ASSESSMENT OF PREDICTORS FOR STREAM EUTROPHICATION POTENTIAL1

ABSTRACT: Predicting stream eutrophication potential from non-point source nutrient loading across large temporal and spatial scales is a significant problem. In this paper we describe how two physiological indicators of P stress of stream bioflims, alkaline phosphatase activity (APA) and stored (surplus) P relate to two predictors of P loading: annual P loading predicted by the watershed model SIMPLE, and stream concentrations of soluble reactive P (SRP) in eight subbasins in the illinois River basin in Oklahoma. Data for APA, surplus P, nutrients and water chemistry were obtained at watershed outlets once during the cold season and twice during the warm season. There was a negative curvilinear relationship between APA and both predictors. Best fit was achieved by APA vs. annual predicted P loading. Both SRP and P. load are potentially useful to identify subbasins requiring no pollution abatement and to establish a regional target for P-load reduction. Surplus P is not as useful as APA in establishing these thresholds.     

Quantifying Legacy Phosphorus Using a Mass Balance Approach and Uncertainty Analysis

Classic agricultural‐conservation practices may not address decades of phosphorus (P) accumulation, known as legacy P. Identifying and quantifying legacy P sources are necessary to identify the most cost‐efficient conservation practices. A method was developed to identify and quantify legacy P at the watershed scale using a mass‐balance approach and uncertainty analysis. The method was applied to two nutrient‐rich watersheds in northeast Oklahoma and northwest Arkansas. Each P import and export to and from the two watersheds was identified and quantified using a probability distribution and uncertainty analysis. The P retained in the soils, reservoirs, and stream systems were estimated from 1925 to 2015. Over 8.5 and 6.1 kg/ha/year of P were added to the Illinois River and Eucha‐Spavinaw watersheds with 53 and 55% from poultry production, respectively. Other major historical sources were attributed to human population and commercial fertilizer. Though currently the net addition of P in the watersheds is small due to the export of approximately 90% of the poultry litter, historically only 14‐19% of all P imported to the Illinois River and Eucha‐Spavinaw watersheds was removed via the reservoir spillways, poultry litter, and food exports. The majority of the retained P is located in the soil, 3.6‐5.8 kg/ha/year, and stream systems, 0.01‐3.0 per ha/year.     

SEASONAL PUMPING VARIATION EFFECTS ON WELLHEAD PROTECTION AREA DELINEATION1

ABSTRACT: Delineation of a welihead protection area (WHPA) is the key element in welihead protection programs for drinking water supplies. WHPAs are often delineated under idealized conditions using simple steady-state assumptions, which lead to an incorrect estimation of area and geometry. In this paper, we compare the results from a simple steady-state procedure commonly employed in WHPA delineation with a more complex transient approach that allows consideration of seasonal variation in pumping rates. We also introduce a transient procedure to delineate time-related capture zones using a numerical ground water flow and transport model. Welihead delineation is examined for two municipal wells in Tipton, Oklahoma, using a ten-year time-of-travel criterion. In the steady-state procedure, where we assumed constant pumping rates, we used GPTRAC, a semi-analytical model, and MOC, a numerical model. The capture zone delineated by GPTRAC is comparable in shape with the capture zone delineated by MOC but not in size due to the differences in solution schemes. In the transient procedure, we used MOC and considered the seasonal variation in pumping rates. The capture zones delineated in this procedure were larger than the capture zones delineated by the steady-state procedure using the same model. Further analysis showed that a higher drawdown was predicted in the transient procedure than in the steady-state procedure, which is the reason for larger capture zones.     

A Hydrologic/Water Quality Model Applicati11

Abstract: This paper presents a procedure for standard application of hydrologic/water quality models. To date, most hydrologic/water quality modeling projects and studies have not utilized formal protocols, but rather have employed ad hoc approaches. The procedure proposed is an adaptation and extension of steps identified from relevant literature including guidance provided by the U.S. Environmental Protection Agency. This protocol provides guidance for establishing written plans prior to conducting modeling efforts. Eleven issues that should be addressed in model application plans were identified and discussed in the context of hydrologic/water quality studies. A graded approach for selection of the level of documentation for each item was suggested. The creation and use of environmental modeling plans is increasingly important as the results of modeling projects are used in decision‐making processes that have significant implications. Standard modeling application protocols similar to the proposed procedure herein provide modelers with a roadmap to be followed, reduces modelers’ bias, enhances the reproducibility of model application studies, and eventually improves acceptance of modeling outcomes.     

