大型蚤标志酶用于城市二级出水毒性的评价

大型蚤是一种国际公认的标准实验生物,广泛应用于污水、地表水等水质毒性检测。毒性水平较低的城市二级出水,对大型蚤往往无急性毒性效应,而具有慢性毒性效应,但慢性毒性检测周期过长,因此探索一种更灵敏的指标,实现快速检测,对于控制二级出水的水质风险具有重要意义。本研究考察了大型蚤在短期暴露于城市二级出水条件下,其体内乙酰胆碱酯酶、超氧化物歧化酶、过氧化氢酶、ATP酶、羧酸酯酶和碱性磷酸酯酶的酶活变化特征,从中筛选出对二级出水毒性响应灵敏的标志酶指标。实验结果表明,碱性磷酸酯酶、过氧化氢酶对二级出水毒性响应相对较灵敏,具有成为标志酶的潜力,研究结果为城市二级出水生物毒性评价方法优化提供新的思路。     

Acute and chronic effects of nano- and non-nano-scale TiO2 and ZnO particles on mobility and reproduction of the freshwater invertebrate Daphnia magna

Among the emerging literature addressing the biological effects of nanoparticles, very little information exists, particularly on aquatic organisms, that evaluates nanoparticles in comparison to non-nanocounterparts. Therefore, the potential effects of nano-scale and non-nano-scale TiO₂ and ZnO on the water flea, Daphnia magna, were examined in 48-h acute toxicity tests using three different test media, several pigment formulations – including coated nanoparticles – and a variety of preparation steps. In addition, a 21-d chronic Daphnia reproduction study was performed using coated TiO₂ nanoparticles. Analytical ultracentrifugation analyses provided evidence that the nanoparticles were present in a wide range of differently sized aggregates in the tested dispersions. While no pronounced effects on D. magna were observed for nano-scale and non-nano-scale TiO₂ pigments in 19 of 25 acute (48-h) toxicity tests (EC50 > 100 mg L⁻¹), six acute tests with both nano- and non-nano-scale TiO₂ pigments showed slight effects (EC10, 0.5–91.2 mg L⁻¹). For the nano-scale and non-nano-scale ZnO pigments, the acute 48-h EC50 values were close to the 1 mg L⁻¹ level, which is within the reported range of zinc toxicity to Daphnia. In general, the toxicity in the acute tests was independent of particle size (non-nano-scale or nano-scale), coating of particles, aggregation of particles, the type of medium or the applied pre-treatment of the test dispersions. The chronic Daphnia test with coated TiO₂ nanoparticles demonstrated that reproduction was a more sensitive endpoint than adult mortality. After 21 d, the NOEC for adult mortality was 30 mg L⁻¹ and the NOEC for offspring production was 3 mg L⁻¹. The 21-d EC10 and EC50 values for reproductive effects were 5 and 26.6 mg L⁻¹, respectively. This study demonstrates the utility of evaluating nanoparticle effects relative to non-nano-scale counterparts and presents the first report of chronic exposure to TiO₂ nanoparticles in D. magna.     

利用发光菌和大型蚤对北方某城市再生水急性毒性的调查

利用发光菌和大型蚤作为受试生物测定了北方某城市5个再生水原水(城市污水厂二级出水)和2个再生水处理系统的各工艺出水的急性毒性.结果表明,各再生水原水对大型蚤和发光菌具有不同程度的毒性效应,其中工业废水占较大比例的K和B厂再生水原水的大型蚤48 h总抑制率分别高达90%和100%,发光菌发光抑制率分别达到74.2%和46...     

