生态风险评价及研究进展

生态风险是当前环境管理研究领域中的一个热点问题,其研究着重关注化学、物理和生物的胁迫因子可能对生态系统或其组分的有害影响.生态风险评价对科学制定环境管理决策有着重要的意义.要对生态系统进行有效地管理,必须预测不利生态影响发生的可能性及后果,减小其对于生态系统或某些组分的损害程度.本文对生态风险评价的研究方法、工具以及研究趋势进行了综述,指出了目前生态风险评价中还需要进一步加强的研究领域,认为在当前城市化水平不断提高的情况下要关注城市生态风险,并针对存在的一些问题提出了今后的研究展望.     

Bateman gradients in field and laboratory studies: a cautionary tale

Since tools of molecular genetics became readily available,our understanding of bird mating systems has undergone a revolution.The majority of passerine species investigated are sociallymonogamous, but have been shown to be genetically polygamous.Data sets from natural populations of juncos suggest that multiplemating by females results in a sexual selection gradient assteep for females as for males (a result that does not supportBateman's predictions). However, in males, fitness is enhanceddirectly through fertilization success with multiple matings;in females fitness benefits may be enhanced immediately throughdirect access to food, protection against predators, or otherresources received from males, or they may be delayed throughimprovement in offspring quality (e.g., through good genes,or greater genetic compatibility between the female and theextra-pair male). But a steep sexual selection gradient forfemales can be difficult to interpret. If all females copulatewith multiple partners that are equally likely to fertilizeeggs, then females that produce larger clutch sizes, for anyreason, will appear to have copulated with more males. Thatis, multiple sires have a higher probability of detection inlarger clutches than in smaller ones, giving the impressionthat females that mate with multiple males increase their reproductivesuccess. Yet, in most studies in which there is a correlationbetween number of offspring produced by females and number ofextra-pair males, causation has not been clearly establishedand other factors may explain the results. Additional complicationsin understanding male and female reproductive strategies are:(1) Molecular studies cannot detect extra-pair copulations thatdid not result in fertilizations; yet if a female acquires foodor other resources from extra-pair males, such extra-pair matingsmay have significant effects on female fitness. Thus, molecularstudies provide only a conservative estimate of the number ofextra-pair copulations or "mates" that a female has. (2) Clutchsize affects the probability that any given male will be successfulin fertilizing a female's eggs. Specifically, at any given point,a male's chances of fertilizing at least one egg in the female'sclutch will be greater as clutch size increases. We predictthat in avian species with small clutch sizes, males may beselected to be choosy and avoid extra-pair copulations, whilefemales should be selected to be less discriminating. Moreover,if extra-pair males provide resources that increase female fitness,the females should seek extra-pair copulations, whether or notthe males are likely to fertilize any of her eggs. Laboratory studies with insects have yielded clearer evidenceof the causal relationship between multiple mating and increasedfemale fitness. We review studies on a tenebrionid beetle inwhich female fecundity increases directly with number of mates.In these experiments, the nutritive value of the spermatophoresdoes not fully explain the increase in female reproductive success.     

Ecological hazard/risk assessment: lessons learned and new directions

A series of workshops held in the 1970s and 1980s, beginning at the University of Michigan Biological Station near Pellston, Michigan (and thus called the Pellston Series), focused on identifying the basic tenets of ecological hazard/risk assessment. The purpose of this discussion, produced roughly two decades after the first Pellston workshop, is to examine the impacts of this series on the development of the ecological hazard/risk assessment process, to explore some barriers hindering the development of this process, and suggest some new directions and challenges yet unaddressed by any of the workshop series. Probably the most important factor identified since the series of workshops began is persuasive circumstantial evidence that the learning process proceeds at different rates for individuals and institutions both in the government and private sectors, including academe. Evidence presently available suggests that individuals are frequently two or three decades ahead of institutions, and some individuals have already rejected paradigms generally accepted by the profession and are developing new ones. The major contribution of the workshops to the profession was connecting toxicity with environmental fate and transformation of chemicals and thus, bioavailability. Astonishingly, before the first Pellston workshop, this now-obvious connection did not play a dominant role in the peer-reviewed professional literature or in government documents, although the indefatigable investigator could find some minor indications that some professionals were aware of the importance of these relationships. Major suggestions for new directions and challenges focus on: (1) an emphasis on ecosystem health or condition rather than on mere absence of deleterious effects; (2) entering the information age requires that the type of information discussed here be integrated with and related to the broader array of other types of information used in making decisions at the societal or system level — failure to do so will mean that hazard/risk information will have little or no impact; (3) restoration ecology must emerge as a field of considerable importance because inevitably some estimates of hazard/risk will be inaccurate and damage will be done to ecosystems, which must then be repaired; (4) for all of this to function, environmental literacy must be markedly improved over its present level.     

