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81.
Yu X Zhou P Zhou X Liu Y 《Environmental science and pollution research international》2005,12(4):221-226
Background Little is known about metabolism rates of environmental chemicals by vegetation. A good model compound to study the variation
of rates among plant species is cyanide. Vascular plants possess an enzyme system that detoxifies cyanide by converting it
to the amino acid asparagine. Knowledge of the kinetic parameters, the half-saturation constant (Km) and the maximum metabolic
capacity (vmax), is very useful for enzyme characterization and biochemical purposes. The goal of this study is to find the
enzyme kinetics (KM and vmax) during cyanide metabolism in the presence of Chinese vegetation, to provide quantitative data
for engineered phytoremediation, and to investigate the variation of metabolic rates of plants.
Methods Detached leaves (1.0 g fresh weight) from 12 species out of 9 families were kept in glass vessels with 100 mL of aqueous
solution spiked with potassium cyanide at 23°C for 28 h. Four different treatment concentrations of cyanide were used, ranging
from 0.44 to 7.69 mg CN/L. The disappearance of cyanide from the aqueous solution was analyzed spectrophotometrically. Realistic
values of the half-saturation constant (KM) and the maximum metabolic capacity (vmax) were estimated by a computer program
using non-linear regression treatments. As a comparison, Lineweaver-Burk plots were also used to estimate the kinetic parameters.
Results and Discussion The values obtained for KM and vmax varied with plant species. Using non-linear regression treatments, values of vmax and
KM were found in a range between 6.68 and 21.91 mg CN/kg/h and 0.90 to 3.15 mg CN/L, respectively. The highest vmax was by
Chinese elder (Sambucus chinensis), followed by upright hedge-parsley (Torilis japonica). The lowest vmax was demonstrated
by the hybrid willow (Salix matssudana x alba). However, the highest KM was found in the water lily (Nymphea teragona), followed
by the poplar (Populus deltoides Marsh). The lowest KM was demonstrated by corn (Zea mays L.). The values of vmax were normally
distributed with a mean of 13 mg CN/kg/h.
Conclusions Significant removal of cyanide from aqueous solution was observed in the presence of plant materials without phytotoxicity,
even at high doses of cyanide. This gives rise to the conclusion that the Chinese plant species used in this study are all
able to efficiently metabolize cyanide, although with different maximum metabolic capacities. A second conclusion is that
the variation of metabolism rates between species is small. All these plants had a similar KM, indicating the same enzyme
is active in all plants.
Recommendations and Outlook Detoxification of cyanide with trees seems to be a feasible option for cleaning soils and water contaminated with cyanide.
For phytoremediation projects, screening appropriate plant species adapted to local conditions should be seriously considered.
More chemicals should be investigated to find common principles of the metabolism of environmental chemicals by plants. 相似文献
82.
光助Fenton氧化、化学絮凝法联合处理R盐废水的研究 总被引:4,自引:0,他引:4
采用光助Fenton氧化、化学絮凝法联合处理生物难降解的R盐废水,考察了不同反应条件对处理效果的影响.试验结果表明,光助Fenton氧化、化学絮凝法联合处理废水,两者之间存在协同作用,可以提高处理效果,降低处理成本.在最佳试验条件下,R盐废水经光助Fenton氧化、化学絮凝法联合处理后,COD去除率可达90%以上. 相似文献
83.
Adsorption of N-nitrosopyrrolidine (NPYR) by zeolite NaZSM-5, Hbeta and NaZSM-11 in acidic solution with pH of 1 was investigated. The NPYR uptake process obeyed the first-rate Lagegren kinetic equation describing adsorption, and the equilibrium data were fitted to the Langmuir or Freundlich adsorption equation. Zeolite ZSM-5, Hbeta and NaZSM-11 possessed a higher adsorption capacity than amorphous silica or ordered mesoporous siliceous SBA-15, implying their potential application for adsorption of nitrosamines in gastric juice to anti-cancer. 相似文献
84.
85.
