Article

Fundamental processes within natural and constructed wetland ecosystems: Short-term versus long-term objectives

February 2001
Water Science & Technology 44(11-12):1-8

DOI:10.2166/wst.2001.0803

Source
PubMed

Authors:

Use of wetland ecosystems for water pollution control consists essentially of sustained induced disturbances as pollutants are loaded to complex biological communities. Objectives are to maximize pollutant loading, incorporation, and retention while maintaining highest levels of community metabolism and minimal alteration of community structure. Several basic processes are emphasized: (a) macrophyte productivity in relation to shoot:root ratios, and nutrient availability; (b) macrophyte life history strategies, succession, and biodiversity under constant pollutant stress; (c) importance of standing dead and particulate detritus; (d) functions and controlling mechanisms of heterotrophic and autotrophic periphyton in pollutant retention and recycling; (e) coupling of microbial metabolism to macrophyte retention of pollutants; (f) gaseous losses to the atmosphere; (g) losses of dissolved organic matter and its utilization; and (h) water losses by evapotranspiration and effects on wetland efficacy. Short-term wetland removal efficiencies are confounded by massive variations in retentive capacities diurnally, seasonally, and spatially, in exceeding physiological tolerance levels, and in species succession. Problems of channelization, altered microhydrology, and assimilation/retention are major in natural and non-engineered ecosystems. Wetlands are highly ephemeral and variable in their capabilities for sequestering and retention of nutrients and other pollutants.

Modelación de la producción primaria fitoplanctónica en el humedal Jaboque, Bogotá D.C.

Article

Full-text available

Jul 2016

Se presenta un modelo de simulación dinámico para explicar el comportamiento general de la producción primaria fitoplántonica en el humedal de Jaboque – Bogotá D.C., Colombia, en tres secciones con características físicas y químicas diferenciales. El modelo tiene en cuenta las variables fisicoquímicas, área de la cubeta, profundidad, precipitación media anual, temperatura del agua, pH y concentración de clorofila_a. La modelación dinámica se basó en ecuaciones diferenciales y se utilizó el método Euler de integración, la modelación se desarrolló utilizando el programa computacional Stella 9.1®. El modelo permite cuantificar la producción primaria fitoplántonica del humedal de Jaboque a partir de la concentración promedio mensual de clorofila_a, para cada sección. Los resultados de la modelación de la Ppf evidencian que las variaciones de la concentración de la Ppf en cada sección del humedal siguen un patrón inverso al comportamiento bimodal de la precipitación. Se encontró un alto grado de correspondencia entre los valores de clorofila_a de campo y la Ppf modelada de la siguiente manera r2 = 0.86 para la primera sección y r2 = 0.86 y r2 = 0.79 para las secciones restantes. La determinación del error relativo fue de 0,57, para la primera sección y 0,35; 0,46, indicando que los resultados no están sobrestimados. El modelo muestra en términos generales los aspectos funcionales del comportamiento de la Ppf y su relación con el proceso de eutroficación, y permite hacer recomendaciones para el manejo y restauración del humedal.

Environmental constraints on macrophyte distribution and diversity in a tropical endorheic freshwater lake (Lake Baringo, Kenya)

Article

Full-text available

Jun 2018

The structure of macrophyte assemblages can be affected by myriad factors, including physical and chemical characteristics of the water body. However, knowledge on the environmental factors affecting macrophyte diversity in endorheic freshwater lakes is limited. In this study the patterns of plant species diversity and composition and their potential determinants in Lake Baringo, Kenya, is described. Macrophyte sampling in Lake Baringo was done monthly from January 2015 to April 2016 using quadrats (1 m × 1 m) placed along transects perpendicular to the shoreline. Water temperature, pH, conductivity, dissolved oxygen (DO), salinity and alkalinity were measured in situ at each of the sampling sites. Findings revealed that macrophyte species composition and assemblage exhibited significant spatial differences (P<0.05), where areas near river inlets had higher species composition and percentage cover. The findings improve the understanding of floristic patterns and plant biodiversity in the lake.

Lively water infrastructure: Constructed wetlands in more-than-human waterscapes

Article

Full-text available

Jul 2022

Water infrastructures are often living infrastructures, whose operation relies on processes involving other-than-human living beings. This article considers the materiality of waterscapes by attending to this liveliness. We argue that critical water research can benefit from situating social relations and water transformations within more-than-human worlds. Our conceptual framework brings hydrosocial scholarship into conversation with more-than-human geography. This opens avenues for interdisciplinary water research that weaves together ecology and qualitative social research. The analytical potential of such a framework is explored through an empirical account grounded in two constructed wetland projects in rural India. These infrastructural assemblages engage humans, other living beings and objects in webs of material-semiotic processes. We present three stories of intra-action that focus on particular plants, microbes and animals within these waterscapes. Our analysis highlights the crucial importance of other-than-human living beings in the production of waterscape knowledge and suggests a need to go beyond the problematisation of ‘uneven’ waterscapes. Approaching waterscapes as more-than-human collectives prompts us to consider the power relations that underpin waterscape knowledge and the politics of multispecies justice. A focus on more-than-human infrastructures opens up the possibility of interdisciplinary water research that is better attuned to the hybrid nature of social and ecological processes, as well as the politics embedded therein.

Efectos sobre la salinidad de los escurrimientos de los ríos Atuel y Salado en la RP Ñochilei-có, La Pampa.

Conference Paper

Full-text available

Sep 2017

El principal impacto que sufren los humedales es el cambio del régimen hidrológico natural, que modifica su dinámica, su caracterización hidroquímica y los servicios ecosistémicos. El área de confluencia de los ríos Atuel y Salado constituye un amplio humedal ubicado en una planicie aluvial, conformado por numerosos cauces y bañados. El objetivo fue describir el régimen hidrológico y su efecto sobre la salinidad del agua superficial y subterránea en el área de confluencia donde se ubica la Reserva Ñochilei-Có. La activación de los humedales depende de los aportes de los ríos Atuel y Salado. Su intermitencia y atenuación actual resulta en la ausencia de conexión entre ambos ríos, en una marcada contracción de los bañados, reducida a depresiones hipersalinas del Salado, y ausencia de escurrimientos del río Chadileuvú. La calidad hidroquímica del agua superficial desmejora drásticamente con la disminución de los escurrimientos, afectando al agua subterránea que manifiesta un incremento de su salinidad en el sentido del escurrimiento. El balance netamente deficitario, resulta en un ambiente salino permanente con predominio de especies halófitas y con valores de salinidad que imposibilitan cualquier uso. Se concluye que para el restablecimiento de los humedales se debe prioritariamente garantizar mayores caudales desde aguas arriba.

A comparative study of rural livelihood benefits from a community-based and a private protected area in Zimbabwe

Chapter

Full-text available

Dec 2021

This Chapter compared livelihood benefits from a community-based and a private protected area in south-eastern Zimbabwe to local communities and employed mixed methods research in gathering primary data. A questionnaire was used to collect quantitative data on livelihood benefits to study communities from the protected areas. One hundred and fifty (150) respondents were selected for questionnaire interviews from each of the targeted communities through simple random sampling. Key-informant interviews and focus group discussions were also conducted for the collection of in-depth qualitative data. With some noted similarities and differences, the main livelihood contributions from the two conservation areas to the target communities included household and community income enhancement, and health and educational services provision. While the livelihood benefits from the protected areas were important, most of the respondents in both study sites noted that these were not adequate in meeting the developmental needs and aspirations of their communities. This calls on the protected areas to bring more meaningful livelihood benefits to the study areas. Community based conservation has dominated conservation-development rhetoric in Zimbabwe since the 1980s. The importance of the results of this Chapter therefore lies in the fact that they highlighted private protected areas as an equally significant platform, just as community conserved areas, on which to simultaneously pursue conservation and livelihoods goals.

External and internal institutional issues affecting the Mahenye community from effectively benefitting from CAMPFIRE

Chapter

Full-text available

Dec 2021

The objective of the study is to examine the hindrances to the flow of livelihood benefits from the Mahenye community conservancy area in south-eastern Zimbabwe to the local community. A questionnaire targeting Mahenye residents; key-informant interviews; a focused group discussion; and document analysis were employed in gathering perceived hindrances to the flow of livelihood benefits. Among the key hindrances internal to the Mahenye community include alleged misappropriation of Communal Areas Management Programme for Indigenous Resources (CAMPFIRE) funds by the Mahenye CAMPFIRE Committee leadership. External hindrances to the maximum enjoyment of livelihood benefits from the community-conserved area to Mahenye residents include lack of complete devolution of appropriate authority in natural resource management to sub-district structures, a low sport hunting quota, a sharp decline in international tourist flows to Zimbabwe, and the undue influence of the chieftaincy upon the community CAMPFIRE project. Considering the dwindling international ecotouristic market into the country, the need for Chilo Lodge to refocus attention towards the domestic tourist market is apparent. While complete devolution of appropriate authority to sub-district structures would be most appropriate, this should be preceded by comprehensive institutional capacity building. Multiple stakeholder engagement would ensure that the community project is transparently managed for the benefit of the whole community and not just a few local elites.

