结合态~(14)C-绿黄隆和/或其降解物的释放与释出物的组成研究

结合态的14C 绿黄隆和 /或其降解物 (14C BR0 )在水稻生态系统中可分解释放。在 1、2、3、4、6μg/ g土14C BR0 中 ,于直播水稻和移栽苗 (4μg/ g土14C BR0 )分别经 3 9d和 2 9d后 ,14C释出率分别达 75 0 %、68 7%、62 6%、5 8 0 %及 70 4 %。其中绝大部分以挥发性态14C逸走 ,其次存留在土壤中 ,少量被秧苗吸收 ,并能抑制秧苗的发育生长。留在土壤中的可提态残留物 (ER2 )对水稻的毒害与绿黄隆相似 ,经HPLC分析 ,检测到它含有绿黄隆及其 2种主要降解物 ,即邻氯苯磺酰胺和均三嗪胺     

~(14)C-绿磺隆在土壤中的可提态残留、结合残留和矿化研究

本文对14 C 绿磺隆在 7种不同类型土壤中形成结合残留 ( 14 C ER)、可提态残留( 14 C ER)以及矿化为14 C CO2 的规律、影响14 C BR的主要因子及其在腐殖质中的分布规律等进行了研究。结果表明 :( 1 ) 14 C 绿磺隆在土壤中形成的14 C ER含量与土壤pH呈显著正相关 ,与土壤粘粒和有机质含量呈显著负相关 ,14 C ER中的绿磺隆母体化合物的消减满足一级反应动力学方程 ,其在 7种土壤中的半减期分别为 1 3 0～ 1 3 3 3d。pH是影响绿磺隆母体化合物降解的主要因子 ;( 2 ) 14 C 绿磺隆在 7种土壤中的14 C BR含量与土壤pH呈显著负相关 ,并与土壤粘粒含量呈显著正相关 ,土壤pH是14 C 绿磺隆在土壤中形成BR的主要影响因子 ;( 3 ) 14 C 绿磺隆形成的14 C BR主要分布在富啡酸和胡敏素中 ;14 C BR分布在胡敏酸中的相对百分比约为 2 % ,在14 C 绿磺隆BR的形成过程中 ,富啡酸的作用 >胡敏素 胡敏酸 ;( 4) 14 C 绿磺隆在 7种土壤中的14 C BR含量 ,在培养 2 0d内均随时间而快速增加 ,2 0d后变化量较小。 7种土壤中的14 C BR含量最大值分别占引入量的 53 5%、40 9%、3 7 8%、1 6 4%、42 5%、41 0 %和 3 1 3 % ;( 5)培养 90d内 ,14 C 绿磺隆通过三嗪杂环开环矿化为14 CO2 的量约占引入量的 4%～9% ,而土壤 1表明14 C     

除草剂降解真菌对氯嘧磺隆的降解作用

利用自行筛选和保存的3种高效降解真菌菌株,对氯嘧磺隆除草剂降解作用的影响进行了系统的研究,采用高效液相色谱法测定其降解率。真菌黑曲霉、黄曲霉、F8酿酒酵母均可以很好的降解氯嘧磺隆,其中黑曲霉的降解率最高,为96.52%;其次是黄曲霉为88.21%。混合菌株对氯嘧磺隆的降解效率均高于其单一菌株,真菌黑曲霉与黄曲霉混合菌株降解率最高,为98.74%;其次是真菌黑曲霉与F8混合菌株为98.22%。在培养基中随着氯嘧磺隆降解率的增加,反应液的pH逐渐降低。     

