1. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Environmental Analytical Chemistry Chapter 6 Ecotoxicology 精品课程

2. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Contents 6.1 Introduction 6.2 Toxicant behaviour in living organisms 6.3 Dose-response relationships of toxicants Contents

3. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Key points and difficulties Key points Toxicant behaviour in living organism Difficulties Dose-response relationships of toxicants

4. Chapter 6 Ecotoxicology Environmental Analytical Chemistry ‘All substances are poison; there is none that is not a poison. The right dose differentiates a poison and a remedy’ --Paracelsus (1493-1541) 帕拉塞尔苏斯 ( 瑞士医学家 )

5. Chapter 6 Ecotoxicology Environmental Analytical Chemistry 6.1 Introduction The term ecotoxicology [ekət ɒ ks ɪ ‘k ɒ ləd ʒɪ ] 生态毒理学 is used to define the branch of toxicology concerned with the study of the toxic effects 毒性作用 ; 毒效 of natural and man-made (anthropogenic) substances on the biotic (living) and abiotic (non- living) components of the biosphere. It is often used synonymously with 与 … 同义使用 the related term environmental toxicology, although the latter strictly encompasses 围绕 the effects of chemicals and other agents on humans. Its ultimate objective is to protect natural communities 群落 of organisms from 保护 …. 免受 the adverse effects 不利影响 of potential toxicants. 6.1 Introduction

6. Chapter 6 Ecotoxicology Environmental Analytical Chemistry A toxicant is an agent that has a harmful effect on a biological system at all levels, from the subcellular, through whole organisms to communities and entire ecosystems. The term is not exactly synonymous with pollutant as the latter may also include toxic agents, such as extremes 极端值 of temperature and pH, deoxygenation 脱氧作用（反应）, noise. While many powerful toxicants, such as heavy metals, sulphur dioxide and aflatoxins [əfleɪ'tɒksɪnz] 黄曲霉毒素, are naturally produced, they usually only occur in relatively small quantities in a very localised 局部的 area in such circumstances. 6.1 Introduction

7. Chapter 6 Ecotoxicology Environmental Analytical Chemistry However, where human activities lead to their release into the environment in large quantities over short periods of time they can exert very damaging environmental effects 施加影响. Also of great significance to the welfare 繁荣 of most natural environments today are the toxic effects of anthropogenic substances. Not only are many of these xenobiotic [,zenəubai‘ɔtik] 异生物质 in the strictest sense, in that they are not produced at all by natural processes, but they too are often found at high levels in many environments. Indeed, there are few 极少，几乎没有 if any, natural environments where detectable traces 检测痕迹 of some anthropogenic substance(s) cannot be found. 6.1 Introduction

8. Chapter 6 Ecotoxicology Environmental Analytical Chemistry 6.2 Toxicant behavior in living organisms The most important factors influencing the toxicity of a substance are its physicochemical properties as these determine its biological activity at the cellular level, which in turn dictates its impact at higher structural levels in a biological system. The use of models derived from the so-called quantitative structure-activity relationships (QSARs) 定量结构活性关系 of potential toxicants is an increasingly important aspect of ecotoxicological work. Here, the physical and structural components of the compound (molecule descriptors) are used as interpreters 解释器, perhaps more importantly, as predictors 预报器 of their likely toxic impact. Some of the more important biochemical and other effects of toxicants on organisms are summarised in Tables 6.1 and 6.2. 6.2 Toxicant behavior in living organisms

9. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Table 6.1 Summary of some important biochemical effects of toxicants Site of actionToxic effect Protein synthesis Depression of protein synthesis in rough ER. Occasionally stimulation of microsomal 微粒体 protein synthesis Lipid metabolism Disturbance of liver function, including cholesterol [ kə’lestərɒl] 胆固醇 synthesis, excess lipid accumulation Carbohydrate metabolism General impairment 损伤 of oxidation and glycolytic [, gla ɪ kə‘l ɪ t ɪ k] 糖 分解 processes Microsomal enzymesInhibition/stimulation of microsomal enzymes Cell membrane Interference with membrane permeability, and disturbance of membrane carrier systems Regulatory and growth processes Adverse effects on structure and activity of regulatory enzymes and function of hormones, decrease in growth rates Respiration Disrupted function 中断功能 of respiratory chain electron transport; uncoupling 解偶 and inhibition of oxidative phosphorylation 磷酸化 Photosynthesis Inhibition of electron transport, uncoupling of electron transport and photophosphorylation 光磷酸化, inhibition of energy transfer 6.2 Toxicant behavior in living organisms

10. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Table 6.2 General effects of toxicants EffectSpecific effects Death Cessation of vital activities 生命活动的终止 Physiological Changes to metabolic functions, including respiration and photosynthesis, nutrition, osmoregulation 渗透调节, circulation, body temperature Behavioural Alterations to sensory 感觉 and learning capacities, motor activities 肌 肉活动， mating behavior, predator-prey relationships, migration Growth Biomass 生物量（质）, body and organ growth, developmental stages Reproduction Changes to viability of gametes, fertility, survival rates of offspring 配子活力、生育、后代存活率 Genetic Chromosomal damage, mutagenic, teratogenic and carcinogenic effects 染色体损伤、致突变、致畸和致癌效应 Histopathological 组织病理学的 Tissue damage, abnormal growths 组织损伤，畸形生长 6.2 Toxicant behavior in living organisms

11. Chapter 6 Ecotoxicology Environmental Analytical Chemistry The effects of toxicants may be elicited immediately on 因为 exposure or may be delayed until some time after exposure has occurred depending on the properties of the toxicant, its mode of action and its susceptibility to metabolic breakdown 代谢分解的敏感性 (biotransformation) by the organism itself. Toxicants that are biotransformed tend to be rapidly excreted [ik’skrit] 排泄 and therefore not likely to have delayed effects. Ecotoxicological effects can be broadly classified in a number of different ways, for example, direct as opposed to indirect toxicity. Direct toxicity arises as a result of internal biochemical changes within organisms brought about by the toxicant. In contrast, indirect toxicity occurs as a result of toxicant effects on factors external to the organism, such as decreases in food organisms, habitat destruction, etc. 6.2 Toxicant behavior in living organisms

12. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Toxic effects can also be categorised as reversible or irreversible. In the case of the former, reversibility may be brought about by the normal repair mechanisms 正常修复机制 of living organisms, perhaps necessarily accompanied 必然伴随着 by escape to a toxicant-free environment to allow this to happen. No such recovery is possible where damage is said to be irreversible and serious damage or death is the inevitable [in’evitəbl] 必然发生的 result. A further distinction can be made on the basis of the site 部位 of action of a toxicant. Where an effect occurs at the primary site of contact 原始接触部位 between an organism and a toxicant, it is termed 被称为 a local effect. 6.2 Toxicant behavior in living organisms

13. Chapter 6 Ecotoxicology Environmental Analytical Chemistry For example, inflammation 炎症 of the surface of the lungs in mammals, or erosion of the gills in fish 鱼鳃 when exposed to corrosive substances in the respiratory medium. Conversely, where a toxicant requires absorption and distribution to a target site 目标部位 distant from the point of entry into the body 远离 进入身体的点位, it is regarded as 被认为是 systemic in effect. 6.2 Toxicant behavior in living organisms

14. Chapter 6 Ecotoxicology Environmental Analytical Chemistry A number of toxicants, such as many industrial solvents, are non- selective in their toxic effects as they appear to be able to act on a range of target sites within organisms. Others are much more selective in that they impair only one type of cell, tissue or function without affecting others, either in the same or a different species. Clearly, this latter mechanism must be due to the interaction of the toxicant with specific receptor (target) sites in cells. Thus, for example, organophosphate insecticides exert their toxic effect only on nervous tissue by irreversibly binding to the enzyme acetylcholine esterase 乙酰胆碱酯酶. 6.2 Toxicant behavior in living organisms

15. Chapter 6 Ecotoxicology Environmental Analytical Chemistry 6.3 Dose-response relationships of toxicants Although many classes of compound can exhibit environmental toxicity, simple exposure to them will not necessarily always elicit a harmful biological effect. Of paramount 至高的 importance is the amount or does of the compound that actually enters an organism to influence the biological processes taking place within it. Also, the relationship between dose and biological response can be very variable and sometimes exposure to low doses of a potential toxicant may have unexpected positive biological effects. For example, the biological productivity of oligotrophic [ɒləgəʊ‘trɒfɪk] 贫营养的 (nutrient-poor) waters will increase when they are subjected to modest doses of sewage effluents 污水. 6.3 Dose-response relationships of toxicants

