PM_(2.5)和甲醛联合暴露致小鼠肺损伤及其分子机制的研究

我国城市当前普遍存在室外大气PM_(2.5)与室内甲醛(FA)联合污染状况,二者均被报道在单独暴露下可以导致肺损伤并诱导和诱发哮喘的急性发作,但其联合污染的具体效应,以及分子机制目前尚不清楚。为探究PM_(2.5)和/或甲醛暴露对小鼠的肺损伤及其可能的机制,分别将雄性Balb/c小鼠分为以下6组:对照组,AZD8055组,PM_(2.5)组,FA组,PM_(2.5)+FA组,PM_(2.5)+FA+AZD8055组。染毒结束后,观察肺组织病理学变化;检测肺组织氧化损伤,活性氧(reactive oxygen species,ROS),还原型谷胱甘肽(glutathione,GSH)和丙二醛(malondialdehyde,MDA)的含量,DNA损伤,DNA-蛋白质交联(DNA-protein crosslink,DPC)系数和8羟基脱氧鸟苷(8-OH-d G)的含量,以及细胞凋亡、半胱氨酸天冬氨酸蛋白酶-3(Caspase-3)的含量。结果表明,当吸入气态甲醛浓度为3 mg·m-3,气道滴注PM_(2.5)浓度为2.5 mg·m L-1时,肺组织出现不同程度的支气管重塑和炎症细胞浸润。ROS显著上升,GSH显著下降,DPC、8-OH-d G以及Caspase-3都显著上升。添加AZD8055后,肺组织损伤效应更加显著。PM_(2.5)复合甲醛的暴露导致小鼠肺损伤具有协同作用,氧化应激及其下游的DNA损伤可能是甲醛联合PM_(2.5)致小鼠肺损伤的一种重要机制。     

Immunotoxic effect of arsenic trioxide on Caenorhabditis elegans

A Pseudomonas aeruginosa–Caenorhabditis elegans pathogenesis model was utilized to assess immunotoxic effects of arsenic trioxide (As₂O₃). After 2 h of As₂O₃ exposure, 500 µmol L^?1 and 1 mmol L^?1 As₂O₃ treatment significantly decreased median survivals of C. elegans (10 h after L4/adult molt). However, 2 h of As₂O₃ exposure caused no significant changes in the survivals rates of C. elegans (2 h after L4/adult molt). Notably, a significant dose-related immunoenhancement was observed in C. elegans (2 h after L4/adult molt) after 12 h of arsenite exposure.     

出生前后全氟辛烷磺酸（PFOS）暴露对大鼠额叶皮质中IGF-Ⅰ、IGF-ⅠR和IGFBP-2 mRNA水平的影响

为研究出生前后不同时期全氟辛烷磺酸(PFOS)暴露对大鼠仔鼠额叶皮质胰岛素样生长因子-Ⅰ(IGF-Ⅰ)、胰岛素样生长因子-Ⅰ受体(IGF-ⅠR)和胰岛素样生长因子结合蛋白-2(IGFBP-2)mRNA水平的影响,将28只受孕Wistar大鼠按3:2:2的比例随机分到对照(C)、低剂量(L)和高剂量(H)组中,从妊娠第0天开始分别自由摄食含0、7.2、14.4mg·kg-(1以饲料中的PFOS计)的粉末状饲料进行连续染毒至出生后28天.采用交叉哺育的方法建立出生前后均不暴露(CC)、仅出生前暴露(LC和HC)、仅出生后暴露(CL和CH)、出生前后均暴露(LL和HH)于PFOS的动物模型.采用半定量RT-PCR法检测各组仔鼠额叶皮质IGF-Ⅰ、IGF-ⅠR和IGFBP-2mRNA水平的变化.结果表明,对照组仔鼠额叶皮质IGF-Ⅰ、IGFBP-2mRNA在PD14时处于较高水平,而在PD1和PD28时水平较低;IGF-ⅠRmRNA在PD1时只处于较低水平,随年龄的增加而逐渐升高.在PD1时,暴露组仔鼠IGF-Ⅰ、IGF-ⅠR、IGFBP-2mRNA水平显著高于对照组(p<0.05).在PD14时,除LC组仔鼠IGF-ⅠRmRNA水平显著高于对照组之外,其余各暴露组仔鼠3者mRNA水平均显著低于对照组(p<0.01).此外,出生后暴露PFOS组的仔鼠额叶皮质IGF-Ⅰ、IGFBP-2mRNA水平降低程度比出生前暴露PFOS组仔鼠更高.在PD28时,暴露组仔鼠IGF-Ⅰ、IGF-ⅠRmRNA水平显著低于对照组(p<0.01),而IGFBP-2mRNA水平与对照组之间的差异无显著性(p>0.05).出生前后不同时期暴露PFOS导致大鼠仔鼠额叶皮质IGF-Ⅰ、IGF-ⅠR和IGFBP-2mRNA水平变化,为PFOS发育神经毒性的研究提供了一定的线索.     

