Use of exposure time and life expectancy in models for toxicity to aquatic organisms

The exposure time is a variable which is usually not incorporated into models for toxicity. However, with persistent organic pollutants (POPs) exhibiting a nonspecific mode of action and lipophilic properties this variable can be modeled by the usage of the internal concentrations as a measure of the toxicity with fish. The bioconcentration process with fish is a relatively well understood and predictable process which allows the calculation of the internal lethal concentration. When the exposure time is relatively short the critical internal lethal concentrations are relatively constant for the group of POPs whereaas the LC50 measured in the ambient water is quite variable. When the exposure time is relatively long, results on the measurement of the critical internal concentration with fish over different exposure times has demonstrated that the internal lethal concentration falls with increasing exposure times in a consistent and predictable manner. This reduction in life expectancy can be described in a model which can be used to estimate the critical internal concentration for any exposure time. It also provides information useful in assessing the risk to fish and potentially other species due to the occurrence of residues of POPs in natural aquatic systems. It is suggested that these relationships can be extended to other groups of organisms and chemicals.     

Measuring and monitoring persistent organic pollutants in the context of risk assessment

Due to growing concerns regarding persistent organic pollutants (POPs) in the environment, extensive studies and monitoring programs have been carried out in the last two decades to determine their concentrations in water, sediment, and more recently, in biota. An extensive review and analysis of the existing literature shows that whilst the vast majority of these efforts either attempt to compare (a) spatial changes (to identify "hot spots"), or (b) temporal changes to detect deterioration/improvement occurring in the environment, most studies could not provide sufficient statistical power to estimate concentrations of POPs in the environment and detect spatial and temporal changes. Despite various national POPs standards having been established, there has been a surprising paucity of emphasis in establishing accurate threshold concentrations that indicate potential significant threats to ecosystems and public health. Although most monitoring programs attempt to check compliance through reference to certain "environmental quality objectives", it should be pointed out that many of these established standards are typically associated with a large degree of uncertainty and rely on a large number of assumptions, some of which may be arbitrary. Non-compliance should trigger concern, so that the problem can be tracked down and rectified, but non-compliance must not be interpreted in a simplistic and mechanical way. Contaminants occurring in the physical environment may not necessarily be biologically available, and even when they are bioavailable, they may not necessarily elicit adverse biological effects at the individual or population levels. As such, we here argue that routine monitoring and reporting of abiotic and biotic POPs concentrations could be of limited use, unless such data can be related directly to the assessment of public health and ecological risks. Risk can be inferred from the ratio of predicted environmental concentration (PEC) and the predicted no effect concentration (PNEC). Currently, the paucity of data does not allow accurate estimation of PNEC, and future endeavors should therefore, be devoted to determine the threshold concentrations of POPs that can cause undesirable biological effects on sensitive receivers and important biological components in the receiving environment (e.g. keystone species, populations with high energy flow values, etc.), to enable derivation of PNECs based on solid scientific evidence and reduce uncertainty. Using the threshold body burden of POPs required to elicit damages of lysosomal integrity in the green mussel (Perna virvidis) as an example, we illustrate how measurement of POPs in body tissue could be used in predicting environmental risk in a meaningful way.     

Biological effects in the management of chemicals in the marine environment

Coastal ecosystems are impacted by many stressors, of which chemicals are possibly not the most important. Chemicals differ from most other stressors such as eutrophication and hypersedimentation in the time scale-effects from the latter act on the scale of weeks or months, whereas effects from chemicals may take years to manifest themselves in population or community changes. There are four different approaches available to manage chemicals in marine ecosystems: target contaminant levels, target individual effects, target community impacts (biodiversity) and, finally, target processes. These four differ in the analytical methods available and the analyst's ability to separate effects from chemicals from other environmental factors and natural variation. There is furthermore, a need to develop a framework to integrate biological effects methods with risk assessment methodology. Such integration will improve the basis for risk-based assessment of chemicals. A problematic issue relevant to all aspects of environmental management are the interactions between chemicals, and between chemicals and eutrophication or sedimentation. There is a clear need for more knowledge about such interactions.     

