ORCID Profile
0000-0002-5740-7624
Current Organisations
University of South Australia
,
University of the Sunshine Coast
,
Covey Associates
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Publisher: MDPI AG
Date: 24-06-2021
DOI: 10.3390/W13131746
Abstract: This study reports the biomass accumulation, plant nutrient concentration, and nutrient uptake rates of plants in a constructed floating wetland (CFW) installed for a sewage treatment application in Australia. Plant biomass accumulation was estimated based on field s lings throughout the duration of the study. Analysis of s les of each plant species was also completed to estimate the mean plant tissue nutrient content. The plant biomass accumulation estimate and the mean plant tissue nutrient concentration were then used to estimate the total nutrient uptake for each species. Each of the species were found to differ in biomass accumulation and plant tissue nutrient concentration and the distribution of biomass and nutrients between the shoots and roots. The nutrient uptake rates varied between the species, with B. articulata having the greatest nutrient uptake rates (shoots: N, 104 ± 31.5 g/m2, P, 12.9 ± 3.87 g/m2 roots: N, 23.9 ± 7.23 g/m2, P, 5.54 ± 1.67 g/m2). Harvesting of the four CFW islands after 375 days of growth removed an estimated 23.2 kg of N and 2.97 kg of P. The results of this study indicate that the use of CFWs with carefully selected plant species can successfully remove significant amounts of nutrients from domestic wastewater.
Publisher: Springer Science and Business Media LLC
Date: 21-09-2013
Publisher: Elsevier BV
Date: 08-2019
DOI: 10.1016/J.SCITOTENV.2019.04.341
Abstract: This study investigated plant growth, nutrient partitioning and total nutrient uptake by tall sedge (Carex appressa) plants in two large-scale Constructed Floating Wetlands (CFW1 and CFW2). These CFWs were installed to treat stormwater runoff discharging into a newly-constructed 2.6-ha lake during the construction phase of a 45-ha residential development. Nutrient concentrations of C. appressa shoot above the mat, biomass within the mat, and roots below the mat were analysed 0, 12 and 16 months after planting. Extensive root growth was evident after 12 and 16 months. Some nutrients (nitrogen, phosphorus, sulphur) were distributed almost evenly among the above-, within-, and below-mat components, while others (aluminium, copper, iron, manganese) were concentrated in or on the roots. Given the low concentrations of nutrients within the water column, large amounts of nutrients were removed from stormwater by the plants. Total nitrogen uptake was 20.20 ± 2.88 kg in CFW1 and 15.00 ± 2.07 kg in CFW2 over the 16-month study period. Total potassium uptake was 12.59 ± 1.64 kg in CFW1 and 7.20 ± 1.56 kg in CFW2. Phosphorus uptake was low as a consequence of low phosphorus availability in the water. High aluminium, iron and manganese concentrations were found in the roots, demonstrating that C. appressa removed and sequestered large quantities of these water pollutants from urban stormwater runoff. For ex le, total aluminium uptake was 7.82 ± 1.73 kg in CFW1 and 5.62 ± 0.75 kg in CFW2. This study demonstrated multiple benefits of CFWs for stormwater treatment in the early stages of an urban development.
Publisher: Elsevier BV
Date: 07-2023
Publisher: International Journal of Geomate
Date: 03-2017
Publisher: Elsevier BV
Date: 09-2022
Publisher: Springer International Publishing
Date: 2023
Publisher: Elsevier BV
Date: 04-2019
DOI: 10.1016/J.SCITOTENV.2019.01.018
Abstract: A Constructed Floating Wetland (CFW) is a relatively recent innovation in stormwater treatment and is a hydroponic device that is designed to move up and down with changing water levels as urban runoff enters a stormwater retention pond. This floating capability is designed to improve the pollutant removal efficiency of the CFW. The CFW studies undertaken so far have produced encouraging results under a range of conditions such as system size, inflow pollutant concentrations, climatic conditions, and coverage ratio. However, these results have not yet been drawn together to better understand how the various design features of a CFW influence its performance. This paper reviews the available field investigations with the aim of helping guide and improve the experimental designs and installations of future CFW installations. This in turn will improve the knowledge and acceptance of these recently developed stormwater treatment systems. One of the findings of this review was that using a percentage coverage design approach may not be as effective as improving the design efficiency. Understanding the hydraulics of the entire pond and CFW system is also critical to effective design. The review also found that the performance evaluation of future CFW installations would be improved if consideration is given to including both baseline monitoring and experimental controls.