16. Chapter 6 Ecotoxicology Environmental Analytical Chemistry In other circumstances no effects are observed until a particular threshold dose 阈剂量 of a toxicant is exceeded. The graph describing the response of a biological system to a toxicant over a range of concentrations is known as 被称为（认为） the dose-response curve, as shown in Figure 6.1. In general terms this relationship holds true for 适用于 virtually 几乎 all toxicants, a notable exception being true allergic [ə’lɜ:dʒɪk] 过敏的 reactions which are particular kinds of changes in the immune system 免疫系 统 of organisms. Allergic reactions arise as a result of a substance stimulating the body to release natural chemicals within the body which are responsible for the response observed, rather than it (response) being a direct effect of the substance itself. 6.3 Dose-response relationships of toxicants

17. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Increasing dose/concentration Increasing effect Range of increasing effect with increasing dose No-effect range Maximum effect range LD 50 /LC 50 threshold Figure 6.1 Dose/concentration-response curve of a toxicant 6.3 Dose-response relationships of toxicants

18. Chapter 6 Ecotoxicology Environmental Analytical Chemistry For practical purposes the following assumptions are made regarding the dose-response relationship. The response is graded 分级的 and a function 函数 of the concentration of the toxicant at the site of action; The concentration of toxicant at the site of action is related to the exposure dose; The response tested is causally related to 与 … 存因果关系 the toxicant; That below a certain dose no response occurs or at least can be detected; That once a maximum response is achieved any additional increases in dose will have no effect. 6.3 Dose-response relationships of toxicants

19. Chapter 6 Ecotoxicology Environmental Analytical Chemistry While in the broadest sense these assumptions hold true 成立, there are various factors that may influence the dose-response relationship as described above. It is important to realize that the concentration of a toxicant at the site of action may not necessarily be related to the dose or environmental concentration to which an organism is exposed. A great varied of factors may influence the rate at which the toxicant enters an organism, including its chemical speciation or particular characteristics of the organism such as surface permeability, physiological state 生理状态, sex, shape, etc. 6.3 Dose-response relationships of toxicants

20. Chapter 6 Ecotoxicology Environmental Analytical Chemistry For example, heavy metals are usually more toxic to organisms in acid environments as they tend to form more biologically available chemical species under conditions of low pH and will therefore be more readily taken into the body. In ecotoxicological studies it is therefore common to place more emphasis on the concentration- response rather than the dose-response relationship, although with the clear recognition that it introduces more uncertainty into these studies. For this reason the term concentration will be largely used hereafter 从此 in preference to 优先于 dose. 6.3 Dose-response relationships of toxicants

21. Chapter 6 Ecotoxicology Environmental Analytical Chemistry In addition, reversible or irreversible reactions may lead to different types of responses with regard to 对 … the concentration of a toxicant at the site of action. Thus a toxicant that elicits a reversible reaction may give no measurable, or at best 顶多 a transient [‘trænz ɪ ənt] response 瞬时响应, at a low-concentration exposure and this will not be affected by repeated or continuous low- concentration exposure. In contrast, where irreversible reactions are involved, a single exposure may be sufficient to elicit a damaging response and repeated or continuous exposure may lead to a cumulative['kju:mjələt ɪ v] 累积的 toxic effect, depending on the turnover rates 周转率 of toxicant-receptor complex 毒物 - 受体络合 物. 6.3 Dose-response relationships of toxicants

22. Chapter 6 Ecotoxicology Environmental Analytical Chemistry While 然而 the causal relationship 因果关系 between toxicant and response is usually straightforward and clearly established, in some cases they may be only indirectly related and therefore do not provide an appropriate basis for a concentration-response study. For example, the inhibition of certain 某些 enzymes may provide the basis for a toxicological study 毒理学研究 but these must be related to the overall toxic effect being measured. The validity of the causal link between concentration and response is particularly vital where epidemiological [,ep ɪ,di:m ɪ ə‘l ɒ d ʒɪ kl] 流行病学 studies are involved and considerable rigor 苛刻、严谨 must be applied to the data to avoid false conclusions 错误结论 being made regarding the cause- effect relationship 因果关系. 6.3 Dose-response relationships of toxicants