Proteomic analysis in Daphnia magna exposed to As(III), As(V) and Cd heavy metals and their binary mixtures for screening potential biomarkers

In this study, the effects of three widespread heavy metals, As(III), As(V) and Cd, and their binary mixtures on the proteomic profile in D. magna were examined to screen novel protein biomarkers using the two-dimensional gel electrophoresis method (2DE). Ten 20d daphnia were exposed to the LC20 concentrations for each of a total of 8 treatments, including the control, As(III), As(V), Cd, [As(III)+As(V)], [As(III)+Cd], [As(V)+Cd], and [As(III), As(V), Cd], for 24 h before protein isolation. Three replicates were performed for each treatment. These protein samples were employed for 2DE experiments with a pH gradient gel strip from pH 3 to pH 10. The protein spots were detected by a silver staining process and their intensities were analyzed by Progenesis software to discover the differentially expressed proteins (DEPs) in response to each heavy metal. A total of 117 differentially expressed proteins (DEPs) were found in daphnia responding to the 8 treatments and mapped onto a 2D proteome map, which provides some information of the molecular weight (MW) and pI value for each protein. All of these DEPs are considered as potential candidates for protein biomarkers in D. magna for detecting heavy metals in the aquatic ecosystem. Comparing the proteomic results among these treatments suggested that exposing D. magna to binary mixtures of heavy metals may result in some complex interactive molecular responses within them, rather than just the simple sum of the proteomic profiles of the individual chemicals, (As(III), As(V), and Cd).     

Nano-TiO2 enhances the toxicity of copper in natural water to Daphnia magna

The acute toxicity of engineered nanoparticles (NPs) in aquatic environments at high concentrations has been well-established. This study demonstrates that, at a concentration generally considered to be safe in the environment, nano-TiO₂ remarkably enhanced the toxicity of copper to Daphnia magna by increasing the copper bioaccumulation. Specifically, at 2 mg L⁻¹ nano-TiO₂, the (LC₅₀) of Cu²⁺ concentration observed to kill half the population, decreased from 111 μg L⁻¹ to 42 μg L⁻¹. Correspondingly, the level of metallothionein decreased from 135 μg g⁻¹ wet weight to 99 μg g⁻¹ wet weight at a Cu²⁺ level of 100 μg L⁻¹. The copper was found to be adsorbed onto the nano-TiO₂, and ingested and accumulated in the animals, thereby causing toxic injury. The nano-TiO₂ may compete for free copper ions with sulfhydryl groups, causing the inhibition of the detoxification by metallothioneins.     

Effects of suspended common-scale and nanoscale particles on the survival,growth and reproduction of Daphnia magna

Suspended particles are a natural component of aquatic ecosystems. This study provides a report on the survival, growth and reproduction of common-scale and nanoscale particles of Daphnia magna Straus exposed to five types of particles (i.e. KN (kaolinite), MN (montmorillonite), MNn (nanoscale MN), NP (natural particles), and NPn (nanoscale NP)). The results of the study show that the suspended particles elicited a dose-dependent toxicity in KN, MN and MNn, with the following toxicity pattern: MN > KN > MNn. On the contrary, NP and NPn did not show any harmful effects on the animals. Instead, NP and NPn, especially NPn, contributed to the survivorship of the animals. The animals were able to survive throughout the 21-day period of bioassays, and when the particle concentration reached 600 mg L⁻¹, they produced many neonates without any addition of food. This experimental results also indicated that the nanoscale particles were less toxic than the common-scale ones, both for MN and NP. Moreover, the results of the 21-day period of bioassays indicated that when the organisms were exposed to particles of different size scales, they showed different selection patterns for allocating resources. This may be due to the generation of different assimilation and digestion patterns.     

A biology-based dynamic approach for the reconciliation of acute and chronic toxicity tests: application to Daphnia magna

There is the need to integrate existing toxicity data in a coherent framework for extending their domain of applicability as well as their extrapolation potential. This integration would also reduce time and cost-consuming aspects of these tests and reduce animal usage. In this work, based on data extracted from literature, we have assessed the advantages that a dynamic biology-toxicant fate coupled model for Daphnia magna could provide when assessing toxicity data, in particular, the possibility to obtain from short-term (acute) toxicity test long-term (chronic) toxicity values taking into account the inherent variability of D. magna populations and the multiple sources of data. The results show that this approach overcomes some of the limitations of existing toxicity tests and that the prediction errors are considerably reduced when compared with the factor from 2 to 5 obtained using acute-to-chronic ratios.     