Modelling the abundance of a non-native mollusk in tropical semi-arid reservoirs

Article

Full-text available

Feb 2022
HYDROBIOLOGIA

This study aimed to investigate the relative importance of abiotic factors and biotic resistance (expressed as species richness of native macroinvertebrates), through a correlative niche-based model, to explain the abundance of the non-native mollusk Melanoides tuberculata. A total of 478 sites were sampled in six reservoirs in a Brazilian semi-arid region in June, September, December (2014) and March (2015). A niche-based model (BRT's), which included all tested predictor variables explained 41.7% total variation in M. tuberculata abundance. Water depth had the highest relative importance (19.0% of relative contribution) followed by temperature (17.2%) and sediment organic matter content (15.4%). The native macroinvertebrate richness explained only 8.0%, evidencing the smaller role of biotic resistance in explaining M. tuberculata abundance. Our results suggest that factors associated with the extent of species’ niches are more important and can determine the multiple invasion processes of this mollusk, especially in terms of population growth and spread. The low explanatory power of biotic resistance on the abundance and distribution of the invasive mollusk may not necessarily indicate a lack of resistance by the native community, and M. tuberculata is not widespread enough to occupy the total potential range.

Quenching the Thirst for Zimbabweans: Anthropogenic Activities and Their Impacts on Freshwater Ecosystems

Chapter

Full-text available

Oct 2021

This Chapter aims to provide an awareness of the impacts of human activities on water and stimulate respect for the aquatic environments. Most human activities are primarily directed towards achieving some specific purposes (e.g., industrial production), though they have indirect and unintended effects on ecosystems (e.g., siltation) which affects freshwater ecosystem integrity and valuable ecosystem services. In Zimbabwe, freshwater ecosystems are being altered and degraded by intense anthropogenic activities such as water abstraction, discharge of untreated sewage, mining etc., leading to water-shortage, and a water-supply crisis that threatens the country's development. Although statutory bodies-such as Environmental Management Agency and Zimbabwe National Water Authority (ZINWA); and legislation-such as the Water Act and Environmental Management Act, responsible for ensuring sustainable management and protection of freshwater resources have been developed, the possibilities of lessening ecological impacts of anthropogenic activities in Zimbabwe remain uncertain at best. This Chapter demonstrates that maintaining healthy aquatic ecosystems while meeting other demands on freshwater will require improvements in the planning and management of freshwater resources.

Fisheries production and management in Zimbabwe. Status, challenges and future.

Chapter

Full-text available

Oct 2021

Chapter 3 Climate change and biodiversity policy: a review of legal and institutional frameworks in Zimbabwe

Chapter

Full-text available

Oct 2021

This Chapter aims to explore the extent to which legal and institutional frameworks for biodiversity management in Zimbabwe mainstream climate change adaptation and mitigation issues. This Chapter focused on mainstreaming of biodiversity and wildlife issues in international, regional climate change policies and how it cascades to the national level in Zimbabwe. A desk top research approach was adopted. Primary literature focusing on legal and policy issues on biodiversity/ wildlife and climate change in Zimbabwe was systematically reviewed. Findings from the review reveal that key international biodiversity related policy instruments such as the United Nations Convection on Biological Diversity (UNCBD) address the climate change agenda. International institutions, which inform local wildlife management plans, are more advanced in mainstreaming biodiversity/ wildlife in the context of climate change than the case at the local level. In Zimbabwe, key biodiversity policy instruments that were developed prior to 2010, particularly the Wildlife Policy and the Parks and Wildlife Act do not address climate change issues. However, the National Constitution, the National Climate Change Response Strategy (NCCRS) as well as the Zimbabwe’s National Biodiversity Strategy and Action Plan (NBSAP) 2013-2020 contain sections related to biodiversity and climate change. In conclusion, there are opportunities for mainstreaming climate change issues in biodiversity frameworks and institutional structures in Zimbabwe. Although the government via the responsible ministry has put in place an overarching climate change policy and strategy, there is need to strengthen climate change action in the biodiversity/wildlife sector particularly adaptation and mitigation. Future studies should focus on the contribution of local policies, projects and programmes aimed at promoting climate change adaptation and mitigation in the wildlife sector.

Wildlife and Fisheries Management in Zimbabwe: A Critical Reflection

Book

Full-text available

Oct 2021

This book is a must-read for anyone with interest to explore (or understand) topical issues in the diverse field of conservation. You will find some wild but useful ideas which others may want to call innovative approaches, and practical strategies for enhancing wildlife conservation in Zimbabwe and beyond. Why wildlife? Could be much easier to answer because of the obvious aesthetic and cultural attachment that you might have. Nevertheless, Whose wildlife? Is a contentious issue that needs unpacking as you will find in this book. When you read this book, you might acquire some Latin phrases such as res nullius and confuse a few friends with new vocabulary in social circles whilst reflecting on the wildlife ownership topic. As you might be already aware, Zimbabwe has an outspoken history of wildlife conservation which dates back to pre-colonial and extends into the post-colonial period, this book takes you through some important reflections of the country`s wildlife journey and paradigm shifts along the process which will certainly help you make sense of the legacies that Zimbabwe cherishes or struggles with today. Biodiversity conservation in the 21st century is faced with shifting climatic changes which some scientists have tried to communicate in emotionally charged publications and threatening headlines in the news, whether that is the inconvenient truth or they are cyclical or irreversible changes-we cannot be certain, however, as this book explores biodiversity policy in a changing climate, focusing on a review of legal and institutional frameworks for biodiversity management in Zimbabwe, it might help you understand some contextualised perspectives. Whilst some people may see sustainable development as a mission impossible in the glaring facts of poverty and food insecurity in sub-Saharan Africa, this book may leave you hopeful when you read about the opportunities in the fisheries production and management, opportunities and challenges of those living adjacent to protected areas in Zimbabwe, reflections on the renowned Communal Areas Management Programme for Indigenous Resources (popularly known as CAMPFIRE) case study, which will inevitably drive you into the Chapter which digs deeper into rural livelihood benefits from community-based initiatives to private sector involvement. As you read this special book, it is important to be mindful of the fact that wildlife in Zimbabwe refers to both flora and fauna and this book could not have been complete without covering non-timber forest products and delicacies such as mopane worm harvesting and utilisation covered in a very interesting research done in the Matabeleland region of Zimbabwe. Since this book is a product of Chinhoyi University of Technology, particularly the School of Wildlife, Ecology and Conservation, do not be surprised to find a topic such as Quenching the Thirst for Zimbabweans, you may want to find out how? Water is an important subject in any context. It should be appreciated that conservation is not for conservationists only-it is everyone`s business and this book is an important resource which will help you understand why and hopefully you will not go wild about my story before you can forage on the important ideas contained herein! With their research prowess, the authors provide an enormously useful range of ideas, innovative strategies across a wide spectrum of topics with a lot of creativity and I look forward to read about technological innovations in the field of wildlife conservation in their next edition.

Protected areas and biodiversity conservation in Zimbabwe: history, threats and challenges

Chapter

Full-text available

Oct 2021

The aim of this Chapter is to highlight the forms of wildlife resource conservation, history and PA resource management regimes, and the threats and challenges to biodiversity in protected areas in Zimbabwe. The study was mainly informed by a documentary review of existing literature focussing on peer-reviewed journal articles, books, edited book chapters, relevant policy, laws, programmes and implementation strategies related to resource conservation, protected area management, threats and challenges to biodiversity conservation. Four forms of resource management regimes are identified, i.e., state protected areas, areas under communal lands, private land, as well as transfrontier conservation areas. The establishment and management of protected areas follow an evolution of various legislative instruments that ascribed biodiversity management and rights to different institutions. Transfrontier conservation areas and partnerships are important emerging conservation arrangements promoting collaborative biodiversity conservation. However, loose coordination and fragmented legislation in natural resource management is one of the challenges facing current conservation efforts. Also, habitat loss, land use conflicts, invasive species, climate change and illegal harvesting of resources are seen to pose serious threats to biodiversity conservation. In order to promote sustainability of resource management in PAs, the Chapter recommends the following: (i) devolution of natural resource management rights to local people as an important incentivizing strategy for community participation in biodiversity conservation, (ii) promoting sustainable financing mechanisms for protected areas through increased revenue generation streams such as product diversification and onsite revenue retention initiatives, (iii) realignment and harmonization of environmental legislation and institutions to eradicate resource management conflicts and foster efficient collaboration.

Wildlife ownership, access and conservation: a reflection from pre-colonial to post-colonial period in Zimbabwe.

Chapter

Full-text available

Oct 2021

Wildlife is a valuable resource in Zimbabwe. This Chapter focuses on the evolution of wildlife ownership regimes, access and conservation in Zimbabwe from pre-colonial to post-colonial period. Evidence was gathered from documentary review of existing literature, primarily focusing on (un)published reports, research articles and books. Google, Google Scholar and Scopus search engines were used to search relevant literature. Study findings indicated that wildlife ownership in Zimbabwe shifted from traditional common pool resource to public and private ownership driven by the need to fulfil the concept of access and benefit sharing. The evolution of the political landscape, legal and institutional framework for management of wildlife resources influenced changes in ownership regimes. Consequently, approaches to wildlife management have also diversified from the colonial fortress conservation approach to a range of management regimes including community-based wildlife management systems. However, community-based approaches to wildlife conservation have faced a myriad of challenges due to lack of devolution and other resource governance related aspects. Despite the evolution of wildlife ownership regimes, the responsibility of maintaining and conserving the wildlife resources still rests in the hands of a few. There is need to promote integrated and innovative approaches to wildlife management to ensure successful conservation and sustainable utilisation of the resource.

