氰化物污染的植物修复可行性研究

氰化物是目前世界范围内最常使用的提取黄金和白银等贵重金属的沥滤剂,其对自然生态环境的污染和破坏以及对人畜和其它生物的毒性作用是众所周知的.本试验用一自行设计的生物反应器来观察黄豆(Glycine max(L)Merr.)和玉米(Zea mays L.)对氰化物污染土壤的原位修复的可能性.室温条件下(23.0～26.0℃),低浓度的氰化物污染液对(≤45.5 CN mg·L^-1)二种测试植物的生长没有产生任何毒性作用;而在高浓度的氰化物试验组(≥91.0 CNmg·L^-1),二种测试植物的生长都出现了明显的滞长现象(生长率下降大于10%),但没有观察到其它毒性反应.同时二种测试植物的叶片细胞用来测定植物细胞线粒体中的氰丙氨酸合成酶(β-cyanoalanine synthase)转化氰化物的潜力.实验是在一封闭的玻璃器皿(100mL)中进行的(100mL的氰化钾溶液中加入1.5g(鲜重)植物的叶片,氰化钾溶液的浓度大约1.0 CNmg·L^-1).在为期28 h的时间内,水溶液中超过90%的氰化物被植物的叶片去除;黄豆和玉米的的叶片细胞对氰化物去除率分别测定为4.43mg CN·kg^-1(鲜重)·h^-1和3.42mg CN·kg^-1(鲜重)·h^-1.本实验结果表明,植物对氰化物污染的土壤原位修复方法是一种可行的和有效的选择.     

柳树对亚铁氰化物的吸收、代谢及其毒性研究

为探明亚铁氰化物在植物体内的迁移、转化及对植物的毒性作用,以长出新根须和嫩叶的垂柳(SalixbabylonicaL.)枝条为材料,在自行设计的250ml生物反应器中生长192h,培养温度为24.0±1℃,亚铁氰化物水溶液的浓度分别为52.99,105.98,211.95和317.93mgCNL-1。结果表明:(1)低浓度实验组(52.99mgCNL-1)水溶液中10.85%的亚铁氰化物被植物吸收,随着浓度的升高吸收到植物体内的亚铁氰化物的比例(%)依次递减,但是统计学分析显示各实验组单位体重(湿重)的植物吸收亚铁氰化物的量无显著性差异;(2)在植物的各个部位都能检测到微量的亚铁氰化物,表明亚铁氰化物通过植物的蒸腾作用在植物体内的迁移。由于没有检测到在气态下的总氰化物,表明植物的蒸腾作用没有将亚铁氰化物释放到大气中;(3)尽管植物吸收到体内的亚铁氰化物是有限的,但物质平衡实验证明其在植物体内迁移的过程中超过96%的都能被植物有效转化;(4)所用的4种亚铁氰化物浓度在192h内没有对柳树产生毒性作用。因此认为:依据亚铁氰化物在水溶液→植物→空气系统内的迁移和转化,亚铁氰化物的植物修复是可能的。     

速生柳树苗对土壤铅的耐性、积累与分配特性研究

耐性植物为环境污染植物修复提供了一条良好的途径。通过盆栽试验研究了垂柳(Salix babylonica Linn.)和苏柳172(Salix jiangsuensis J172)扦插苗对人工添加土壤铅污染的耐性及其对铅的积累和分配。结果发现:柳树生物量与土壤有效铅含量呈显著负相关关系,中低浓度的铅污染对两种柳树的根系生物量影响不大,Pb2+浓度为1600 mg·kg-1时显著降低垂柳根系生物量,苏柳172在Pb2+浓度为1 200和1 600 mg·kg-1时根系生物量极显著降低,说明垂柳对高浓度的Pb2+耐性要好于苏柳172;垂柳和苏柳172根系长度、根表面积、根体积和根直径随着土壤铅浓度的增加持续下降,在Pb2+浓度为1600 mg·kg-1时,垂柳根系长度、根表面积、根体积和根直径分别比对照下降了50.40%、45.15%、44.44%、9.10%,苏柳172分别下降了45.00%、45.88%、47.02%、37.14%。柳树吸收的铅绝大部分积累在根部,迁移到茎部和叶部的数量较少,铅在2种柳树体内不同部位的积累量均为根茎叶。当Pb2+浓度为800 mg·kg-1时,垂柳和苏柳172的耐性指数为91.15%和84.26%,其对土壤中铅的吸收量达140.20和149.49 mg,表明两种柳树对中等土壤铅污染的修复具有较大潜力。     

