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Short-term studies of wetlands show that wetlands scavenge pollutants, thereby mitigating the pollution of downstream water bodies. However, there are few long-term studies that demonstrate this effect. This study provides a wealth of data demonstrating that there is variable long-term mobility of metals and arsenic in wetland-lake systems. More than 900 samples were analyzed from 14 soil and sediment cores collected from six wetland-lake systems in the same floodplain. Cores were analyzed for a suite of trace elements (As, Co, Cu, Ni, Pb, Zn are reported in this paper), organic matter content, clay content, and water content. Sediment age was estimated using 210 Pb and 137 Cs data, facilitating comparison of element concentrations in contemporaneous wetland and lake sediments. In all six systems, sediment-laden water passes through the wetland before settling into the lake. In three of the systems, element concentrations were consistently higher in lake sediments, indicating a history of remobilization of wetland elements and subsequent deposition in lake sediments. Results in the other three lakes were variable, documenting unique long-term histories of element mobility and sequestration in otherwise similar systems. [ABSTRACT FROM AUTHOR]

Service-learning courses at the university level provide a unique opportunity for students to learn about sustainability. The seniorlevel and graduate-level elective course Service-Learning for Water Treatment at the University of Mississippi's (UM) School of Engineering combines educational and service activities on drinking water--treatment infrastructure for underprivileged communities. Students learn in person how to build and operate demonstration treatment systems and then test new prototype configurations. This course format allows engineering students to bring the evaluation of an infrastructure project to completion, apply sustainability principles, interact with a collaborating partner, and provide a real service. The three pillars of sustainability--environmental, social, and economic--are immediately apparent to students, who document their learning in reflection essay assignments during the semester. Essay assignments about sustainability are evaluated using open coding to assess students' knowledge of the three pillars. It is apparent that through the service-learning experience, students were able to closely relate to all three pillars, especially the social pillar. [ABSTRACT FROM AUTHOR]

Storms cause a substantial increase in the fecal indicator bacteria (FIB) concentrations in stream water as a result of FIB-laden runoff and the release of FIB from stream sediments. Previous work has emphasized the association between FIB and bed sediments finer than sand. The objectives of this work were to elucidate the effect of various velocities on the entrainment of bed-dwelling coliforms in sand-bed streams and to refine methodologies for quantifying sandy streambeds as sources of FIB. Pump-induced hydrographs were created using a stainless steel nonrecirculating flume. Experiments consisted of simulating four storm hydrographs and collecting water samples upstream and downstream of a sand bed at selected intervals. Bed sediment samples were collected before and after each event. The highest concentrations of total coliform and suspended sediments generally occurred in the downstream samples during the rising limb of the hydrographs as a result of entrainment of coliforms and sand from the bed to the water column. There was a first flush effect in the system, as the upper layer of sand was influenced by a rapidly increasing velocity at ~0.2 m s-1. Coliforms downstream of the sand bed increased rapidly as velocity exceeded this threshold but then declined even as velocity and discharge continued to increase. This likely reflects the depletion of coliforms as the more densely populated sediment layer was flushed out. There is evidence that streams with sand beds harbor enough FIB that development of total maximum daily loads (TMDLs) should include consideration of them as a source. [ABSTRACT FROM AUTHOR]

SODIS, solar disinfection of water in plastic bottles, is a well-known water treatment method utilized in communities lacking water treatment infrastructure. While SODIS is commonly employed by individuals and family units needing clean drinking water, a larger, community-scale solar disinfection system is presented in this paper as an alternative, appropriate, humanitarian engineering technology. A community-scale system may be acceptable for communities that reject the individual-bottle SODIS method. To test the treatment effectiveness of such a system, experiments were conducted to quantify the solar inactivation rate of total coliform bacteria from contaminated source water. Solar disinfection configurations in tanks and bottles were analyzed for the effect of ultraviolet (UV) light index, water temperature, tank color, plastic covering, and duration of sun exposure. A black tank, covered with a clear, plastic drop cloth with a thickness of 2 MIL (0.0508 mm) provided an effective inactivation rate of total coliforms. A contour plot of UV index versus water temperature provides guidelines for minimum required sun exposure times for disinfection. [ABSTRACT FROM AUTHOR]

A common remedial technology for properties with subsurface soil and groundwater contamination is multiphase extraction (MPE). MPE involves the extraction of contaminated groundwater, free-floating product, and contaminated soil vapor from the subsurface. A network of recovery wells conveys fluids to a vacuum pump and to the treatment system for the contaminated groundwater and soil vapor. This article describes a study of MPE operational data from nine similar remediation projects to determine the most important design parameters. Design equations from guidance manuals were used to estimate the expected radius of influence (ROI) based on measured field data. ROIs were calculated for the vapor flow rate through the subsurface and for the groundwater drawdown caused by the MPE remediation activities. The calculated ROIs were compared to the measured ROIs to corroborate the assumptions made in the calculations. Once it was established that the calculated and field-measured ROIs were comparable, a sensitivity analysis determined ranges of different design and operational parameters that most affected the ROIs. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