溶解性有机碳的主要组成对青鳉鱼铜急性毒性的影响

为揭示溶解性有机碳(DOC)的组成对生物配体模型(BLM)预测铜的生物毒性准确性的影响,研究了不同浓度黄腐酸(FA)、腐殖酸(HA)和两者不同浓度比例混合物影响铜对青鳉急性毒性。结果表明:在相同水质条件下,黄腐酸或腐殖酸浓度增加时,铜对青鳉的LC50均增加;两者共存时,当腐殖酸质量百分比从10%增至90%时,铜对青鳉的LC50也增加。当天然水中DOC的组成不确定时,可假设HA和FA的组成比例为1∶1,此时BLM预测铜对青鳉的LC50的偏差最小。     

Factors influencing the distribution and coexistence of Pachygrapsus crassipes and Hemigrapsus oregonensis (Decapoda: Grapsidae) in a California salt marsh

It has recently been demonstrated that acute midultraviolet irradiation (UV-B, 290 to 320 nm) of the marine copepod Acartia clausii results in reduced survival and fecundity. In the present study, immature late copepodites were separted by sex and exposed to three UV-B exposure levels (0, 25, and 50 effective_DNA Jm^-2). The irradiated copepods were then reared to sexual maturity, and adult virgin survivors were mated according to prior exposure, supplying 7 different types of mating crosses (M0F0, M0F25, M25F0, M25F25, M0F50, M50F0, M50F50). Six replications of each cross were maintained for the duration of an experiment. Two experiments are documented. There was a significant effect of UV-B radiation on the survival of the parents as well as a reduction in the number of eggs and the number of living nauplii produced. For each experiment, 30 nauplii from each type of cross were separated, reared to maturity and counted, providing information on the survival capability of non-irradiated offspring from the 7 different mating types. Previous exposure of parental stock did not significantly affect the survival, and development to maturity, of these nauplii 15 d after separation.     

Cytotoxicity and cell membrane depolarization induced by aluminum oxide nanoparticles in human lung epithelial cells A549

The cytotoxicity of 13 and 22 nm aluminum oxide (Al₂O₃) nanoparticles was investigated in cultured human bronchoalveolar carcinoma-derived cells (A549) and compared with 20 nm CeO₂ and 40 nm TiO₂ nanoparticles as positive and negative control, respectively. Exposure to both Al₂O₃ nanoparticles for 24 h at 10 and 25 µg mL^?1 doses significantly decreased cell viability compared with control. However, the cytotoxicity of 13 and 22 nm Al₂O₃ nanoparticles had no difference at 5–25 µg mL^?1 dose range. The cytotoxicity of both Al₂O₃ nanoparticles were higher than negative control TiO₂ nanoparticles but lower than positive control CeO₂ nanoparticles (TiO₂ < Al₂O₃ < CeO₂). A real-time single cell imaging system was employed to study the cell membrane potential change caused by Al₂O₃ and CeO₂ nanoparticles using a membrane potential sensitive fluorescent probe DiBAC₄(3). Exposure to the 13 nm Al₂O₃ nanoparticles resulted in more significant depolarization than the 30 nm Al₂O₃ particles. On the other hand, the 20 nm CeO₂ particles, the most toxic, caused less significant depolarization than both the 13 and 22 nm Al₂O₃. Factors such as exposure duration, surface chemistry, and other mechanisms may contribute differently between cytotoxicity and membrane depolarization.     