植物氰化物对宝石上华蜗牛食物选择的影响

为验证植物氰化物能影响植食性动物的食物选择以及植食性动物的采食能诱导植物合成氰化物的假设,本研究分别在野外围栏和实验室内测定了宝石上华蜗牛Cathaica(Pliocathaica)orithyia对氰化物含量不同而其他营养成分相近的红三叶草Trifolium pratense和白三叶草T.repens的选择性,以及在宝石上华蜗牛的采食作用下,2种三叶草再生叶片中氰化物含量的变化。结果表明,无论在野外围栏还是在实验室条件下,宝石上华蜗牛均嗜食氰化物含量较低的红三叶草,而避食氰化物含量较高的白三叶草;实验个体对经其采食后的2种三叶草再生茎叶24 h的采食量较初次对三叶草24 h的采食量均显著降低;2种三叶草被宝石上华蜗牛取食后,其叶片中氰化物的含量均显著升高。因此,三叶草中的氰化物能有效阻遏宝石上华蜗牛对其采食,同时,宝石上华蜗牛的采食能诱导三叶草中氰化物的合成。     

丽格海棠的组织培养与快速繁殖

1　植物名称　丽格海棠 (Begoniaelatiorhybrids)。2　材料类别　叶片、嫩茎。3　培养条件　分化与增殖培养基 :( 1 )MS ;( 2 )MS+ 6 BA 0 .1mg·L- 1 (单位下同 ) ;( 3)MS + 6 BA 0 .2 +NAA 0 .0 1 ;( 4 )MS + 6 BA 0 .5 +NAA 0 .0 5。生根培养基 :( 5 ) 1 /2MS +IBA 0 .1 ;( 6) 1 /2MS ;( 7)MS。上述各培养基均加 3%食用白糖 ,0 .35 %琼脂固化 ,pH 5 .8,培养温度为 ( 2 0± 5 )℃ ,每天光照 1 0h左右 ,光照度约 1 5 0 0lx。4　生长与分化情况4.1　无性系建立　用常规组织培养法 ,将灭菌的叶片、嫩茎切块 (段 )接种在培养基 (…     

大豆叶片蔗糖酶的分离纯化及其特性

大豆叶片提取液中存在很高的蔗糖酶活力,皆在30 mg还原糖·克鲜重~(-1)·小时~(-1)以上。经DEAE-纤维素柱层析分离出了三种蔗糖酶。然后分别经Sephadex G—200凝胶过滤,或再经CMC柱层析,最后经聚丙烯酰胺凝胶电泳证明,三种蔗糖酶都得到了较好的纯化。它们的反应有相近的最适pH范围,蔗糖酶Ⅰ最适pH在5左右,酶Ⅱ和Ⅲ的最适pH在4～5之间。三种蔗糖酶的Km值(蔗糖)基本相同,约为1.3×10~(-2)M。它们的Vmax相差较大,酶Ⅰ、Ⅱ和Ⅲ可分别达100.57和13 mg还原糖·mg蛋白~(-1)·小时~(-1)。三种蔗糖酶的分子量非常接近,在71,000～76,000之间。     

龙须草叶片形态结构与生理功能的研究

利用定样平行配套观测方法 ,研究了龙须草叶片形态结构和光合、蒸腾等生理功能 ,结果表明 :龙须草叶片呈长剑形 ,叶长为 35～ 1 50 cm,最长可达 2 0 0 cm以上 ,叶宽为 0 .1 9～0 .48cm;功能叶结构具有典型的 C4 “花环结构”;上表皮中具有十分发达的保护水分过度蒸腾的“泡状细胞”;上表皮气孔分布密度大于下表皮。功能叶叶绿素 a/ b值为 3.2 8± 0 .2 6。背面叶平均光合强度为 62 .4( CO2 mg/ dm2 · h)、呼吸强度为 3.57( CO2 mg/ dm2 · h)、蒸腾强度为 372 6( H2 O mg/ dm2 · h)、气孔阻力为 0 .2 1 ( sec./ cm)、水分利用效率为 1 6.747。背面叶的光合强度和蒸腾强度明显高于腹面叶。     

