Steven C. Chapra

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The PhATE (Pharmaceutical Assessment and Transport Evaluation) model presented in this paper was developed as a tool to estimate concentrations of active pharmaceutical ingredients (APIs) in U.S. surface waters that result from patient use (or consumption) of medicines. PhATE uses a mass balance approach to model predicted environmental concentrations(More)
QUAL2Kw is a framework for the simulation of water quality in streams and rivers. Dynamic diel heat budget and water quality kinetics are calculated for one-dimensional steady-flow systems. The framework includes a genetic algorithm to facilitate the calibration of the model in application to particular waterbodies. The genetic algorithm is used to find the(More)
Models addressing excessive nutrient loading in the environment originated over 50 years ago with the simple nutrient concentration thresholds proposed by Sawyer (1947. Fertilization of lakes by agricultural and urban drainage. New Engl. Water Works Assoc. 61, 109-127). Since then, models have improved due to progress in modeling techniques and technology(More)
Recent advances in computer technology and water resource modeling, availability of real-time hydroclimatic data, and improvements in our ability to develop user-friendly graphical model interfaces have led to significant growth in the development and application of decision support systems ~DSSs! for water resource systems. This study provides an example(More)
As human populations increase and land-use intensifies, toxic and unsightly nuisance blooms of algae are becoming larger and more frequent in freshwater lakes. In most cases, the blooms are predominantly blue-green algae (Cyanobacteria), which are favored by low ratios of nitrogen to phosphorus. In the past half century, aquatic scientists have devoted much(More)
Photochemical and microbial processes in surface waters can result in changes in the chemical quality of dissolved organic matter (DOM), which may in turn influence other ecosystem processes. Microbially-derived non-humic DOM can enter the aquatic ecosystem through extracellular release. Further, it has been hypothesized that microbially-derived fulvic acid(More)
A mathematical model of the Great Lakes total phosphorus budgets indicates that a 1 milligram per liter effluent restriction for point sources would result in significant improvement in the trophic status of most of the system. However, because large areas of their drainage basins are devoted to agriculture or are urbanized, western Lake Erie, lower Green(More)
A passive method for remote sensing of the nuisance green algae Cladophora glomerata in rivers is presented using an unmanned aerial vehicle (UAV). Included are methods for UAV operation, lens distortion correction, image georeferencing, and spectral analysis to support algal cover mapping. Eighteen aerial photography missions were conducted over the summer(More)
We investigated the transport and production of dissolved organic matter (DOM) in an alpine lake in the Colorado Front Range during snowmelt and the summer ice-free season by employing a new approach for distinguishing between three pools of DOM based on fractionation and spectroscopic characterization. Reactive transport modeling results confirm that(More)
Recent developments in web technologies including evolution of web standards, improvements in browser performance, and the emergence of free and open-source software (FOSS) libraries are driving a general shift from server-side to client-side web applications where a greater share of the computational load is transferred to the browser. Modern client-side(More)