毒性废水稀释中强度改变与浓度改变的跟随性研究

适用于已知毒物和毒性应用剂量测定的经典技术方法,以样品稀释过程中毒性强度改变与浓度改变的等比率跟随性为基础。废水中的毒性物质常以未知和混合为特征,高毒性的样品现状浓度距离方法预试验中最小全致死浓度较远,以已知毒物重铬酸钾毒性为对照,形成5种毒物高层级等强度毒性,通过这些高毒性废水同步等比率稀释后毒性改变的同步性测定试验,证明毒性废水稀释中强度改变与浓度改变的跟随状态具有不确定性。     

Discrimination of excess toxicity from narcotic effect: Comparison of toxicity of class-based organic chemicals to Daphnia magna and Tetrahymena pyriformis

The discrimination of excess toxicity from narcotic effect plays a crucial role in the study of modes of toxic action for organic compounds. In this paper, the toxicity data of 758 chemicals to Daphnia magna and 993 chemicals to Tetrahymena pyriformis were used to investigate the excess toxicity. The result showed that mode of toxic action of chemicals is species dependent. The toxic ratio (TR) calculated from baseline model over the experimentally determined values showed that some classes (e.g. alkanes, alcohols, ethers, aldehydes, esters and benzenes) shared same modes of toxic action to both D. magna and T. pyriformis. However, some classes may share different modes of toxic action to T. pyriformis and D. magna (e.g. anilines and their derivatives). For the interspecies comparison, same reference threshold need to be used between species toxicity. The excess toxicity indicates that toxicity enhancement is driven by reactive or specific toxicity. However, not all the reactive compounds exhibit excess toxicity. In theory, the TR threshold should not be related with the experimental uncertainty. The experimental uncertainty only brings the difficulty for discriminating the toxic category of chemicals. The real threshold of excess toxicity which is used to identify baseline from reactive chemicals should be based on the critical concentration difference inside body, rather than critical concentration outside body (i.e. EC₅₀ or IGC₅₀). The experimental bioconcentration factors can be greatly different from predicted bioconcentration factors, resulting in different toxic ratios and leading to mis-classification of toxic category and outliers.     

Statistical uncertainty in hazardous terrestrial concentrations estimated with aquatic ecotoxicity data

Since chemicals’ ecotoxic effects depend for most soil species on the dissolved concentration in pore water, the equilibrium partitioning (EP) method is generally used to estimate hazardous concentrations (HC50) in the soil from aquatic toxicity tests. The present study analyzes the statistical uncertainty in terrestrial HC50s derived by the EP-method. For 47 organic chemicals, we compared freshwater HC50s derived from standard aquatic ecotoxicity tests with porewater HC50s derived from terrestrial ecotoxicity tests. Statistical uncertainty in the HC50s due to limited species sample size and in organic carbon–water partitioning coefficients due to predictive error was treated with probability distributions propagated by Monte Carlo simulations. Particularly for specifically acting chemicals, it is very important to base the HC50 on a representative sample of species, composed of both target and non-target species. For most chemical groups, porewater HC50 values were approximately a factor of 3 higher than freshwater HC50 values. The ratio of the porewater HC50/freshwater HC50 was typically 3.0 for narcotic chemicals (2.8 for nonpolar and 3.4 for polar narcotics), 0.8 for reactive chemicals, 2.9 for neurotoxic chemicals (4.3 for AChE agents and 0.1 for the cyclodiene type), and 2.5 for herbicides–fungicides. However, the statistical uncertainty associated with this ratio was large (typically 2.3 orders of magnitude). For 81% of the organic chemicals studied, there was no statistical difference between the hazardous concentration of aquatic and terrestrial species. We conclude that possible systematic deviations between the HC50s of aquatic and terrestrial species appear to be less prominent than the overall statistical uncertainty.     

Identifying potential receptors and routes of contaminant exposure in the traditional territory of the Ouje-Bougoumou Cree: Land use and a geographical information system

Great concern has been raised with respect to the 13 traplines that constitute the traditional territory of the Ouje-Bougoumou Cree located in the James Bay region of northern Quebec, Canada, with respect to mine wastes originating from three local mines. As a result, an “Integrative Risk Assessment” was initiated consisting of three interrelated components: a comprehensive human health study, an assessment of the existing ecological/environmental database, and a land use/potential sites of concern study. In this paper, we document past and present land use in the traditional territory of the Ouje-Bougoumou Cree for 72 heads of households, including 13 tallymen, and use a Geographic Information System (GIS) to layer harvest/hunting and gathering/collecting data over known mining areas and potential sites of concern. In this way, potential receptors of contamination and routes of human exposure were identified. Areas of overlap with respect to land use activity and mining operations were relatively extensive for certain harvesting activities (e.g., beaver, Castor canadensis and various species of game birds), less so for fish harvesting (all species) and water collection, and relatively restrictive for large mammal harvesting and collection of firewood (and other collection activities). Potential receptors of contaminants associated with mining activity (e.g., fish and small mammals) and potential routes of exposure (e.g., ingestion of contaminated game and drinking of contaminated water) were identified.     