Characterising and modelling pollutant dynamics in urban stormwater constructed wetlands

Thesis

Full-text available

Aug 2021

Mohamed Bosnina

Constructed wetlands (CWs) are a worldwide growing natural treatment technology for their effective treatment of various polluted waters, especially urban stormwater, to meet the requirements of authority legislations and for environmentally friendly and cost effective application. Using a novel tidal flow vertical flow CW (VFCW) mainly overcomes the lack of flow distribution, oxygen supplementation, nitrate-nitrogen (NO3-N) reduction and land availability. Therefore, the aim was to understand and model of the various urban stormwater pollutants immobilisation in the long-term operation of novel pilot-scale VFCWs designed with different substrates configuration receiving different loading rates (catchment area sizes) and wet-dry operation conditions. Generally, the results showed that VFCWs configurations of substrate type, pollutants loading, and wet-dry operation conditions affect the stormwater pollutants retention performance variably based on the mass balance analysis. From the experimental data of the first four VFCWs used loamy sand, gravel, and BFS as main substrates, significant changes in the chemical structure of the medias were noticed indicating chemical adsorption and calcium precipitation play a vital role in retaining heavy metals and nutrients causing the significant differences (p ≤ 0.01) in the performance while total suspended solids (TSS) alongside with the metals in the particulate form were more likely removed via straining, settling, and interception mechanisms. Six loamy sand VFCWs were experimentally and statistically evaluated to account the effect of three cases of both wetland to watershed area ration (WWAR) and wet-dry operation condition. Changing WWAR values influence significantly on the removal performance of TSS, iron (Fe), and phosphorus (P) while no significant impact on the removal performance of both total nitrogen (TN) and zinc (Zn) was accounted. The operation condition impact negatively on the removal of TSS as the condition changes from wet to partially and extended dry while these conditions did not influence statistically the VFCWs performance towards Fe, Zn, TN, and P retentions, which could be elicited to increase the substrate porosity as a result of shrinkage during the dry period and in the same enhance the diffusion of the pollutant into substrate’s surface. All experimental data extracted from various operation conditions were gathered to build statistical predicting models using partial least square analysis (PLS). The resulted models were able with a high degree of accuracy to predict both the training and test data of Fe, Zn, TN, TP, and PO4-P at various operation conditions based on the pollutant loading rate and mass of substrate. III The internal N transformation dynamics were established theoretically and then with the experimentally measured data of stormwater VFCWs 1 and 2 were methodically modelled using STELLA software. The model produced a good agreement between the observed effluent data of organic-N, NH4-N, NO3-N, and TN and the predicted once for both model calibration and validation. The model revealed that N mostly removed via NH4-N adsorption (41%) while 19% and 9.55% of TN were removed via denitrification and plants uptake respectively. Altogether, results showed that CW configuration has a great impact, not on stormwater pollutants removal but also the performance prediction. However, further research at field scale would be beneficial to understand practically more the underline processes of N transformation dynamics and also to enhance P adsorption.

Use of two plants to remove pollutants in wastewater in constructed wetlands in southern Iraq

Research

Full-text available

Jul 2020

Industrialization, urbanization and population are the most important reasons for pollution in Iraq, these factors have decreased the quality of water resources. Evaluating the treatment of polluted water (sew-age) in nontraditional ways and assessing consumption in the agriculture sector are the main purposes of this study. Two Plants were used in the current study Schoenoplectus litoralis and Hordeum vulgare to remove heavy metals and nutrients, making this technique effective in pollution control. Samples were collected from the storage terminal of the wastewater station in Al-Nassiriya (Indian station), Physicochemical analysis of both sewage and tap water was performed for following parameters; Ion Hydrogen (pH), electrical conductivity (EC), Total Dissolved Solids (TDS), Total Suspended Solid (TSS), Carbon Dioxide CO 2 , Magnesium (Mg 2+), Calcium (Ca 2+), Sodium (Na +), total hardness, alkalinity, Chloride (Cl À), sulphates (SO 4 2À) , phosphates (PO 4 3À), nitrates (NO 3 À) , Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD 5) were evaluated. Moreover, four trace metals [Lead (Pb +2), Nickel (Ni +2), Copper (Cu +2) and Cadmium (Cd +2)] and the sodium adsorption ratio (SAR) were evaluated. The plants varied in their responses to metals. This study revealed that plants have a high heavy metal removal capacity.

Carbon, nitrogen, and phosphorus variation along a green roof chronosequence: Implications for green roof ecosystem development

Article

Jun 2021
ECOL ENG

While the developmental dynamics of ecosystems have been studied in many natural systems, it is unclear if these patterns are to be expected in engineered ecosystems where components have not co-developed over time. Green roofs often begin with a nutrient rich substrate that is paired with slow-growing plants adapted to nutrient poor conditions - perhaps resulting in different developmental dynamics than natural ecosystems. We evaluated changes over time in green roof nutrient content and vegetation communities using a chronosequence in southern Sweden of similarly designed but different aged green roofs spanning between 2 and 22 years. Substrate depth, substrate nitrogen (N), and total N pool sizes varied positively with roof age. These dynamics suggest an accumulation of 2.9 ± 1.1 g N/m²/yr with no indication of leveling off after 22 years. Plant N content (%) positively varied with roof age but plant biomass, plant nutrient pools, and plant diversity did not vary with age. These dynamics indicate a novel developmental scenario where the ecosystem begins with near-stable plant biomass but still accumulates N in the substrate at rates on par with many secondary successional systems. The apparent accumulation of N could not be accounted for by N deposition rates for the region, suggesting substantial N-fixation. The novel developmental dynamics outlined in this study point to the need for a new or expanded ecosystem developmental paradigm that better suits green roofs and perhaps other emerging engineered ecosystems.

Constructed Wetlands

Chapter

Jul 2017

Use of two plants to remove pollutants in wastewater in constructed wetlands in southern Iraq

Article

Full-text available

Jul 2020

Afrah Maktoof

Industrialization, urbanization and population are the most important reasons for pollution in Iraq, these factors have decreased the quality of water resources. Evaluating the treatment of polluted water (sewage) in nontraditional ways and assessing consumption in the agriculture sector are the main purposes of this study. Two Plants were used in the current study Schoenoplectus litoralis and Hordeum vulgare to remove heavy metals and nutrients, making this technique effective in pollution control. Samples were collected from the storage terminal of the wastewater station in Al-Nassiriya (Indian station), Physicochemical analysis of both sewage and tap water was performed for following parameters; Ion Hydrogen (pH), electrical conductivity (EC), Total Dissolved Solids (TDS), Total Suspended Solid (TSS), Carbon Dioxide CO2, Magnesium (Mg²⁺), Calcium (Ca²⁺), Sodium (Na⁺), total hardness, alkalinity, Chloride (Cl⁻), sulphates (SO4²⁻), phosphates (PO4³⁻), nitrates (NO3⁻), Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD5) were evaluated. Moreover, four trace metals [Lead (Pb⁺²), Nickel (Ni⁺²), Copper (Cu⁺²) and Cadmium (Cd⁺²)] and the sodium adsorption ratio (SAR) were evaluated. The plants varied in their responses to metals. This study revealed that plants have a high heavy metal removal capacity.

MODELACIÓN DINÁMICA DE LOS SÓLIDOS SUSPENDIDOS TOTALES EN EL HUMEDAL JABOQUE, BOGOTÁ (COLOMBIA) Dynamic modeling of total suspended solids in the wetland Jaboque, Bogotá (Colombia)

Article

Full-text available

Jun 2014

RESUMEN Se propone un modelo de simulación dinámico para explicar de manera general el comportamiento de los sólidos suspendidos totales en el humedal Jaboque, Bogotá (Colombia), en tres secciones con características físicas y químicas particulares. El modelo predijo altas concentraciones de sólidos suspendidos totales en abril, mayo, junio, octubre y noviembre, los valores modelados fluctuaron entre 85 mg L-1 y 101 mg L-1 con un promedio de 65.12 mg L-1 con un tiempo hidráulico de retención entre ocho y nueve días año-1 para la primera sección, en la segunda sección entre 57 y 69 con un promedio de 50 mg L-1 con un tiempo hidráulico entre 20 y 23 días año-1 y en la tercera sección entre 56 mg L-1 y 67 mg L-1 con un promedio de 48,8 mg L-1 y un tiempo hidráulico de retención entre 24 y 26 días año-1. En diciembre, enero, febrero, agosto y septiembre se presentó una tendencia a la disminución de los valores modelados. Se compararon los valores estimados de sólidos suspendidos totales con los modelados, de esta forma se evidenció una correspondencia aceptable, R 2 = 0.95; 0.71; 0.67; en todos los casos. El error relativo para cada sección en su orden fue de 0.10, 0.20 y 0.26, esto muestra que el modelo no tiende a la sobrestimación de los resultados. ABSTRACT We propose a dynamic simulation model to provide a general explanation for the behavior of total suspended solids in the Jaboque wetland (Bogotá DC). The analyses were performed in three areas with distinct physical and chemical characteristics. The model predicted concentrations of total suspended solids in the months of April, May, June, October and November. Values ranged from 85 mg L-1 and 101 mg L-1 with an average of 65.12 mg L-1 with a hydraulic time retention between eight and nine days per year for the first area, the second area between 57 and 69 with an average of 50 mg L-1 with a hydraulic time between 20 and 23 days per year and in the third area between 56 mg L-1 and 67 mg L-1 with a mean of 48.8 mg L-1 and a hydraulic retention time between 24 and 26 days per year. The months of December, January, February, August and September showed a tendency to have lower values. The estimated values of total suspended solids based on our model had an acceptable correspondence, R 2 = 0.95, 0.71, 0.67, with the actual values in all cases. The relative error for each area was 0.10, 0.20 and 0.26, demonstrating that the model does not overestimate the results. Artículo de investigación

Modelación dinámica de los sólidos suspendidos

Article

Full-text available

Oct 2012

Se propone un modelo de simulación dinámico para explicar de manera general el comportamiento de los sólidos suspendidos totales en el humedal Jaboque, Bogotá (Colombia), en tres secciones con características físicas y químicas particulares. El modelo predijo altas concentraciones de sólidos suspendidos totales en abril, mayo, junio, octubre y noviembre, los valores modelados fluctuaron entre 85 mg L-1 y 101mg L-1 con un promedio de 65.12mg L-1 con un tiempo hidráulico de retención entre ocho y nueve días año-1 para la primera sección, en la segunda sección entre 57 y 69 con un promedio de 50mg L-1 con un tiempo hidráulico entre 20 y 23 días año-1 y en la tercera sección entre 56mg L-1 y 67mg L-1 con un promedio de 48,8mg L-1 y un tiempo hidráulico de retención entre 24 y 26 días año-1. En diciembre, enero, febrero, agosto y septiembre se presentó una tendencia a la disminución de los valores modelados. Se compararon los valores estimados de sólidos suspendidos totales con los modelados, de esta forma se evidenció una correspondencia aceptable, R2 = 0.95; 0.71; 0.67; en todos los casos. El error relativo para cada sección en su orden fue de 0.10, 0.20 y 0.26, esto muestra que el modelo no tiende a la sobrestimación de los resultados.

