VU Research Portal Subsurface landfill leachate - home to complex and dynamic eukaryotic communities Brad, T. 2007 document version Publisher's PDF, also known as Version of record Link to publication in VU Research Portal citation for published version (APA) Brad, T. (2007). Subsurface landfill leachate - home to complex and dynamic eukaryotic communities. Gildeprint Drukkerijen BV. 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Oct. 2021 Subsurface landfill leachate - home to complex and dynamic eukaryotic communities Traian Brad © 2007 Traian Brad, Amsterdam, The Netherlands No part of this publication may be reproduced or transmitted in any form or by any means without permission in writing from the copyright owner ISBN: 978-90-8659-169-5 Cover: aquifer sediments from Banisveld and groundwater fauna that we firstly looked for and we never found Cover design: Traian Brad (photo) Mirela Bagyo (design) Layout: Traian Brad Printing: Gildeprint Drukkerijen BV, Enschede The Netherlands VRIJE UNIVERSITEIT Subsurface landfill leachate - home to complex and dynamic eukaryotic communities ACADEMISCH PROEFSCHRIFT ter verkrijging van de graad Doctor aan de Vrije Universiteit Amsterdam, op gezag van de rector magnificus prof.dr. L.M. Bouter, in het openbaar te verdedigen ten overstaan van de promotiecommissie van de faculteit der Aard- en Levenswetenschappen op woensdag 12 december 2007 om 13.45 uur in de aula van de universiteit, De Boelelaan 1105 door Traian Brad geboren te Alba Iulia, Roemenië promotor: prof.dr. N.M. van Straalen copromotor: dr. W.F.M. Röling “… to know or not to know , that is the question! Not to know means: superstitions, blind egoism, untamed competition, disagreement, enmity, war, starvation, disaster. To know means for humanity: solid organization, rational activity, cooperation, solidarity, peaceful evolution. To know means for human being living the time to be with satisfaction, and waiting for the moment not to be with serenity” Emil G. Racoviţă, 1927 dedicated to my parents Contents CHAPTER 1: General introduction 11 CHAPTER 2: Spatial heterogeneity in sediment-associated bacterial and eukaryotic communities in a landfill leachate- contaminated aquifer 27 CHAPTER 3: Eukaryotic diversity in an anaerobic aquifer polluted with landfill leachate 51 CHAPTER 4: Spatiotemporal dynamics in microbial community structure and hydrochemistry in a landfill leachate- contaminated aquifer 77 CHAPTER 5: Nutrient recycling by protozoan predation can enhance overall bacterial degradation of organic matter 97 CHAPTER 6: Thesis synthesis and general discussion 119 Bibliography 129 Summary 149 Samenvatting 155 Rezumat 161 Lifestory. Instead of curriculum vitae 167 Publications list 169 Acknowledgements 173 CHAPTER 1: General introduction Chapter 1 General introduction Background on importance of groundwater After glaciers, which enclose approximately 24 million km 3 of frozen freshwater, the subsurface comprises 97% of all freshwater in the world (Gibert et al., 1994), which makes it the largest and the most important reservoir of available freshwater on Earth (Shiklomanov, 1993). The remaining 3% of freshwater exists as surface waters (i.e. lakes, rivers and wetlands). As a comparison, the volume of water in the subsurface (10 million km 3) is approximately 100 times larger than that in freshwater lakes (91.000 km 3), and 5.000 times larger than the water in rivers (2.000 km 3) (Shiklomanov, 1993). Groundwater ecosystems reside in all water reserves stockpiled in the subsurface. Groundwater may be captured in large karstic aquifers, it accompanies and flows under rivers forming a hyporheic environment (i.e. the water saturated sediments along and underneath rivers) (Orghidan, 1959), or flows in phreatic regime through permanently saturated voids in any type of rock (Fig. 1). Groundwater is an important component of the natural water cycle; its hydrogeochemistry depends largely on, and is directly influenced by the quality and recharge of the percolating surface waters. Pristine groundwater is generally oligotrophic (Gounot, 1994), and its chemistry is influenced by the type of rock and minerals it passes and dissolves (Drever, 1997). The environmental characteristics of groundwater, such as temperature, pH or dissolved oxygen, remain relatively constant during all seasons. While groundwater was long imagined