Embryo toxicity of pesticides and heavy metals to the ramshorn snail, Marisa cornuarietis (Prosobranchia)

An invertebrate embryo toxicity test with the ampullariid snail, Marisa cornuarietis, to assess the toxicity of pesticides and heavy metals recently was established. Snail embryos were treated with atrazine (100, 1000, 10 000, and 30 000 μg/L), imidacloprid (10 000, 25 000, and 50 000 μg/L), Ni²⁺ (0.1, 1, 10, and 100 μg/L) or Zn²⁺ (100, 200, 500, 1000, 2000, and 5000 μg/L). The effect of these substances was examined by monitoring the following endpoints: mortality, formation of tentacles and eyes, heart rate, hatching, and weight after hatching. Effects in term of a significant delay on the formation of both tentacles and eyes were found after treatment with 100 μg/L Ni²⁺ or 200 μg/L Zn²⁺. The heart rate was shown to significantly decrease at 25 000 μg/L imidacloprid or 1000 μg/L Zn²⁺. At 100 μg/L atrazine, 10 μg/L Ni²⁺, or 1000 μg/L Zn²⁺ a significant delay in hatching became visible. No significant mortality was observed for the tested concentrations of atrazine, imidacloprid, or Ni²⁺, while 5000 μg/L Zn²⁺ resulted in 100% mortality after 10 d. The weight of freshly hatched individuals remained unaffected in all treatments. On the basis of the lowest observed effect concentrations (LOECs) recorded, we could show the M. cornuarietis embryo toxicity test (MariETT) to react up to three orders of magnitude more sensitive (for metals) and at least one order of magnitude more sensitive (for the tested organics) than the established Danio rerio embryo test.     

The toxicity of sulfamethazine to Daphnia magna and its additivity to other veterinary sulfonamides and trimethoprim

Sulfonamides (SAs), the oldest chemotherapeutic agents used for antimicrobial therapy, still play an important role in veterinary mass treatments. Consequently, traces of these compounds, alone or in combinations, have been repeatedly detected in the environment. Sulfamethazine (SMZ) deserves particular attention not only because it is the most used veterinary SA, but also due to its proven effects on fertility in mice and on thyroid hormone homeostasis in rats. In this study, after evaluating the acute toxicity to Daphnia magna of six veterinary SAs and trimethoprim (TMP), the additivity of SMZ to each other compound was tested using the isobologram method. Two reproduction tests on the same biological model were also performed in order to derive LOEC and NOEC of SMZ. The acute EC₅₀ was in the range 131–270 mg L⁻¹ for all the compounds tested with the exception of sulfaguanidine (EC₅₀ = 3.86 mg L⁻¹). In acute binary tests SMZ showed a complex interaction with sulfaquinoxaline (superadditivity, additivity or subadditivity) at the three different combination ratios tested, simple additivity to TMP and less than additive interaction when paired to the other SAs. LOEC and NOEC of SMZ obtained from reproduction tests were 3.125 and 1.563 mg L⁻¹, respectively. In conclusion, SMZ should not harm the crustacean population at environmentally realistic concentrations. Its toxicity is comparable to that of other systemic SAs, and their binary interactions are less than additive. The same can not be entirely said for enteric SAs, and considering that these compounds are administered at high doses and mostly excreted in unmetabolised form, further evaluation of their impact to the aquatic environment seems advisable.     