Different Stages of Aquatic Vegetation Succession Driven by Environmental Disturbance in the Last 38 Years

Article

Full-text available

Jul 2019

In recent years, investigating the trend of aquatic plant diversity in response to different disturbance events has received increasing interest. However, there is limited knowledge of the different stages of aquatic vegetation succession over a long period in eutrophic lakes. In this study, we analyzed aquatic plant species richness and its relation to the physical and chemical characteristics of water in Chenghai Lake for the period of 1980–2018. This study shows that the richness and distribution of aquatic vegetation in Chenghai Lake are related to chlorophyll-a concentration, dissolved nutrients, base cations, and micronutrients. The results show that the long-term succession of aquatic plants in this lake classified in different stages: (I) A peak in species richness occurred at an intermediate stage that lasted from 1980 to 1992, and this was caused by more aquatic species being able to coexist since the competition for resources was lower; (II) after 26 years of secondary succession (1992–2018), the diversity and distribution area of aquatic plants gradually declined because pioneer species or human activities may have altered habitat conditions to render habitats less beneficial to pioneer species and more suitable for new aquatic plant species. Thus, species diversity and growth performance of aquatic plants in their communities may be useful indicators of Chenghai Lake’s trophic status, especially during the transition period from a mesotrophic lake to a eutrophic one.

Constructed Wetland for Wastewater Treatment

Article

Full-text available

Mar 2018

Constructed wetland is a candidate method for waste water treatment due to its cost effective, less energy sensitive, simple operation and maintenance, little secondary pollution and favorable environmental appearance. The objective of the present study is to investigate the efficacy of subsurface flow constructed wetland system for treatment of domestic wastewater. The methodology includes design and construction, transplantation and start-up, operation and monitoring and sampling and analysis. A horizontal subsurface flow constructed wetland (HSSFCW) designed as per Tennessee Valley Authority method, (1.5 x 0.6 x 0.3) m size, aspect ratio of 2.5:1, with treatment zone of 0.27 m 3 , 0.7% longitudinal bottom slope, was constructed. It was filled with the first layer of 0.15 m coarse aggregate gravel 2 cm size, the second layer of 0.15 m of fine aggregate sand 2 mm size, and 0.075 m freeboard. After establishment over one month in natural bed, the wetland plant Phragmitesaustralis having 0.3 m stem were transplanted at a density of 2 seedlings per m 2 .The HSSFCW was operated under batch mode with 6 days hydraulic retention time for one year. The concentrations of TSS, COD, BOD, TN and TP of the source influent ranged 22-572 mg l-l , 249-1946 mg l-l , 99-658 mg l-l , 2.1-138 mg l-l , and 1.69-35 mg l-l , respectively, whereas the treated effluent ranged 10-348 mg l-l ,51-1187 mg l-l , 18-139 mg l-l ,0.2-70.2 mg l-l , and 0.24-29.8 mg l-l , respectively, and percentage removal ranges were 33-70%, 24-79%, 70-85%, 3-90% and 12-87%.Constructed wetlands should be encouraged as a cost-effective and sustainable solution of wastewater treatment for small communities.

Constructed wetlands for greywater recycle and reuse: A review

Article

Feb 2018

Adapting the Relaxed Tanks-in-Series Model for Stormwater Wetland Water Quality Performance

Article

Full-text available

Sep 2017

Across the globe, water quality standards have been implemented to protect receiving waters from stormwater pollution, motivating regulators (and consequently designers) to develop tools to predict the performance of stormwater control measures such as constructed stormwater wetlands (CSWs). The goal of this study was to determine how well the relaxed tanks-in-series (P-k-C*) model described the performance of CSWs in North Carolina. Storm events monitored at 10 CSWs in North Carolina were used for calibrating the model, and statistical evaluations concluded the model could adequately predict the performance for all pollutants except organic nitrogen. Nash–Sutcliff calibration/validation values were determined to be 0.72/0.78, 0.78/0.74, 0.91/0.87, 0.72/0.62, 0.88/0.73, and 0.91/0.63 for total nitrogen, total ammoniacal nitrogen, oxidized nitrogen, organic nitrogen, total phosphorus, and total suspended solids, respectively. Sensitivity analysis revealed only one calibration parameter with strong sensitivity, the Arrhenius coefficient (temperature dependent model coefficient). With this model, CSWs can be optimized to treat watershed-specific influent concentrations to meet effluent targets. In general, the current design technique used in North Carolina and many other locations (a first flush volume detention method) oversizes CSWs for water quality vis-à-vis the method herein, suggesting improved designs for water quality may be possible through scientifically-informed methods.

Including Nature in Engineering Decisions for Sustainability

Chapter

Dec 2017

This article describes methods and concepts for emulating and including nature's role in engineering activities, with the expectation that they will contribute to sustainable engineering. Existing nature-inspired methods function at different levels ranging from individual products to large integrated networks. These include methods such as biomimicry and industrial symbiosis that mimic some characteristic property of a natural system but depend on technological improvements for sustainability; ecological engineering and green infrastructure that depend on nature-based solutions as means for sustainability and techno-ecological synergy that integrates technological and ecological systems by adopting a holistic perspective of design.

Constructed Wetlands: An Emerging Phytotechnology for Degradation and Detoxification of Industrial Wastewaters

Chapter

Full-text available

Aug 2017

Development/ripening of ecosystems services in the first two growing seasons of a regional-scale constructed stormwater wetland on the coast of North Carolina

Article

Sep 2016
ECOL ENG

A well-functioning constructed stormwater wetland (CSW) will provide many ecosystem services. However, there has not been an effort to monitor and evaluate these services as a CSW develops in the first years after construction – the ‘ripening’ period. In this study, ecosystem services development was assessed during the first two growing seasons of a CSW located on the coast of North Carolina. The CSW research site was a regional-scale stormwater project with two different flow regimes: event and base flow. The full potential of some ecosystem services of this CSW were realized immediately such as volume reduction, TSS and NO2,3 treatment. Others were fully developed after the 1st growing season, e.g. TAN, ON, TN, and TP treatment. Mostly, ripening of the CSW was complete, as areal C densities exceeded median C densities observed in other stormwater wetlands, and vegetation biodiversity measurements aligned with other stormwater wetlands in North Carolina, just one year after construction. The establishment of vegetation was deemed the most important design goal during this vital period, as vegetation is interlinked with other services: evapotranspiration, water quality improvement, and C input to the soil.

Assessing the Capacity of Local Ecosystems to Meet Industrial Demand for Ecosystem Services

Article

May 2016
AICHE J

Despite the importance of ecosystems, engineering activities continue to ignore or greatly undervalue their role. Consequently, engineered systems often overshoot nature’s capacity to support them, causing ecological degradation. Such systems tend to be inherently unsustainable, and they often fail to benefit from nature’s ability to provide essential goods and services. This work explores the idea of including ecosystems in chemical processes, and assesses whether such a techno-ecological synergistic system can operate within ecological constraints. The demand for ecosystem services is quantified by emissions and resources used, while the supply is provided by ecosystems on the manufacturing site. Application to a biodiesel manufacturing site demonstrates that ecosystems can be economically and environmentally superior to conventional technologies for making progress toward zero emissions and net positive impact manufacturing. These results highlight the need for shifting the paradigm of engineering from that of dominating nature to embracing nature and respecting its limits.

Longitudinal macroinvertebrate assemblages in contrasting discontinuities: The effects of damming in tropical streams

Article

Full-text available

Mar 2016

The study assessed the impact of damming on water quality and macroinvertebrate assemblages. It also assessed the response of macroinvertebrate-based indices of water quality to damming. Macroinvertebrate community and physicochemical variables data were collected from 86 sites. Twenty-nine sites downstream of dams were compared with 27 sites above impoundments and 30 sites on nearby unregulated streams. Of the downstream sites, 13 were situated <1 km from a dam while the other 16 were situated >1 km from a dam. A decrease in temperature, dissolved oxygen, conductivity and total dissolved solids was observed in sites immediately downstream of impoundments. Macroinvertebrate community structure and South African Scoring System (SASS) scores closely followed the damming-induced changes in water quality. However, water quality variables, macroinvertebrate community structure and SASS scores reverted back to typical upstream conditions in distances around 1 km from dams. Stream recovery from dam-induced changes was demonstrated with streams recovering at distances around 1 km from the point of regulation in corroboration with predictions of the serial discontinuity concept (SDC). These dam-induced changes also reflected themselves in SASS scores suggesting potential usefulness of SASS in monitoring ecological integrity of tropical rivers following disturbances like damming.