Two stage biological treatment of a diazo reactive textile dye and the fate of the dye metabolites

A two stage anaerobic/aerobic bacterial process was used to decolorize and partially mineralize a reactive vinyl sulfone diazo dye C.I. Reactive Black 5 (RB5) in a synthetic wastewater. Since the anchor group of reactive dyes reacts during the dyeing process, the effect the degree of hydrolysis of the vinyl sulfone dye had on decolorization, mineralization and toxicity in each stage was investigated. An overall color removal of approximately 65% was found for both the fully and partially hydrolyzed dye. Partial mineralization of the fully hydrolyzed RB5 was achieved in the two stage rotating disc reactors. While the anchor group metabolite p-aminobenzene-2-hydroxyethylsulfonic acid (p-ABHES) was mineralized, an oxidized form of the center metabolite (1,2-ketimino-7-amino-8-hydroxynaphthalene-3,6-disulfonic acid) remained in the aerobic stage effluent, causing the effluent to be colored although no RB5 was present. Partially hydrolyzed dye in the influent with vinyl forms of the anchor group caused cessation of biogas production and a reduction in decolorization efficiency in the anaerobic stage. No evidence for mineralization of the partially hydrolyzed dye or its metabolites was found. A method for evaluating dye mineralization using lumped parameters is presented.     

Estimating irrigation water demand in the Moroccan Drâa Valley using contingent valuation

Irrigation water management is crucial for agricultural production and livelihood security in Morocco as in many other parts of the world. For the implementation of an effective water management, knowledge about farmers' demand for irrigation water is crucial to assess reactions to water pricing policy, to establish a cost-benefit analysis of water supply investments or to determine the optimal water allocation between different users. Previously used econometric methods providing this information often have prohibitive data requirements. In this paper, the Contingent Valuation Method (CVM) is adjusted to derive a demand function for irrigation water along farmers' willingness to pay for one additional unit of surface water or groundwater. An application in the Middle Draa Valley in Morocco shows that the method provides reasonable results in an environment with limited data availability. For analysing the censored survey data, the Least Absolute Deviation estimator was found to be a more suitable alternative to the Tobit model as errors are heteroscedastic and non-normally distributed. The adjusted CVM to derive demand functions is especially attractive for water scarce countries under limited data availability.     

PRIORITIZING NONPOINT SOURCE PHOSPHORUS LOADING USING A GRASS-MODELING SYSTEM1

ABSTRACT: A UNIX-based windows application was developed to integrate a phosphorus transport model with the Geographic Resources Analysis Support System (GRASS). The system prioritizes potential phosphorus loading from fields or cells in a watershed and can evaluate the effects of alternate management practices on phosphorus yield. The model simulates phosphorus loading by using a daily mass balance on a unit-area basis and incorporates the effects from rainfall, topography, soil properties, fertilizer and animal waste application, and management. Model predictions include dissolved and sediment-bound phosphorus yield, runoff volume, and sediment yield. Within the integrated GRASS-modeling system, the user can obtain model input data, execute the model using various options, rank model input and out. put data, and display them as GRASS-based maps or data tables. All functions are menu driven, developed using C language and X-window tools to run on a SUN workstation platform. The system provides a powerful and efficient tool for prioritizing phosphorus loading from nonpoint sources.     

