated with researchers and consultants to explore opportunities to improve the resiliency of the management of the Oldman and South Saskatchewan River subbasins. Streamflow scenarios for 2025‐2054 were constructed by the novel approach of regressing historical river flows against indices of large‐scale ocean‐atmosphere climate oscillations to derive statistical streamflow models, which were then run using projected climate indices from global climate models. The impacts of some of the most extreme scenarios were simulated using the hydrologic mass‐balance model Operational Analysis and Simulation of Integrated Systems (OASIS). Based on stakeholder observations, the project participants proposed and evaluated potential risk management and adaption strategies, e.g., modifying existing infrastructure, building new infrastructure, changing operations to supplement environmental flows, reducing demand, and sharing supply. The OASIS model was applied interactively at live modeling sessions with stakeholders to explore practical adaptation strategies. Our results, which serve as recommendations for policy makers, showed that forecast‐based rationing together with new expanded storage could dramatically reduce water shortages.     

Longitudinal‐Vertical Hydrodynamic and Turbidity Simulations for Prediction of Dam Reconstruction Effects in Asian Monsoon Area1

Abstract: This research investigates possible impacts of enlarged water body according to dam reconstruction on the hydrodynamics and water quality of the reservoir using a laterally averaged, two‐dimensional hydrodynamic and transport model, CE‐QUAL‐W2. The lake was formed by the artificial dam in 1983 for agricultural water supply and is currently under consideration of reconstruction so as to expand the volume of reservoir for flood control as well as water supply in downstream areas. To calibrate and validate the model, field‐collected data were compared with model predictions for water level fluctuations and water temperature during the years of 2001 (from January to December) and 2003 (from March to November). The model results showed a good agreement with field measurements both in calibration and verification. Utilizing the model, impacts of dam reconstruction on the thermal hydrodynamics and turbid current were predicted. From the model results, dam reconstruction limited the depth of thermal stratification below 10 meter and formed steep temperature gradient between epilimnion and hypolimnion. The restricted thermal stratification persisted up to the end of September. This result indicated that thermal stratification would become stronger during summer and stay longer after dam reconstruction. In addition, the restricted thermal stratification caused vertical circulation of water mixing lower than 10 meter and isolated the upper water layer from the lower water layer which increased the volume of hypolimnetic water with low temperature. The vertical circulation near the surface also mitigated propagation of density plume within the depth of 10 m which would remain the hypolimnetic water clean.     

DECISION SUPPORT FOR ALLOCATION OF WATERSHED POLLUTION LOAD USING GREY FUZZY MULTIOBJECTIVE PROGRAMMING1

ABSTRACT: This paper uses the grey fuzzy multiobjective programming to aid in decision making for the allocation of waste load in a river system under versatile uncertainties and risks. It differs from previous studies by considering a multicriteria objective function with combined grey and fuzzy messages under a cost benefit analysis framework. Such analysis technically integrates the prior information of water quality models, water quality standards, wastewater treatment costs, and potential benefits gained via in‐stream water quality improvement. While fuzzy sets are characterized based on semantic and cognitive vagueness in decision making, grey numbers can delineate measurement errors in data collection. By employing three distinct set theoretic fuzzy operators, the synergy of grey and fuzzy implications may smoothly characterize the prescribed management complexity. With the aid of genetic algorithm in the solution procedure, the modeling outputs contribute to the development of an effective waste load allocation and reduction scheme for tributaries in this subwatershed located in the lower Tseng‐Wen River Basin, South Taiwan. Research findings indicate that the inclusion of three fuzzy set theoretic operators in decision analysis may delineate different tradeoffs in decision making due to varying changes, transformations, and movements of waste load in association with land use pattern within the watershed.