23. Chapter 6 Ecotoxicology Environmental Analytical Chemistry There is controversy [‘k ɑ ntrə,və:si] 争议 over 对是否 the existence of a so-called ‘no effect or threshold’ concentration for any toxicant. Indeed, detection of any response is dependent on the sensitivity of the methods used to measure it. The more sensitive the methods used the easier it is to detect some kind of response, however minimal it might be 无论它可能有多么低. In the case of carcinogenic toxicants, exposure to only a few molecules may be sufficient to trigger 引发 the development of a tumour [‘tju:mə(r)] 肿瘤 in the longer term and therefore no true ‘threshold’ exposure level can be determined for such substances. 6.3 Dose-response relationships of toxicants

24. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Despite these and other reservations 保留意见, the concentration- response curve is nevertheless a useful way of quantifying ecotoxicological effects and parameters derived from it are valuable for comparative purposes and the establishment of safe, or at least acceptable, environmental limits 环境限制. In practical terms 实际上 it is the linear portion of the sigmoid curve S 型曲线 shown in Figure 6.1 that is most usefully employed to quantify effects and establish useful parameters. To this end 为此 the conversion of the whole curve into a linear form (Figure 6.2) using probit analysis 概率分析法 is a standard practice. Probit analysis depends on dividing the sigmoid concentration-response curve into multiples 倍数 of the standard deviation from the median concentration, 6.3 Dose-response relationships of toxicants

25. Chapter 6 Ecotoxicology Environmental Analytical Chemistry i.e. when 50% of test organism(s) elicit the response in question 讨论 中的. When the logarithm [‘l ɒ gər ɪ ðəm] 对数 of the concentration is used the curve becomes linear and 68% and 95.4% of the test population is included within one and two standard deviations either side of the median respectively. The median concentration has a special significance in ecotoxicological studies as it is associated with the inherent variability of biological organisms that dictates that not all test organisms, even those very closely related genetically, will respond in an identical manner to the effects of any toxicant. 6.3 Dose-response relationships of toxicants

26. Chapter 6 Ecotoxicology Environmental Analytical Chemistry The resistance to the toxicant will vary among the members of a test population 在某个测试群体的成员之间 with the most sensitive individuals succumbing [sə'k ʌ m] 屈服 ; 死亡 first, the most resistant last and others at various points between. The median concentration is a mathematical measure 数学指标 and therefore its accuracy is improved with 采用 repetition of the experiments from which it is derived. The slope of the concentration-response curve can be an important measure 指标 of the type of toxic response being studied. As shown in Figure 6.3(see p458), the steep slope of curve A indicates a narrow toxic concentration range and a site of action at 处于 a basic, fundamental level in the metabolism of the test organism. Conversely, the shallower 6.3 Dose-response relationships of toxicants

27. Chapter 6 Ecotoxicology Environmental Analytical Chemistry slope of curve B is indicative of a less specific toxic reaction associated with more inherent variables 更多的内生变量. A number of measures 量，指标 of the toxicity of a substance can be derived from the concentration-response curve, one of the simplest of which is its lethality [l ɪ ‘θæl ɪ t ɪ ] 致命性 that, despite its acknowledged crudity as a measure, is still widely used. It is also an example of an ‘all or nothing’ as opposed to 而不是 a ‘graded’ response. The principal measure of lethal toxicity used is the so- called LC 50, which represents the concentration at which 50% of the test population is killed. 6.3 Dose-response relationships of toxicants

28. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Its usefulness resides [r ɪ ‘za ɪ d] in the ease with which it can be used to compare the lethality of different toxicants 难易程度, provided 假 设 the same species of test organism(s) was employed under the same conditions of exposure. The related term LD 50 is more commonly used in mammalian [mæ'me ɪ l ɪ ən] 哺乳动物, including human, toxicological studies (see Table 6.3). Two toxicants may have a reversed toxicity relationship as 随着 their LC values vary. Thus, toxicant A in Figure 6.3 has a lower LC 50 (higher toxicity) but higher LC 20 (lower toxicity) than toxicant B. Therefore, predictions made on the basis of the ecotoxicity 生态 毒性 of these substances based on the standard LC 50 may be erroneous [I’rə ʊ niəs] 错误的. 6.3 Dose-response relationships of toxicants

29. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Further, a toxicant with 具有 a large LC 50 can be regarded as practically nontoxic, but this does not mean that it will not produce harmful effects, even at small concentrations. In this context 在这种 背景下, another measure, the TC 50 is used. This represents the concentration that will produce signs of toxicity 中毒症状, as opposed to death, in 50% of the test organisms. These and other common measures used in toxicity studies are defined in Table 6.3. 6.3 Dose-response relationships of toxicants

30. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Table 6.3 Some commonly used terms in toxicology TermDefinition LC 50 Lethal concentration of a substance that causes the death of 50% of test organisms LD 50 Lethal dose of a substance that causes the death of 50% of test organisms EC 50 Effective concentration of a substance that produces a change in sublethal 亚致死 behavior or physiological response in 50% of test organisms ED 50 Effective dose of a substance that produces a change in sublethal behavior or physiological response in 50% of test organisms IC 50 Inhibitory concentration 抑制浓度 that reduces response of an organism by 50% TC 50 Concentration at which a substance produces a toxic response in 50% of test organisms TD 50 Dose at which a substance produces a toxic response in 50% of test organisms SCMaximum concentration of a potential toxicant that is harmless to organisms after long-term exposure of at least one generation MATCMinimum allowable toxicant concentration 6.3 Dose-response relationships of toxicants

31. Chapter 6 Ecotoxicology Environmental Analytical Chemistry All these measures have drawbacks since toxicity assessment is a complex process with many factors such as temperature, light, food, stress 压力, age, sex, health and others influencing the results of any tests undertaken. A true assessment of the ecotoxicity of a particular substance involves a comparison of many concentration-response curves covering a range of toxic effects. For example, a toxicant may be extremely toxic if swallowed 吞咽 (oral exposure 口腔接触 / 暴露 ) but have low toxicity if inhaled (respiratory exposure) or applied to the skin (topical exposure). 吸入（呼吸暴露）或应用到皮肤（局 部暴露） 6.3 Dose-response relationships of toxicants

32. Chapter 6 Ecotoxicology Environmental Analytical Chemistry As well as 除了 the concentration-response relationship of toxicants, their so-called time-effect 时间 - 效应 relationships are also important to understanding their effects. Figure 6.4 shows the relationship between LC 50 and time for a typical aquatic toxicant. The principal feature of this curve is the point at which the concentration becomes asymptotic [æs ɪ mp‘t ɒ t ɪ k] to 渐渐接近 the time axis and thereby defines the ‘threshold’ or ‘incipient’ [ ɪ n’s ɪ piənt] 初始的 LC 50. This is important as concentrations below this level will not cause lethality in the short term and may be used in establishing risk criteria for organisms exposed to potential chronic pollution (see below). 建立暴露于潜在的慢性污染的生物风险标准 6.3 Dose-response relationships of toxicants

33. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Assignment and preview

34. Chapter 6 Ecotoxicology Environmental Analytical Chemistry References 1.Fifield F.W. and Haines P.J. Environmental Analytical Chemistry (Second Edition). Blackwell Science Ltd, 2000. 2. 但德忠主编. 环境分析化学. 高等教育出版社, 2009. 3. Radojevic Miroslav. Practical Environmental Analysis. The Royal Society of Chemistry, MPG Books Ltd, Bodmin, Cornwall, UK, 1999 4. 胡国成, 许木启, 等. 硫丹对水生生物毒理效应研究进展. 中国 水产科学,2007,14(6): 1042-1047 References

35. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Contents 6.4 Toxicants and the environment 6.5 Toxicity testing 6.6 Ecological risk assessment Contents

36. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Teaching requirements Mastery of the basic methods of ecological toxicology analysis; Comprehension of the basic methods of ecological risk assessment. Teaching requirements

37. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Key points and difficulties Key points Some bioassays methods of ecotoxicology Difficulties Ecological risk assessment of toxicant in living organism

38. Chapter 6 Ecotoxicology Environmental Analytical Chemistry 6.4 Toxicants and the environment When a toxicant enters the natural environment it will be subject to a variety of interactions with both naturally occurring constituents and any other toxicants present and therefore its effects on the living organisms it encounters may be modified. Mechanisms of such interactions, as suggested by Anderson and D’Apollonia (1978), include: Environment phase 环境相. Chemical interactions to produce new compounds, complexes or changes to the physicochemical properties of toxicants. 6.4 Toxicants and the environment

39. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Dynamic phase 动态相位. Many toxicants acting at the same target site(s) 靶位点 or at different sites but contributing to the same adverse effect. Multiple toxicants mutually [‘mjut ʃ uəli] 相 互，彼此 producing a toxic response that differs from that produced by each individually or where one changes the response of an organism to others. Kinetic phase 动力学相. Multiple toxicants alter the availability of toxicants to the target site(s) or induce excess metabolites [m ɪ ‘tæbəla ɪ t] 代谢物 compared to individual toxicants. 6.4 Toxicants and the environment

40. Chapter 6 Ecotoxicology Environmental Analytical Chemistry In general terms, the reaction of two substances is said to be 被称为 是 synergistic [‘s ɪ n ɚ d ʒɪ st ɪ k] 协同的 when, in combination, their toxic effects are greater than those manifested when they are administered separately. If one of them is previously nontoxic but is rendered toxic by the interaction, this is more correctly termed potentiation [pəten ʃ i’ei ʃ ən] 增强作用. Thus, exposure of plants to ozone and sulphur dioxide simultaneously is more damaging than exposure to either gas alone. Conversely and more rarely, there are occasions when the simultaneous exposure of an organism to two toxicants results in less damaging effects than when they are administered separately. This is called antagonism 拮抗作用 6.4 Toxicants and the environment

41. Chapter 6 Ecotoxicology Environmental Analytical Chemistry and is known to occur, for example, between certain heavy metals, such as copper and zinc, where they compete for the same sites of uptake in several species of mammals. Toxicants entering the environment can have a variety of adverse ecological effects that may involve short- or long-term changes to the normal functioning 正常的功能 of ecosystems and result in social, economic or aesthetic [ ɛ s‘θ ɛ t ɪ k] 美学上的 losses. Short-term or acute 急性的 toxic effects of a substance are generally more readily measured than its long-term or chronic 慢性的 impacts. They may also be of lesser significance in terms of 就 … 而言 the ultimate survival 最终的生存 of an ecosystem. 6.4 Toxicants and the environment

42. Chapter 6 Ecotoxicology Environmental Analytical Chemistry A good example of acute toxicity is the sudden and massive 巨大 impact of a large crude oil spill 原油泄漏, such as those resulting from the Torrey Canyon and Amoco Cadiz oil tanker disasters 油轮 灾难. These brought about 造成 the virtual 事实上的 wholesale destruction of shoreline and benthic biological communities 底栖生 物群落 in the affected areas as a result of the adverse effects of the physicochemical properties of the crude oil. However, once the oil had been naturally or artificially removed from the environment, rapid recovery of these communities took place to such an extent that their effects became barely noticeable 几乎不易看到 within 5- 10 years. 6.4 Toxicants and the environment

43. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Chronic toxicity, which involves the sustained input 持续输入 of low levels of toxicants into an environment, may have greater and certainly more insidious [ ɪ n‘s ɪ d ɪ əs] 隐伏的 effects than acute events. Typical examples of these are low level but continuous seepages 渗 漏 of toxic substances into the environment from industrial plants, such as oil refineries 炼油厂 or metal smelters 金属冶炼厂. Here, the ecosystem is adversely affected by 由于 the low-level contamination itself and by the lack of opportunity to recover because of the constant input of contaminants over a prolonged period 长时间. 6.4 Toxicants and the environment

44. Chapter 6 Ecotoxicology Environmental Analytical Chemistry 6.5 Toxicity testing A great variety of toxicity tests have been developed to examine the effects of toxicants in a broad range of ecosystems using a wide variety of species 物种. The majority, termed bioassays 生物检测, have strictly defined formats 格式 relating to such factors as methodology, apparatus, details of test organisms, test materials, safety precautions, references, data analysis methodologies and reliability criteria. These have been developed to allow for the uniformity 一致性 and comparability 可比性 of experimental procedures that can be readily replicated 复制 by different laboratories, whose results can then be combined if necessary. They also provide a useful baseline 基线 from which other studies can be launched 得以展开 and to set criteria 制定标准 regarding 关于 6.5 Toxicity testing