大型溞投放密度对湖库水体水质改善及底泥污染物影响

向北京市沙河水库投放大型溞(Daphnia magna),利用其摄食藻类、促进悬浮颗粒态污染物沉降的特性,以提升水体的透明度,为后续沉水植物群落的恢复创造条件,并探索大型溞的投放密度,以及投放后对水质及底泥主要污染物的影响。结果表明：向沙河水库投加大型溞的最佳密度为5~15 ind·L⁻¹;在该条件下,水体透明度可在3~5 d由40 cm提升至100 cm,浊度由19.7 NTU降至3 NTU,藻密度由2.4×10⁶ cell·mL⁻¹降至(4~6)×10⁴ cell·mL⁻¹;大型溞可在沙河水库长期存活,并可长期抑制藻类、维持水体的透明度;水体COD并未发生明显改变;大型溞的分泌物促进了悬浮颗粒态氮、磷的沉降,使TN和TP的去除率分别达到70.2%和54.9%;由于投溞后藻类浓度迅速下降,藻对NH₃-N的吸收量降低,使水体NH₃-N升高了32.2%;底泥中有机质、TN、TP均出现了一定程度的升高。针对于湖库水体透明度低的问题,应投放适宜密度的大型溞,调整水质状态,并结合水中藻类、底泥污染物等条件,综合考虑有效改善水质的方法。     

乙酰甲胺磷对斜生栅藻的毒性及细菌降解研究

采用血球计数法测定斜生栅藻细胞数目,研究了乙酰甲胺磷对斜生栅藻的毒性作用,并通过藻类培养液中接种经过筛选得到的乙酰甲胺磷高效降解菌测定其对乙酰甲胺磷毒性的去除影响。研究结果表明,乙酰甲胺磷对斜生栅藻的抑制中浓度(EC50)大于159 mg/L,急性毒性为低毒。但进一步研究发现,在7 d后,EC50为174.68 mg/L,明显低于24 h的1 128.57 mg/L,存在亚慢性毒性。通过藻类培养液接种高效降解菌Y-6,乙酰甲胺磷对藻类的生长抑制程度减轻。     

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.     

好氧反硝化去除低浓度NOx的动力学模型研究

在好氧条件下,对利用生物滴滤塔(bio-tricklingfilter,BTF)反硝化净化废气中NOx的过程进行了理论模型探讨,并用实验结果进行了验证.在分析NOx在BTF内传质以及生物降解过程的基础上,建立了NOx在气相和生物膜相的质量守恒方程,结合Fick定律和好氧条件下的Monod微生物反应动力学方程,最终得到了...     

Surfactant-based oil dispersant toxicity to developing nauplii of Artemia: effects on ATPase enzymatic system

The paper deals with the toxicity of a surfactant-based oil dispersant to the ATPase activities of two naupliar stages of Artemia (instar I & II). Both instars were exposed to sub-lethal and lethal concentrations derived from acute toxicity data. The chosen concentrations were near to LOECs and NOECs. An eightfold difference indicated between the instars was instar-exposure time dependent. The most prominent effects were the inhibition and the stimulation of Na⁺/K⁺-ATPase and Mg²⁺-ATPase activities, respectively. The cause of these effects was related to the dispersant components, the surfactants. The pattern stimulation/inhibition of Mg²⁺-ATPase and Na⁺/K⁺-ATPase activities could be used to indicate toxic stress by surfactant-based oil dispersants since previous studies with other contaminants have shown different ATPase activity patterns.     

耐寒人工湿地植物石龙芮和酸模联用研究

为了提高人工湿地在寒冷季节的运行效率,对2种非夏季植物作为湿地植物处理生活污水的可行性进行了研究。结果表明,在本实验条件下2种植物对N、P元素都具有很好的去除效果,对COD的去除也达到45%～50%。通过单一植物系统和复合植物系统的处理效果比较,发现石龙芮酸模复合植物系统对污水中的P元素和COD的去除率更高。研究表明,石龙芮和酸模作为人工湿地植物具有可行性,与常规植物互补使用能在一定程度上延长人工湿地的运行时间。     

地表水中隐孢子虫和贾第鞭毛虫微球的混凝去除

以向地表水中投加的隐孢子虫微球和贾第鞭毛虫微球为对象,研究通过对给水混凝工艺对其的去除效果进行比较,着重考察了不同混凝剂种类、投加量及水样pH值对去除效果的影响.结果表明,混凝工艺可较为有效地去除地表水中的两虫微球,去除率最高可达4 lg.相比常规的金属盐类混凝剂,高分子的PAC、PAFC混凝剂对两虫微球的混凝去除率更...     

