Bioassays

Advanced Methods and Applications

Donat Hader, Gilmar Erzinger

• Publisher: Elsevier
• Year: 2017
• Print ISBN: 9780128118610
• eBook ISBN: 9780128118900
• Topic: Biological Sciences
• Subtopic: Ecology
• Index: Biological Sciences

Bioassays: Advanced Methods and Applications provides a thorough understanding of the applications of bioassays in monitoring toxicity in aquatic ecosystems. It reviews the newest tests and applications in discovering compounds and toxins in the environment, covering all suitable organisms, from bacteria, to microorganisms, to higher plants, including invertebrates and vertebrates. By learning about newer tests, water pollution control testing can be less time and labor consuming, and less expensive. This book will be helpful for anyone working in aquatic environments or those who need an introduction to ecotoxicology or bioassays, from investigators, to technicians and students. - Features chapters written by internationally renowned researchers in the field, all actively involved in the development and application of bioassays - Gives the reader an understanding of the advantages and deficiencies of available tests - Addresses the problem of understanding the impact of toxins in an aquatic environment and how to assess them

1

Introduction

Donat-P. Häder¹ and Gilmar S. Erzinger², ¹Friedrich-Alexander University, Erlangen-Nürnberg, Germany, ²University of Joinville Region – UNIVILLE, Joinville, SC, Brazil

Abstract

Only a small fraction of the water on our planet is available for human usage while the major part is either saltwater or bound as snow and ice. The dwindling resources are in sharp contrast to the increasing demands for drinking water, irrigation of crop plants as well as industrial usage by a rapidly growing human population. Simultaneously, the available freshwater reserves are being polluted by municipal and industrial effluents, inorganic toxicants including heavy metals, persistent organic pollutants as well as personal care products and pharmaceuticals. The growing use of fertilizers and the indiscriminate application of pesticides in agriculture add to the burden of pollutants. As a result, an estimated 780 million people do not have access to clean freshwater, and about 2.2 billion lack safe sanitation. Marine ecosystems are also being polluted by terrestrial runoff, accidental spills, and plastic debris, which affect both coastal regions and open oceans. Terrestrial ecosystems are contaminated by heavy metals from mining and industry as well as organic pollutants which may be taken up by and accumulate in crop plants. Additional pollutants are air-born which may drift over hundreds or thousands of miles. Recently nanoparticles have found increasing attention since they may affect human health and cause mortality. Another stress factor is increasing solar UV radiation due to stratospheric ozone depletion by anthropogenically released fluorochlorocarbons and other gaseous pollutants. The large numbers of natural and synthetic chemicals, which count in the thousands, render systematic chemical analysis of pollutants in ecosystems almost impossible. Only major classes of chemicals are being analyzed and toxic substances are often not identified. Upper limits for concentrations of toxic substances differ between countries and change over time. In addition, reactions with other substances or environmental stress factors may increase the toxicity of chemicals and multifactorial pollution may exert synergistic effects on the biota and pose a threat for human health. An alternative is the employment of bioassays. By definition, these systems do not identify the chemical nature of a pollutant but provide a warning when toxic levels exceed a threshold and pose a hazard for the ecosystem or humans. This volume discusses a multitude of bioassays based on bacteria, cell lines, invertebrates and vertebrates, unicellular or multicellular algae and plants. The endpoints cover biochemical reactions, growth, and photosynthesis as well as motility, orientation, and mortality. Modern bioassays need to be sensitive, accurate, fast, inexpensive, and easy to use. The technology and the application of these bioassays will also be discussed.

Keywords

Air; aquatic ecosystems; bioassays; chemical analysis of toxicity; drinking water; pollution; terrestrial ecosystems

The occurrence of humans on this planet and its—in evolutionary terms—rapid expansion and explosive population growth has shaped the Earth and the environment in most cases in a negative way. The conquest of all continents and the (mis-)usage of the oceans have led to alterations of almost all ecosystems with only a few regions left in their original status [1]. This unprecedented expansion into all fields of the biosphere takes its toll on the quality of the atmosphere, the terrestrial and aquatic ecosystems, and even the vast glaciers and snow-covered areas on the poles and in high alpine regions. It has also resulted in mass destruction of native populations and started a rapidly enhancing extinction of species in all taxa [2]. Typical examples are the extinction of large vertebrates such as the mammoth, the mastodon and the saber-tooth tiger during the last millennia [3] and the loss of the passenger pigeon, of which hundreds of millions of these once most abundant birds on this planet were killed [4]. In addition, we are losing many microbial, plant, and animal species every day often without even knowing them. This loss is increased by the effects of global climate change: Extinction risks for some sample areas covering some 20% of the Earth’s terrestrial surface have been estimated as 15%–37% over the next three to four decades [5].

1.1 Freshwater ecosystems

Most of the Earth’s water is located in the oceans where it is too salty for human consumption. Large quantities are bound in the form of glaciers and snow covering the poles and high mountains. Thus only a small fraction of less than 1% of the global water is available for human usage [6,7]. Simultaneously the need for potable and uncontaminated freshwater for households, industry, and agriculture has multiplied during the past few centuries. Even with a stabilization of the human population further needs for freshwater are predicted [8].

In contrast to the growing need for freshwater, the limited resources are diminished by pollution from domestic, agricultural, and industrial wastes [9]. Industrial wastes include persistent organic pollutants (POPs) such as chlorinated organic chemicals and microplastics [10,11] as well as heavy metals such as Hg, Pb, Cu, Cr, and As which accumulate in lakes, rivers, and coastal waters [12]. POPs have been linked with type 2 diabetes [13]. Contamination by heavy metal pollutants may cause cardiovascular problems, damaged or reduced mental and central nervous functions, lower energy levels, and damage to blood composition, and may affect lungs, kidneys, liver, and other vital organs [14,15]. Especially in developing countries these effluents are often dispatched into rivers, lakes, or the groundwater untreated or only filtrated to remove particulate substances (cf. Chapter 18: Ecotoxicological monitoring of wastewater and Chapter 21: Environmental monitoring using bioassays, this volume).