as an inexhaustible resource, today the availability of groundwater is compromised in many parts of the world, as human society depends largely on this resource as drinking water supply (Vörösmarty et al., 2000). For example, about 75% of the inhabitants of the European Union depend on groundwater for their water supply (Gibert, 2001). Although the importance and the 11 CHAPTER 1: General introduction great necessity of groundwater for human society and ecosystem health are now largely recognized, aquifers are heavily subjected to pollution wherever human activity exists. The depletion of clean groundwater reserves is due to various causes (Fig. 1) such as the world general population increase, causing an increase in water demand, agricultural practices and landscape alteration, increase in urban area and demand for public drinking water, industrial activities including electricity production and mining, tourism and climate change (Danielopol et al., 2003). The understanding manifested in this respect by society appears insufficient since, all over the world, groundwater is still a main sink for hazardous contaminants such as fertilizers, pesticides, herbicides, oil products, chlorinated solvents, and heavy metals. FIG. 1. Schematic view upon various types of groundwater ecosystems with possible sources of groundwater pollution. Groundwater biota are presented for each subsurface aquatic environment. 12 CHAPTER 1: General introduction This thesis regards the threatening effects of a particular source of groundwater contamination, which is represented by landfills. Percolating rainwater carries the contaminants present in municipal or industrial waste disposals into nearby aquifers with consequences for the quality of groundwater. While in solution, the pollutants in groundwater may become even more hazardous as they can be carried away, polluting also other places (e.g. phreatic aquifers, cave ecosystems), and can be taken up easier by subsurface organisms. Landfills consist primarily of organic materials, but hazardous contaminants such as monoaromatic hydrocarbons of the BTEX complex (benzene, toluene, ethylbenzene and xylene), chlorinated compounds or heavy metals, can also be present (Christensen et al., 2001; Kjeldsen et al., 2002). Most of the landfills, especially those constructed in the past (up to 4.000 old landfills in The Netherlands alone) (Röling et al., 2000b), were not sealed with liners preventing the leaching of pollutants. Although landfilling operations are discontinued in many countries, discharge of contaminants into the environment continues, and usually large changes occur in the hydrogeochemistry and microbiology of the adjacent aquifers (Christensen et al., 1994; Kjeldsen et al., 2002). Pollution plumes generally form and migrate large distances, sometimes towards residential areas and other places of public interest, polluting drinking water supplies and the adjacent surface aquatic ecosystems such as rivers, lakes, or wetlands (Cozzarelli et al., 2000; Grossman et al., 2002; Ludvigsen et al., 1998; Ludvigsen et al., 1999). Natural attenuation in groundwater ecosystems The awareness arisen in the 1980s and manifested in recent years of the reduced quality of groundwater led lately to the development of remedial measures. The first strategies were based on physical removal of pollution by soil excavation (National Research Council, 2004) in combination with treatment and controlled storage, pumping and cleaning the contaminated groundwater, or techniques to physically retain the pollution by, for example, filtration or particle settling. These techniques are sometimes hard or even impossible to apply due to the high costs, or they have limited effect (Swett and Rapaport, 1998). Research performed in the last decade suggests that the subsurface has 13 CHAPTER 1: General introduction an intrinsic potential to attenuate the contaminants. Usually, pollutant concentrations decrease with the distance from the source due to physicochemical processes such as dilution, sorption, precipitation or dispersion (Christensen et al., 1994). Natural attenuation, which is believed to be the least expensive means of bioremediation (Röling and Van Verseveld, 2002), relies especially upon the activity of naturally occurring microorganisms (Christensen et al., 2001, Lovley, 2001). Unlike other processes involved