Cu2+胁迫对2种速生柳幼苗生长及生理特性的影响

以营养溶液中培养的‘苏柳172’(Salix jiangsuensis CL J-172)和垂柳(Salix babylonica Linn)幼苗为材料,分析它们在不同浓度Cu2+溶液(0、20、40、80、100、200、300μmol.L-1)下的生长以及部分生理指标的变化,以明确2种速生柳树用于植物修复的潜力。结果显示:2种柳树幼苗的生物量、叶片色素含量、根系活力以及根系形态的各指标都随Cu2+浓度的增加而显著降低。它们叶片SOD和POD活性以及脯氨酸含量随Cu2+浓度的增加呈先上升后下降的趋势,‘苏柳172’和垂柳中SOD活性在Cu2+浓度为20μmol.L-1时最大,其POD活性分别在Cu2+浓度为100和40μmol.L-1时达到最大,而其脯氨酸含量在Cu2+浓度为200μmol.L-1时达到最大。可见,2种柳树生长均受到Cu2+胁迫的抑制,它们能够在一定程度上通过增加保护酶活性和脯氨酸含量来提高对Cu2+的耐受性,且‘苏柳172’对Cu2+的忍耐力强于垂柳。     

草毡寒冻雏形土CO2释放特征

研究了植物生长季节海北高寒草甸生态系统高寒嵩草草甸覆被下草毡寒冻雏形土的 CO2 释放速率。其结果表明 :CO2 释放速率有明显的日变化和季节动态。日最大排放速率多出现在 1 4 :0 0～ 1 6:0 0时 ,最小排放速率在 6:0 0～ 8:0 0时。植物生长季日最大振幅为 797.75mg/m2·h,最小振幅 1 97.33mg/m2·h。CO2 排放白天大于夜晚。不同物候期 CO2 释放速率不同 ,其顺序为草盛期 >枯黄期 >返青期。生长季土壤 CO2 释放速率的范围是 4 41 .72 mg/m2 · h± 1 55.2 9mg/m2· h,最大日均值为 681 .0 6mg/m2 · h( 7月 1 6日 ) ,最低值 1 76.65mg/m2 · h ( 6月 1日 )。退化草地土壤 CO2 释放速率明显低于未退化草地 ,生长季平均日均值低 1 37.4 7mg/m2·h。相关分析表明 :土壤 CO2 排放速率与气温、地表温度、土壤5cm、1 0 cm、1 5cm、2 0 cm、30 cm地温均呈显著和极显著相关关系。温度是影响土壤 CO2 释放速率的主要因子。     