4株苯磺隆降解菌的分离鉴定及其生长特性

从长期受农药苯磺隆污染的土壤中通过采用富集培养分离技术得到4株以苯磺隆为唯一碳源生长的细菌,分别将其命名为B1、B2、B3和B4。通过观察这4种菌株的形态学特征,研究其生理生化特性以及分析其16S rDNA序列,初步鉴定菌株B1为铜绿假单胞菌(Pseudomonas aeruginosa),B2为戴尔福特菌(Delftia sp.),B3为微杆菌(Microbacterium sp.),B4为产碱杆菌(Alcaligenes sp.)。并通过研究温度、初始pH值、接种量、苯磺隆初始浓度、培养基体积、氮源、碳源、Mg2+浓度等因素对4种菌株生长情况的影响,确定了菌株的最佳生长条件。结果显示,B1菌株的最适温度为35℃,其他3株菌株均为30℃。菌株B3最适pH为8.0,其余3株菌株均为pH7.0。B1和B3菌株最适接种量为15%,B2和B4最适接种量为10%。菌株B3最适苯磺隆初始浓度为100mg·L-1,其余菌株最适苯磺隆初始浓度均为200mg·L-1。4株菌株最适培养基体积均为75mL,最适氮源均为硝酸铵,最适碳源均为葡萄糖。B2菌株最适Mg2+浓度为100mg·L-1,其余3株菌株均为200mg·L-1。B1和B4菌株最适NaCl浓度为20g·L-1,B2菌株NaCl浓度为5~30g·L-1,B3菌株最适NaCl浓度为50g·L-1。该结果为利用微生物对农药苯磺隆污染的土壤进行原位生物修复提供理论依据。     

一株高效氯嘧磺隆降解菌的分离鉴定及其降解机理初探

消除农业生产中除草剂残留是现代农业绿色发展的关键,为发掘更多磺酰脲类除草剂高效降解微生物资源,系统阐述氯嘧磺隆的微生物降解途径。以氯嘧磺隆为唯一氮源,从某磺酰脲类除草剂生产厂废水处理活性污泥中分离出的高效氯嘧磺隆降解菌LAM2021。生理生化特性和16S rRNA基因序列比对分析结果表明,该菌株属小坂菌属(Kosakonia sp.)。单因素试验结果经RSM优化后,菌株LAM2021在无机盐培养基中对50 mg/L氯嘧磺隆的最佳降解条件为:接种量5%、培养温度30℃、pH 6.0,11 h后降解率可达94.6%。利用高效液相色谱(HPLC)对接菌后降解体系内代谢产生的酸类物质进行分离与鉴定,结果表明产物主要为柠檬酸。推测菌株LAM2021受高浓度氯嘧磺隆胁迫,利用葡萄糖产生柠檬酸,通过降低环境pH使氯嘧磺隆发生水解,从而解除其胁迫。从菌株全基因组信息中发现有参与氯嘧磺隆降解的酯酶编码基因。采用液相色谱-质谱联用(LC-MS)对菌株LAM2021与氯嘧磺隆混合培养后的代谢产物进行检测与鉴定,共有5种主要物质被检测到。根据氯嘧磺隆的化学结构式和中间代谢产物特征,推测菌株LAM2021降解氯嘧磺隆的代谢途径为:氯嘧磺隆中的脲桥先水解断裂成2-氨基-4-氯-6-甲基嘧啶和邻甲酸乙酯苯磺酰胺,随后酯键被脱酯断裂成邻甲酸乙酯苯磺酰胺,最后环化为N-醛基糖精。     

降解菌S113对甲磺隆污染土壤生物修复作用的研究

在室内条件下,研究了降解菌S113(Methylopila sp.)对甲磺隆污染土壤的修复作用。S113能够以甲磺隆为唯一碳源生长,72h对50mgL-1甲磺隆的降解率达98.38%。投加降解菌S113可显著提高土壤中甲磺隆的降解速率。当甲磺隆浓度为10mgkg-1干土,S113接种量为108个g-1土时,第30天土壤中甲磺隆降解率为76.9%,对照土壤中甲磺隆降解率仅为11.9%。S113降解甲磺隆的速率和接种量呈正相关,当接种量减少为105个g-1干土时,降解菌对甲磺隆的降解作用微弱。在土壤中甲磺隆浓度较低的条件下,S113的降解效果显著,而当土壤中甲磺隆浓度达到50mgkg-1时,甲磺隆降解率仅为39.6%。S113降解土壤中甲磺隆的最适温度为30℃,第30天的降解率可达75.9%。当温度为25℃、20℃时,第30天甲磺隆降解率仅为53.5%和23.9%。S113菌剂灌根,能不同程度地缓解土壤中浓度为40、80μgkg-1的甲磺隆对玉米生长的抑制作用,但当甲磺隆浓度增加到120μgkg-1时,接种S113对药害解除作用不显著。结果表明,人工接种降解菌S113,能有效去除土壤中甲磺隆残留。     