Effect of formaldehyde exposure on structure and function of epididymis in adult rats: a histological and biochemical study

Formaldehyde (FA), a ubiquitous environmental pollutant, is extensively used in hospitals, laboratories, and industrial settings. Previous studies showed that FA exerts adverse effects on testicular function and as epididymis is known to play an important role in the maturation and storage of sperm, the effects of FA were examined on epididymis. In particular, this study was designed to investigate the influence of FA on structure and function of epididymis in adult male rats using histological and biochemical methods. Sprague-Dawley adult rats were randomly allotted to three groups and exposed to FA at a 0 (control), 0.5, or 10 mg m^?3 by inhalation for 28 days. The results indicated that epididymal toxicity of FA was concentration dependent. Epdididymal structure and function in rats of 0.5 mg m^?3 FA exposure group showed no apparent difference from control. However, epididymal weight, sperm count and motility, the activities of superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) were significantly decreased, whereas the levels of malondialdehyde (MDA) was significantly increased in epididymis of rats exposed to 10 mg m^?3 FA. Moreover, microscopy with hematoxylin and eosin (H&;E) staining showed atrophy of epididymal tubules, disintegration of epididymal epithelium, disorganization, and even vacuolar denaturalization of epididymal epithelial cells. There was hyperemia in interstitial vasculature and lumina were oligozoospermic in rats of 10 mg m^?3 FA exposure group. In conclusion, FA exposure alters the epididymal structure and function by inducing oxidative stress in epididymis of adult rats.     

Synthesis and antibacterial activity of a Fe3O4–AgCl nanocomposite against Escherichia coli

In this investigation, Fe₃O₄ magnetic nanoparticles (MNPs) were prepared by the alkalinization of an aqueous medium containing ferrous sulfate and ferric chloride. In the next step, a Fe₃O₄–AgCl magnetic nanocomposite was fabricated by the drop-by-drop addition of silver nitrate solution into a NaCl solution containing Fe₃O₄ MNPs. All prepared nanoparticles were characterized by transition electron microscopy (TEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). Both particle types varied in size from 2.5 to 20?nm, with an average size of 7.5?nm for Fe₃O₄ MNPs and 12.5?nm for Fe₃O₄–AgCl nanocomposites. The antibacterial effect of the Fe₃O₄ MNPs and fabricated Fe₃O₄–AgCl nanocomposites against Escherichia coli (ATCC 35218) were investigated by conventional serial agar dilution method using the Müller–Hinton Agar medium. The minimum inhibitory concentration was 4?mg?mL^?1 for Fe₃O₄ MNPs and 2?mg?mL^?1 for the Fe₃O₄–AgCl magnetic nanocomposites. Time-kill course assays showed that the Fe₃O₄–AgCl magnetic nanocomposites successfully killed all inoculated bacterial cells during an exposure time of 60?min. The antibacterial activity of recycled Fe₃O₄–AgCl magnetic nanocomposites over four 60?min cycles of antibacterial treatment was further tested against E. coli by the colony-forming unit (CFU) method. The antibacterial efficiency of the nanocomposites was constant over two cycles of antibacterial testing.     

Metal Interactions in carcinogenesis†

Mixed exposures to a number of metallic compounds may give rise to a carcinogenic response in humans.

An interaction between occupational exposure to arsenic and cigarette smoking has been documented epidemiologically. A multiplicative effect was indicated concerning the occurrence of lung cancer when both of the exposures were present. Several experimental studies have been reported in the literature concerning interactions between benzo(a)pyrene and Fe₂O₃ as well as some other metallic compounds like Ni₃S₂, PbO, MgO and TiO₂ in relation to respiratory carcinogenicity. There is also limited evidence of a positive interaction between arsenic trioxide and benzo(a)pyrene. Particles containing V and Ni were obtained from the flue gases of power plants burning heavy fuel oil. Such particles were not carcinogenic themselves but enhanced the carcinogenicity of benzo(a)pyrene even more efficiently than Fe₂O₃.

Increased dietary selenium intakes can decrease the carcinogenicity of several organic carcinogens in animals and dietary zinc can effectuate both enhancement and inhibition of carcinogenicity depending on dietary concentration.     

