锑的表生地球化学行为与环境危害效应

锑(Sb)是一种典型的有毒有害重金属元素。由于自然过程和人为活动的影响,锑及其化合物广泛分布于大气、土壤、水体等表生环境中,锑的环境污染日益严重。Sb不是植物必需元素,但能够被植物体及农作物吸收。Sb对人体和动物体产生慢性毒性及潜在致癌性。本文主要通过分析Sb的主要矿物、锑及其化合物在表生环境中的分布与迁移特性,来阐述人体可能的锑暴露途径及由此产生的环境危害效应。     

家用洗衣粉中磷对斜生栅藻生长的影响

以洗衣粉中的有机磷为磷源,通过室内模拟的方法研究在不同磷浓度的水体条件下斜生栅藻的生长情况,以及磷对斜生栅藻的生长是否有毒害作用.通过显微计数测定藻细胞数目来探讨洗衣粉中磷对斜生栅藻生长的影响;同时分析了洗衣粉中磷对斜生栅藻96 h生长期中光合色素的影响.结果表明,洗衣粉中的磷除了促进藻生长外,其浓度过低或过高都会抑制藻的生长.由实验结果可得,磷对藻生长的富营养化作用和毒性作用取决于磷浓度的高低.     

A fluorescence-based bioassay for aquatic macrophytes and its suitability for effect analysis of non-photosystem II inhibitors

Background, Goals and Scope During the last years the miniaturization of toxicity test systems for rapid and parallel measurements of large quantities of samples has often been discussed. For unicellular algae as well as for aquatic macrophytes, fluorescence-based miniaturized test systems have been introduced to analyze photosystem II (PSII) inhibitors. Nevertheless, high-throughput screening should also guarantee the effect detection of a broad range of toxicants in order to ensure routinely applicable, high-throughput measuring device experiments which can cover a broad range of toxicants and modes of action others than PSII inhibition. Thus, the aim of this study was to establish a fast and reproducible measuring system for non-PSII inhibitors for aquatic macrophyte species to overcome major limitations for use. Methods A newly developed imaging pulse-amplitude-modulated chlorophyll fluorometer (I-PAM) was applied as an effect detector in short-term bioassays with the aquatic macrophyte species Lemna minor. This multiwell-plate based measuring device enabled the incubation and measurement of up to 24 samples in parallel. The chemicals paraquat-dichloride, alizarine and triclosan were chosen as representatives for the toxicant groups of non-PSII herbicides, polycyclic aromatic hydrocarbons (PAHs) and pharmaceuticals and personal care products (PPCPs), which are often detected in the aquatic environment. The I-PAM was used (i) to establish and validate the sensitivity of the test system to the three non-PSII inhibitors, (ii) to compare the test systems with standardized and established biotests for aquatic macrophytes, and (iii) to define necessary time scales in aquatic macrophyte testing. For validation of the fluorescence-based assay, the standard growth test with L. minor (ISO/DIS 20079) was performed in parallel for each chemical. Results The results revealed that fluorescence-based measurements with the I-PAM allow rapid and parallel analysis of large amounts of aquatic macrophyte samples. The I-PAM enabled the recording of concentration-effect-curves with L. minor samples on a 24-well plate with single measurements. Fluorescence-based concentration-effect-curves could be detected for all three chemicals after only 1 h of incubation. After 4–5 h incubation time, the maximum inhibition of fluorescence showed an 80–100% effect