The role of Sand, Marble chips and Typha latifolia in domestic Wastewater Treatment – A Column Study on Constructed Wetlands

Article

Full-text available

Feb 2016

The relative importance of sand, marble chips and wetland plant Typha latifolia is evaluated in constructed wetlands (CWs) for the treatment of domestic wastewater intended for reuse in agriculture. The prototype CWs for the experiments are realized in polyvinyl chloride (PVC) columns, which are grouped into four treatments viz. sand (<2 mm) + Typha latifolia (cattail), sand, marble chips (5-20 mm) + cattail, and marble chips. The removal percentage of organic and nutritional pollutants from the wastewater is measured at varying hydraulic retention time (HRT) in the columns. The statistical analysis suggests that, the main effects of sand and cattail are found to be significant (p<0.05) for the removal of biological oxygen demand (BOD) and chemical oxygen demand (COD) from the wastewater. The presence of cattail significantly (p<0.01) contributes for the conversion of total nitrogen in wastewater into NO3(-) by fostering the favorable microbes for the nitrification. The removal of PO4(3-) and turbidity from the wastewater is significantly (p<0.01) influenced by sand than the presence of cattail. The maximum PO4(3-) adsorption capacity of the sand is estimated to be 2.5 mg/g. Marble chips have significantly (p<0.01) influenced the removal of SO4(2-) and its maximum removal capacity is estimated to be 9.3 mg/g. The negative correlation between the filter media biofilm and column hydraulic conductivity is also reported for all the treatments. Thus, the findings of this study elucidates the role of low cost and easily available filter media and it will guide the environmental practitioners in designing the cost-effective CWs for the wastewater treatment.

Estimates of Carbon Reservoirs in High-Altitude Wetlands in the Colombian Andes

Article

Full-text available

Oct 2009
J AGR RURAL DEV TROP

The observed increase in emission of greenhouse gases, with attendant effects on global warming, have raised interests in identifying sources and sinks of carbon in the environment. Terrestrial carbon (C) sequestration involves capture of atmospheric C through photosynthesis and storage in biota, soil and wetlands. Particularly, wetland systems function primarily as long-term reservoirs for atmospheric carbon dioxide (CO2) and as sources of atmospheric methane (CH4). The objective of this study was to evaluate the patterns of carbon reservoirs in two high-altitude wetlands in the central Andean mountain of Colombia. Carbon cycle in both systems is related mainly with the plant biomass dynamics from the littoral zone. Thus, total organic carbon concentrate an average up to 329 kg of N ha-1 and 125 kg of P ha-1 every year vs only 17 kg N ha-1 and 6 kg P ha-1 in the water column of the limnetic zone in the wetland, evidencing spatial differences in carbon concentrations for these types of ecosystems. Results revealed that these systems participate in the balance and sequestration of carbon in the Colombian Andes.

MODELACIÓN DINÁMICA DE LOS SÓLIDOS SUSPENDIDOS TOTALES EN EL HUMEDAL JABOQUE, BOGOTÁ (COLOMBIA)

Article

Full-text available

Dec 2012

We propose a dynamic simulation model to provide a general explanation for the behavior of total suspended solids in the Jaboque wetland (Bogotá DC). The analyses were performed in three areas with distinct physical and chemical characteristics. The model predicted concentrations of total suspended solids in the months of April, May, June, October and November. Values ranged from 85 mg L-1 and 101 mg L-1 with an average of 65.12 mg L-1 with a hydraulic time retention between eight and nine days per year for the first area, the second area between 57 and 69 with an average of 50 mg L-1 with a hydraulic time between 20 and 23 days per year and in the third area between 56 mg L-1 and 67 mg L-1 with a mean of 48.8 mg L-1 and a hydraulic retention time between 24 and 26 days per year. The months of December, January, February, August and September showed a tendency to have lower values. The estimated values of total suspended solids based on our model had an acceptable correspondence, R2 = 0.95, 0.71, 0.67, with the actual values in all cases. The relative error for each area was 0.10, 0.20 and 0.26, demonstrating that the model does not overestimate the results.

Effect of high-pressure steam treatment on enzymatic saccharification of oil palm empty fruit bunches

Article

Full-text available

Aug 2012
BIORESOURCES

The effectiveness of high-pressure steam treatment (HPST) with various treatment temperatures (170, 190, 210, and 230 °C) on the enzymatic hydrolysis yield of oil palm empty fruit bunches (OPEFB) was successfully investigated. Analysis of the compositions of raw and treated OPEFB showed that significant changes occurred after the HPST was performed. Scanning electron microscopy (SEM) analysis showed that the treated OPEFB gave better results in removing the silica bodies as compared to the untreated OPEFB. This analysis was in agreement with FTIR results, which revealed a significant decrease in the content of hemicelluloses after HPST. During saccharification, the amount of sugar produced was higher for treated OPEFB than untreated OPEFB. Thus, the results suggest that HPST can be applied as an alternative treatment method for the alteration of OPEFB structure and to enhance of the digestibility of the biomass, therefore improving enzymatic hydrolysis.

Participation of planktonic and benthic bacteria in the polyphosphate accumulating process in mesocosms contaminated with phosphates and nitrates

Article

Full-text available

Jan 2012

Participation of planktonic and benthic bacteria in accumulation of polyphosphates in conditions of nitrates and phosphates overload was investigated in model mesocosms with natural water containing hydrobionts and curtains of Typha angustifolia. Experiments were performed in seasonal dynamics. Dynamic of number of bacterioplankton and benthic bacteria was studied in ecosystems of water and ground. It was detected that structure and number of bacterioplankton and benthic bacteria depended on the presence of higher aquatic plants in model biotopes. In overgrown biotopes overload on nitrates and phosphates resulted in development of planktonic and benthic bacteria. Reduction of trophic status of hydro ecosystem on bacterioplankton and low concentrations of biogens were favorable conditions for accumulation of polyphosphates by bacteria.

Wetlands, Livelihoods and Human Health

Chapter

Aug 2015

In developing countries millions of people live a life of subsistence agriculture, mired in poverty, with limited access to basic human needs, such as food and water. Under such circumstances wetlands, through the provision of a range of direct and indirect ecosystem services, play a vital role in supporting and sustaining peoples’ livelihoods and hence, their health. This chapter discusses the role of wetlands in the context of the sustainable livelihoods framework in which wetlands are viewed as an asset for the rural poor in the form of “natural capital”. The framework is used to illustrate how ecosystem services, livelihoods and health are entwined and how the ecosystem services provided by wetlands can be converted to human health either directly or via other livelihood assets. It highlights the contributions that wetlands make to basic human needs and, either directly or through transformations to other forms of livelihood capital, the support they provide to livelihoods and overall wellbeing.

The efficiency of Pontederia Cordata in nitrogen removal from landscape water under varying flow rates

Article

Full-text available

Aug 2015
Water Pract Tech

The Green Origio biological system, a two-stage, solar-powered constructed wetland mesocosm situated in Shanghai Jiao Tong University's plant park was used for nitrogen removal in the institution's landscape water. Whereas the first tank was anaerobic, the second tank containing fully grown Pontederia cordata was operated under aerobic conditions. The system was designed with an overflow by-pass pipe to prevent hydraulic overloading. Pump discharge values of 53, 74, 112, 120, 205 and 270 m3/day were recorded during the study. However, the corresponding flow rate values into the tanks were 16.25 m3/day, 29.47 m3/day, 36.79 m3/day, 50.57 m3/day, 71.38 m3/day and 80.52 m3/day, respectively. Experiments conducted between August and October, 2013 revealed a significant concentration decrease for total nitrogen (TN), ammonia (NH3-N), nitrate (NO3-N), nitrite (NO2-N) and total organic carbon (TOC). Whereas the Multi N/C 3100 Analyzer was used for simultaneous analysis of TN and TOC, the nitrogen fractions were analyzed using spectrophotometric methods. The TN, NO3-N, NH3-N, NO2-N and TOC removal rates under a flow rate of 16.25 m3/day were 55.65%, 75.19%, 74.03%, 95.43% and 29.87%, respectively. TN and NO2-N removal efficiencies of 4.92% and 83.64%, respectively, were observed under a flow rate of 80.52 m3/day. Concentration increase in the effluent caused by washout of accumulated concentrations was noted for NO3-N, NH3-N and TOC.

Effects of annual harvesting on plants growth and nutrients removal in surface-flow constructed wetlands in northwestern China

Article

Jul 2015
ECOL ENG

SubWet 2.0. Modeling the Performance of Treatment Wetlands

Article

Dec 2014
Dev Environ Model

Increasingly strict water quality standards and the increasing application of treatment wetlands for wastewater treatment is an ever-growing motive for the development of better process design tools. This chapter reviews the SubWet 2.0 model, a horizontal subsurface flow modeling program initially intended to provide support for the design of constructed wetlands by providing environmental engineers and planners answers to the size of wetlands needed to accommodate anticipated flow rates and desired levels of treatment. The recent SubWet 2.0 version has been modified to allow its application to cold climate areas. This modification was accomplished by calibrating the model with data collected from natural tundra wetlands currently in use for the treatment of municipal effluents within the Kivalliq region of Nunavut, Canada. The calibration of this model with Arctic data has demonstrated its ability to model treatment performance within natural tundra wetlands and thus provide an additional predictive tool to aid northern stakeholders in the treatment of municipal effluents. Three different data sets are presented to illustrate how SubWet 2.0 can be calibrated to specific wetlands. Two data sets are from natural tundra wetlands in Arctic Canada; one is from a constructed wetland in Tanzania. The merits as well as disadvantages of some simple and some more elaborate design models with regard to the design of subsurface flow constructed wetlands are briefly compared with SubWet. Compared to other models, it is suggested that SubWet provides one of the best modeling options available for natural tundra wetlands. It uses a variety of rate constants that are calibrated to site conditions and provides a simulated response of the whole wetland that integrates both known processes and accounts for the possibility that other poorly defined influences (e.g.; inflow of melt waters) may also be operative.