不同水温下鲴鱼对铜绿微囊藻的控制作用及对水质的影响

在室内受控模拟条件下开展实验,研究了在19、23、27、31、35℃5个水温梯度下鲴鱼对铜绿微囊藻和水质的影响。研究结果表明,在不同水温下,鲴鱼对铜绿微囊藻具有较强的控制作用,实验结束时铜绿微囊藻密度减少至初始密度的18%~30%,摄食率和消化率分别为6.83×104~8.32×104cells/(g·d)、93%~98%;叶绿素a的去除率为68%~88%;实验组TP、TN去除率分别为22%~25%、20%~38%,对照组的分别为80%~94%、28%~40%。对照组NH+4-N浓度变化很小(0.071~0.073 mg/L),而实验组氨氮浓度显著增大(2.222~3.645 mg/L),分别为初始值的31、34、42、51和46倍。     

Discrepancies in the acute versus chronic toxicity of compounds with a designated narcotic mechanism

In this study, it was illustrated that even for certain simple organic compounds with a designated mode of action (MOA) (i.e. narcotic toxicity) unexpected differences in acute and chronic toxicity can be observed. In a first part of the study, species sensitivity distributions (SSDs) based on either acute or chronic toxicity data of three narcotic test compounds (methanol, ethanol and 2-propanol) were constructed. The results of the acute SSDs were as expected for narcotic compounds: rather similar sensitivity and small differences in toxicity were observed among different species. On the contrary, the chronic SSDs of methanol and ethanol indicated larger interspecies variation in sensitivity. Furthermore, the chronic toxicity trend (ethanol > methanol > 2-propanol) was unexpectedly different from the acute toxicity trend (2-propanol > ethanol > methanol) and acute versus chronic extrapolation could not be successfully described for methanol and ethanol using an ACR of 10 (as suggested for narcotic compounds). In contrast to the interspecies approach in the first part of this study, the second part of the study was focused on the assessment of acute and chronic toxicity of the three test compounds in Daphnia magna, which was identified as one of the most sensitive organisms to methanol and ethanol. Here, the differences in acute and chronic toxicity trend were in accordance to the results of the SSDs. The enhancement of membrane penetration due to the small molecular size of methanol and ethanol, in combination with the higher toxicity of their respective biotransformation products were suggested as potential causes of the increased chronic toxicity. Furthermore, it was stressed that larger awareness of these irregularities in acute to chronic extrapolations of narcotic compounds is required and should receive additional attention in further environmental risk assessment procedure.     

Euglena gracilis as a model for the study of Cu and Zn toxicity and accumulation in eukaryotic cells

We have observed the effect of copper and zinc on the biology of Euglena gracilis. The cells displayed different sensitivities to these metals, as the apparent LC₅₀ for Cu²⁺ was 0.22 mM, and for Zn²⁺ it was 0.88 mM. While Zn²⁺ was able to increase cell proliferation even at 0.1 mM, the minimal CuCl₂ concentration tested (0.02 mM) was sufficient to impair cell division. Higher concentrations of these metals not only inhibited cell division in a concentration-dependent manner, but also interfered with the metabolism of E. gracilis. A higher accumulation of proteins and lipids per cell was observed at the DI₅₀ concentration for metal-treated cells. These results suggest that the test concentration of both metals leads to a failure in completing cell division. Ultrastructural analysis indicated a chloroplast disorganization in copper-treated cells, as well as the presence of electron dense granules with different shapes and sizes inside vacuoles. Microanalysis of these granules indicated an accumulation of copper, thus suggesting a detoxification role played by the vacuoles. These results indicate that E. gracilis is an efficient biological model for the study of metal poisoning in eukaryotic cells. They also indicate that copper and zinc (copper being more poisonous) had an overall toxic effect on E. gracilis and that part of the effect can be ascribed to defects in the structure of chloroplast membranes.