for the chemicals tested. The EC50 after 24 h incubation were estimated to be 0.06 mg/L, 0.84 mg/L and 1.69 mg/L for paraquatdichloride, alizarine and triclosan, respectively. Discussion The results obtained with the I-PAM after 24 h for the herbicide paraquat-dichloride and the polycyclic aromatic hydrocarbon alizarine were in good accordance with median effective concentrations (EC50s) obtained by the standardized growth test for L. minor after 7 d incubation (0.09 mg/L and 0.79 mg/L for paraquat-dichloride and alizarine, respectively). Those results were in accordance with literature findings for the two chemicals. In contrast, fluorescence-based EC50 of the antimicrobial agent triclosan proved to be two orders of magnitude greater when compared to the standard growth test with 7 d incubation time (0.026 mg/L) as well as with literature findings. Conclusion Typically, aquatic macrophyte testing is very time consuming and relies on laborious experimental set-ups. The I-PAM measuring device enabled fast effect screening for the three chemicals tested. While established test systems for aquatic macrophytes need incubation times of ≥ 7 d, the I-PAM can detect inhibitory effects much earlier (24 h), even if inhibition of chemicals is not specifically associated with PSII. Thus, the fluorescence-based bioassay with the I-PAM offers a promising approach for the miniaturization and high-throughput testing of chemicals with aquatic macrophytes. For the chemical triclosan, however, the short-term effect prediction with the I-PAM has been shown to be less sensitive than with long-term bioassays, which might be due to physicochemical substance properties such as lipophilicity. Recommendations and Perspectives The results of this study show that the I-PAM represents a promising tool for decreasing the incubation times of aquatic macrophyte toxicity testing to about 24 h as a supplement to existing test batteries. The applicability of this I-PAM bioassay on emergent and submerged aquatic macrophyte species should be investigated in further studies. Regarding considerations that physicochemical properties of the tested substances might play an important role in microplate bioassays, the I-PAM bioassay should either be accompanied by evaluating physicochemical properties modeled from structural information prior to an experimental investigation, or by intensified chemical analyses to identify and determine nominal concentrations of the toxicants tested. The chemicals paraquat-dichloride, alizarine and triclosan were chosen as representatives for the toxicant groups of non-PSII herbicides, PAHs and PPCPs which are often detected in the aquatic environment. Nevertheless, in order to ensure a routinely applicable measuring device, experiments with a broader range of toxicants and samples of surface and/or waste waters are necessary. ESS-Submission Editor: Dr. Markus Hecker (MHecker@Entrix.com)     

