The effectiveness of constructed wetland for treatment of woodwaste leachate

Percolation of rainfall through woodwaste piles leaches natural chemicals from the wood residuals that can have adverse impacts on the environment. A study was conducted on a woodwaste storage site, adjacent to the Lower Fraser River, near Mission, BC, Canada. The objective of this research was to evaluate the effectiveness of constructed wetland for treatment of this woodwaste leachate. The leachate was characterized by high oxygen demand, tannin and lignin, and volatile fatty acids (VFAs), but low pH and nutrients. Diluted leachate passed through six pilot-scale wetland cells, four planted with cattail (Typha latifolia) and two unplanted controls, with a hydraulic retention time of 7 days and an average depth of 40 cm. Nutrient addition and pH adjustments were made to improve contaminant removal. Reductions in contaminants were consistently achieved, with average removals for BOD, COD, VFAs and tannin and lignin of 60, 50, 69 and 42%, respectively. Climatic conditions had an impact on the performance of the constructed wetland. Further operation of the system will help to elucidate the seasonal fluctuations. Aging of the constructed wetland system increased the treatment performance.     

Evaluation of past and potential phosphorus uptake at the Orlando Easterly Wetland

The Orlando Easterly Wetland (OEW), located near Christmas, Florida, USA, is among the longer-lived treatment wetlands in the United States. It was established in the late 1980s to reduce nitrogen and phosphorus concentrations from tertiary treated wastewater bound for the St. Johns River. A goal of 0.07 mg/l total phosphorus concentration has been set by the regulating agency (St. Johns River Water Management District). In order to understand and define the operating conditions for which this target could be met, a systematic study of historic phosphorus uptake was performed using a traditional first-order model. Phosphorus uptake performance is shown to correlate well with hydraulic performance for two parallel upstream cells. The first-order model is enhanced with predictive capabilities that acknowledge the correlation between the phosphorus uptake rate constant and the hydraulic loading rate observed in the system. Inherent limitations with the first-order modeling approach are addressed and uncertainty in model performance is used to bound predictions.     

Systems ecological accounting for wastewater treatment engineering: Method,indicator and application

Wastewater treatment facility is vital for sustainable urban development. In the course of removing contaminants and discharging ready-for-reuse water, wastewater treatment consumes resources and triggers environmental emission during its lifetime. A comprehensive framework to analyze the embodied ecological elements as natural resources and environmental emissions of wastewater treatment is presented in this work. The systems method as a combination of process and input–output analyses is applied and a set of indicators are accordingly devised. Two representative ecological elements, i.e., greenhouse gases emissions and solar emergy of alternative wastewater treatment systems, i.e., a traditional activated sludge wastewater treatment plant and a constructed wetland have been taken into consideration. For each ecological element, five indicators have been calculated and compared to assess the impact on climate change and resources utilizing style of the case systems. The framework raised in this paper is fully supportive for optimal decision-making among different wastewater treatment technologies, and could be transplanted to be applied to systems ecological accounting for other production systems.     

Exploring the global decline of music education

This article seeks to explain the disjuncture between the decline of music education in schools and the importance music has in popular youth culture and in creativity within the new knowledge economy. The data discussed in this article have been derived from analyses of major documents on curriculum reform as well as e-mail responses from music educators around the world. This analysis reveals that these music educators agree with the perception of a demise in music education around the world, as well as the significance of the disjuncture alluded to. The four major reasons found for the decline in music education are: (1) the model of curriculum supported in educational reforms; (2) an emphasis on standardized evaluation; (3) less resources available; and (4) a wrong approach on music advocacy.     

Rhizome dynamics and resource storage in Phragmites australis

Seasonal changes in rhizome concentrations of total nonstructural carbohydrates (TNC), water soluble carbohydrates (WSC), and mineral nutrients (N, P and K) were monitored in two Phragmites australis stands in southern Sweden. Rhizome biomass, rhizome length per unit ground area, and specific weight (weight/ length ratio) of the rhizomes were monitored in one of the stands.Rhizome biomass decreased during spring, increased during summer and decreased during winter. However, changes in spring and summer were small (< 500 g DW m-2) compared to the mean rhizome biomass (approximately 3000 g DW m^–2). Winter losses were larger, approximately 1000 g DW m-2, and to a substantial extent involved structural biomass, indicating rhizome mortality. Seasonal changes in rhizome length per unit ground area revealed a rhizome mortality of about 30% during the winter period, and also indicated that an intensive period of formation of new rhizomes occurred in June.Rhizome concentrations of TNC and WSC decreased during the spring, when carbohydrates were translocated to support shoot growth. However, rhizome standing stock of TNC remained large (> 1000 g m^–2). Concentrations and standing stocks of mineral nutrients decreased during spring/ early summer and increased during summer/ fall. Only N, however, showed a pattern consistent with a spring depletion caused by translocation to shoots. This pattern indicates sufficient root uptake of P and K to support spring growth, and supports other evidence that N is generally the limiting mineral nutrient for Phragmites.The biomass data, as well as increased rhizome specific weight and TNC concentrations, clearly suggests that reloading of rhizomes with energy reserves starts in June, not towards the end of the growing season as has been suggested previously. This resource allocation strategy of Phragmites has consequences for vegetation management.Our data indicate that carbohydrate reserves are much larger than needed to support spring growth. We propose that large stores are needed to ensure establishment of spring shoots when deep water or stochastic environmental events, such as high rhizome mortality in winter or loss of spring shoots due to late season frost, increase the demand for reserves.     

