几种重金属离子对Pistia stratiotes叶绿素含量及光合活性的影响(英文)

对在pH6.5时含不同浓度锰、锌、铁和铅的培养液中,预处理3天的Pistia stratiotes 叶片,进行了O_2的吸收与释放及其叶绿素a,b含量的测定。结果表明:4种金属离子抑制O_2的释放而促进叶片对O_2的吸收。锌预处理可以提高叶绿素a,b的含量,而铅使叶绿素含量减少。用铁和锰处理时,可使叶绿素a积累而叶绿素b减少。上述结果意味着金属离子防碍叶绿素的形成及光合电子的转移。     

冬季重剪桑树实行中间采伐与桑品种的关系

对4个实行冬季重剪的桑树品种,在夏蚕5龄盛食期采取中间采伐,即剪去枝条1/2.结果表明,秋叶质量明显提高,而秋叶产量与桑品种有关,桐乡青、小冠桑、新一之濑比对照增产10%以上,嘉陵9号的产叶量则大幅度下降.因此,选择耐剪伐的桑品种实行中间采伐,不仅可提高秋叶质量,为养蚕提供稚蚕用桑,而且还可提高桑叶产量.     

Botulinum neurotoxin type A heavy chain intervenes in expression of general proteins in spinal cord after unilateral spinal cord injury in rats

AIM: To observe the effect of botulinum neurotoxin type A heavy chain (BoNT/A HC) on the pattern of spinal protein expression by intrathecal injection after spinal cord injury in rats, and to explore the role of BoNT/A HC intervention in spinal protein expression and some of its mechanisms in nerve regeneration after injury. METHODS: The model of unilateral lumbar spinal cord injury was established. The effects of BoNT/A HC intervention at different doses (2 μg, 4 μg, 6 μg and 8 μg) on the general pattern of protein expression in the spinal cord tissues at the injury site and the cranial part adjacent to the injury site was measured and evaluated by SDS-PAGE and Coomassie brilliant blue staining first, and then by two-dimensional SDS-PAGE. RESULTS: The histological structure of the ipsilateral side of lumbar spinal cord showed obvious destruction and degradation, mainly affecting both gray and white matter of the left side of the cord. The result of SDS-PAGE with Coomassie brilliant blue staining from injured spinal cord tissue displayed that the expression of some proteins after one-time BoNT/A HC treatment appeared obviously different from that without BoNT/A HC treatment. Moreover, the pattern of the protein expression affected by BoNT/A HC was similar to that of the normal spinal cord. The more detail information from two-dimensional SDS-PAGE indicated that more than 10 proteins with different molecular weight and isoelectronic points were differentially expressed at day 2 and day 20 after local injection of 6 μg BoNT/A HC. This altered expression actually appeared a tendency toward the pattern shown in normal group. CONCLUSION: The immediate application of BoNT/A HC at the injury site after unilateral lumbar spinal cord injury is able to affect the pattern of local protein expression. The altered protein expression by injury could be reversed back to normal or approximately normal by local BoNT/A HC administration.     

土壤重金属不同污染评价方法比较:以潼关县金矿排水沟为例

为了比较不同的土壤重金属污染评价方法,利用单因子污染指数法、地质累积指数法及内梅罗综合污染指数法,对潼关县某金矿排水沟沿线土壤样品中5种重金属(Sb,Sn,Pb,Ti,Ba)进行了污染评价对比。结果表明:单因子污染指数和地质积累污染指数评价结果均表明,5种重金属污染程度依次为Sb>Sn>Pb>Ti>Ba;内梅罗综合污染指数评价结果显示,35个样区均处于严重污染状态;3种方法中地质累积指数法较适宜对所选矿区的污染评价。     

近岸海域环境中鱼体对重金属污染物的响应浅析

以鲈鱼和大黄鱼为例,通过测定各组织器官中铜、锌、铅、镉的含量,探讨这四种重金属元素在鱼体内吸收、转移、分布规律,结果表明:1.在脑、眼、皮、肉、鳔和性腺等可食用部位中,脑和性腺是重金属的主要靶器官,肌肉组织中重金属含量最低;2.重金属在鳃、消化道和皮的单位质量含量的差异与对应的三种吸收途径的不同贡献有关;3.血液循环系统和代谢系统各脏器分别在重金属的转移和解毒代谢方面起重要作用,但不同重金属的响应并不一致。     

凹凸棒石-污泥共热解生物炭对玉米苗期生长特性和重金属富集效应的影响

利用凹凸棒石和污泥制备7种不同比例(0、5%、10%、15%、20%、25%、30%)的凹凸棒石-污泥共热解生物炭。通过盆栽试验调查凹凸棒石-污泥共热解生物炭对玉米生长和土壤中重金属(Cu、Zn、Pb、Ni、Cd)富集的影响。结果表明:凹凸棒石添加量为15%的凹凸棒石-污泥共热解生物炭显著促进了玉米的出苗率和株高,分别增加了55.87%和24.35%,凹凸棒石添加量为20%时,根长、鲜质量和干质量分别增加了65.57%、79.85%和76.84%。凹凸棒石-污泥共热解生物炭对重金属的富集有显著抑制作用,凹凸棒石添加量为15%时,显著抑制了玉米对Cu、Zn、Ni、Cd的富集,分别减少了55.01%、49.27%、54.87%、41.99%,凹凸棒石添加量为20%时,使重金属Pb的富集量减少了34.01%。凹凸棒石的添加增强了污泥生物炭的钝化功能,为污泥安全利用提供了一种新方法。     