土壤中结合残留态甲磺隆的微生物降解研究

主要进行了优选菌株青霉 (Penicilliumsp .)对土壤中结合残留态甲磺隆的降解研究 ,结果表明 ,优选菌株的引入对土壤中可提态甲磺隆的影响不大 ,但对结合残留态甲磺隆的降解和矿化有较大影响。在结合残留态甲磺隆中 ,优选菌株青霉的引入有利于松结态甲磺隆尤其是松结态富里酸甲磺隆的降解。     

苯磺隆降解菌的分离鉴定和特性研究

为解决苯磺隆残留问题,本试验利用富集驯化培养分离法,从连续多年使用苯磺隆的田间土壤中,分离筛出一株能以苯磺隆为唯一碳源、氮源生长的降解菌。通过形态学、生理生化测定及16S r DNA序列系统发育分析,鉴定该菌株为产碱杆菌。抗生素敏感试验和底物敏感试验表明:降解菌株BHL对试验浓度范围内的所有供试抗生素都表现为敏感,其中对硫酸阿米卡星最为敏感;菌株BHL可以很好的利用试验所用磺酰脲类除草剂和有机磷农药,同时还可以利用部分芳香族化合物。本研究为功能农药残留降解菌的研究提供了理论基础。     

甲磺隆降解菌FLDA的分离鉴定及其降解特性研究

从生产甲磺隆的农药厂内采取污泥，经驯化富集后筛选到一株能高效降解甲磺隆的细菌FLDA，根据表型特征、生理生化特性及16S rDNA序列同源性分析，将FLDA初步鉴定为假单胞菌（Pseudomonas sp）。该菌能在含甲磺隆（30mgL^-1）的基础盐液体培养基中降解甲磺隆，5d降解率达72．6％，该菌降解甲磺隆的最适pH为7．0，最适温度为30℃，该菌降解甲磺隆的速率和起始接种量呈正相关。酶的定域实验表明，该菌中甲磺隆水解酶为胞内酶。FLDA投加土壤，可提高土壤中甲磺隆的降解速率。     

氯嘧磺隆降解菌筛选及基于16S rDNA序列的系统学分析

氯嘧磺隆是长残留除草剂,污染土壤后影响土壤肥力和后茬作物生长。筛选氯嘧磺隆降解菌21株,纯培养条件下,7 d对初始浓度50 mg/L氯嘧磺隆的降解达到0.75%~80.77%。对筛选到的氯嘧磺隆降解菌进行了16S rDNA基因扩增、序列测定和系统学分析,结果显示,所选菌株在系统发育地位上分别属于肠杆菌、短杆菌、柠檬酸杆菌、志贺氏菌、寡养单胞菌、无色杆菌、假单胞菌等7个属。     

Pb<Superscript>2+</Superscript> adsorption on birnessite affected by Zn<Superscript>2+</Superscript> and Mn<Superscript>2+</Superscript> pretreatments

Purpose  

Lead contamination is ubiquitous, and much attention has been paid due to its toxicity. The phyllomanganate birnessite is the most common Mn oxide in soils. The MnO₆ octahedral layers may have significant Mn vacancies in the hexagonal birnessites. Among heavy metal ions, birnessites possess the greatest adsorption affinity and capacity for Pb²⁺. The aim of this study was to understand the relationship between vacant Mn octahedral sites and Pb²⁺ adsorption.     