Influence of cadmium accumulation and dietary status on fatty acid composition in two colour forms of shore crabs, Carcinus maenas

 The effects of cadmium exposure and dietary status on cadmium accumulation, fatty acid (FA) content and profiles were investigated in two colour forms of the shore crab Carcinus maenas. Groups of shore crabs were either starved or fed with blue mussels, Mytilus edulis, during a 40 d exposure period to 2 or 6 μM Cd²⁺ (as CdCl₂). Starved green individuals accumulated more cadmium in haemolymph and hepatopancreas than did red crabs and green crabs fed during the experiments. In the red colour form, no difference in cadmium accumulation was observed between starved and fed individuals. In both colour forms, hepatopancreas contained more FA than gills and muscle. The FAs often present in the largest amounts in the tissues were 16:0, 16:1ω7, 18:1ω7, 18:1ω9, 20:4ω6, 20:5ω3 and 22:6ω3. However, saturated (SAFA) and mono-unsaturated fatty acids (MUFAs) were dominant in hepatopancreas, whereas poly-unsaturated fatty acids (PUFAs) were dominant in gills and muscles. At the beginning of the experiment, the total FA content in the hepatopancreas was 111.6 mg g⁻¹ (dry weight) for red crabs and 78.4 mg g⁻¹ for green shore crabs. During the experiment, however, the FA content decreased in red crabs. This decrease was more pronounced for starved individuals than for fed individuals. Also, the decrease in FA content was more pronounced in crabs exposed to 6 μM cadmium compared to crabs exposed to 2 μM or crabs not exposed to cadmium. No change in FA content was observed in green shore crabs, irrespective of diet and cadmium exposure. For both colour forms, no change in FA content was observed for gills and muscle. In red crabs, a decrease was observed for all FAs in the hepatopancreas. This decrease, however, was more pronounced for SAFAs and MUFAs than for PUFAs, indicating that the metabolism of FAs during starvation and cadmium exposure is selective. The experiments indicate that green colour forms of shore crabs are more tolerant of natural stress such as starvation and anthropogenic stress, e.g. cadmium exposure, than are red colour forms of shore crabs. Received: 23 September 1999 / Accepted: 29 April 2000     

镉胁迫对脊尾白虾的毒性效应研究

为揭示重金属镉对脊尾白虾的毒性效应,采用急性毒性实验方法,研究了不同浓度镉(Cd~(2+))对脊尾白虾(Exopalaemon carinicauda)血清氧化应激相关生理指标的活性以及肌肉组织中腺苷酸转移酶基因(ANT)和热激蛋白70基因(HSC70)表达水平的影响。共设置4个Cd2+浓度胁迫(0、0.0002、0.001、0.005 mmol·L~(-1)),分别在0、3、6、9、12、24、36、48、72和96 h共10个时间点对相关指标进行测定。结果显示:不同浓度镉胁迫下,脊尾白虾血清中H_2O_2含量、MDA含量和GSH含量均表现为先升高后降低的趋势,H2O2含量在胁迫3 h时即出现明显的升高,而MDA和GSH则均在9 h时出现升高趋势,表现为一定的滞后性。H2O2含量在0.005 mmol·L~(-1)胁迫3 h时出现峰值,MDA含量在0.005 mmol·L~(-1)胁迫9 h时出现峰值,GSH含量在0.001mmol·L~(-1)胁迫48 h时出现峰值,且均与对照组存在显著性差异(P0.05)。HSC70基因的表达量在不同浓度胁迫下均表现为先升高后降低的趋势,且均在24 h时达到峰值,具体表达量水平的顺序为:0.0002 mmol·L~(-1)0.001 mmol·L~(-1)0.005 mmol·L~(-1)。ANT基因的表达量在不同浓度下则均表现为明显的下调趋势。由此可见,急性Cd~(2+)胁迫不仅影响脊尾白虾的氧化应激相关生理指标,还影响机体内组成型HSC70及与能量传递有关的ANT基因的表达水平。     