次氯酸钠处理终冷水中氰化物硫化物的研究 总被引:1,自引:0,他引:1
以次氯酸钠为氧化剂,用正交实验研究了次氯酸钠处理终冷水中氰化物和硫化物,得出正交实验中各因素的主次关系及对除氰除硫的影响。研究结果表明,反应体系的pH是影响脱氰脱硫的重要因素。在最佳处理条件,即pH为10.0,反应温度为25℃,投氯量系数为1.4,反应时间为45min.能使氰化物的质量浓度降至0.267mg/L,脱氰率高达99.8%,硫化物的质量浓度降到0.387mg/L,脱硫率达92.0%,达到≤0.5mg/L的国家排放标准。文章还对工业化提出了一些设想。 相似文献
86.
采用高压水和喷嘴的引射原理,使水射流通过喷嘴后高效雾化,达到降尘的目的,并主要沉降5μm以下对人体具有致命危害的呼吸性粉尘。当更换喷嘴后也可进行积上和物体的表面清洗。 相似文献
87.
88.
Factors influencing farmers’ decisions on nitrogen fertilizer application in the Liangzihu Lake basin,Central China 总被引:3,自引:0,他引:3
Jin Zhang Günther Manske Pi Qi Zhou Bernhard Tischbein Mathias Becker Zhao Hua Li 《Environment, Development and Sustainability》2017,19(3):791-805
Overuse of nitrogen (N) fertilizers in agriculture activities has caused severe water pollution in China. The lack of data at producer level hampers decision makers in the development and implementation of efficient policies to curb excessive N-fertilizer use. In a survey of 300 farm households in the Liangzihu Lake basin, we identified factors associated with farmers’ decisions on N-fertilizer use and application rate. Household survey and multiple linear regression models indicate that the average application rate in the study region is 229 kg N ha?1, which exceeds the recommended rate for maximum profit for cereal crops (maize, wheat, and rice) in China of 150–180 kg N ha?1. High N-application rates are associated with low farmland productivity (coefficient = ?15.66, p = 0.02), a high share of off-farm income (coefficient = 27.14, p = 0.003), and a low education level of the household head (coefficient = ?10.83, p = 0.039). Neither physical infrastructure nor access to input markets appears to be related to N-application rates. It may be concluded that excessive use of N in agriculture of Central China is mainly a problem of insufficient awareness and high share of off-farm income. 相似文献
89.
Zhang Yao Liu Wenxin Khan Sufyan Ullah Swallow Brent Zhou Chaohui Zhao Minjuan 《Environmental science and pollution research international》2022,29(5):6886-6899
Environmental Science and Pollution Research - Economies that depend on natural resources can experience a resource drag effect when economic growth is limited by constraints on the availability of... 相似文献
90.
通过向NH4+-N质量浓度为30 mg·L−1的合成废水中投加不同剂量磺胺嘧啶(SDZ)(0、1、3、5、7和10 mg·L–1),比较了SDZ浓度对一台60 L单级纯膜移动床生物膜反应器(pure MBBR)的氨氧化速率、amoA基因丰度和氨氧化细菌(AOB)种群结构的影响,揭示了磺胺嘧啶对纯膜MBBR系统中氨氧化作用的影响机制。结果表明:1~3 mg·L–1的SDZ显著提升了纯膜MBBR系统的氨氧化速率(P<0.05),出水${\rm{NH}}_4^{+} $ -N质量浓度可降低至(0.19±0.10) mg·L–1;5~10 mg·L–1的SDZ仍能促进${\rm{NH}}_4^{+} $ -N去除,但氨氧化速率变化相对平缓。相比于氨氧化古菌(AOA),AOB为纯膜MBBR氨氧化的主导者,AOB amoA基因丰度是AOA amoA基因丰度的12.2~168.5倍。1~10 mg·L–1的磺胺嘧啶暴露显著抑制了AOB amoA基因丰度(P<0.05),但能有效刺激AOA amoA基因丰度上调(P<0.05)。高通量测序结果表明,添加磺胺嘧啶改变了AOB的种群多样性及结构,且1~3 mg·L–1的SDZ能显著促进AOB种群多样化和亚硝化螺菌属(Nitrosospira)生长(P<0.05)。SDZ对氮源的补充、对AOB与AOA丰度占比的改变、对微生物耐药性的促进以及对AOB种群结构的干扰是其影响纯膜MBBR氨氧化过程的主要机制。 相似文献