Growth, photosynthetic and respiratory responses to sub-lethal copper concentrations in Scenedesmus incrassatulus (Chlorophyceae)

In the present paper we investigated the effects of sub-lethal concentrations of Cu²⁺ in the growth and metabolism of Scenedesmus incrassatulus. We found that the effect of Cu²⁺ on growth, photosynthetic pigments (chlorophylls and carotenoids) and metabolism do not follow the same pattern. Photosynthesis was more sensitive than respiration. The analysis of chlorophyll a fluorescence transient shows that the effect of sub-lethal Cu²⁺ concentration in vivo, causes a reduction of the active PSII reaction centers and the primary charge separation, decreasing the quantum yield of PSII, the electron transport rate and the photosynthetic O₂ evolution. The order of sensitivity found was: Growth > photosynthetic pigments content = photosynthetic O₂ evolution > photosynthetic electron transport > respiration. The uncoupled relationship between growth and metabolism is discussed.     

Integrated catalytic wet air oxidation and aerobic biological treatment in a municipal WWTP of a high-strength o-cresol wastewater

This study examines the feasibility of coupling a Catalytic Wet Air Oxidation (CWAO), with activated carbon (AC) as catalyst, and an aerobic biological treatment to treat a high-strength o-cresol wastewater. Two goals are pursued: (a) To determine the effect of the main AC/CWAO intermediates on the activated sludge of a municipal WasteWater Treatment Plant (WWTP) and (b) To demonstrate the feasibility of coupling the AC/CWAO effluent as a part of the influent of a municipal WWTP. In a previous study, a high-strength o-cresol wastewater was treated by AC/CWAO aiming to establish the distribution of intermediates and the biodegradability enhancement. In this work, the biodegradability, toxicity and inhibition of the most relevant intermediates detected in the AC/CWAO effluent were determined by respirometry. Also, the results of a pilot scale municipal WWTP study for an integrated AC/CWAO-aerobic biological treatment of this effluent are presented. The biodegradation parameters (i.e. maximum oxygen uptake rate and oxygen consumption) of main AC/CWAO intermediates allowed the classification of the intermediates into readily biodegradable, inert or toxic/inhibitory compounds. This detailed study, allowed to understand the biodegradability enhancement exhibited by an AC/CWAO effluent and to achieve a successful strategy for coupling the AC/CWAO step with an aerobic biological treatment for a high-strength o-cresol wastewater. Using 30%, as COD, of AC/CWAO effluent in the inlet to the pilot scale WWTP, the integrated AC/CWAO-biological treatment achieved a 98% of total COD removal and, particularly, a 91% of AC/CWAO effluent COD removal without any undesirable effect on the biomass.     

苯酚类化合物对日本长腿蛙蝌蚪的急性毒性与构效关系研究

利用半静态法测定了21种取代苯酚类化合物对日本长腿蛙蝌蚪的24h 急性致死毒性(24h-LC50),并进行了定量结构活性相关研究.研究表明:大部分酚类化合物的毒性表现为极性麻醉作用.影响毒性的因素有化合物的疏水性、电性及离解行为等.     

苯酚、苯胺及其衍生物对斜生栅列藻的急性毒性及QSAR研究

本文应用ＯＥＣＤ标准方法测定了１８种酚类胺类化合物对斜生栅列藻的４８ｈ－ＥＣ６０值,选择参数ＥＬＵＭＯ和ｌｇＫｏｗ进行了ＱＳＡＲ分析,得到下列回归方程：－１ｇＥＣ５０＝２．５４１－０．６４９ＥＬＵＭＯ＋０．２９９ＬｇＫｏｗ,ｎ＝１８,ｒ＝０．９０３,ＳＥ＝０．３１４应用所得方程计算了化合物的毒性,探讨了毒机理。     

土壤中4-溴苯胺降解动力学及其生态毒性追踪

秀谷隆是一种被广泛应用的取代脲类除草剂,其主要降解产物为４－溴苯胺（４－ＢＡ）,研究４－溴苯胺在不同土壤中的降解动力学规律,并用土壤环境指示动物弹尾目跳虫Ｃｏｌｌｅｍｂｏｌａ（Ｆｏｌｓｏｍｉａ ｃａｎｄｉｄａ）跟踪指示该化合物在进一步降解过程中的毒性,结果表明：４－溴苯胺在土壤中的降解行为可用一级反应动力学方程来较好地描述,其生态毒性明显高于母体化合物秀谷隆,该化合物在粘土中的残留量低于砂土,但毒     

氯代苯酚结构与农作物毒性关系的研究

卤代苯酚是一种环境污染物。本文通过水培发芽试验和幼苗土壤盆栽试验,研究了卤代苯酚系列污染物结构与冬小麦、萝卜、油菜等作物毒性的关系。结果表明,氯代苯酚系列污染物都可抑制他们的发芽和幼苗生长,其毒性都大于苯酚,并与浓度成显著性正相关。在浓度相同时,其毒性随苯环上氢原子被氯取代个数的增加而加大。在浓度和取代个数都相同时,不同取代部位的毒性不同,邻位取代毒性最大。不同农作物对它们的抗性不同;在取代个数、浓度和取代部位都相同时,小麦受害程度最轻,油菜最重。     

铜的植物毒性与植物蓄积的关系

重金属是一类重要的环境污染物,铜是其中毒性大、分布广的一种。本文介绍了铜对植物的毒性与植物蓄积之间的关系,认为植物对铜的蓄积部位和络合方式能极大地影响铜的毒性。过量的铜能影响细胞膜的透性和细胞内酶系统的活性,影响光和色素的合成及光合作用过程。细胞壁是植物蓄积铜的重要部位;植物体内的络合物质能在细胞内将铜络合而解毒。