This paper presents the results of a community-scale drinking water treatment system assessment by University of Mississippi School of Engineering students and the organization Living Waters for the World (LWW). Communities facing a severe lack of sustainable and clean drinking water use LWW microfiltration, ozone water treatment, ultraviolet, and chlorination systems worldwide. Students worked on two projects: (1) evaluation of the ozonation system by measuring several water quality parameters, and (2) creation of a chlorine concentration table based on strength and volume of bleach added to a batch of water. The students' assessment determined that the LWW ozone disinfection and microfiltration system effectively treats water by removing and inactivating bacteria that could cause adverse health effects in humans. When developing the chlorination table, students considered typical units of measurement and tools available in disadvantaged communities. Students learned and performed water quality testing while considering technical and social implications of the treatment systems. [ABSTRACT FROM AUTHOR]

Fecal indicator bacteria (FIB) have long been used as a marker of fecal pollution in surface waters subject to point source and non-point source discharges of treated or untreated human waste. In this paper, we set out to determine the source(s) of elevated FIB concentrations in Cucamonga Creek, a concrete-lined urban stream in southern California. Flow in the creek consists primarily of treated and disinfected wastewater effluent, mixed with relatively smaller but variable flow of runoff from the surrounding urban landscape. Dry and wet weather runoff contributes nearly 100% of FIB loading to Cucamonga Creek, while treated wastewater contributes significant loading of nutrients, including dissolved organic carbon (DOC), phosphorus, nitrate, and ammonium. FIB concentrations are strongly positively correlated with DOC concentration in runoff (Spearman's ρ ≥ 0.66, P ≤ 0.037), and microcosm studies reveal that the survival of Escherichia coli and enterococci bacteria in runoff is strongly dependent on the concentration of both DOC and phosphorus. Below threshold concentrations of 7 and 0.07 mg/L, respectively, FIB die off exponentially (die-off rate 0.09 h-1). Above these thresholds, FIB either grow exponentially (growth rate 0.3 h-1) or exhibit a periodic steady-state in which bacterial concentrations fluctuate around some mean value. The periodic steady-state pattern is consistent with a Lotka—Volterra predator—prey oscillation model, and the clearance rate (20 μL predator-1 h-1) obtained by fitting the model to our data is consistent with the hypothesis that predacious protozoa regulate FIB concentrations in runoff at high DOC concentrations. Collectively, these results indicate that FIB impairment of Cucamonga Creek is best viewed as an ecological phenomenon characterized by both bottom-up and top-down control. [ABSTRACT FROM AUTHOR]

Field studies were conducted to characterize the concentration vs streamflow relationships (or ‘flow fingerprints’) of fecal pollution and suspended solids in stormwater runoff from the Santa Ana River watershed, the largest watershed in southern California. The concentrations of fecal indicator bacteria and F+ coliphages (viruses infecting E. coli) exhibit little-to-no dependence on streamflow rates, whereas the concentrations of total suspended solids (TSS) exhibit a very strong (power-law) dependence on streamflow rates. The different flow fingerprints observed for fecal pollutants, on one hand, and TSS, on the other hand, reflect different sources and transport pathways for these stormwater constituents. The flow-independent nature of fecal indicator bacteria and F+ coliphages is consistent with the idea that these contaminants are ubiquitously present on the surface of the urban landscape and rapidly partition into the surface water as the landscape is wetted by rainfall. The flow-dependent nature of TSS, on the other hand, is usually ascribed to the shear-induced erosion of channel bed sediments and/or the expansion of drainage area contributing to runoff. The apparent ubiquity of fecal indicator bacteria and F+ coliphages, together with the very high storm-loading rates of fecal indicator bacteria and the low detection frequency of human adenovirus and human enterovirus, suggest that fecal pollution in stormwater runoff from the Santa Ana River watershed is primarily of nonhuman waste origin. [ABSTRACT FROM AUTHOR]

Passive acoustic technology has potential as a surrogate method for monitoring coarse bedload transport in rivers and streams. This has been demonstrated by both laboratory experiments and field studies where it was found that acoustic energy generated by particle collisions was proportional to the amount of bedload in transport. One factor that has inhibited further development of the technique is that comparison of acoustic data is complicated by the wide variety of hardware used. A second factor is the need for each research group to assemble hardware, which is often expensive and designed for laboratory use. In addition, the hardware used in the field is rarely calibrated. In order to demonstrate how an entire acoustic data acquisition system should be calibrated for coarse bedload data collection, this manuscript presents the assembly and calibration of an inexpensive acoustic system comprised of readily available equipment. The following are presented here: assembly of the system, key operating parameters and suggested specifications, system calibration, and experiences from multiple deployments of the example system. [ABSTRACT FROM AUTHOR]