An elemental and stable isotope assessment of water strider feeding ecology and lipid dynamics: synthesis of laboratory and field studies

1. Despite the ubiquity and abundance of water striders (Hemiptera: Gerridae) in temperate streams and rivers and their potential usefulness as sentinels in contaminant studies, little is known about their feeding ecology and lipid dynamics. 2. In this study we used stable isotopes of carbon (δ¹³C) and nitrogen (δ¹⁵N) and elemental carbon to nitrogen ratios (C/N) to assess dietary habits and lipid content, respectively, for water striders. 3. To determine diet‐tissue fractionation factors, nymphs of the most common species in New Brunswick, Canada, Aquarius remigis were reared in the laboratory for 73 days and exhibited rapid isotopic turnover in response to a switch in diet (C half‐life = 1.5 days, N half‐life = 7.8 days). Their lipid content increased towards the end of the growing season and resulted in lower δ¹³C values. Diet‐tissue fractionation factors were established after correction of δ¹³C data for the confounding effect of de novo lipid synthesis (strider δ¹³C_adj– diet δ¹³C_adj = 0.1‰, strider δ¹⁵N – diet δ¹⁵N = 2.7‰). 4. Water striders from the majority of 45 stream sites (83%) in New Brunswick had less than 50% contribution of aquatic carbon to their diets but showed a gradual increase in the contribution of this carbon source to their diet with increasing stream size. 5. These data indicate that striders exhibit a strong connection to terrestrial carbon sources, making them important users of energy subsidies to streams from the surrounding catchment. However, this dependence on terrestrial organic matter may limit their utility as indicators of contamination of aquatic systems by heavy metals and other pollutants.     

"Neuroethoendocrinology": integration of field and laboratory studies in insect neuroendocrinology

Progress in the field of insect neuroendocrinology has been rapid despite the relatively small number of investigators working on insect systems. This progress, in part, reflects the ease of studying insect behavior in the laboratory, and a historical perspective reveals that insect neuroendocrinology has been dominated since its inception by laboratory studies. Recent advances in methodology and a renewed interest in the concept of behavioral state in insects suggest that it might be useful for insect neuroendocrinologists to spend a little more time in the field.     

Feeding responses of Asplanchna brightwelli (rotifera): laboratory and field studies

Laboratory-reared A. brightwelli were offered 16 different prey rotifer species from the genera Anuraeopsis, Brachionus, Epiphanes, Filinia, Hexarthra, Lecane, Lepadella, Pompholyx, Proalides and Trichocerca. Feeding responses (prey encounter, escape, capture, rejection and ingestion) were recorded. In general, the predator's ingestion time was positively correlated with prey length. B. falcatus and H. intermedia were never captured. Once captured, smaller rotifer species were ingested. Gut contents of field-collected A. brightwelli revealed increased occurrence of prey numbers when concentrated plankton samples were preserved after some delay.     

A comparison of laboratory and field studies of cold response

The recent application of physiological techniques to anthropological studies of cold stress in different human groups has produced evidence of considerable variation in response to cold. The usual anthropological procedure has been to compare the adult males of two different ethnic groups under standardized laboratory conditions, and then to generalize the conclusions in an evolutionary or ecological context. Several assumptions behind this procedure are examined. Four studies of response to cold in the same Quechua Indian group of Southern Peru are discussed. Two of the studies deal with variation in response to cold in a standardized laboratory situation. The other two describe responses as detected under actual cold conditions experienced by the subjects as they go about their daily routines. The results of the laboratory and field studies are compared. It is suggested that adult males studied in the laboratory may represent only a minor part of the variation which exists in the group and that their responses may not be indicative of those of the entire population. It is also proposed that the validity of laboratory studies for an evolutionary interpretation may be limited by the laboratory approximation of the actual cold stress experienced by the group.     