水生态评价方法研究进展及展望

水生态系统是人类赖以生存的基础,近年来气候变化和水资源开发、水体污染、过度捕捞等人类活动导致水生态系统严重受损,水生态系统的保护和修复已成为全球面临的重大挑战。科学合理的水生态评价方法是实现水生态系统稳定、健康和可持续管理的基本保障,也是目前我国各相关管理部门高度重视的关键问题,多个部门围绕水生态评价展开了积极探索与实践。本文系统回顾了水生态评价方法的发展历程并阐释了水生态评价的内涵,梳理了常用的水生态评价方法,明晰了各方法的基本理念和应用场景,分析了各方法的优点和不足,提出了基于生态完整性的水生态健康评价方法,最后对目前我国水生态评价需进一步完善的工作进行了展望。本文以期与相关领域研究者和管理者在水生态评价理论和方法方面进行探讨,为我国水生态考核工作提供理论支持。     

Hazard distribution and risk assessment in the network systems

In the age when transport flows in the railway and road systems, information flows in the internet channels, etc. intensify, hazard distribution in the network systems becomes a more relevant and important issue. In the paper various theoretical hazard type distributions in the network systems are analysed. Conditions and assumptions that hazard in the network system cells would settle and became steady are defined. Cases are analysed, when hazard is initiated in one or several network nodes, while in other nodes hazard is decreased, i.e. they have immunity to the hazard. In all cases hazard distribution equilibrium equations are constructed and their solutions‘ existence conditions are defined. Theoretical results are illustrated by simulation of hazard fuel transportation in the Lithuanian roads. It is shown that using this methodology it is possible to construct an algorithm, which enables to operate and decrease fuel transportation hazard and risk. The novelty of the work is associated with employing Markov process to describe hazard distribution mechanism and to determine limited hazard distribution in the nodes of networks. The hazard of tank trucks in the network of Lithuanian roads has been assessed for the first time.     

Differences in the acute toxicities of tributyltin between the Caprellidea and the Gammaridea (Crustacea: Amphipoda)

Tests for the acute toxicity of tributyltin (TBT) were conducted on amphipod crustaceans collected from Otsuchi Bay, Japan. Five species of caprellids and three species of gammarids, which belong to a closely related ecological niche, were used for the exposure experiments at seven test concentrations (0, 0.001, 0.01, 0.1, 1, 10 and 100 microg TBTCl/l) for 48 h at 20 degrees C. The 48-h LC50 values of the caprellids were 1.2-6.6 microg TBTCl/l, and these were significantly lower than those of the gammarids (17.8-23.1 microg TBTCl/l). This suggests that caprellids are more sensitive to TBT than gammarids. Furthermore, the proportions of TBT and its derivatives, dibutyltin (DBT) and monobutyltin (MBT), were measured in the amphipods collected from Otsuchi Bay. In the caprellids, TBT was the predominant compound, accounting for 72% of the total butyltin which reflected the butyltin ratio in seawater, while in the gammarids, TBT's breakdown products (DBT and MBT) predominated, accounting for 75% of the total butyltin. This difference suggests that caprellids may have lower metabolic capacity to degrade TBT than gammarids. Therefore, the difference in sensitivity to TBT among the amphipods is thought to be related to the species-specific capacity to metabolize TBT.     

地震观测环境调查评估及监控

地震观测数据的准确性和连续性,不仅取决于观测仪器、观测方法和观测技术水平,在很大程度上还依赖于良好的地震观测环境。客观、全面地对地震台站的观测环境进行调查评估,并建立地震观测环境监控体系,对于观测数据的质量控制、地震预报水平的提高和地震行政执法均具有重要意义。     

Concentrations of trace elements in marine fish and its risk assessment in Malaysia

Concentrations of trace elements (V, Cr, Mn, Co, Cu, Zn, Ga, Se, Rb, Sr, Mo, Ag, Cd, Sn, Sb, Cs, Ba, Hg, Tl, Pb and Bi) were determined in muscle and liver of 12 species of marine fish collected from coastal areas in Malaysia. Levels of V, Cr, Mn, Co, Cu, Zn, Ga, Sr, Mo, Ag, Cd, Sn, Ba and Pb in liver were higher than those in muscle, whereas Rb and Cs concentrations showed the opposite trend. Positive correlations between concentrations in liver and muscle were observed for all the trace elements except Cu and Sn. Copper, Zn, Se, Ag, Cd, Cs and Hg concentrations in bigeye scads from the east coast of the Peninsular Malaysia were higher than those from the west, whereas V showed the opposite trend. The high concentration of V in the west coast might indicate oil contamination in the Strait of Malacca. To evaluate the health risk to Malaysian population through consumption of fish, intake rates of trace elements were estimated on the basis of the concentrations of trace elements in muscle of fish and daily fish consumption. Some specimens of the marine fish had Hg levels higher than the guideline value by US Environmental Protection Agency (EPA), indicating that consumption of these fish at the present rate may be hazardous to Malaysian people. To our knowledge, this is the first study on multielemental accumulation in marine fish from the Malaysian coast.     