Arsenic pollution has become a major problem in many countries. In Asia alone at least 140 million people drink arsenic-polluted water [16]. More than 18 million small wells have been dug into the soil in India over the past 30 years in order to avoid surface water which is often contaminated by bacteria or other pollutants. Rapid pumping of water from these wells has changed the courses of previously clean underground streams so that they now flow through arsenic-containing sediments. While developed countries with arsenic-polluted groundwater such as the Southwest US have the means to filter out the toxicant from the water, developing countries lack that option because of the high costs of, e.g., the conventional aluminum-based drinking-water treatment [17]. The upper limit of arsenic in drinking water has been set to 10 µg L⁻¹ by the World Health Organization (WHO) but the Indian government allows 50 µg L⁻¹; however, even this value is often far exceeded in many wells [18]. Pyrite minerals containing high concentrations of arsenic are eroded from the Himalayan Mountains and carried into India, Bangladesh, China, Pakistan, and Nepal. After reaction with oxygen and heavy metals such as iron it forms granules which are concentrated in the sediments from which it leaches out into the water which is tapped by the newly dug wells.

Arsenic taken up with the drinking water or ingested with vegetables which have been irrigated with polluted water causes a number of serious chronic diseases in animals and humans [19]. One of the first symptoms is scarring of the skin [20]. When it accumulates over time in the body it causes brain damage, heart disease, and cancer [21,22]. Heavy metals accumulate in the aquatic food web. They are taken up by phyto- and zooplankton, which in turn are ingested by secondary consumers such as crustaceans, fish, birds, and mammals—which are finally consumed by humans. This bioaccumulation may pose a major threat for human health [23,24]. The degree of bioaccumulation can be determined by calculating a biomagnification (or bioconcentration) factor [25]. E.g., B, Ba, Cd, Co, Cr, Cu, and Ni have been calculated to accumulate in muscle and fat tissue of fish such as carp and tilapia in the Yamuna river, Delhi [26]. Similar concentrations of heavy metals were found in rivers in Pakistan and India [27,28].

Organic pollutants as well as inorganic toxic substances accumulate in sediments and pose considerable long-term risks for human health and the biota [29]. Chlorophenol compounds produced by degradation of pesticides and chlorinated hydrocarbons [30] are among the most toxic pollutants in aquatic ecosystems because of their chemical stability and low degradability [31,32].

Even in developed countries industrial wastes are often not completely removed from the effluents and cause pollution of groundwater, drinking-water reservoirs, and natural ecosystems. In addition, raw oil and refined petrol components pose a major threat for the dwindling freshwater resources [33]. Climate change, water acidification, and exposure to solar UV radiation transform petrol components which have reached the water by oil spills [34]. These derivatives can be even more toxic than the original substances.

The excessive employment of fertilizers in agriculture causes accumulation of nitrogen and phosphorous compounds in surface and groundwater due to runoff from fields and gardens [35]. Nitrate has become a major problem in many countries. The upper limit of 50 mg L⁻¹ in groundwater (European Union, 44 mg L⁻¹ in the US) [36] can often only be reached by dilution with clean water from mountain streams before usage as drinking water. In Germany about 30% of the country distributes drinking water which is close to or exceeds this limit concentration. Nitrate itself is not toxic but can be converted to nitrite via the nitrate-nitrite-nitric oxide pathway [37]. Even at low concentration in the water nitrate accumulates in the blood and muscles of e.g., insects, mollusks, crustaceans, fish, and mammals including humans, causing acute and chronic toxicity [38–40].

Uncontrolled use of pesticides such as chemicals against insects, nematodes, mollusks, and fungi increase the level of toxicants in the water of artificial reservoirs and natural ecosystems. For a long time mosquitoes have been attacked by spraying oil products on the surface of infested water reservoirs [41]. These residues as well as the mosquitocidal essential oils nowadays being used [42] have also been found to be toxic to aquatic organisms [43]. Alternatively, dichlordiphenyltrichlorethan (DDT) has been employed as an organochlorine insecticide mainly against malaria-transmitting mosquitoes as contact or food poison since the 1940s. The production is fairly simple and inexpensive and the chemical was used under many trade names for several decades [44]. More than 1.8 million tonnes have been produced globally. It shows l...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• List of Contributors
• Preface
• 1. Introduction
• 2. Chemical analysis of air and water
• 3. Historical development of bioassays
• 4. Regulations, political and societal aspects, toxicity limits
• 5. Image analysis for bioassays – the basics
• 6. Growing algal biomass using wastes
• 7. Toxicity testing using the marine macroalga Ulva pertusa: Method development and application
• 8. Pigments
• 9. Photosynthesis assessed by chlorophyll fluorescence
• 10. Ecotox
• 11. Daphniatox
• 12. Bioluminescence systems in environmental biosensors
• 13. Image processing for bioassays
• 14. Express detection of water pollutants by photoelectric recording from algal cell suspensions
• 15. Fish
• 16. Bioassays for solar UV radiation
• 17. A comparison of commonly used and commercially available bioassays for aquatic ecosystems
• 18. Ecotoxicological monitoring of wastewater
• 19. Marine toxicology: Assays and perspectives for developing countries
• 20. Applications for the real environment
• 21. Environmental monitoring using bioassays
• Index