Heavy Metals Removal in a Horizontal Rotating Tubular Bioreactor

Mixed microbial culture was isolated from heavy metal-contaminated ground soils located inside iron, vinyl and cement factory area. Isolated mixed microbial culture was used for the heavy metal ions (Fe²⁺, Cu²⁺, Ni²⁺ and Zn²⁺) removal process in horizontal rotating tubular bioreactor (HRTB). In this research, the effect of bioreactor process parameters on the bioprocess dynamics in the HRTB was studied. Results of this research have shown that profiles of heavy metals concentration were gradually reduced along HRTB at all combinations of bioreactor process parameters [inflow rates (0.5?C2.0 L?h^-1) and rotation speed (5?C30 min^-1)]. Hydrodynamic conditions and biomass sorption capacity have main impact on the metal ions removal efficiency that was varied in the range of 38.1% to 95.5%. Notable pH gradient (cca 0.7 pH unit) along the HRTB was only observed at the inflow rate of 2.0 L?h^-1. On the basis of obtained results, it is clear that medium inflow rate (F) has higher impact on the heavy metal removal process than bioreactor rotation speed (n) due to the fact that increase of inflow rate was related to the reduction of equilibrium time for all examined metal ions. Furthermore, equilibrium times for all metal ions are significantly shorter than medium residence times at all examined combinations of bioreactor process parameters. The main impact on the biofilm sorption capacity has covalent index of metal ions and biofilm volumetric density. The sorption capacity of suspended microbial biomass is closely related to its concentration. Results of this research have also shown that the removal of heavy metals ion can be successfully conducted in an HRTB as a one-step process.     

Enhanced Adsorption of Metal Ions Onto Polyethyleneimine-Impregnated Palm Shell Activated Carbon: Equilibrium Studies

In this study, palm shell activated carbon was impregnated with polyethyleneimine (PEI) and the effect of impregnation on batch adsorption of Ni²⁺, Cd²⁺or Pb²⁺ as well as the equilibrium behavior of adsorption of metal ions on PEI-impregnated AC were investigated. PEI impregnation evidently increased the single metal adsorption capacities of Ni²⁺ or Cd²⁺except for Pb²⁺, where its adsorption capacities were reduced by 16.67% and 19.55% for initial solution pH of 3 and 5 respectively. This suggested that PEI-impregnated AC could be used for selective separation of Pb²⁺ ions from other metal ions. The adsorption data of all the metal ions on both virgin and PEI-impregnated AC for both initial solution pH of 3 and 5 generally fitted the Langmuir and Redlich-Peterson isotherms considerably better than the Freundlich isotherm.     

KINETICS OF ION EXCHANGE IN SOIL ORGANIC MATTER. IV. ADSORPTION AND DESORPTION OF Pb2+, Cu2+, Cd2+, Zn2+ AND Ca2+ BY PEAT

The equilibria as well as the rates of adsorption and desorption of the ions Pb²⁺, Cu²⁺, Cd²⁺, Zn²⁺, and Ca²⁺ by soil organic matter were determined in batch experiments as a function of the amount of metal ions added to an aqueous suspension of HCl-washed peat. Simultaneous determination of the metal ions and hydrogen ions in the solution by atomic absorption spectrophotometry and pH-measurements showed that the adsorption of one divalent metal ion by peat was coupled with the release of two hydrogen ions. Since this equivalent ion-exchange process causes a corresponding increase of the electric conductivity of the solution, the rates of the adsorption and desorption processes were determined by an immersed conductivity electrode. The distribution coefficients show that the selective order for the metal adsorption by peat is Pb²⁺ > Cu²⁺ > Cd²⁺≌ Zn²⁺ > Ca²⁺ in the pH range of 3·5 to 4·5. The slope of -2, as observed in a double logarithmic plot of the distribution coefficients versus the total solution concentration confirms the equivalence of the ion-exchange process of divalent metal ions for monovalent H₃O⁺ -ions in peat. The absolute rates of adsorption, as well as the rates for the fractional attainment of the equilibrium, increase with increasing amounts of metal ions added. This behaviour is also observed for the subsequent desorption of the metal ions by H₃O⁺-ions. At a given amount of metal ions added, the absolute rates of adsorption decrease in the order Pb²⁺ > Cu²⁺ > Cd²⁺ > Zn²⁺ > Ca²⁺, while the rates for the fractional attainment of the equilibrium decrease in the order Ca²⁺ > Zn²⁺≌ Cd²⁺ > Pb²⁺ > Cu²⁺. The half times for adsorption and desorption were in the range of 5 to 15 sec.     