45. Chapter 6 Ecotoxicology Environmental Analytical Chemistry the suitability 适宜性 of the test data for decision-making by regulatory and other authorities 监管和其他当局决策. However, it should be noted that while 虽然 standardized and other tests have certain advantages they are usually only designed to provide answers to very specific, narrow questions of ecotoxicological concern. The tests may be 可以是 of both short- and long-term duration and involve single or multiple species. Tests of limited duration are termed 称为 acute tests and cover only a small period of the test organism’s life span 寿命. Since many acute tests typically range from 24h to a maximum of only a few days, the longer lived the test species the smaller the proportion of their life span the test occupies. 6.5 Toxicity testing

46. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Where unicellular 单细胞 test organisms with generation times 其 传代时间 that are measured in hours are used, the term acute may not be applicable 合适的 in any circumstances. Mortality 死亡率 is the most common parameter measured during acute tests but others include immobilization 固定（化） and other behavioural and reproductive effects (see Table 6.4). 6.5 Toxicity testing

47. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Table 6.4 Summary of principal methods used for bioassays Type of organismMethod of assay Bacteria, fungi [‘f ʌ nd ʒ a ɪ ] 真菌, Protozoa [prə ʊ tə'zə ʊ ə] 原生动物 Mutagenicity [,mju:təd ʒ ə‘n ɪ sət ɪ ] 致突变性 BOD Nitrification [,na ɪ trəf ɪ ‘ke ɪʃ ən] 硝化作用 studies Decomposition studies Algae[‘æld ʒ i] 藻类 and other plants Biostimulation 生物刺激 and growth rates Reproductive rates 繁殖率 Photosynthetic rate 光合速率 Respiratory rate 呼吸速率 Chlorophyll [‘kl ɔ rəf ɪ l] 叶绿素 content Mutagenicity [,mju:təd ʒ ə‘n ɪ sət ɪ ] 致突变性 Morphological and histological effects 形态学和组织学影响（效应） Invertebrates [ ɪ n’və:təbr ɪ t] 无脊椎动物 and vertebrates 脊椎动物 Lethal effects 致死效应 Reproductive rates Development abnormalities 发育异常 Growth rates; Feeding rates 摄食率 Respiratory rates; Biochemical changes Morphological and histological effects Behavioural changes 行为改变 6.5 Toxicity testing

48. Chapter 6 Ecotoxicology Environmental Analytical Chemistry In contrast, chronic tests are designed to last 维持 for a significant proportion of a test organism’s life span but are not usually designed to be multigenerational 多代同堂的. The parameters tested are very variable, but commonly involve the measurement of respiratory, feeding 摄食的, growth and reproductive rates and of biochemical, carcinogenic or teratogenic [,terətəu‘d ʒ enik] effects 致癌致畸作用. Full field studies on the effects of a toxicant are the most difficult and expensive part of ecotoxicological monitoring and are greatly influenced by the vast heterogeneity [,hetərə‘d ʒ ə’ni:ət ɪ ] 异质性，不 均匀性 of natural environments, even in a localized area 局部. 6.5 Toxicity testing

49. Chapter 6 Ecotoxicology Environmental Analytical Chemistry 6.6 Ecological risk assessment This often renders it difficult to translate laboratory-derived data to 把 … 转化为 the situation in the field 现场 and often even from one field situation to another. Continuing research in this area is therefore of vital importance 至关重要的 to the future of ecotoxicological monitoring. Toxicants are only one of a number of stressors 压力源 that may adversely affect an ecological system. Others include fires, ionizing radiation, genetically engineered 基因工程的 or introduced organisms. The process by which the probability that one or more stressors will cause such adverse effects is called ecological risk assessment and may very well be the objective of an ecotoxicological study but not necessarily 未必 the only one.

50. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Risk assessment is a management tool for making decisions 作出 决策 and, unlike those based on scientific results, its endpoint(s) 终点 has greater uncertainty as it may be significantly influenced by societal perceptions and values. 社会观念和价值 Therefore, a chemical 在种化学品 may be shown by a scientific hazard assessment to be highly toxic to wildlife 野生生物 but its use may be permitted if it is considered of economic importance or that the risk of it entering the environment in large quantities is minimal. Thus, the internal combustion engine is indisputably 无可争辩地 responsible for the introduction of large amounts of a variety of toxicants, such as tetraethyl lead 四乙基铅 and polyaromatic 6.6 Ecological risk assessment

51. Chapter 6 Ecotoxicology Environmental Analytical Chemistry hydrocarbons 多环芳烃, into the atmosphere. However, because of the enormous value that society attaches to 依附（恋）于 the use of this device this is generally regarded as 被认为是 an acceptable risk to the environment and humans, despite the obvious damage caused. A generally agreed summary framework 共同议定的总结性框 架 for ecological risk assessment is shown in Figure 6.5.(see p469) Problem formulation 公式化 involves an evaluation of stressor characteristics, identification of the ecosystem(s) at risk, ecological impacts, endpoint selection, e.g. mortality 死亡率 of selected organisms, type and quality of input data and potential modeling systems. 6.6 Ecological risk assessment

52. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Analysis involves the characterization of the ecosystem of concern, which is sometimes difficult to delineate [d ɪ ‘l ɪ n ɪ e ɪ t] 勾画，描绘 given the size and complexity of many ecosystems and the fact that they are dynamic entities undergoing constant change 不断变化 的动态实体. Also included under this heading 标题 is an assessment of exposure, i.e. the environmental concentration of the stressor, or better still the dose received, by the biota. This is particularly problematic because of the interaction of stressors with the biotic and abiotic 生物和非生物 components of an ecosystem, biotransformations 生物转化 and possible uncertainties regarding routes of entry and levels of toxicants present. 6.6 Ecological risk assessment

53. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Analytical chemistry plays an important role in determining these parameters and is used in conjunction with certain assumptions about contact and uptake of toxicants by components of the environment and mathematical models to assess exposure. However, considerable uncertainty will inevitably remain. An absolutely critical aspect 绝对关键的方面 of analysis associated with ecological risk assessment includes an evaluation of the ecological effects of the stressor. Data on the toxicity of the stressor is compiled 汇编 ; 编辑 from various sources, including both laboratory and field studies and a so-called stressor-response profile can be built up to match ecosystem impacts to 与 … 匹配 6.6 Ecological risk assessment

54. Chapter 6 Ecotoxicology Environmental Analytical Chemistry stressor concentrations. However, this is not as straightforward as it appears. For example, complications 复杂化 are introduced by the almost inevitable need to draw upon 利用 qualitative data when quantifying this relationship and the requirement usually to extrapolate [ ɪ k‘stræpəle ɪ t] 推算，推断 data from single species to multiple species, from laboratory studies to natural environments and from one species to another so-called phylogenetic [fa ɪ lə ʊ d ʒ ə’net ɪ k] 系统发育的 extrapolation 推断. Thus, uncertainties can arise from using a single algal [‘æl ɡ əl] 海藻的 species in a test to represent all photosynthetic organisms, which in reality it clearly cannot. 6.6 Ecological risk assessment

55. Chapter 6 Ecotoxicology Environmental Analytical Chemistry The final stage 最后阶段 of the risk assessment process is risk characterization, which requires the analysis and integration 分析 与整合 of risk estimation 估计 and risk description elements to 以 determine the probability of the effects of a stressor given its 给定其 particular distribution in the environment under study. Throughout the entire process of risk assessment the acquisition 采集, verification and monitoring of data is essential, as are discussions between the risk assessor and risk manager. It is the latter that will pave the way to 为 … 铺平道路 the final decision-making 决策 process by the risk manager. 6.6 Ecological risk assessment

56. Chapter 6 Ecotoxicology Environmental Analytical Chemistry Ecotoxicology 6.6 Ecological risk assessment

57. Chapter 6 Ecotoxicology Environmental Analytical Chemistry

58. Chapter 6 Ecotoxicology Environmental Analytical Chemistry References 1.Fifield F.W. and Haines P.J. Environmental Analytical Chemistry (Second Edition). Blackwell Science Ltd, 2000. 2. 但德忠主编. 环境分析化学. 高等教育出版社, 2009. 3. Radojevic Miroslav. Practical Environmental Analysis. The Royal Society of Chemistry, MPG Books Ltd, Bodmin, Cornwall, UK, 1999 4. 庄一延. 水生生物毒理实验在水环境监测中的应用 [J]. 福建 环境， 1996 ， 13 （ 6 ）： 12-13 References

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