Basics of qualitative research: Grounded theory procedures and techniques

The term ''urban stream syndrome'' describes the consistently observed ecological degra- dation of streams draining urban land. This paper reviews recent literature to describe symptoms of the syndrome, explores mechanisms driving the syndrome, and identifies appropriate goals and methods for ecological restoration of urban streams. Symptoms of the urban stream syndrome include a flashier hy- drograph, elevated concentrations of nutrients and contaminants, altered channel morphology, and reduced biotic richness, with increased dominance of tolerant species. More research is needed before generaliza- tions can be made about urban effects on stream ecosystem processes, but reduced nutrient uptake has been consistently reported. The mechanisms driving the syndrome are complex and interactive, but most impacts can be ascribed to a few major large-scale sources, primarily urban stormwater runoff delivered to streams by hydraulically efficient drainage systems. Other stressors, such as combined or sanitary sewer overflows, wastewater treatment plant effluents, and legacy pollutants (long-lived pollutants from earlier land uses) can obscure the effects of stormwater runoff. Most research on urban impacts to streams has concentrated on correlations between instream ecological metrics and total catchment imperviousness. Recent research shows that some of the variance in such relationships can be explained by the distance between the stream reach and urban land, or by the hydraulic efficiency of stormwater drainage. The mech- anisms behind such patterns require experimentation at the catchment scale to identify the best management approaches to conservation and restoration of streams in urban catchments. Remediation of stormwater impacts is most likely to be achieved through widespread application of innovative approaches to drainage design. Because humans dominate urban ecosystems, research on urban stream ecology will require a broadening of stream ecological research to integrate with social, behavioral, and economic research.

https://www.jstor.org/stable/10.1899/04-028.1

The urban stream syndrome: current knowledge and the search for a cure

Membranes have an increasingly important role in alleviating water scarcity and the pollution of aquatic environments. Promising molecular-level design approaches are reviewed for membrane materials, focusing on how these materials address the urgent requirements of water treatment applications.

Materials for next-generation desalination and water purification membranes

As photovoltaic penetration of the power grid increases, accurate predictions of return on investment require accurate prediction of decreased power output over time. Degradation rates must be known in order to predict power delivery. This article reviews degradation rates of flat-plate terrestrial modules and systems reported in published literature from field testing throughout the last 40 years. Nearly 2000 degradation rates, measured on individual modules or entire systems, have been assembled from the literature, showing a median value of 0·5%/year. The review consists of three parts: a brief historical outline, an analytical summary of degradation rates, and a detailed bibliography partitioned by technology. Copyright © 2011 John Wiley & Sons, Ltd.

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Photovoltaic Degradation Rates—an Analytical Review

In the last few decades, pharmaceuticals, credited with saving millions of lives, have emerged as a new class of environmental contaminant. These compounds can have both chronic and acute harmful effects on natural flora and fauna. The presence of pharmaceutical contaminants in ground waters, surface waters (lakes, rivers, and streams), sea water, wastewater treatment plants (influents and effluents), soils, and sludges has been well doccumented. A range of methods including oxidation, photolysis, UV-degradation, nanofiltration, reverse osmosis, and adsorption has been used for their remediation from aqueous systems. Many methods have been commercially limited by toxic sludge generation, incomplete removal, high capital and operating costs, and the need for skilled operating and maintenance personnel. Adsorption technologies are a low-cost alternative, easily used in developing countries where there is a dearth of advanced technologies, skilled personnel, and available capital, and adsorption appears to be the most broadly feasible pharmaceutical removal method. Adsorption remediation methods are easily integrated with wastewater treatment plants (WWTPs). Herein, we have reviewed the literature (1990-2018) illustrating the rising environmental pharmaceutical contamination concerns as well as remediation efforts emphasizing adsorption.

Pharmaceuticals of Emerging Concern in Aquatic Systems: Chemistry, Occurrence, Effects, and Removal Methods.

As large areas of global landscapes become increasingly urbanized, the world’s rivers and streams degrade, with resultant alarming losses of biodiversity and capacity to provide ecosystem services (Dudgeon et al. 2006). This widespread degradation has spurred large investments in urban stream restoration programs that usually involve increasing in-stream habitat complexity or replanting riparian vegetation (Bernhardt et al. 2005). This approach is a fundamental mismatch with the scale and cause of such degradation: alteration of land cover and drainage pathways across catchments (Bernhardt and Palmer 2011). Assessment of the ecological effectiveness of such reachscale stream modification projects has been rare (Palmer et al. 2005), but recent studies suggest that resulting improvements in in-stream ecological structure and function are rare and, at best, marginal (Louhi et al. 2011, Violin et al. 2011). Effective restoration probably requires actions at the catchment-scale to directly redress degrading processes. The dispersed, land-based causes of stream degradation present a major challenge for stream ecologists who seek to understand the interactions of stream ecosystems with their catchments. To achieve such understanding, stream ecologists must work with the human community and natural resource managers who inhabit and work in the socioecological systems that constitute catchments (Collins et al. 2010). Projects aiming to achieve measurable restoration of stream ecosystems through catchment-scale actions are rare, particularly within an experimental framework. Catchment-scale experimentation requires collaboration among research disciplines and with a diverse range of actors in socioecological systems. In this cluster of papers, we report on a catchment-scale stream restoration experiment in Melbourne, Australia. The project was instigated by a stream ecologist (CJW) and a hydrologist (TDF). The task of garnering support for the project from funders, policy makers, stream managers, urban land managers, and the community of the experimental catchment has spanned a decade and has taken us well outside the comforts of our disciplines. Our experiences are no doubt unique in many ways, but we report here the approaches taken, mistakes made, and lessons learned to inform the future catchment-scale studies that are required to arrest the global decline of the world’s rivers. We begin with a paper outlining the rationale, experimental design, history of the project, and perspectives on our relationships and interactions with the diverse group of people involved in the project (Walsh et al. 2015). The following 3 papers in the cluster present project reviews from the perspective of 3 important collaborators: the catchment community (Bos and Brown 2015); the local government authorities who regulate, implement, and manage the drainage infrastructure of the catchment (Burns et al. 2015); and the regional waterway management authority that was the primary funder of the project (Prosser et al. 2015). Each of these papers comes from a social science discipline that is unusual for Freshwater Science, but we think this disciplinary perspective is