Catalytic effect of various metal ions on the methylation of mercury in the presence of humic substances

Methylation of Hg²⁺ (Hg(NO₃)₂) in the presence of fulvic acid (FA) and various metal ions has been studied. The concentrations of Hg²⁺ and FA ranged from 5 to 20 mg L^?1 and 171 to 285 mg L^?1 DOC, respectively. The pH range was 3 to 6.5. FA was isolated from an acid brown-water lake by XAD-8 polymeric adsorbent. Methylmercury production in the dark during 2 to 4 days incubation at 30 °C increased with increasing concentrations of Hg²⁺ ion and FA as well as with additions of metal ions (5 to 10 × 10^?5 mole L^?1 The observed catalytic activity of metal ions followed the order Fe³⁺ (Fe²⁺) > Cu²⁺ ≈ Mn²⁺, > Al³⁺. The production of methylmercury had a pH-optimum around 4 to 4.5 at the conditions tested.     

不同土地利用方式土壤对铜、镉离子的吸附解吸特征

采用一次平衡法对Cu²⁺、Cd²⁺在城市及城郊农田、林地、草地3种土地利用方式土壤中的吸附解吸过程进行比较研究, 结果表明: Cu²⁺、Cd²⁺在3种土地利用方式土壤中的吸附量均随平衡液浓度的增加而增大, Cu²⁺、Cd²⁺在农田土壤上的吸附量均高于林地和草地土壤。分别用Langmuir和Freunlich两种等温吸附方程对吸附过程进行拟合, 3种土壤对Cu²⁺的吸附过程运用Langmuir方程拟合效果好, 而对Cd²⁺的吸附过程运用Freunlich方程拟合效果更好。Cu²⁺在3种土壤的解吸量大小顺序为农田>林地>草地, Cd²⁺在3种土壤的解吸量大小顺序为农田>草地>林地。两种离子在3种土壤中的动态吸附是个快速反应的过程, 随时间延长, 吸附反应趋于平衡。运用双常数函数方程和Elovich方程能较好地拟合重金属在土壤上的吸附动力学过程。Cu²⁺、Cd²⁺的吸附与土壤黏粒含量、有机质含量、CEC和pH均有关。     

Activation of soil pyrophosphatase by metal ions

Inorganic pyrophosphatase activity in three soils decreased when exchangeable and soluble metals were removed by leaching with in NH₄OAc (pH 8). The effect of added metal ions at various concentrations in the leached soils showed that, at certain concentrations, Ba²⁺, Ca²⁺, Co²⁺, Mg²⁺, Mn²⁺, Ni²⁺ and Zn²⁺ promoted, K⁺ and Na⁺ had no effect, and Fc²⁺ and Cu²⁺ decreased pyrophosphatase activity. At high concentrations (>50 mM). Co²⁺, Mn²⁺, Ni²⁺ and Zn²⁺ inhibited pyrophosphatase activity in two soils. The concentration of metal ion needed for optimum activity of pyrophosphatase varied among the soils. The efficiency of the metal ions at optimum concentrations (average percentage increase for three soils in parentheses) in promoting pyrophosphatase was Ca²⁺ (47) > Mg²⁺ (42) > Ba²⁺ = Co²⁺ (29) > Ni²⁺ (27) > Zn²⁺ (20) > Mn²⁺(16). Pyrophosphatase activity in two leached soils adjusted to 50, 75, 100 or 150 mM PPi and Ca²⁺ or Mg²⁺ concentrations from 0 to 250 mM was at an optimum when the metal ion: PPi ratio was 1:1. Soil pyrophosphatase in the presence of 200 mM CaCl₂ or MgCl₂ was protected against inactivation by heat (90 C for up to 30 min).     