Temporal and Spatial Turbidity Patterns Over 30 Years in a Managed Forest of Western Washington1

Abstract: Forest practices have progressively changed over the last 30 years in the Pacific Northwest to address water quality concerns. There have been some assessments of these new management practices made at a site scale but very few studies have attempted to evaluate their efficacy at reducing cumulative sediment production at a watershed scale. Such an evaluation is difficult due to the spatial and temporal variability in sediment delivery and transport processes. Due to this inherent variability, detecting a response to management changes requires a long‐term data record. We utilized a water quality dataset collected over 30 years at four locations in the Deschutes River watershed (western Washington) to assess trends in turbidity and whether sediment control procedures implemented over this time period had any detectable influence. The sample sites ranged from small headwater streams (2.4 and 3.0 km²) to the mainstem of the Deschutes River (150 km²). Declining trends in turbidity were detected at all the permanently monitored sites. The mainstem Deschutes River site, which integrates sediment processes from the entire study watershed, showed dramatic declines in turbidity even with continued active forest management. For the small basins, logging and road construction occurred in the 1970s and 1980s and turbidity declined thereafter, achieving prelogging levels by 2000. There are no temporal trends in flow that could be responsible for the observed trends in turbidity. Our results suggest that increased attention to reducing sediment production from roads and minimizing the amount of road runoff reaching stream channels has been the primary cause of the declining turbidity levels observed in this study.     

Fly-ash-amended sand as filter media in bioretention cells to improve phosphorus removal.

This study identified material with high phosphorus sorption suitable for bioretention filter media. Materials examined were fly ash, two expanded shales, peat moss, limestone, and two common Oklahoma soils--Teller loam and Dougherty sand. The peat moss was a phosphorus source, while the two soils, limestone, and one expanded shale had only modest sorption capacity. One expanded shale and the fly ash had significant phosphorus sorption. Fly ash is unsuitable for use in a pure form, as a result of its low permeability, but phosphorus sorption on the sand was increased significantly with the incorporation of small amounts of fly ash. Column leaching experiments found that the sand with 2.5 and 5% fly ash and the better expanded shale had linear, non-equilibrium transport retardation factors of 272, 1618, and 185, with first-order rate coefficients of 0.153, 0.0752, and 0.113 hour(-1), respectively. Desorption experiments showed that the phosphorus sorption on the sand/fly ash mixture is largely nonreversible. Transport simulation assuming a 1-m-deep sand/fly ash treatment layer, with 5% of the watershed area, showed that the sand/fly ash filter media could effectively treat 1 mg/L influent for 12 years in a paved watershed and 34 years in a grassed watershed before exceeding Oklahoma's scenic rivers' phosphorus criterion of 0.037 mg/L. Significant phosphorus removal would continue for over 100 years.     

Book reviews

Deregulation in the European Union: environmental perspectives. U. Collier (Ed.), 1998, London, Routledge, ISBN 0 415 15694 7, £47.50 (hbk)

Protecting the European Environment: enforcing EC environmental law. H. Somsen (Ed.), 1996, London, Blackstone Press, ISBN 185 431 6044, £19.95

Green Parties and Politics in the European Union. Elizabeth Bomberg, 1998, London, Routledge, ISBN 0 415102 650, £15.99 (pbk)

British Environmental Policy and Europe. Philip Lowe & Stephen Ward (Eds), 1998, London, Routledge, ISBN 0 415155 010, £16.99 (pbk)

Wolf in the Garden: the land rights movement and the new environmental debate. Philip D. Brick & R. McGreggor Cawley (Eds), 1996, Lanham, MD, Rowman & Littlefield, ISBN 08476 8184 X, US$67.50 (hbk) ISBN 08476 8185 8, US$24.95 (pbk)

Fresh Water. E. C. Pielou, 1998, Chicago, IL, University of Chicago Press, ISBN 0 226 66815 0, US$24/£19.25 (hbk)

Environment and Politics. Timothy Doyle & Doug McEachern, 1998, London, Routledge, ISBN 0415 14776, £10.99

Eat Your Genes: how genetically modified food is entering our diet. S. Nottingham, 1998, London, Zed Books, ISBN 1 85649 577 9, £32.95 (hbk) ISBN 1 85649 578 7, £11.95 (pbk)

Working for Better Environmental Performance in SMEs. PACTE programme of the European Commission, 1997, Project of Berlin, Bristol, Copenhagen and Vienna¹ (no charge)

Love Canal, the Story Continues. Lois Marie Gibbs, 1998, Gabriola Island, BC, New Society Publishers, ISBN 0 86571 382 0, US$16.95/Can$19.95 (pbk)