关于改进可电离有机化学品水生危害评估方法和模型的建议

有机酸、碱等可电离有机化学品（IOCs）是一类重要的物质，需要进行水生危害评估。尽管IOCs的水生毒性高度依赖于水的pH值，在文献中的许多毒性研究由于没有记录pH或在实验期间pH不恒定而无法进行解释，这说明需要对测试指南进行改进。pH对毒性的调节作用主要是由pH依赖性吸收和IOCs的生物积累引起的，这可以通过离子捕获和毒代动力学模型来描述。由于生物体和细胞具有维持稳定的内部pH环境的能力，IOCs的内部效应浓度与外部pH无关。如果外部pH接近于内部pH，可以使用离子化校正脂质体水分配比代替正辛醇-水分配系数作为疏水性描述符，即通过对靶脂质模型的修饰改写现有的适用于中性有机物的定量结构-活性关系（QSAR）。一种IOC的带电离子、两性离子和中性粒子可通过浓度加成混合物效应或通过不同类型粒子的相互作用（例如线粒体呼吸解偶联）帮助解释观察到的毒性。对于具体作用的IOCs，我们推荐两步筛选程序：首先用离子捕获/ QSAR模型来预测基线毒性，然后使用来自体外系统的毒性比率进行调整。受体或血浆结合模型也有助于阐明IOCs的毒性。本篇综述的目的是帮助阐释IOCs的生态毒性，并提供其危害和风险评估的建议。     

Demonstration of sex pheromones in the predaceous diving beetle Rhantus suturalis (MacLeay 1825) (Dytiscidae)

Sex pheromones are used by a wide variety of species in terrestrial ecosystems. Much less is known about these pheromones in aquatic systems e.g., for diving beetles. To test the use of pheromones and visual signals for mate finding by the diving beetle Rhantus suturalis (MacLeay 1825), behavioral experiments were performed using three different types of vessels containing conspecific. In experiments with non-permeable glass flasks, which did not allow the diffusion of chemical substances, males and females did not stimulate any reaction by conspecific of either sex. In experiments with opaque but water permeable vessels, and in experiments with vessels made of finely woven steel, which allowed the perception of chemical as well as optical cues, male diving beetles were significantly attracted to females. Females were attracted to other females only in the last experiment, when simultaneously perceiving chemical and optical cues. These results indicate that R. suturalis females release sex pheromones to attract mating partners, which is the first experimental demonstration of pheromones in the Dytiscidae.     

Recovery of a freshwater wetland from chemical contamination after an oil spill

In March 2009, a cargo ship spilled 250 tons of heavy fuel oil off the Queensland coast of Australia. The pristine National Park Moreton Island, seven nautical miles to the east of the spill site, was most affected by the oil slick. Contamination of the island's shoreline was widespread, with freshwater wetlands particularly slow to recover as clean-up needed to be carefully managed to avoid damage to this sensitive ecosystem. During the clean-up process on Moreton Island a monitoring program was initiated using traditional chemical analysis in combination with bioanalytical techniques to assess the extent and variability in contamination at sites on the shoreline and freshwater wetlands. Water accommodated fractions (WAF) of oil residues from samples taken directly after the spill on the shoreline showed the same level of toxic potency as samples from the wetland while baseline-toxicity equivalent concentrations (baseline-TEQ) and 2,3,7,8-tetrachlorodibenzodioxin equivalent concentrations (TCDDEQ) were much lower in oil collected from the sandy beach. The umuC assay for genotoxicity and the E-SCREEN assay for estrogenic effects indicated the extracts were not genotoxic or estrogenic. PAH concentrations and toxicity in grab water samples were below detectable levels, however, extracts from time integrated silicone passive samplers deployed for several weeks at the contaminated sites gave measurable responses in the bioassays with TCDDEQ levels increased relative to the control site. The low levels of baseline-TEQ and TCDDEQ present after 8 months had further decreased 6 months later indicating satisfactory recovery of this pristine ecosystem after an oil spill.     