Microbial aerosol generation during laboratory accidents and subsequent risk assessment

AIM: To quantify microbial aerosols generated by a series of laboratory accidents and to use these data in risk assessment. METHODS AND RESULTS: A series of laboratory accident scenarios have been devised and the microbial aerosol generated by them has been measured using a range of microbial air samplers. The accident scenarios generating the highest aerosol concentrations were, dropping a fungal plate, dropping a large bottle, centrifuge rotor leaks and a blocked syringe filter. Many of these accidents generated low particle size aerosols, which would be inhaled into the lungs of any exposed laboratory staff. Spray factors (SFs) have been calculated using the results of these experiments as an indicator of the potential for accidents to generate microbial aerosols. Model risk assessments have been described using the SF data. CONCLUSIONS: Quantitative risk assessment of laboratory accidents can provide data that can aid the design of containment laboratories and the response to laboratory accidents. SIGNIFICANCE AND IMPACT OF THE STUDY: A methodology has been described and supporting data provided to allow microbiological safety officers to carry out quantitative risk assessment of laboratory accidents.     

基于信息网络模型的生态风险评价

人类开发活动造成剧烈的生态系统自然条件变化,生态风险评价可以对受到人为干扰下生态系统(包括物种和群落等)的潜在影响进行模拟和量化。通过对信息流量的概念和网络控制分析,综合考虑生态系统组分间的直接和间接作用,提出一种能实现全局风险模拟的生态网络模型,即信息网络模型。在该模型基础上,建立了面向整体生态系统的生态风险评价框架,同时实现兼容多胁迫因子统一模拟和多风险受体间的风险追踪。以澜沧江漫湾水库为例,在估算重金属Hg、Pb和Cd初始环境风险后,利用信息网络模型追踪分析生态系统中不同生态功能组分之间的风险传递路径,评估各生态组分和整体系统的危险程度。结果表明,在累积效应作用下,对于生态系统和部分群落,整合网络风险值与初始环境风险值之间有着显著差别;在发生环境胁迫时,虽然处于食物网底层的生物类群可能最先受险,但在控制信息作用下食物网上层类群也会受险,甚至其最终受到的潜在威胁比前者更大。信息网络模型可识别出复杂的风险流动路径和群落间的风险累积,从而为生态系统风险评价和管理提供更为系统综合的理论依据。     

Ecological risk assessment of transgenic plant releases: an Austrian perspective

Some prerequisites for ecological risk assessment of transgenic plant releases are examined, with the aim of identifying research needs in Austria. Austria harbours high habitat diversity, extending from the Alps to the Pannonian continental lowlands. The Pannonian flora includes potential cross-breeding partners of several crops, which do not occur in western Europe. The border zones of major biogeographical regions contain high biodiversity, both in terms of species and habitat diversity; whether the genetic variability of widespread plant species is also increased in these areas requires further investigation. Especially in Alpine regions, transgenic grasses might eventually cause profound changes in community structure. Ecological risk assessment of transgenic crop releases should not only consider adverse effects on non-target species and ecosystems, but also their likely impact on the agroecosystems.     

基于多风险源胁迫的西南地区生态风险评价

西南地区生态环境复杂、人地矛盾突出,生态系统面临着多种风险胁迫,进行生态风险评价对区域生态风险的预警和防控具有重要的意义。基于西南地区的生态环境特征,将生态风险分为自然灾害风险与人类活动风险,从风险源危险性、生态系统潜在损失度、生态系统易损性3个方面构建单一风险评价模型,将单一风险评价结果进行综合分析得到西南地区综合生态风险结果。研究表明,西南高生态风险区面积为17.02万km2,占研究区总面积7.4%,主要分布在念青唐古拉山、邛崃山、哀牢山、无量山、金沙江、怒江、澜沧江、大渡河流域等地,以及成都、重庆、贵阳等人地作用强烈的大城市周边。这些地区环境复杂,灾害易发,应加强防控与监测,优化产业结构,继续推进生态保护工程,降低生态风险。     

Recommendations for the design of laboratory studies on non-target arthropods for risk assessment of genetically engineered plants