Models for the physiological effects of short O3 exposures on plants

Some published effects of ozone on plant photosynthesis and evaporation are detailed, and attempts were made to develop explanatory models of increasing complexity. Stomatal regulation, which keeps the CO₂ concentration inside the lead constant, is assumed. The O₃ concentration inside the leaf is assumed to be neglible, so O₃ uptake, CO₂ uptake and stomatal conductance must be proportional. The suppression of photosynthesis is assumed to be proportional to the integrated effective O₃ uptake. For a first model, a differential equation is derived from these assumptions and a simple analytical solution is found. A second model includes a threshold O₃ flux. The repair process is discussed and three models are investigated with a constant repair rate, a repair rate dependent on the stage of injury, and with a repair rate dependent on the photosynthetic rate. A comparison of the analytical solutions of the appropriate differential equations with literature data shows that the model with repair dependent on photosytheesis is the most successful one, but a constant repair rate also gives a fair approximation. The model with repair dependent on photosynthesis implies the existence of a threshold level for the suppression of photosynthesis which separates reversible and irreversible O₃ effects. With the assumption of an inhomogeneous leaf a model to predict visible leaf injury is derived. The possible existence of a maximum leaf injury index for one exposure concentration is explained from the properties of the models. The restrictions and possible extensions of the models are discussed. The concept of a threshold O₃ flux and of a critical suppression of photosynthesis are shown to give possible explanations of antagonistic and synergistic effects of O₃, SO₂ and NO₂.     

2,2’,4,4’-四溴联苯醚对大型溞的毒性效应

以实验室培养的大型溞为受试生物,进行了2,2’,4,4’-四溴联苯醚(BDE-47)对大型溞的48h急性毒性实验和21d慢性毒性实验,并研究了暴露在不同质量浓度和处理时间的BDE-47中,大型溞的抗氧化酶系中的超氧化物歧化酶(SOD)和谷胱甘肽硫转移酶(GST)的酶活性变化。结果表明,BDE-47对大型溞的48h的半致死浓度为1.04mg·L-1,属于高毒物质;在BDE-47慢性毒性实验低浓度处理组中,大型溞的体长及繁殖能力受到了抑制,而高浓度处理组中大型溞的体长及繁殖能力上升,其中第一次产仔数和产卵总数是表征BDE-47慢性毒性的最灵敏参数。随着BDE-47浓度的增加,大型溞SOD和GST活性均呈现出低浓度诱导高浓度抑制的现象。SOD和GST均表现出一定的敏感性,但相对SOD,GST对BDE-47暴露更为敏感。     

甲醛暴露时间延长加剧小鼠哮喘模型肺氧化损伤并促进IL-17表达

为了探究不同暴露时间甲醛对小鼠哮喘模型肺氧化应激及IL-17表达的影响,用浓度为3.0 mg·m~(-3)的甲醛气体吸入染毒,同时将48只雄性Balb/c小鼠随机分为6组:(1)对照组(生理盐水组);(2)ovalbumin(OVA)致敏组;(3)0.5 h甲醛+OVA组;(4)1h甲醛+OVA组;(5)1.5 h甲醛+OVA组;(6)2 h甲醛+OVA组,以不同时间长度进行甲醛暴露,连续35 d。OVA致敏组、0.5 h甲醛+OVA组、1 h甲醛+OVA组、1.5 h甲醛+OVA组、2 h甲醛+OVA组均在第11、18及25天腹腔注射OVA致敏液(5 mg OVA+175 mg Al(OH)_3+30 mL生理盐水),第29~35天(共计1周)进行1%OVA雾化(30 min·d~(-1)),每日1次,诱发哮喘。第36天进行以下操作:取肺组织测定肺系数并制作肺匀浆,检测肺组织中活性氧自由基(ROS)、丙二醛(MDA)和还原型谷胱甘肽(GSH)的含量,并采用ELISA法检测肺组织中IL-17的水平。同时,采用HE染色法观察小鼠肺部气道的病理学变化。结果显示,在浓度为3.0 mg·m~(-3)的甲醛气体吸入染毒条件下,与对照组相比,1.5 h甲醛+OVA染毒组、2 h甲醛+OVA染毒组ROS、MDA、IL-17含量上升,具有统计学意义(P0.01)。同时,随着暴露时间长度的增加,小鼠肺部气道出现明显病理学变化。综上所述,每天2 h甲醛+OVA染毒能对小鼠肺造成损伤并恶化OVA对小鼠肺的损伤,产生炎症反应,并通过氧化应激反应介导。     