Hazard assessment of silicone oils (polydimethylsiloxanes, PDMS) used in antifouling-/foul-release-products in the marine environment

Non-eroding silicone-based coatings can effectively reduce fouling of ship hulls and are an alternative to biocidal and heavy metal-based antifoulings. The products, whose formulations and make up are closely guarded proprietary knowledge, consist of a silicone resin matrix and may contain unbound silicone oils (1-10%). If these oils leach out, they can have impacts on marine environments: PDMS are persistent, adsorb to suspended particulate matter and may settle into sediment. If oil films build up on sediments, infiltration may inhibit pore water exchange. PDMS do not bioaccumulate in marine organisms and soluble fractions have low toxicity to aquatic and benthic organisms. At higher exposures, undissolved silicone oil films or droplets can cause physical-mechanic effects with trapping and suffocation of organisms. These 'new' effects are not covered by current assessment schemes. PDMS make the case that very low water solubility and bioavailability do not necessarily preclude damage to marine environments.     

The state of the aquatic environment and biota during operation of trout-breeding pond farms

The paper presents the results of studying chemical and biological quality characteristics of the aquatic environment in the area of operation of trout farms in Kondopoga Bay, Onega Lake. The concentrations of biochemically labile substances and phosphorus were found to increase near the ponds. The development dynamics of phytoplankton, zooplankton, and benthic organisms in the zone of pond farms. When the procedure of fish production is strictly followed, the effect of ponds on the aquatic environment and biota is minimal.     

Toxicity assessment of metals in sediment from the lower reaches of the Haihe River Basin in China

The aqueous environmental quality of the Haihe River Basin is crucial for the ecological health of local catchments and the Bohai Sea. For the routine management neglected sediment tests and no legitimate tool supported the toxicity evaluation yet, one supplementary monitoring was implemented to examine the occurrence and toxic level of sediment metals in the lower reaches of the Haihe River Basin in 2009. Both world-widely used consensus-based sediment quality guidelines and China's environmental quality standard for soils (EQSS) were used as assessment tools. Cu, Zn, As, Hg, Cd, and Pb were detected in all 24 samples, while Cr was detected in 18 samples. Assessment results showed 9 samples were toxic and the most dominant toxic element was As. Although the river water quality is getting better, sediment metals have accumulated over thirty years due to continuous industrial development, with toxicity far beyond safety limitations. The highest toxicity levels were encountered in Binhai New Area, suggesting three rivers should be given priority for restoration. It is found that EQSS is also applicable for sediment toxicity assessment until a dedicated tool for Haihe River Basin is available, except for that EQSS is too conservative for Pb.     

论有机氮磷在湖泊水环境中的作用和重要性

长期以来,国内外学者对湖泊中氮磷等营养物质及其循环开展了大量研究,在其污染过程、控制和管理等方面取得了许多重要进展。然而,现有研究主要集中在总氮、总磷和无机氮磷等方面,对有机氮磷的来源、循环及生物和生态学效应的研究相对缺乏。近期研究显示:有机氮磷是湖泊水体和沉积物中的重要组分,可以通过酶解和微生物活动转化成生物可利用性营养盐,在湖泊生态系统中起着十分重要的作用。本文简要分析了有机氮磷已有的研究进展,论述了有机氮磷在湖泊水环境研究中的重要性、研究难点、主要技术突破及存在的科学问题,指出有机氮磷研究将有助于加深目前对水生态系统和富营养化机理的认识,并对水质标准制定、环境质量评价、污染控制和生态修复具有十分重要的价值。研究表明:在各种无机氮磷研究的基础上,开展各种有机氮磷等营养组分的时空分布特征、在主要界面的迁移转化及其生物有效性研究,揭示有机氮磷与湖泊生命过程的耦合关系,完善氮磷循环理论,将是未来该领域的主要研究方向。     

Risk tolerance measure for decision-making in fuzzy analysis: a health risk assessment perspective

In risk assessment studies it is important to determine how uncertain and imprecise knowledge should be included into the simulation and assessment models. Thus, proper evaluation of uncertainties has become a major concern in environmental and health risk assessment studies. Previously, researchers have used probability theory, more commonly Monte Carlo analysis, to incorporate uncertainty analysis in health risk assessment studies. However, in conducting probabilistic health risk assessment, risk analyst often suffers from lack of data or the presence of imperfect or incomplete knowledge about the process modeled and also the process parameters. Fuzzy set theory is a tool that has been used in propagating imperfect and incomplete information in health risk assessment studies. Such analysis result in fuzzy risks which are associated with membership functions. Since possibilistic health risk assessment studies are relatively new, standard procedures for decision-making about the acceptability of the resulting fuzzy risk with respect to a crisp standard set by the regulatory agency are not fully established. In this paper, we are providing a review of several available approaches which may be used in decision-making. These approaches involve defuzzification techniques, the possibility and the necessity measures. In this study, we also propose a new measure, the risk tolerance measure, which can be used in decision making. The risk tolerance measure provides an effective metric for evaluating the acceptability of a fuzzy risk with respect to a crisp compliance criterion. Fuzzy risks with different membership functions are evaluated with respect to a crisp compliance criterion by using the possibility, the necessity, and the risk tolerance measures and the results are discussed comparatively.     