Biotite weathering by <Emphasis Type="Italic">Aspergillus niger</Emphasis> and its potential utilisation

Purpose

Biotite, as a type of associated mineral, is normally applied as a filling material for buildings, or is discarded as tailings. However, as a potassium-bearing phyllosilicate mineral, biotite can be easily weathered by fungi, which leads to its internal potassium being released for agricultural production (1), and the mineral residues being weathered by the fungus may be applied for adsorption of heavy metal ions (2).

Materials and methods

This work investigates the weathering of biotite by Aspergillus niger through the analysis of the differences in ion dissolution from biotite, producing of organic acids, the change of mineral morphology and composition by inductively coupled plasma optical emission spectrometry (ICP-OES), high-performance liquid chromatography (HPLC), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Besides, the mineral residues were applied for adsorption of heavy metal ions.

Results and discussion

Results showed that the mycelia envelope the mineral and form fungal–mineral aggregates. The fungus can secrete a variety of organic acids including citric acid and oxalic acid; these attacked the surface and cleavage of biotite to release ions (Al³⁺, Fe³⁺, Mg²⁺, and K⁺). During incubation with A. niger, biotite weathered as shown by the relative decrease in biotite content and increase in interlayer spacing. Moreover, a certain concentration of phytic acid and tween-80 could promote the release of K⁺, and the fermentation liquid of rice bran has the same effect. Biotite residues showed a good adsorption for Cd²⁺, Pb²⁺, Zn²⁺, and Cu²⁺.

Conclusions

The results indicate that biotite can be biotransformed and release K⁺, of which the production can be acted as heavy metal ion adsorbent. It provides a reference for application of biotite in agriculture and control of heavy metal ion pollution in soil.

     

Speciation of cadmium,copper, lead,and zinc in contaminated soils

Abstract

To investigate the activity of free cadmium (Cd²⁺), copper (Cu²⁺), lead (Pb²⁺), and zinc (Zn²⁺) ions and analyze their dependence on pH and other soil properties, ten contaminated soils were sampled and analyzed for total contents of Cd, Cu, Pb, and Zn (Cd_T, Cu_T, Pb_T, and Zn_T, respectively), 0.43 MHNO₃‐extractable Cd, Cu, Pb, and Zn (Cd_N, Cu_N, Pb_N, and Zn_N, respectively), pH, dissolved organic matter (DOC), cation exchange capacity (CEC), ammonium oxalate extractable aluminum (Al) and iron (Fe), and dissolved calcium [Ca²⁺]. The activity of free Pb²⁺, Cd²⁺, Cu²⁺, and Zn²⁺ ions in soil solutions was determined using Donnan equilibrium/graphite furnace atomic absorption (DE/GFAA). The solubility of Cd in soils varied from 0.16 to 0.94 μg L^‐1, Cu from 3.43 to 7.42 μg L^‐1, Pb from 1.23 to 5.8 μg L^‐1, and Zn from 24.5 to 34.3 μg L^‐. In saturation soil extracts, the activity of free Cd²⁺ ions constituted 42 to 82% of the dissolved fraction, for Cu²⁺the range was 0.1 to 7.8%, for Pb²⁺ 0.1 to 5.1% and for Zn²⁺2 to 72%. The principal species of Cd, Cu, Pb, and Zn in the soil solution is free metal ions and hydrolyzed ions. Soil pH displayed a pronounced effect on the activity of free Cd²⁺, Cu^2t, Pb²⁺, and Zn²⁺ ions.