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.

/pdf/photovoltaic-degradation-rates-an-analytical-review-a86in1nx10.pdf

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.

Green or vegetated roofs are increasingly built in cities to provide multiple environmental and social benefits and are an emerging horticultural industry in Australia. Since 2008, researchers at the University of Melbourne s Burnley Campus have undertaken transdiciplinary research developing and evaluating green roofs for southern Australian conditions which are characterised by hot, dry summers. We have quantified plant performance through experiments on roofs and in controlled environments, using both Australian native and exotic species, to identify plant physiological and morphological traits that will improve green roof performance. We have developed lightweight mineral substrates based on scoria, bottom-ash from coal fired power stations and crushed roof tiles and evaluated water retention additives to improve water holding capacity and plant survival. Hydrology studies have found that 10-cm deep green roofs with scoria substrate can reduce stormwater runoff in Melbourne by 43-88%, depending on season and plant species. We found that a 12.5-cm deep green roof reduces building energy use by 38% in summer. Environmental psychology research demonstrates that people prefer green roofs with flowering meadow like vegetation and that viewing this type of green roof improves concentration and improves work performance. Our results have been embraced by the Australian green roof industry, resulting in construction of green roofs with our best performing substrates and plants and the development of science-based guidelines for future green roof projects.

Developing Australian green roofs: overview of a 5-year research program.

http://www.roclagroup.com.au/Rocla/ProductLiterature/Poelsma_et_al_WSUD_2009_Paper.pdf

Development of a new stormwater collection and treatment unit

The Little Stringybark Creek restoration project is the first of its kind, focusing on reducing stormwater runoff using LID strategies across an entire sub-watershed. Urban streams around the globe demonstrate common characteristics associated with the increased imperviousness of their watersheds, including a flashy hydrograph, elevated concentrations of pollutants, altered channel morphology, and increased dominance of pollution tolerant species. Urban streams cannot be restored to pre-disturbance stream health conditions without addressing the combined water quality and hydrologic disturbance (increased volume and frequency of polluted stormwater runoff) from impervious areas delivered by drainage infrastructure in developed watersheds. This poses a great challenge for stream restoration, since it is much easier to implement local or reach scale in-stream or riparian projects than to reduce the stormwater impacts of impervious areas in a catchment. One of the key needs for the protection or restoration of streams in urban or urbanizing catchments is, therefore, a better understanding of specific and practical stormwater management objectives at the catchment and site scale aimed at addressing hydrologic characteristics that affect streams. © 2009 American Society of Civil Engineers.

Tim D. Fletcher

Papers

Developing Australian green roofs: overview of a 5-year research program.

Development of a new stormwater collection and treatment unit

Stream Restoration through Stormwater Runoff Management and Retrofit: New Objectives, New Approaches

Advancing biofilter design for co-optimised nitrogen and phosphorus removal

Not just a flow problem: How does urbanization impact on the sediment regime of streams?