长江流域外来鲟入侵风险评估、适生区预测及影响因素分析

长江流域外来鲟的养殖规模庞大,养殖逃逸成为外来鲟进入长江流域的主要途径,影响本地鲟种群生存。根据世界鱼类数据库(FishBase),10种主要养殖的外来鲟中,西伯利亚鲟已被列为德国和奥地利的入侵物种,匙吻鲟已被列为白俄罗斯的入侵物种。为了评估长江流域外来鲟的入侵风险,量化流域内入侵风险最高的外来鲟的适生区,本文使用水生物种入侵性筛查工具(AS-ISK)评估10种主要养殖的外来鲟和5种相关鱼类(虹鳟、尼罗罗非鱼、斑点叉尾鮰、鲮和丁鱥)的入侵风险;使用最大熵算法,基于当前和未来时期(2021—2040年)气候模式下的生物气候变量以及海拔,对于入侵评分最高的外来鲟在流域内的适生区进行预测与分析。结果表明,匙吻鲟在外来鲟中入侵评分最高,表明其在长江流域入侵风险最高。适生区预测时,最热季降水量、年降水量、最热月份最高温度、最冷月份最低温度、昼夜温差的月平均值和降水季节性变异系数是影响匙吻鲟在长江流域分布的主要变量。当前时期,匙吻鲟在长江流域中下游地区具有较大范围的适生区,主要包含湖南、湖北、安徽和江西等省份的部分地区,其中Ⅲ级适生区(高适生区)面积约为2996.8 km²;...     

Analysis of the mechanism and mathematical modeling of diethylhexylphthalate degradation in aquatic environment

Degradation mechanism of diethylhexylphthalate, a pollutant of water bodies, is analyzed. A modified first-order equation with a correction for a nondegradable fraction is suggested. The succession of biochemical reactions in the process of anaerobic degradation of monoethylhexylphthalate is considered, and two stages—ester hydrolysis and phthalic acid transformation into methane and carbon dioxide—are identified as limiting the overall rate. A one-dimensional distributed model is used to describe the degradation of three phthalates with different water solubility: diethylphthalate DEP, which has a relatively high solubility; dibutyl phthalate DBP, poorly soluble; and diethylhexylphthalate DEHP, almost insoluble. The physicochemical processes of sorption/desorption play an important role in the process of their degradation. The enzymatic splitting, carried out by microorganisms, reduces the concentration of dissolved diethylhexylphthalate and can facilitate desorption processes.     

Integrating toxicology and ecology: putting the "eco" into ecotoxicology

Environmental toxicology has been and continues to be an important discipline (e.g., single-species testing for screening purposes). However, ecological toxicology (ecotoxicology--more realism in tests, test species and exposures) is required for predicting real world effects and for site-specific assessments. Ecotoxicology and ecology have shown similar developmental patterns over time; closer cooperation between ecologists and toxicologists would benefit both disciplines. Ecology can be incorporated into toxicology either extrinsically (separately, e.g., providing information on pre-selected test species) or intrinsically (e.g., as part of test species selection)--the latter is preferable. General guidelines for acute and chronic testing and criteria for species selection differ for ecotoxicology and environmental toxicology, and are outlined. An overall framework is proposed based on ecological risk assessment (ERA), for combining ecology and toxicology (environmental and ecological) for decision-making. Increased emphasis on ecotoxicology represents a shift from reductionist to holistic approaches.     

Geological risk assessment for the rapid development area of the Erhai Basin

For low-slope hilly land development to have more new land space in a watershed, it is particularly important that to coordinate the sharply increasing conflicts between mountainous and urban land utilization in the city. However, development of low-slope hilly land easily induce potential risks of geologic hazards such as landslide and landslip. It may lead to further environmental losses in a watershed. Hence, it is necessary to study potential risks of geo-hazards in low-slope hilly land development in urban area. Based on GIS spatial analysis technique, we select a study area, Dali City in the Erhai Basin located in watershed belt of Jinsha River, Lancang River and Red River in Yunnan Province of China. Through studying some relevant key indexes and parameters for monitoring potential risks of geo-hazards, we establish a composite index model for zoning the area with potential risks of geo-hazards in development of low-slope hilly land in the study area. Our research findings indicate that the potential risks of geo-hazards in eastern Dali City is relatively low while of that on slow hills with gentle slopes in the western area are relatively high. By using a zoning research method, generated maps show geological information of potential risks of geo-hazards on low-slope hilly land which provide important messages for guarding against natural geo-hazards and potential environmental losses in a watershed.