PERFORMANCE OF CONSTRUCTED TREATMENT WETLANDS: MODEL-BASED EVALUATION AND IMPACT OF OPERATION AND MAINTENANCE

Article

Jan 2005

D Rousseau

‘Constructed wetlands’ (CWs) zijn door de mens aangelegde moerassen waarin het natuurlijke zelfreinigende vermogen van een dergelijk aquatisch ecosysteem door middel van een doordacht ontwerp en een aangepaste bedrijfsvoering geoptimaliseerd wordt. Uit veelvuldig onderzoek sinds de jaren 1970 en vooral ook uit praktijkervaring blijkt dat CWs in veel situaties voor een degelijke zuivering zorgen die evenwel afhankelijk is van factoren zoals temperatuur, organische en hydraulische belasting, ... Wat de mechanismen achter deze waarnemingen zijn, is echter nog grotendeels een vraagteken. En in zoverre bepaalde mechanismen wel opgehelderd zijn, bestaat er nog steeds onduidelijkheid over hun interacties en hun respectievelijk aandeel in de zuivering van afvalwater. Een eerste doelstelling van dit doctoraat was dan ook de ‘black box’ die CWs tot nog toe zijn doorzichtiger te maken, enerzijds door aangepaste metingen, anderzijds door middel van mechanistische dynamische modellen. Allereerst werden hoog-frequente metingen uitgevoerd als aanvulling op een bestaande dataset met wekelijkse metingen van influent en effluentconcentraties van een tweetraps pilootschaal CW. Op die manier werd een optimaal beeld bekomen van trage en snelle processen en hun respectievelijke dynamiek. Verder werd ook een nieuw model van een wortelzone CW ontwikkeld waarin acht verschillende microbiële gemeenschappen, samen met de rietplanten en een aantal fysische processen, interageren en voor zuivering van afvalwater zorgen. De respectievelijke submodellen werden opgebouwd naar analogie met bestaande actief slib modellen en anaërobe vergistingsmodellen. Kalibratie van een dergelijk uitgebreid model is een zeer complexe taak en zou veel meer gegevens vereisen dan wat realistischerwijze kan worden verkregen. Daarom werden van alle gevalideerde submodellen telkens de standaard parameterwaarden gebruikt, waarna het model werd uitgetest op twee datasets van respectievelijk een experimenteel (0,55 m2) en een pilootschaal (55 m2) CW. Met inachtneming van alle onzekerheden bleek het model toch behoorlijk goed in staat om de effluentkwaliteit te voorspellen en liet het vooral toe om de experimentele resultaten beter te verklaren en om nieuwe richtingen voor experimenteel onderzoek aan te geven. Alhoewel een degelijk ontwerp logischerwijze aan de basis ligt van een goede performantie, zijn de daaropvolgende bedrijfsvoering en onderhoud eveneens van cruciaal belang. Praktijkervaring uit Vlaanderen en het Verenigd Koninkrijk toonde evenwel aan dat CWs vaak als ‘build-and-forget’ oplossingen worden beschouwd. Op basis van experimenteel onderzoek kon evenwel duidelijk aangetoond worden dat doeltreffend onderhoud bijdraagt tot een langere levensduur van CWs.

Spatial Distribution of Plant-Associated Invertebrates and Environmental Bioassessment in a Natural Riverine Lake (Lake Fibreno, Central Italy)

Article

Jan 2014
JWARP

Municipal wastewater treatment in horizontal and vertical flows constructed wetlands

Article

Full-text available

Dec 2013
ECOL ENG

Two large-scale subsurface constructed wetland pilot plants were designed, implemented and operated for almost three years for the treatment of a real municipal wastewater. One unit was running in a horizontal flow (HFCW) with a surface area of 654.5 m(2), while the other one was a sub-tidal vertical flow (VFCW) with 457.6 m(2) surface area. The two wetland units were operated at a hydraulic load of 20 m(3)/day for each unit and at temperature ranged from 15 to 30 degrees C. The organic loading rate was 2.02 kg BOD/day. The two pilot units were planted with three kinds of plants namely; Canna, Phragmites and Cyperus. Monitoring and evaluation of the performance of the two pilot units were carried out through regular physico-chemical as well as biological analysis of the inlet and outlet wastewater. In addition, nutrient uptake in the plants was also measured. The results indicated significant removals of different pollutants in both HFCW and VFCW in terms of COD, BOD and TSS. The average removal efficiencies of COD, BOD and TSS in HFCW were 91.5%, 92.8% and 92.3%, while it reached 92.9%, 93.6% and 94% in VFCW. However, VFCW proved to be more efficient than HFCW not only in COD, BOD removals but also for nitrification because of the tidal vertical flow, which allows the penetration of more oxygen, beside its small size and long detention time. The removal rate of ammonia due to nitrification reached 62.3% in VFCW, while in HFCW it reached 57.1%. In addition, the results indicated that most of the plants survived for almost 12 months and their growth depend on the type of constructed wetlands (CW) used. In conclusion VFCW proved to be more effective for wastewater treatment than HFCW due to its smaller size, high quality effluent and better nitrification.

PDF JWARP 2014073013511729

Data

Mar 2015

Assessing the Development of Ecosystem Services in Constructed Stormwater Wetlands

Conference Paper

Jan 2012

Stormwater control measures (SCMs) such as constructed stormwater wetlands (CSWs) are designed to regulate runoff hydrology and quality. In addition to these functions, these engineered ecosystems also provide a range of other benefits, or ecosystem services. Research on these additional services is in its infancy; the initial development of ecosystem services is of interest since it may inform future CSW designs. In this study, the development of ecosystem services, including biodiversity, carbon sequestration, and cultural services, will be assessed for two CSWs in North Carolina over a 3-year time period. The first CSW is located in Cary, NC. Its surface area is of 0.32 hectares and has a highly urbanized contributing catchment of 7.69 hectares. The second CSW is to be located in New Bern, NC with a surface area of 11.33 hectares and a partially urbanized contributing watershed of 311.61 hectares. Biodiversity will be quantified in terms of the richness and Shannon diversity index for vegetative and aquatic macroinvertebrate communities. Carbon sequestration will be estimated spatially and temporally through the changes in carbon content of the wetland sediments. Cultural services will be qualitatively assessed based on the potential for recreational and educational opportunities at each site. Monitoring and sampling of the Cary CSW commenced in November 2011, 3 months after construction was finished. Sampling frequency will be bi-monthly throughout the study, with increased frequency of biodiversity (monthly) sampling in the spring and summer months of the first growing season. Sampling of the New Bern CSW will commence in Fall of 2012, immediately after construction is completed. This study will provide a more detailed tracking of the development of these services over time instead of previously reported studies which typically just substituted space for time.

Southern California Bight 2008 Regional Monitoring Program: VIII. Estuarine Eutrophication

Technical Report

Full-text available

Aug 2012

Hydrobiology and productivity of Kuntbhyog Lake, (District Mandi, Himachal Pradesh), India

Article

Full-text available

Jan 2014

Studies on the biodiversity on Kuntbhyog Lake (Himachal Pradesh) were made on species composition and population dynamics of phytoplankton, zooplankton, nekton, productivity in relation to seasonal variations in physico-chemical characteristics of water. Among phytoplankton, members of Bacillariophyceae and Chlorophyceae constituted the dominant group, whereas Cyanophyceae and Euglenophyceae were the subdominant component. Among zooplankton, Rotifera and Arthropoda formed the dominant group, whereas Protozoa Subdominant and Ostracoda were rare in occurrence. The plankton revealed abundance during summer and post monsoon while the minimum number were recorded during winter. Factors affecting the seasonal distribution of organisms have been discussed. Shannon's Species Diversity and Nygaard's Trophic State indices have been calculated. On the basis of the hydrobiological characteristics, according to the classification of waters for various purposes given by Central Pollution Control Board (CPCB) (www.cpcbnic.in/classi.htm), the water of the lake could be categorising as 'B'. He obtained his MSc (Hons.) and PhD in Zoology from Panjab University, Chandigarh. He has teaching/research experience of over 30 years in fish and fisheries, environmental biology and wildlife. He has more than 60 research publications to his credit in reputed journals and has supervised a number of MSc, MPhil and PhD research students. He is also a reviewer of various research journals. Currently, he is engaged in studies relating to productivity, population dynamics, seasonal distribution and species diversity of aquatic organisms in relation to hydrobiological factors of lentic and lotic waters of North India; assessment and impact of pollution; and bioindicators of pollution.

Removal of Nitrogen Oxyanion (Nitrate) in Constructed Wetlands

Chapter

Full-text available

Jul 2021

The increasing levels of nitrogen oxyanion pollution especially nitrate in water environments have become a critical issues of concern because of the potential risk on ecology and human health. Owing to its distinctive merits of sustainability, lesser operational and maintenance expenditure, the utilization of constructed wetland systems for the treatment of wastewater has turned out to be predominant worldwide. Its nitrogen oxyanion removal performance has received significant attention in the last two decades. This chapter presents a comprehensive outline of the application of constructed wetlands (CW) for nitrogen oxyanion removal from water and wastewater. The removal mechanisms and transformations of nitrogen are also discussed. In addition, the major factors that influence the removal performances in CWs are elucidated, especially the types of carbon sources commonly used, and how it affects the denitrification process. This chapter would be useful to engineers and researchers in the field of water and wastewater engineering.