https://www.jstor.org/stable/10.1086/682394

Stream experiments at the catchment scale: the challenges and rewards of collaborating with community and government to push policy boundaries

To restore streams degraded by urbanisation, bioretention basins (‘raingardens’) are implemented worldwide to reduce stormwater volumes, peaks flows and pollutant loads entering streams. While they...

The hydrologic, water quality and flow regime performance of a bioretention basin in Melbourne, Australia

Stormwater biofilters process diverted runoff through dense vegetation followed by vertical filtration through a porous soil-based media. The plant community is an essential component of a biofilter, yet the evaluation of the efficacy of plants for biofiltration has predominantly been attempted only as single-plant pot experiments. This paper investigates the effects of multi-species planting on pollutant removal to reveal how the relationship between two plants frequently used in biofilters affects effluent water quality. Carex appressa and Lomandra longifolia plants were grown in laboratory scale stormwater biofilters in groups of four, with plant communities comprising a monoculture, 25:75, 50:50 and 75:25 percent for each species. The biofilters were dosed with semi synthetic stormwater three times per week with effluent samples collected after 6, 12 and 18 weeks and analysed for Total Suspended Solids (TSS), Total Nitrogen (TN), Total Phosphorus (TP) and their species. Plant ratios containing a monoculture of C. appressa or a mixture of C. appressa and L. longifolia yield up to 23% greater nutrient removal than the monoculture of Lomandra for TN; and up to 42% higher for nitrate/nitrite (NOx). All plant ratios consistently remove in excess of 90% TSS, ammonia (NH3), TP and filterable reactive phosphorus (FRP) by the third sampling period. This work indicates that plantings incorporating C. appressa and L. longifolia in biofilters can improve pollutant removal over a monoculture of L. longifolia.

Mixed plantings of Carex appressa and Lomandra longifolia improve pollutant removal over a monoculture of 'L. longifolia' in stormwater biofilters

Water infrastructure in cities is complex and requires proactive management to optimise function. The scale and distribution of assets across municipalities requires affordable systems which can trigger alerts. Systems underpinned by low-cost sensors could meet increasing monitoring needs: more assets, more often, and at a better resolution. However, low-cost sensors require appropriate testing to assess their performance and optimise their use. Here, we focus on low-cost water level sensors, often considered as the main monitoring parameters for water-related infrastructures. We developed a platform and testing protocol to assess the suitability of low-cost sensors. We assessed the performance of three widely used low-cost sensors: laser-ranging, ultrasonic-ranging, and pressure. Our main results showed that the ultrasonic sensor offers the best price to accuracy ratio, and the pressure sensor provides the highest accuracy while still at a very low cost. Our platform and protocol provide a standardised testing and calibration method which can be applied to any sensor. The platform can be used to gather and share results, to enhance community knowledge and encourage the use of new (low-cost or not) sensors. The development of low-cost sensors is an important step toward the wider use monitoring systems for water infrastructure.

A platform and protocol to standardise the test and selection low-cost sensors for water level monitoring

Hydraulic conductivity of soil used in biofiltration systems is one of the key parameters to assess when designing and building such systems. However, changes in hydraulic conductivity over time may be a real issue and may lead to a loss of treatment capacity, more frequent overflow and problems with stagnant water. This article aims to study clogging phenomena using a laboratory approach, in order to assess the influence of design parameters (vegetation, size, soil type and inflow concentration) on hydraulic conductivity and its evolution. Hydraulic conductivity was measured on 125 biofiltration columns over a 72 week period. Initial values were within Australian guidelines (50 – 200 mm/h), with a median value of 186 mm/h. After almost 1.5 year of operation, hydraulic conductivity dropped to 27% of the initial value (median of 51 mm/h). Vegetation did not have an influence on clogging, except when a species with course roots, such as Melaleuca, is used. In this case, hydraulic conductivity increases over time. The size of the system relative to its catchment is of prime importance. Small systems (in our case, systems designed at 0.7% of their catchment) are more prone to rapid clogging than are larger systems (designed at 2% or 4% of their catchment). Clogging rate is also influenced by the inflow concentration, increasing with higher concentrations of sediment. These results will inform improved design guidelines for biofilters.

Tim D. Fletcher

Papers

Stream experiments at the catchment scale: the challenges and rewards of collaborating with community and government to push policy boundaries

The hydrologic, water quality and flow regime performance of a bioretention basin in Melbourne, Australia

Mixed plantings of Carex appressa and Lomandra longifolia improve pollutant removal over a monoculture of 'L. longifolia' in stormwater biofilters

A platform and protocol to standardise the test and selection low-cost sensors for water level monitoring

Influence of time and design on the hydraulic performance of biofiltration systems for stormwater management