Emergency response plan for boiler explosion with toxic chemical releases at Nan-Kung industrial park in central Taiwan

A large amount of hazardous materials and equipment has been extensively employed to produce useful chemicals for our daily lives, but many serious accidents, such as fires, explosions, toxic releases, and so on, that harm human beings and impact the environment have occurred during preparation, operation, and transportation of these chemicals. On 17 May 2007, a toxic release from a boiler explosion in a chemical firm triggered a large amount of xylene (7 ton), isopropanol (8 ton), phosphorus trichloride (44.7 ton), and dimethyl formamide (DMF) (1.37 ton) to be released to the atmosphere with total damages of 2000 m² level ground. Through concerted efforts from the Yunlin Emergency Response Information Center (YERIC), sponsored by the Environmental Protection Administration (EPA) of Taiwan and other government sectors, this accident was eventually well controlled after 37 h with 107 people being involved in the rescue action. This study could be applied to lessen the degree of hazard for relevant accidents with an emergency response plan (ERP), and, via Fourier transform infrared (FTIR) spectroscopy and photo ionization detector (PID) the toxic concentrations of airborne chemicals that occurred in the industrial area could be analyzed.     

Assessment of pollution in road runoff using a Bufo viridis biological assay

Road runoff is a major source of environmental pollution, significantly threatening nearby aquatic habitats. Chemical analyses indicate high pollutant concentrations in the road’s “first flush”, but bioassays are more advantageous for addressing the cumulative effects of the numerous pollutants within the runoff. We used Bufo viridis embryos and larvae to assess the toxicity of road runoff from two major highways in Israel. We show, for the first time, that exposure to midseason runoff not only has an adverse effect on growth and development rates of B. viridis larvae but can also lead to increased rates of morphological deformations. Seasonal first flushes, despite having higher metal concentrations, did not adversely affect the toad larvae, apparently due to a counter effect of organic matter that potentially served as a supplementary energy resource. Road runoff can be a major cause for a qualitative decrease in the quality of aquatic habitats threatening amphibians in Israel.     

3-D dispersion model for simulation of accidental toxic gas releases in a metropolitan area

Computational fluid dynamic (CFD) simulations were performed to assess the potential chlorine leak scenario in the super-urban area of South Korea, where the human population density is very high and numerous buildings exist near operational water treatment facilities. Flame acceleration simulator (FLACS) was used to predict the consequence from accidental chlorine releases out of one of the water treatment facilities for the nearby area having a size of 5 km × 3 km approximately. The ability to precisely implement 3-D geometries is crucial for a successful 3-D simulation. Thus, a method was proposed to rapidly and accurately implement geometry by importing computer aided-design (CAD) files provided by a government agency, and processing them using Auto CAD and MicroStation software programs. An accidental release from an 18-ton tank was simulated with three different wind directions to determine the expected evacuation distances. Results from the study showed that the endpoint distances varied depending on the density and arrangement of the buildings. Moreover, we employed physical barriers with varying heights for mitigating the effects of toxic gas releases and simulated how effectively they decreased the concentration of released chlorine.     

Determination of toxic metals in discarded Liquid Crystal Displays (LCDs)

This study focused on the determination of the toxic metal content of Liquid Crystal Displays (LCDs) present in various Waste Electrical and Electronic Equipment (WEEE). The main objective was the identification and quantification of toxic metals detected in LCD panels. An experimental procedure which involved dismantling, shredding, pulverization, digestion and chemical analysis was followed for the sorting, separation and analysis of LCD monitors from various electronic devices that are currently on the market. Nine selected devices were examined, originated from four different types of e-waste (WEEE); TVs, computers, mobile phones and tablets. Eleven metals were measured in all examined samples. In addition, concentration values of chromium (Cr), cadmium (Cd), lead (Pb) and mercury (Hg) were compared with the respective limits set by the RoHS 2002/95/EC Directive that was recently renewed by the 2012/19/EU recast. The comparison revealed that the examined toxic metals on LCD panels did not exceed the limits set by the European Union (EU). Furthermore, when results were compared to the TTLC regulatory limits it was revealed that in three samples As concentrations were higher than the limit. Finally, when the TCLP test was implemented the aforementioned samples did not exhibit proportionally elevated values in their leachates.     

Urgently reveal longly hidden toxicant in a familiar fabrication process of biomass-derived environment carbon material

Biomass-derived N-doped carbon (BNC) is an important environmental material and widely used in the fields of water purification and soil remediation. However, the toxicant in the commonly used synthesis process of BNC materials have been largely ignored. Herein, we firstly report the presence of a highly toxic by-product (KCN) in the activation process of BNC materials consequential of the carbothermal reduction reaction. Because this carbothermal reduction reaction also regulates the N-doping and pore development of BNC materials, the KCN content directly relates with the properties of BNC material properties. Accordingly, a high KCN content (∽ 611 mg) can occur in the production process of per g BNC material with high specific surface area (∽ 3600 m²/g). Because the application performance of BNC material is determined by the surface area and available N doping, therefore, production of a BNC material with high performance entails high risk. Undoubtedly, this study proves a completely new risk recognition on a familiar synthesis process of biomass-based material. And, strict protective device should be taken in fabrication process of biomass-derived carbon material.