Nitrogen removal in response to plants harvesting in two kinds of enhanced hydroponic root mats treating secondary effluent

Article

Mar 2019
SCI TOTAL ENVIRON

Hydroponic root mats (HRMs) are a green technology for various wastewaters purification. However, plants wilting will inevitably reduce the purification efficiency of HRMs. Harvesting as an important way of plant management for a better understanding of sustainability of HRMs has always been highly controversial. The goal of this study was to investigate the impacts and sustainability of harvesting on nitrogen removal and greenhouse gases (CH 4 , N 2 O) emissions of the two kinds of enhanced hydroponic root mats: autotrophic hydroponic root mat (AHRM) and heterotrophic hydroponic root mat (HHRM) for treating secondary effluent. The results showed that harvesting temporarily decreased nitrogen removal efficiency of the two systems, and removal efficiency recovered quickly because of the existence of external electron donors. The effects of harvesting are ordered as: HHRM > AHRM, NO 3⁻ -N > NH 4⁺ -N. Increasing C/N, S/N would reduce the impact of temperature on harvesting systems. Harvesting also increased the emission of greenhouse gases, and increasing C/N(=6), S/N(=1.1) could significantly reduce greenhouse gases emission of the harvesting systems at low temperature. In addition, composition analysis of the shoots of the harvested plants was also conducted, and the results showed that N contents of growing shoots were significantly higher than that of withered shoots. In order to make the hydroponic root mats sustainable, harvesting before the plants wilt is more effective in removing nitrogen from the system permanently and maintain a sustainable system.

Phytoremediation Applications for Waste Water and Improved Water Quality

Chapter

Sep 2016

Macrophytes play an important role in natural and constructed wetlands (CWs). Their most important function is removal of excessive levels of some substances, such as nutrients, total suspended solids, trace elements, etc. CWs are widely used all around the world to treat many types of wastewater, with relatively high removal efficiency (5-day biochemical oxygen demand [BOD5]—around 80 %, total nutrients—approx. 40 % in the case of domestic sewage). Considering the purpose of CWs application, a few types were created with several variants in certain environmental conditions and for many effluent types with various loads of many substances. Two main types of flow through CWs are considered—surface and subsurface flow. The latter is further divided into horizontal and vertical flow. The most popular use of CWs is for domestic and municipal wastewater as secondary and tertiary treatment stages. Among macrophytes applied for phytoremediation, great diversity of plant species has been observed, especially native species and a wide range of ubiquitous species, such as Phragmites australis and Typha spp. Most macrophyte species also play an important role in natural ecosystems in improvement of surface water quality. Many species are utilized as indicators of water quality, even when low pollutant levels occur, while others are important for phytoextraction or phytostabilization.

Land management meeting several environmental objectives. Minimizing impacts on greenhouse gas emissions, biodiversity and water. Knowledge compilation and systems perspective

Book

Full-text available

Jan 2012

Physicochemical property changes of oil palm mesocarp fibers treated with high-pressure steam

Article

Full-text available

Nov 2012
BIORESOURCES

High-pressure steam treatment (HPST) is a potential alternative method for the modification of lignocellulosic materials. The effect of HPST on oil palm mesocarp fibers (OPMF) was successfully investigated with treatment conditions of 170 °C/ 0.82 MPa, 190 °C/ 1.32 MPa, 210 °C/ 2.03 MPa, and 230 °C/ 3.00 MPa for 2 min. treatment time. Significant changes in the colour, smell, and mechanical properties of the samples were observed after the treatment. Scanning electron microscope (SEM) images revealed changes in the surface morphology of the OPMF after the pretreatment. The degradation of hemicelluloses and changes in the functional groups of the lignocellulosic components were identified using Fourier Transform Infrared (FTIR) and Thermogravimetric (TG) analysis. These results suggest that HPST is a promising method for the pretreatment of OPMF.

Benthic Algae and Nutrient Cycling in Lentic Freshwater Ecosystems

Chapter

Dec 1996

Robert G. Wetzel

Clonal Growth in Typha Latifolia: Population Dynamics and Demography of the Ramets

Article

Jul 1985

(1) Ramet demography and growth in a mature natural population of Typha latifolia shoots in south-central Michigan, U.S.A. were studied. Records of 1981 individually-tagged shoots, observed at 1- or 2-week intervals for two growing seasons, included height, number of leaves and status of each leaf. Biomass was determined by harvesting replicate plots. (2) Shoots emerged in three main pulses each year, resulting in three major cohorts. These pulses were timed similarly in 2 years. The first cohort emerged in early spring, grew throughout the summer and senesced completely in late autumn. The second emerged in midsummer; 82% (year 1) and 76% (year 2) of these shoots senesced completely in autumn, while the remainder resumed growth the following spring. The third emerged in late summer and early autumn; 78% (year 1) and 92% (year 2) of all its shoots resumed growth the following spring. (3) Shoot mortality within 3 weeks of emergence was minor (13%, year 1; 6%, year 2). (4) The ranges in live shoot density were very similar for the 2 years: 12.7-43.9 shoots m-2 in year 1 v. 11.2-41.9 shoots m-2 in year 2. In year 1, however, live shoot density increased gradually throughout the growing season, while in year 2 a rapid increase in shoot density resulted in a density of 40.1 shoots m-2 by mid-May. This density was maintained throughout the second growing season. (5) Because the density of shoots growing from early spring was 60% greater in year 2 than in year 1, we were able to evaluate the applicability of genet-based, density-mediated competition theory (based on eight expected consequences) to ramet-level populations. We conclude that density-mediated competition does not regulate ramet populations in mature stands of T. latifolia.

Effects of the emergent macrophyte Juncus effusus L. on the chemical composition of interstitial water and bacterial productivity

Article

Mar 2000

Release of oxygen from the roots of aquatic macrophytes into anaerobic sediments can affect the quantity of interstitial dissolved organic matter and nutrients that are available to bacteria. Nutrient and dissolved organic carbon (DOC) concentrations were compared between subsurface (interstitial) waters of unvegetated sediments and sediments among stands of the emergent herbaceous macrophyte Juncus effusus L. in a lotic wetland ecosystem. Concentrations of inorganic nitrogen (NH4/+, NO3/-, and NO2/-) were greater from sediments of the unvegetated compared to the vegetated zone. DOC concentrations of interstitial waters were greater in sediments of the unvegetated zone both in the winter and spring compared to those from the vegetated zone. Although DOC concentrations in hydrosoils collected from both zones increased from winter to spring, bacterial productivity per mg DOC in spring decreased compared to winter. Greater initial bacterial productivity occurred on DOM collected from the vegetated compared to the unvegetated zone in winter samples (days 1 and 4), with increased bacterial productivity on samples collected from the unvegetated zone at the end of the study (day 20). Bacterial productivity was significantly greater on all sampling days on DOM from vegetated samples compared to unvegetated samples. In nutrient enrichment experiments, bacterial productivity was significantly increased (p < 0.05) with phosphorus but not nitrogen only amendments.

Inhibition of phosphatase activity by dissolved humic substances and hydrolytic reactivation by natural ultraviolet light

Article

Sep 1998

1. Phosphatases released extracellularly by aquatic micro-organisms often complex with humic compounds that are released from decomposing tissues of plants and imported in dissolved and colloidal forms to lakes and rivers. 2. Dissolved humic substances from several natural sources formed complexes with phosphatases of bacterial and algal origin and reduced hydrolytic activity by non-competitive inhibition. Restoration of the hydrolytic enzyme activities from the humic substances–enzyme complexes increased progressively over time when exposed experimentally to natural and artificial ultraviolet (UV) irradiance. 3. Greater phosphatase restoration occurred from humic acid–phosphatase complexes when humic acids were extracted from dissolved organic matter (DOM) of mixed natural plant sources, than when humic acids were isolated from a decomposing single plant species. 4. The data support a previously suggested hypothesis that phosphatases and other enzymes in aquatic ecosystems can complex with humic substances that dominate the DOM pool. These humic substances–enzyme complexes, in which the enzyme is temporarily inactivated, can be transported with water movements and displaced to other sites within the ecosystem. Upon exposure to UV irradiance in the photic zone, functional enzymes can be released. The potential for inactivation and storage of enzyme activity, relocation within the ecosystem, and subsequent reactivation holds important implications for regulation of nutrient cycling in fresh waters.

Simultaneous use of 14C and 3H to determine autotrophic production and bacterial protein production in periphyton

Article

Nov 1995

A method of simultaneously quantifying photoautotrophic (algae and cyanobacteria) and bacterial production in periphyton communities by 14C-bicarbonate and 3H-leucine incorporation was investigated and applied to communities subjected to specific intensities of photosynthetically active radiation (400–700 nm). Maximum photosynthetic output (2.23 ± 0.29 (SE) µg C cm-2 h-1) and bacterial production (0.07 ± 0.006 µg C cm-2 h-1) occurred at the highest photon flux density (400 µmol m-2 s-1). Over a photon flux density range of 20–400 µmol m-2 s-1, bacterial and autotroph productivity were significantly and positively correlated (r = 0.89). Furthermore, application of 3-(3,4-dichlorophenyl)-1,1-dimethyl urea, a photosystem 11 inhibitor, to periphyton films reduced bacterial production by 46%, but it had no such effect on bacteria-only cultures. Therefore, the magnitude of bacterial production in periphyton was coupled to the photosynthesis/metabolism of algae and/or cyanobacteria.

Shoot:root dynamics during growth stages of the rush Juncus effusus L.