Boundary Layer Evolution and its Influence on Ground-Level Ozone Concentrations

Accurate determination of the planetary boundary layer (PBL) height (i.e., mixing height (MH)) is critical to properly simulating pollutant levels with the grid-based photochemical models. In this study, the daytime mixing heights based on the parcel and bulk Richardson number methods are compared with those obtained directly from a numerical mesoscale meteorological model in an effort to evaluate the uncertainties in the estimation of the PBL evolution. Mixing heights are estimated from hourly outputs of meteorological variables of the Penn State/NCAR Mesoscale Model Version 3.3 (MM5V3) with two PBL schemes (Blackadar and Gayno-Seaman) during July 1999 over Philadelphia, PA. An analysis of the diurnal variation in the urban PBL and its influence on ground-level ozone (O₃) levels is presented in this paper. The results indicate that on average, the MHs determined from the bulk Richardson number were larger than those estimated from the parcel method. The MHs from the MM5V3 output were much smaller than those derived from the parcel and bulk Richardson number methods, especially for the Gayno-Seaman scheme that is based on turbulent kinetic energy. The MH and ground-level O₃ concentration have been found to be twice as much on episode days than on non-episode days. The average hourly MH growth rate and O₃ tendency (i.e. rate of change in O₃) were largest during the morning hours (0700 to 1000 eastern standard time (EST)), suggesting that vertical mixing contributes significantly to the accumulation of ground-level O₃ in urban areas in the morning hours.     

Accumulation and release of petroleum-derived aromatic hydrocarbons by four species of marine animals

Survival of Ctenodiscus crispatus during exposure to hypoxia (P _{O 2}<3 mm Hg) at 5°C is greater than that of any echinoderm reported in the literature, the LT₅₀ being 248 h; this is reduced to 236 h in the presence of hydrogen sulfide. Unlike Asterias vulgaris and A. forbesi, both of which lose the tube foot response to tactile stimulation long before death from hypoxia occurs, C. crispatus remains responsive until death. The extension of the highly protrusible epiproctal cone, which occurs in 75% of the mud stars simultaneously exposed to hypoxia and H₂S, serves to maintain burrow contact with the overlying water. The rate of oxygen consumption remains constant down to an ambient oxygen partial pressure of 10 to 25 mm Hg, becoming more oxygen-dependent after prior exposure of the asteroids to hypoxia. C. crispatus exhibits a clear oxygen-debt phenomenon as well as a compensatory reduction in the residual P _{O 2} (oxygen partial pressure at which oxygen consumption ceases) from 2.4 to 0.2 mm Hg after hypoxic exposure.     

Determination of F2-isoprostanes in cultured human lung epithelial cells after exposure to metal oxide and silica nanoparticles by high-performance liquid chromatography/tandem mass spectrometry

The environmental impact of nanotechnology has caused a great concern. Many in vitro studies showed that many types of nanoparticles were cytotoxic. However, whether these nanoparticles caused cell membrane damage was not well studied. F₂-isoprostanes are specific products of arachidonic acid peroxidation by nonenzymatic reactive oxygen species and are considered as reliable biomarkers of oxidative stress and lipid peroxidation. In this article, we investigated the cytotoxicity of different nanoparticles and the degree of cellular membrane damage by using F₂-isoprostanes as biomarkers after exposure to nanoparticles. The human lung epithelial cell line A549 was exposed to four silica and metal oxide nanoparticles: SiO₂ (15 nm), CeO₂ (20 nm), Fe₂O₃ (30 nm), and ZnO (70 nm). The levels of F₂-isoprostanes were determined by using high-performance liquid chromatography/mass spectrometry. The F₂-isoprostanes’ peak was identified by retention time and molecular ion m/z at 353. Oasis HLB cartridge was used to extract F₂-isoprostanes from cell medium. The results showed that SiO₂, CeO₂, and ZnO nanoparticles increased F₂-isoprostanes levels significantly in A549 cells. Fe₂O₃ nanoparticle also increased F₂-isoprostanes level, but was not significant. This implied that SiO₂, CeO₂, ZnO, and Fe₂O₃ nanoparticles can cause cell membrane damage due to the lipid peroxidation. To the best of our knowledge, this is the first report on the investigation of effects of cellular exposure to metal oxide and silica nanoparticles on the cellular F₂-isoprostanes levels.     