This paper provides recommendations on experimental design for early-tier laboratory studies used in risk assessments to evaluate potential adverse impacts of arthropod-resistant genetically engineered (GE) plants on non-target arthropods (NTAs). While we rely heavily on the currently used proteins from Bacillus thuringiensis (Bt) in this discussion, the concepts apply to other arthropod-active proteins. A risk may exist if the newly acquired trait of the GE plant has adverse effects on NTAs when they are exposed to the arthropod-active protein. Typically, the risk assessment follows a tiered approach that starts with laboratory studies under worst-case exposure conditions; such studies have a high ability to detect adverse effects on non-target species. Clear guidance on how such data are produced in laboratory studies assists the product developers and risk assessors. The studies should be reproducible and test clearly defined risk hypotheses. These properties contribute to the robustness of, and confidence in, environmental risk assessments for GE plants. Data from NTA studies, collected during the analysis phase of an environmental risk assessment, are critical to the outcome of the assessment and ultimately the decision taken by regulatory authorities on the release of a GE plant. Confidence in the results of early-tier laboratory studies is a precondition for the acceptance of data across regulatory jurisdictions and should encourage agencies to share useful information and thus avoid redundant testing.     

Monomethylarsonic acid and dimethylarsinic acid: developmental toxicity studies with risk assessment

BACKGROUND: The toxicity of arsenic compounds is highly dependent on the valence and methylation state of the compound. Although there is extensive published literature on the potential developmental toxicity of inorganic arsenic compounds, little exists on organic arsenic compounds and, in particular, studies conducted in accordance with conventional regulatory guidelines appropriate for risk assessment are rare. The organic arsenic compounds, monomethylarsonic acid (MMAV) and dimethylarsinic acid (DMAV, also called cacodylic acid), are the active ingredients in pesticide products that are used mainly for weed control. MMAV and DMAV are also metabolites of inorganic arsenic formed intracellularly by most living organisms (animals, plants and bacteria). In mammals, this occurs predominantly in liver cells. METHODS: Conventional developmental toxicity studies of orally administered MMAV and DMAV in the Sprague-Dawley rat and New Zealand White rabbit were conducted in commercial contract laboratories in the late 1980 s for regulatory compliance. The results of these studies are summarized and presented to broaden the data available in the public domain. RESULTS: In both species, data shows an absence of dose-related effects at organic arsenic exposures that were not maternally toxic. MMAV doses of 0, 10, 100, and 500 mg/kg/day (rat) and 0, 1, 3, 7, and 12 mg/kg/day (rabbit) and DMAV doses of 0, 4, 12, and 36 mg/kg/day (rat) and 0, 3, 12, and 48 mg/kg/day (rabbit) were administered by oral gavage daily during organogenesis (Gestation Day [GD] 6-15, rat; GD 7-19, rabbit) and the litters examined at maternal sacrifice (GD 20, rat; GD 29, rabbit). After treatment with MMAV, maternal and fetal toxicity were observed at the highest doses of 500 mg/kg/day (rat) and 12 mg/kg/day (rabbit), but no treatment-related developmental toxicity at the lower doses, even in the presence of minimal maternal toxicity in the rat at 100 mg/kg/d. There was no evidence of teratogenicity associated with MMAV treatment. With DMAV, maternal and developmental toxicity were observed in the rat at 36 mg/kg/day, with a higher than spontaneous incidence of fetuses with diaphragmatic hernia. In the rabbit at 48 mg/kg/day, there was marked maternal toxicity, culminating for most females in abortion and with no surviving fetuses for evaluation. There was no treatment-related maternal or developmental toxicity in the rat or rabbit at 12 mg/kg/day. Based on pregnancy outcome, the developmental toxicity no observed adverse effect level (NOAEL) for orally administered MMAV were 100 and 7 mg/kg/day in the rat and rabbit, respectively, and for DMAV were 12 mg/kg/day in both species. CONCLUSIONS: Margins of exposure estimated based on conservative estimates of daily intakes of arsenic in all of its forms indicate that exposure to MMAV or DMAV at environmentally relevant exposure levels, by the oral route (the environmentally relevant route of exposure) is unlikely to pose a risk to pregnant women and their offspring.     

东北地区森林资源生态风险评价研究

根据区域生态风险评价的理论和方法体系,对东北地区森林资源进行了生态风险评价．东北林区生态风险问题形成的主要胁迫包括物理胁迫、化学胁迫、生物胁迫和社会胁迫,其权重系数分别为0．30、0．22、0．11和0．37．东北93个林业局中,轻风险占64．4％,中风险占21．2％,重风险占13．3％。严重风险占1．1％,符合偏正态分布．东北区森林生态风险的地域分异明显,靠近长白山区的森林处于轻风险和中风险等级,向西生态风险越来越重,处于重风险和严重风险等级的林业局主要集中在小兴安岭地区．必须加强东北区风险管理和森林景观的修复与重建。