右美托咪啶对脓毒症大鼠肾脏Toll受体4 的影响

目的：观察右美托咪啶对脓毒症大鼠肾脏功能及Toll 受体4 表达的影响,探讨减轻脓毒症损害的潜在治疗方案。方法：选择 雄性SD 大鼠作为研究对象,采取盲肠结扎穿孔方法建立脓毒症模型;取模型制备成功的大鼠按照数字随机法分为3 组,A 组为 空白对照组,泵注1.0 mL/kg 生理盐水,B 组为对照组,术毕泵注1.0 mL/kg 生理盐水,维持10 min,持续泵注NS 1.0 mL/kg·h,C 组为实验组,术毕给予右美托咪定5 滋g/kg,维持10 min,持续泵注右美托咪定4.5 滋g/kg·h,3 组均持续泵注24 h,并于6 h、12 h、 24 h各组分别取8 只大鼠检测中性粒细胞明胶酶相关脂质运载蛋白（NGAL）表达水平进行比较,并观察比较3 组研究对象尿素 氮（BUN）、肌酐清除率（Ccr)以及肾脏组织Toll 受体4水平及TLR4 mRNA水平。结果：C 组大鼠应用右美托咪定后,BUN于6 h、 12 h、24 h分别为（13.4± 1.2）mmol/L、（12.5± 1.3）mmol/L、（11.4± 1.1）mmol/L,均低于A 组、B组,均P<0.05;Ccr 于6 h、12 h、24 h 分别为（77.4± 9.9）mL/min、（75.4± 10.2）mL/min、（78.5± 11.3）mL/min,均明显低于A 组、B 组,P<0.05;C 组6 h、12 h、24 h NGAL 表达水平分别为（39.2± 9.9）pg/mL、（41.6± 9.8）pg/mL、（38.2± 9.9）pg/mL,均明显低于A组、B组,P<0.05;C 组泵注6 h、12 h、24 h Toll受体4 水平及TLR4 mRNA 水平均低于A 组、B 组,P<0.05。结论：右美托咪啶可降低脓毒症大鼠Toll 受体4表达,有助于减 轻脓毒症炎性反应与减轻肾损害,具有重要临床价值。     

Effect of temperature on the uptake and metabolism of cyanide by weeping willows

Plants' uptake and metabolism of cyanide in response to changes in temperature was investigated. Pre-rooted weeping willows (Salix babylonica L.) were exposed to hydroponic solution spiked with potassium cyanide for 2-3 d. Ten different temperatures were used, ranging from 11 degrees C to 32 degrees C. Cyanide in water, plant tissue, and air was analyzed spectrophotometrically. The results revealed that significant amounts of the applied cyanide were removed from the aqueous solutions in the presence of plants. Small amounts of free cyanide were detected in plant materials in all treatments, but there was no clear trend that showed an increase or decrease in the accumulation in plant material with temperature. The highest cyanide metabolism rate for weeping willows was found at 32 degrees C with a value of 2.78 mg CN/(kg x d), whereas the lowest value was 1.20 mg CN/(kg x d) at ll degrees C. The temperature coefficient, Q10, which is the ratio of metabolism rates at a 10 degrees C difference, was determined for weeping willows to be 1.46. In conclusion, changes in temperature have a substantial influence on the uptake and metabolism of cyanide by plants, but cyanide accumulation does not increase with temperature.     

Chemical and biological removal of cyanides from aqueous and soil-containing systems

A study was conducted to determine the effect of various factors on the rate and extent of potassium cyanide and potassium hexacyanoferrate (II, complex form) removal from aqueous and soil-containing systems. In a sterile aqueous system at neutral pH, the concentration of free cyanide was reduced by 42% in 334 h as a result of the protonation of CN^– and the volatilization of the HCN formed. In the presence of aerobic mixed consortium of the Institute of Gas Technology and a methylotrophic culture, Isolate 3, the concentration of free cyanide was reduced by 59% and 66% in 357 h, respectively, as a result of combined chemical conversion and microbial degradation. In the sterile aqueous system amended initially with the complex form of cyanide, a less-than-20% reduction in cyanide occured. The sorption equilibria for free and complex cyanides in slurries of the topsoil and manufactured gas plant (MGP) soil was reached in less than 22 and 4 days, respectively. The extent of desorption of cyanides from topsoil and MGP soil into water decreased with time. In sterile systems containing topsoil and MGP soil that were previously equilibrated to cyanides, only a 2% reduction in cyanide concentration occurred in 336 h due to chemical conversion. In the presence of microbial cultures, the concentration of cyanide was reduced by less than 15% and 7% in the slurries of topsoil and MGP soil, respectively. The comparison of the rate and extent of cyanide removal from the aqueous and soil-containing systems in the presence of micro-organisms suggests that cyanides were retained by the solid phase of the soil-containing systems and therefore were less available for biodegradation.     