Publisher: Springer Science and Business Media LLC
Date: 2013
Publisher: Elsevier
Date: 2019
Publisher: MDPI AG
Date: 08-06-2016
DOI: 10.3390/W8060244
Publisher: MDPI AG
Date: 18-01-2019
Abstract: Constructed Floating Wetlands (CFWs) are increasingly being used globally in freshwater environments such as urban lakes and ponds to remove pollutants from urban stormwater runoff. However, to date there has been limited research into the use and performance of these systems in saline environments. This study compared the root and shoot biomass growth and nutrient uptake of five different plant species, Chrysopogon zizanioides, Baumea juncea, Isolepis nodosa, Phragmites australis and Sarcocornia quinqueflora, in three different saltwater treatments over a 12-week period. The aim of the study was to identify which of the plant species may be most suitable for use in CFWs in saline environments. Plant nutrient uptake testing revealed that Phragmites australis had the greatest percentage increase (1473–2477%) of Nitrogen mass in the shoots in all treatments. Sarcocornia quinqueflora also had impressive Nitrogen mass increase in saltwater showing an increase of 966% (0.208 ± 0.134 g). This suggests that the use of Phragmites australis and Sarcocornia quinqueflora plants in CFWs installed in saline water bodies, with regular harvesting of the shoot mass, may significantly reduce Nitrogen concentrations in the water. Isolepis nodosa had the greatest percentage increase (112% or 0.018 ± 0.020 g) of Phosphorous mass in the shoots in the saltwater treatment. Baumea juncea had the greatest percentage increase (315% or 0.026 ± 0.012 g) of Phosphorous mass in the roots in the saltwater treatment. This suggests that the use of Isolepis nodosa and Baumea juncea plants in CFWs installed in saline water bodies may significantly reduce Phosphorous concentrations in the water if there was a way to harvest both the shoots above and the roots below the CFWs. The study is continuing, and it is anticipated that more information will be available on CFW plants installed in saline environments in the near future.
Publisher: Wiley
Date: 06-04-2020
DOI: 10.1111/AJAD.13028
Abstract: Postpartum women represent a large population with opioid exposure who also have an increased risk of experiencing mood and anxiety disorders. However, the effect that mood and anxiety disorders have on opioid use postpartum has received little attention in the literature. Therefore, the objective of this study was to examine the association of mood and anxiety disorders with filling opioid prescriptions within the first 3 months postpartum. A retrospective cohort study (n = 25 279) was completed using claims data for a s le of privately insured women who gave birth in the state of Iowa. The interactive effects of mood and anxiety disorders and delivery mode on filling at least one and two or more opioid prescriptions were examined in logistic regression models. The presence of mood and anxiety disorders among women who delivered vaginally increased their odds of filling at least one opioid fill by nearly 50% (odds ratio [OR]: 1.48, 95% confidence interval [CI]: 1.35‐1.63) and by 20% (OR: 1.20, 95% CI: 1.00‐1.43) among women with cesarean delivery. Postpartum women with mood and anxiety disorders were more likely to fill opioid prescriptions postpartum compared to women without these conditions. This study extends prior research by examining the intersection of risk of mood and anxiety disorders and opioid use postpartum. Findings from this study support the need for future research to identify the drivers of increased opioid use among postpartum women with mood and anxiety disorders. (Am J Addict 2020 :463–470)
Publisher: Elsevier BV
Date: 06-2022
Publisher: MDPI AG
Date: 22-09-2017
DOI: 10.3390/SU9101687
Location: Australia
No related grants have been discovered for Christopher Walker.