广州市某A2/O工艺城镇污水处理厂出水对大型溞的生殖毒性作用

城镇污水处理厂废水中存在大量生物毒性物质,但该废水对动物的生殖能力影响研究还十分缺乏。利用大型溞暴露实验,检测广州市某采用A~2/O工艺的城镇污水处理厂出水的急性毒性和生殖毒性。48 h急性毒性实验表明,所有水样均未表现出急性毒性效应。慢性生殖毒性(14 d)测试结果表明:(1)从进水到缺氧池出水均能显著提高第一胎产溞数量;(2)进水和沉砂池出水显著增加受试期总产溞数量;(3)从厌氧池到出水工艺段受试溞的第一胎产溞时间均推后;(4)好氧池出水的毒性显著降低,但仍然对大型溞具有生殖毒性。研究表明,好氧池(A~2/O)工艺能够显著去除具有大型溞生殖毒性的物质,但污水处理厂废水的生殖毒性仍需要引起关注。     

Accumulation and elimination of cadmium and lead in juvenile milkfish during sublethal exposure

Pollution of aquatic environments by trace metals is a worldwide environmental problem. Metal pollutants are increasingly being released into the environment as a result of industrialization. In this study, the bioaccumulation of cadmium and lead in young juvenile milkfish liver (Chanos chanos) was investigated after exposure to three sublethal concentration of each pollutants (1/20, 1/10, and 1/5 LC₅₀ of 96-h LC₅₀) for acute time 12, 24, and 96 h and subchronically for 7, 14, and 21 days. Cadmium and lead accumulation in liver increased with the exposure period and concentrations of pollutant. Compared to controls, the uptake of cadmium is much higher than that of lead. Accumulation factors showed an increase with exposure time and for lead an inverse relationship between accumulation factor and exposure concentration. The elimination of the two pollutants during the 30 days depuration was investigated after 30 days depuration time. During this phase, cadmium and lead concentrations decreased.     

Physiological responses to fluctuation in temperature of salinity in invertebrates. Adaptations ofAlpheus viridari (Decapoda,Crustacea),Terebellides parva (Polychaeta) andGolfinigia cylindrata (Sipunculida) to the mangrove habitat

The snapping shrimpAlpheus viridari (Armstrong, 1949), the polychaeteTerebellides parva Solis-Weiss, Fauchald and Blankensteyn 1990, and the sipunculanGolfingia cylindrata (Keferstein, 1865) are commonly found in the same mangrove habitat, where they experience frequent, acute fluctuations in temperature and salinity. Ecological studies indicate a temporal variation, including occasional absence, in the distribution of bothG. cylindrata andT. parva; this fed us to examine the physiological adaptations of the three species (collected at Western Bay, Twin Cays, Belize in 1985, 1986 and 1988). Each was subjected to acute, repeated exposure to either control (35 S) and decreased (25 S) salinity or to control and increased (45 S) salinity. Ability to regulate water and ion content (g H₂O or mol g^-1 solute free dry wt) was examinedA. viridari behaved as a hyperosmotic conformer at decreased salinity but as an osmoconformer at increased salinity. Regardless of direction of salinity change,A. viridari regulated water content through change in Na⁺, K⁺, and Cl^– contents. In contrast,G. cylindrata behaved as an osmoconformer and did not demonstrate ability to regulate water content.T. parva behaved as an osmoconformer, showed incomplete regulation of water content via change in Na⁺, K⁺, and Cl^– contents but had limited survival following exposure to 45 S. Each species was also exposed to change in temperature. Species were subjected to acute, repeated exposure either to control (28°C) and decreased (21°C) temperature or to control and inereased (35°C) temperatureA. viridari regulated water and ion content under both experimental conditions. In contrast,T. parva did not regulate water and ion content under either experimental temperature.G. cylindrata did not regulate water and ion content during exposure to decreased temperature and did not survive exposure to increased temperature. ForA. viridari, weight specific oxygen uptake rates (mg O₂ g^-1 ash-free dry wt) were determined. Exposure to decreased salinity or to increased temperature resulted in a small sustained elevation in O₂ uptake. It is concluded that, unlikeA. viridari, T. parva andG. cylindrata are only marginally adapted to withstand the salinity and temperature stresses, respectively, of the mangrove habitat. The inability ofT. parva andG. cylindrata to fully adapt to extremes in the mangrove habitat could well explain the temporal variation seen in the distribution of these two species.Contribution number 380. Caribbean Coral Reef Ecosystems, National Museum of Natural History, Smithsonian Institution