Removal of metal cyanides from aqueous solutions by suspended and immobilized cells of Rhizopus oryzae (MTCC 2541)

This paper presents a study on biodegradation and simultaneous adsorption and biodegradation (SAB) of zinc and iron cyanides by Rhizopus oryzae (MTCC 2541), with a brief process review. Granular activated carbon was used for the immobilization of Rhizopus oryzae (MTCC 2541) for the SAB study. pH and temperature were optimized at an initial cyanide concentration of 100 mg/L for biodegradation and SAB. The microbes adapted to grow at maximum cyanide concentration were harvested and their ability to degrade cyanide was measured in both biodegradation and SAB. The removal efficiency of the SAB process was found to be better as compared to the biodegradation process. In the case of biodegradation, removal was found up to a maximum cyanide concentration of 250 mg CN^?/L for zinc cyanide and 200 mg CN^?/L for iron cyanide, whereas in the case of SAB, about 50% removal of cyanide at 400 mg CN^?/L zinc cyanide and 300 mg CN^–/L iron cyanide was possible. It was found that the SAB process is more effective than biodegradation.     

Modeling studies on mono and binary component biosorption of phenol and cyanide from aqueous solution onto activated carbon derived from saw dust

Biosorption is an effective treatment method for the removal of phenol and cyanide from aqueous solution by saw dust activated carbon (SDAC). Batch experiments were achieved as a function of several experimental parameters, i.e. influence of biosorbent dose (5–60 g/L) contact time (2–40 h), pH (4–12), initial phenol concentration (100–1000 mg/L) and initial cyanide concentration (10–100 mg/L) and temperature (20–40 °C). The biosorption capacities of the biosorbent were detected as 178.85 mg/g for phenol with 300 mg/L of initial concentration and 0.82 mg/g for cyanide with 30 mg/L of initial concentration. The optimum pH is found to be 8 for phenol and 9 for cyanide biosorption. The mono component biosorption equilibrium data for both phenol and cyanide were well defined by Redlich–Peterson model and binary component adsorption equilibrium data well fitted by extended Freundlich model. The percentage removal of phenol and cyanide using SDAC was 66.67% and 73.33%, respectively. Equilibrium established within 30 h for phenol and 28 h for cyanide. Kinetic studies revealed that biosorption of phenol followed pseudo second order indicating adsorption through chemisorption and cyanide followed pseudo first order kinetic model indicating adsorption through physisorption. Thermodynamic studies parameters, i.e., enthalpy (Δh₀), entropy (ΔS₀) and Gibb’s free energy (ΔG₀) have also been considered for the system. Thermodynamic modeling studies revealed that the process of cyanide biosorption was endothermic and phenol biosorption was exothermic in nature.     

Rapid sodium cyanide depletion in cell culture media: outgassing of hydrogen cyanide at physiological pH

During the course of in vitro studies on cyanide exposure with SH-SY5Y human neuroblastoma cells, we found that sodium cyanide (NaCN) up to a concentration of 10 mM had no significant toxic effect under our culture conditions. Further investigation of this apparent cyanide resistance revealed that the sodium cyanide was being rapidly depleted from the cell culture medium. Cyanide was interacting with constituents of the cell culture medium and was somehow being detoxified or removed from solution. The reaction of cyanide with cell culture media in 96-well culture plates reduced cyanide concentrations rapidly (80-90% in 2 h at 37 degrees C). Running the same reaction in capped tubes significantly reduced cyanide loss from solution. Incubation of cyanide with individual constituents of the cell culture medium in solution showed that glucose, phenol red, and amino acids all acted to detoxify or remove cyanide from solution. When amino acids or buffers were incubated with sodium cyanide in aqueous solution at pH 7.4, hydrogen cyanide (HCN) was found to degas from the solutions. We compared HCN outgassing over a range of pH values. As expected, HCN remained very soluble at high pH, but as the pH was reduced to 7.0, the rate of HCN formation and outgassing increased dramatically. Acid-base reactions involving cyanide and proton donors, such as amino acids and other cell culture media constituents, at physiological pH result in rapid HCN outgassing from solution at 37 degrees C. These results indicate that previous in vitro cyanide toxicity studies done in standard culture media with prolonged incubation times using gas-exchanging culture containers might have to be reevaluated in light of the fact that the effective cyanide concentrations in the culture media were significantly lower than reported.     