In vitro bioassay for reactive toxicity towards proteins implemented for water quality monitoring

Reactive organic chemicals comprise a large number of compounds with a variety of reactive moieties. While most assays for reactive toxicity focus on DNA damage, reactivity towards proteins can also lead to irreparable damage, but reactivity towards proteins is typically not included in any test battery for water quality assessment. Glutathione (GSH) is a small tripeptide whose cysteine moiety can serve as a model for nucleophilic sites on proteins. GSH is also an important indicator of detoxification processes and the redox status of cells and due to its protective role, depletion of GSH ultimately leads to adverse effects. A bioassay based on genetically modified Escherichia coli strains was used to quantify the specific reactivity towards the protein-like biological nucelophile GSH. The significance of GSH for detoxification was assessed by comparing the growth inhibition induced by reference chemicals or water samples in a GSH-deficient strain to its fully functional parent strain. The GSH deficient strain showed the same sensitivity as the GSH proficient strain to non-reactive and DNA damaging chemicals, but was more sensitive to chemicals that attack cysteine in proteins. The difference in effect concentrations for 50% inhibition of growth assessed as biomass increase (EC(50)) between the two strains indicates the relevance of GSH conjugation as a detoxification step as well as direct reactivity with cysteine-containing proteins. Seven reference compounds serving as positive and negative controls were investigated. The E. coli strain that lacks GSH was four times more sensitive towards the positive control Sea-Nine, while negative controls benzo[a]pyrene, 2-aminoanthracene, phenol, t-butylhydroquinone, methyl methane sulfonate and 4-nitroquinoline oxide showed equal effect concentrations in both strains. Water samples collected across an indirect potable reuse scheme representing the complete water cycle from sewage to drinking water in South East Queensland, Australia were used to evaluate the applicability of the E. coli assay for reactive toxicity in water samples. While the EC(50) values of the GSH+ strain showed similar trends as in other biological endpoints over the various treatment chains, the specific response indicative of protein damage was only observed in samples that had undergone chlorination as a disinfection process. High natural organic matter or other matrix components disturbed the bioassay so much that we recommend it for future routine testing only in tertiary treated water or drinking water.     

Biodegradability of a polyacrylate superabsorbent in agricultural soil

Superabsorbent polymers (SAP) are used, inter alia, as soil amendment to increase the water holding capacity of soils. Biodegradability of soil conditioners has become a desired key characteristic to protect soil and groundwater resources. The present study characterized the biodegradability of one acrylate based SAP in four agricultural soils and at three temperatures. Mineralisation was measured as the ¹³CO₂ efflux from ¹³C-labelled SAP in soil incubations. The SAP was either single-labelled in the carboxyl C-atom or triple-labelled including additionally the two C-atoms interlinked in the SAP backbone. The dual labelling allowed estimating the degradation of the polyacrylate main chain. The ¹³CO₂ efflux from samples was measured using an automated system including wavelength-scanned cavity ring-down spectroscopy. Based on single-labelled SAP, the mean degradation after 24 weeks varied between 0.45 % in loamy sand and 0.82 % in loam. However, the differences between degradation rates in different soils were not significant due to a large intra-replicate variability. Similarly, mean degradation did not differ significantly between effective temperature regimes of 20° and 30 °C after 12 weeks. Results from the triple-labelled SAP were lower as compared to their single-labelled variant. Detailed results suggest that the polyacrylate main chain degraded in the soils, if at all, at rates of 0.12–0.24 % per 6 months.     

Increased metal concentrations in exhaled breath condensate of industrial welders

It was the aim of this study to evaluate the effect of different devices on the metal concentration in exhaled breath condensate (EBC) and to prove whether working conditions in different welding companies result in diverse composition of metallic elements. The influence of two collection devices (ECoScreen, ECoScreen2) on detection of metallic elements in EBC was evaluated in 24 control subjects. Properties of ECoScreen and a frequent use can alter EBC metal content due to contamination from metallic components. ECoScreen2 turned out to be favourable for metal assessment. Concentrations of iron, nickel and chromium in EBC sampled with ECoScreen2 were compared between non-exposed controls and industrial welders. Metal concentrations in EBC were higher in 36 welders recruited from three companies. Exposure to welding fumes could be demonstrated predominantly for increased iron concentrations. Concentrations of iron and nickel differed by working conditions, but chromium could not be detected in EBC.