Article

Nov 1997
AQUAT BOT

Growth relationships between above- and belowground portions of Juncus effusus L. were examined in cultures that allowed examination of changes in tissue parameters (length, volume, surface area, mass) nondestructively. Mean shoot:root ratios (AFDM ± SE) decreased 83% (3.68 ± 0.31 to 0.64 ± 0.06) over a 98-day study period. These changes in carbon allocation, even though the aboveground biomass was still increasing, were confirmed with 14CO2 pulse-labelling experiments which indicated a shift toward increased allocation of carbon to roots, particularly during periods of cohort establishment in this species. Root mass (length-specific AFDM, mg cm−1) was poorly correlated with shoot characteristics, but root length was strongly positively correlated with shoot biomass measurements (height; surface area). Analyses of shoot:root biomass relationships indicated decreasing root mass per unit length as shoot biomass increased.

Methane production and methane consumption: A review of processes underlying wetland methane fluxes

Article

Apr 1998

Rien Segers

Potential rates of both methane production and methane consumptionvary over three orders of magnitude and their distribution is skew.These rates are weakly correlated with ecosystem type, incubationtemperature, in situ aeration, latitude, depth and distanceto oxic/anoxic interface. Anaerobic carbon mineralisation is amajor control of methane production. The large range in anaerobicCH4:CO2 production rates indicate that a largepart of the anaerobically mineralised carbon is used for reduction ofelectron acceptors, and, hence, is not available for methanogenesis.Consequently, cycling of electron acceptors needs to be studied tounderstand methane production. Methane and oxygen half saturationconstants for methane oxidation vary about one order of magnitude.Potential methane oxidation seems to be correlated withmethanotrophic biomass. Therefore, variation in potential methaneoxidation could be related to site characteristics with a model ofmethanotrophic biomass.

Microcommunities and microgradients: Linking nutrient regeneration, microbial mutualism, and high sustained aquatic primary production

Article

Jul 1993

Robert G. Wetzel

Nutrient regeneration is essential to sustained primary production in the aquatic environment because of coupled physical and metabolic gradients. The commonly evaluated ecosystem perspective of nutrient regeneration, as is illustrated among planktonic paradigms of lake ecosystems, functions only at macrotemporal and spatial scales. Most inland waters are small and shallow. Consequently, most organic matter of these waters is derived from photosynthesis of emergent, floating-leaved, and submersed higher plants and microflora associated with living substrata and detritus, including sediments, as well as terrestrial sources. The dominant primary productivity of inland aquatic ecosystems is not planktonic, but rather is associated with surfaces. The high sustained rates of primary production among sessile communities are possible because of the intensive internal recycling of nutrients, including carbon. Steep gradients exist within these attached microbial communities that (a) require rapid, intensive recycling of carbon, phosphorus, nitrogen, and other nutrients between producers, particulate and dissolved detritus, and bacteria and protists: (b) augment internal community recycling and losses with small external inputs of carbon and nutrients from the overlying water or from the supporting substrata; and (c) encourage maximal conservation of nutrients. Examples of microenvironmental recycling of carbon, phosphorus, and oxygen among epiphytic, epipelic, and epilithic communities are explained. Recalcitrant dissolved organic compounds from decomposition can serve both as carbon and energy substrates as well as be selectively inhibitory to microbial metabolism and nutrient recycling. Rapid recycling of nutrient and organic carbon within micro-environments operates at all levels, planktonic as well as attached, and is mandatory for high sustained productivity.

Pressurised ventilation in emergent macrophytes: The mechanism and mathematical modelling of humidity-induced convection

Article

Jul 1996
AQUAT BOT

Humidity-induced diffusion (HID) and convection (HIC: pressure flow) are described for a simple physical model and are mathematically modelled. The physical model comprises a cylindrical chamber, partially filled with water, and capped by a micro-porous partition (membrane); an outflow pipe with a tap vents gases from the header space to the outside. The mathematical model comprises a series of equations which embrace the effects of header space depth and boundary layer thickness, the diffusive- and any Poiseuille-flow resistances of the partition, and the venting path resistance.For membrane pore diameters within (i.e. ≤ 0.1 μm) or outside the Knudsen regime, close correlations are found between experimental values of static and dynamic pressure and convective flows, and those obtained from the mathematical model. The findings suggest that for plants, compromises are necessary between factors such as small pore widths, which can help generate high dynamic pressures, and the need for wider pore widths to support greater flows. It is shown that the fastest flows are generated at pore diameters of ca. 0.2 μm, and it is suggested that the high rates of flow found in Phragmites are achieved because of an optimum leaf sheath stomatal pore width coupled to very low venting resistance through the plant. The benefits of a sustained humidifying source close to the base of the pores is also highlighted, and attention is drawn to thermally enhanced HIC and the continuance of HIC when temperatures within the plant might be lower than outside.The results have important implications for understanding convective gas flow generation in plants and its potential for enhancing ‘greenhouse gas’ emissions from wetlands.

Loading and utilization of dissolved organic carbon from emergent macrophytes

Article

Mar 1996
AQUAT BOT

The very high productivity of emergent macrophytes can provide major sources of dissolved organic matter to recipient aquatic ecosystems. Leachate was collected from live and senescent tissues of Juncus effusus L. and Typha latifolia L. and analyzed for dissolved organic carbon (DOC; mg C 1−1 cm−2 surface area) and its availability to wetland bacteria. Leachate DOC ranged from 1.9 to 5.2 mg C 1−1 cm−2 across a gradient of fully photosynthetic to fully senescent culms. In culms to senescent, there was no significant difference (P > 0.05) in leachate DOC concentrations between the photosynthetic and senescent portions of culms. DOC in the leachate of J. effusus culms decreased significantly (P < 0.05) from an average of 336.8 mg C 1−1 cm−2 in January 1994 to 68.3 mg C 1−1 cm−2 in July 1994. Bacterial growth efficiencies (ratio of bacterial biomass produced, measured by [3H] leucine incorporation, to leachate DOC utilized) on the leachate of J. effusus ranged from 16 to 34%. DOC concentrations in the leachate from T. latifolia were 1.4 (photosynthetic leaves) and 145.3 (senescent leaves) mg C 1−1 cm−2 and supported bacterial efficiencies of 45% (photosynthetic leaves) and 4% (senescent leaves), respectively.

Photosynthesis and stomatal conductance of Juncus effusus in a temperate wetland ecosystem

Article

Mar 1999
AQUAT BOT

Net photosynthesis and stomatal conductance of the emergent macrophyte Juncus effusus L. was measured in six plots in the Talladega Wetland Ecosystem (Hale County, AL) over diel and annual periods to evaluate the effects of water table fluctuations on photosynthesis and water losses. Half of the plots were in the areas where sediments remained saturated annually (stable water table) and the remaining plots were in the areas where water table heights fluctuated and sediments (upper 20 cm) did not remain continuously saturated. Annual patterns of average net photosynthesis were similar among all sample plots at the wetland (p > 0.05; repeated measures ANOVA), which suggested that no differences in net photosynthesis resulted from the observed differences in sediment saturation. A marked seasonal pattern of net photosynthesis occurred with the greatest average photosynthesis during winter, summer (1997), and spring (11.0, 10.2, and 9.03 μmol CO2 m−2 s−1, respectively) compared to autumn and summer (1996) (6.64 and 5.93 μmol CO2 m−2 s−1, respectively). Average apparent photosynthetic efficiency of J. effusus was 1.43% and varied seasonally with the highest values in winter (1.86%) followed by spring (1.69%), autumn (1.34%), and summer (0.80 and 1.13%; 1996 and 1997, respectively). Although significant differences (p < 0.05) in stomatal conductance occurred among sample plots within the wetland, no correlation was found between stomatal conductance and sample plot location or sediment saturation within the wetland. Seasonally, greater transpiration by J. effusus occurred during the summer (1996) and autumn months (0.43 and 0.28 mol H2O m−2 s−1, respectively) compared to winter, spring, and summer (1997) (0.22, 0.20, and 0.16 mol H2O m−2 s−1, respectively). Seasonal measurements of diel photosynthesis and stomatal conductance showed that daily net photosynthesis was variable among sample plots and among the seasons at the wetland, with maximum photosynthesis from 1000 to 1400 hours. Diel measurements of stomatal conductance showed significantly higher transpirative water loss during evening hours compared to high light periods.

High perennial plant achieved by continuous growth and synchronized population dynamics

Article

Jun 1999
AQUAT BOT

Continuous changes in the population dynamics, above- and belowground biomass, growth rates, and production of the emergent rush Juncus effusus were evaluated over an annual period in a subtemperate riparian wetland. Extant and emerging individual photosynthetic culms (shoots) were labeled individually and their growth dynamics quantified in replicated plots. Lengths of living (chlorophyllous) portions and basal diameters of several thousand individual culms were determined at weekly intervals and converted to biomass by regression of surface areas to mass. Shoots emerged continuously at all times of the year; the number of ramets increased four times from summer to winter (12,000 – >30,000 culms m-2). Individual culms in November–December, however, were generally smaller (41–52%) than in summer. Maximum growth of individual new culms ranged from a maximum of 6.4 mg per day in June (40–50 days to maximum biomass) to 1.1 mg per day in November (70–110 days to reach maximum biomass in winter). Due to continuous recruitment and gradual culm senescence, numerous multiple cohorts occurred on an annual basis. Root production was also evaluated from changes in seasonal biomass and from experimental studies of changes in aboveground biomass in relation to those of rooting tissues. Annual root production was approximately 42% of shoot production. Average annual production estimates of combined above- and belowground components was 9832 g AFDM m−2 per year. The extremely high production rates of this Juncus species result from the continuous growth while simultaneously shoot densities changed as the inverse of biomass seasonally. These processes maximized photosynthetic carbon fixation under mild climatic conditions of the winter and spring seasons. This dynamic growth strategy is likely to be common among herbaceous perennial emergent aquatic plants in mild climatic regions.

Fundamental processes within natural and constructed wetland ecosystems: Short-term versus long-term objectives

Abstract

No full-text available

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