Removal of Cyanide Contaminants from Rhizosphere Soil

Cyanide and cyanide-containing compounds from anthropogenic sources can be an environmental threat because of their potential toxicity. A remediation option for cyanide-contaminated soil may be through the use of plants and associated rhizosphere microorganimsms that have the ability to degrade cyanide compounds. Cyanogenic plant species are known to produce cyanide, but they also have the ability to degrade these compounds. In addition, the presence of these plants in soil may result in an increase in cyanide degrading microorganisms in the rhizosphere. Two cyanogenic species (Sorghum bicolor and Linum usitassium) and a noncyanogenic species (Panicum virgatum) were selected for a 200-day phytoremediation study to assess their potential use for removal of cyanide from soil. For both cyanogenic species, approximately 85% of the iron cyanide in soil was removed, whereas very little iron cyanide was removed in the unvegetated control or in the presence of Panicum virgatum. In addition, the activity of microbial communities in the rhizosphere of cyanogenic plants was higher than in cyanide-contaminated soil from unvegetated soil.     

Effects of cyanide and dissolved oxygen concentration on biological Au recovery

The number of discarded electric devices containing traces of Au is currently increasing. It is desirable to recover this Au because of its valuable physicochemical properties. Au is usually dissolved with relatively high concentrations of cyanide, which is associated with environmental risk. Chromobacterium violaceum is able to produce and detoxify small amounts of cyanide, and may thus be able to recover Au from discarded electric devices. This study investigated the effects of cyanide and dissolved oxygen concentration on biological Au recovery. Cyanide production by C. violaceum was sufficient to dissolve Au, while maintaining a high cyanide concentration did not enhance Au dissolution. Increased oxygen concentration enhanced Au dissolution from 0.04 to 0.16 mmol/l within the test period of 70 h. Electrochemical measurement clarified this phenomenon; the rest potential of Au in the cyanide solution produced by C. violaceum increased from -400 to -200 mV, while in the sterile cyanide solution, it was constant in cyanide concentrations ranging from 0 to 1.5 mmol/l and increased in dissolved oxygen concentrations ranging from 0 to 0.25 mmol/l. Therefore, it was clarified that dissolved oxygen concentration is the main factor affecting the efficiency of cyanide leaching of gold by using bacteria.     

Stability of Prussian Blue in Soils of a Former Manufactured Gas Plant Site

Soil contamination with iron-cyanide complexes is a common problem at former manufactured gas plant (MGP) sites. Dissolution of the cyanide, from Prussian Blue (ferric ferrocyanide), creates an environmental hazard, whereas the risk of groundwater contamination depends on the stability of dissolved iron–cyanide complexes. Lack of a standard leaching method to determine the water-soluble (plant-available) cyanide fraction generates potential limitations for implementing remediation strategies like phytoremediation. Applicability of neutral solution extraction to determine the water-soluble cyanide fraction and the stability of Prussian Blue in surface and near-surface soils of an MGP site in Cottbus, undersaturated and unsaturated water conditions, was studied in column leaching and batch extraction experiments. MGP soils used in the long-term tests varied according to the pH (5.0–7.7) and the total cyanide content (40–1718 mg kg^?1). Column leaching, after four months of percolation, still yielded effluent concentrations exceeding the German drinking water limit (> 50 μg L^?1) and the solubility of Prussian Blue reported in the literature (< 1 mg L^?1) from both alkaline and acidic soils. Long-term (1344 h) extraction of MGP soils with distilled water was sufficient to dissolve 97% of the total cyanide from the slightly alkaline soils and up to 78% from the acidic soils. Both experiments revealed that dissolution of ferric ferrocyanide under circum-neutral pH and oxic water conditions is a function of time, where the released amount is dependent on the soil pH and total cyanide content. Unexpectedly high and continuous solubility of Prussian Blue, both in acidic and slightly alkaline MGP soils, implies the need to introduce an additional cyanide fraction (“readily soluble fraction”) to improve and specify cyanide leaching methods. Long-term extraction of cyanide-contaminated soil in neutral solution seems to be a promising approach to evaluate the potential hazard of groundwater pollution at the MGP sites.