Restoration and creation of freshwater wetlands using seed banks

The minimum information about a seed bank needed for a wetland restoration or creation project is a species list. There are two basic techniques for determining the composition of seed banks: (1) mechanical separation of seeds from a volume of soil and (2) germination of seeds from a volume of soil under appropriate environmental conditions. The latter method always gives biased results. It is best to collect as many random samples as possible when sampling a wetland seed bank. These can be combined as needed for processing. Field studies in India have demonstrated that vestigial seed banks can be used to re-establish a former vegetation type in a monsoonal wet-land that had become overgrown by a species of grass. In less than a year, 9 of 1 I species in the vestigial seed bank were found growing in areas cleared of the grass. Vestigial seed banks of drained prairie wetlands in the northcentral United States contained a few wetland species after 70 years, although species diversity and seed density declined significantly after 20 to 30 years of drainage and cultivation. In Florida, U.S.A., wetlands have been established in strip-mined areas using donor soils from existing wetlands. Newly established wetlands quickly developed a dense cover of vegetation, although this vegetation often lacked many desirable wetland species. Experimental studies of soil moisture conditions using a seed bank from the Delta Marsh, Canada, demonstrated that soil moisture affected both the total number of seeds, and the relative proportion of seeds of each species that germinated from a seed bank. The density of seedlings of emergent wetland species in the treatments was directly proportional to soil moisture, while that of terrestrial annuals was inversely proportional. Emergent species made up nearly 90% of the seedlings in the wettest treatment and 0% in the driest.From a paper presented at the Third International Wetlands Conference, 19–23 September, 1988, University of Rennes, France.     

The choice between desiccation of wetlands or the spread of Rhine water over The Netherlands

The dry summer of 1976 triggered a wholesale installation of sprinkler systems for agriculture. This dry summer also revealed areas in The Netherlands most susceptible to drought, namely sandy regions and the coastal fringe. This resulted in distribution of Rhine water to new areas, and in quantities hitherto unknown. The Second National Water Management Plan (1982) consequently focussed on enlarging the capacity of water distribution works. This distribution has led to a multitude of ecological effects, such as changes in salinity and nutrient concentration, as well as the spreading of contaminants. Consequently, the Third National Water Management Plan (1990) includes fewer distribution works because of the adverse environmental effects and the reduced feasibility due to increasing costs and decreasing agricultural benefits.A climatic change as predicted may result in climatic conditions in The Netherlands resembling those of France or the Mediterranean, implying drier summers and more precipitation in winter. An increased frequency of dry summers will no doubt revive water distribution plans now shelved and may even bring new ones to the drawing board. An increase in Rhine water distribution will have serious consequences for many aquatic and terrestrial ecosystems, as will a lowering of the groundwater table. In this paper we will discuss the dilemma of choosing between allowing increased desiccation of wetlands as the climate becomes drier or increasing the distribution of Rhinewater and the potential ecological effects of these choices. Alternative strategies to water management also are discussed.This article is largely based on Duel et al. 1989.     

Wetland vegetation ecology on a reclaimed coal surface mine in southern Illinois,USA

An early successional wetland complex on a reclaimed surface coal mine in southern Illinois was studied 1985–1987. Seasonally, biomass was low, with above-ground values of 10–210g m^–2 and below-ground biomass of 1.5–2435 g m^–2. Biomass peaked in spring and did not vary much throughout the remainder of the growing season. Stem densities were high (179–1467 m^–2) because large numbers of seedlings became established as falling water levels exposed large areas of mudflats. Fluctuating water levels led to a lack of community zonation. Species diversity (H) was low to moderate over all sites with diversity values ranging between 1.86 and 3.27.