苏南某些水稻土中Cu Pb Hg As的剖面分布及其影响因素

采用田间深度间隔采样法,分析了苏南6个处于不同环境影响下的水稻土剖面中Cu、Pb、As和Hg全量深度分布。结果表明,4种元素在土壤剖面中的移动能力均较差;在工业环境下田块的土壤中的Hg、Cu、Pb的表层富集和垂直分异较为明显,而在非工业环境下,重金属纵向分异不明显;个别田块存在较严重的As污染,耕层As达56.93 mg.kg-1,超出国家土壤环境质量二级标准;重金属元素在稻田土壤中表层富集系数大于果园利用下的旱地土壤。工业化进程中污染物的输入是影响供试土壤中重金属元素含量的主导因素,土壤的基本性质也在一定程度上影响了重金属的纵向迁移。重金属剖面分布特征可以在一定程度上反映水稻土的重金属污染积累程度。     

Heavy‐metal displacement in chelate‐treated soil with sludge during phytoremediation

Heavy metals (HMs) in domestic sewage sludge, applied to land, contaminate soils. Phytoremediation is the use of plants to clean‐up toxic HMs from soil. Chelating agents are added to soil to solubilize the metals for enhanced uptake. Yet no studies report the displacement of HMs in soil with sludge following solubilization with chelates. The objective of this work was to determine the uptake or leaching of HMs due to a chelate added to a soil from a sludge farm that had received sludge for 25 y. The soil was placed in long columns (105 cm long; ?? 39 cm) in a greenhouse. Columns either had a plant (hybrid poplar; Populus deltoides Marsh. × P. nigra L.) or no plant. After the poplar seedlings had grown for 144 d, the tetrasodium salt of the chelating agent EDTA was irrigated onto the surface of the soil at a rate of 1 g per kg of soil. Drainage water, soil, and plants were analyzed for three toxic HMs (Cd, Ni, Pb) and four essential HMs (Cu, Fe, Mn, Zn). At harvest, extractable and total concentrations of each HM in the soil with EDTA were similar to those in soil without EDTA. The chelate did not affect the concentrations of HMs in the roots or leaves. With or without plants, EDTA mobilized all seven HMs and increased their concentrations in drainage water. Lower concentrations of Cd, Cu, Fe, Ni, and Zn in leachate from columns with EDTA and plants compared to columns with EDTA and no plants showed that poplars can reduce groundwater contamination by intercepting these HMs in the soil. But the poplar plants did not reduce Pb and Mn in the leachate from columns with EDTA. Concentrations of Cd and Pb in the leachate mobilized by EDTA remained above drinking‐water standards with or without plants. The results showed that a chelate (EDTA) should not be added to a soil at a sludge farm to enhance phytoremediation. The chelate mobilized HMs that leached to drainage water and contaminated it.     

Genetic variability in tolerance to cadmium and accumulation of heavy metals in pea (Pisum sativum L.)

Ninety-nine wild growing and primitive varieties of garden pea (Pisum sativum L.) were screened for tolerance to cadmium (Cd) toxicity in quartz sand culture. Cadmium tolerance was determined by the time to plant death when treated with a lethal Cd concentration (13 mg kg^-1), and by a tolerance index (TI) calculated as a ratio between biomasses of Cd-treated and untreated plants in the presence of toxic Cd concentrations (7 mg kg^-1 and 5 mg kg^-1). The Cd-tolerance index varied significantly between pea genotypes from 35% to 90% and from 54% to 100% in the presence of 7 and5 mg Cd kg^-1, respectively. Shoot Cd concentration of tolerant and sensitive genotypes grown in the presence of 5 mg Cdkg^-1 varied between 35 mg Cd kg^-1and 135 mg Cd kg^-1 (dry weight) and was negatively correlated with TI. Certain tolerant pea genotypes were characterized by a high Cd concentration in shoots. All varieties were also screened for their ability to take up heavy metals (HMs) from a slightly contaminated soil. The concentration of Cd, chromium, copper, nickel, lead, strontium and zinc in plant shoots varied between pea genotypes by a factor of 2.8, 4.9, 2.7, 3.5, 9.7, 3.9 and 4.0, respectively. The coefficients of variation between pea genotypes for HM concentration were high, varying from 23%to 39% depending on the metal. The distribution patterns for varieties based on Cd tolerance (sand culture) and HM concentrations (soil culture) were characterised by positive skewness coefficients, suggesting that the majority of pea genotypes was relatively sensitive to Cd toxicity and tended to avoid excessive accumulation of HMs in shoots. These results show that a high genetic variability exists in pea with regards to Cd tolerance and HM accumulation. Concentrations of different HMs in plants grown in soil correlated positively with each other, with the exception of chromium. There was no correlation between Cd tolerance of the varieties in sand culture, shoot concentration of HMs in soil culture, biomass production, subspecies and geographical origin of the varieties. The genetic systems controlling Cd tolerance, HM accumulation and morphological traits are therefore independent to some extent, suggesting a possibility for breeding pea cultivars characterised by high tolerance to and low concentration of HMs in shoots. This revised version was published online in August 2006 with corrections to the Cover Date.