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砷对水稻生长发育的影响及其原因 总被引：18，自引：0，他引：18
低浓度的砷对水稻生长发育有刺激作用,砷浓度较高时则会对水稻产生严重的毒害作用。砷的毒害作用不仅有十分明显的外观症状,而且还会使水稻的生长发育推迟。刺激作用的机理可能与砷合理地抑制植物呼吸、减少光合产物的无益消耗有关。砷的毒害作用所造成的水稻籽粒减产,是由于穗粒数、结实率、有效穗、千粒重四个产量构成因素受砷的毒害作用共同影响的结果。刚进入土壤系统时,As（Ⅲ）的毒性比As（Ⅴ）大;但随着时间的推移,它们在对土壤和植物系统的影响方面的差异会不断缩小。 相似文献
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不同性质铁铝土对砷酸根吸附特性的比较研究 总被引：4，自引：0，他引：4
采用批平衡法研究了8种不同性质铁铝土对砷酸根的吸附特性,分别运用Langmuir单表面方程和Langmuir双表面方程对等温吸附数据进行拟合,以较优拟合方程求出土壤对砷的最大吸附量,并采用简单线性相关分析法探讨土壤性质对砷吸附能力的影响。结果显示,铁铝土对砷吸附强烈,吸附等温线均为非线性。双表面方程对吸附等温线的拟合效果优于单表面方程。采用双表面方程预测的吸附量和实测值的决定系数(0.935～0.978)大于采用单表面方程预测获得的决定系数(0.989～0.998)。土壤的砷吸附能力可采用高能表面和低能表面两种吸附位点进行解释。采集于云南昆明的砂页岩母质发育的红壤具有最强的砷吸附能力,根据Langmuir双表面方程计算的最大吸附量为3 498 mg kg-1。土壤的砷吸附能力受到土壤中游离氧化铁、全铝、全铁、黏粒和全磷含量的显著影响,最大吸附量与这几种土壤组成与性质因子呈显著正相关关系。 相似文献
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随着现代科学技术的发展，人们充分认识到砷制剂在促进动物生长的同时，也具有较强的发育毒性和致癌性。本文综述了砷制剂的毒副作用及其对生态环境的负面效应，并提出了减轻或消除砷制剂负面影响的应对措施。 相似文献
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利用共沉淀水热法制备镁铝阴离子黏土材料,研究了其水溶液对砷酸根[As（V）]离子的吸附热力学及其机理。结果表明：在303～333 K和试验浓度范围内,阴离子黏土对水中As（V）的吸附平衡数据符合Langmuir和Freundlich吸附等温方程。阴离子黏土对水中As（V）的吸附是吸热过程;根据热力学函数关系计算出As（V）在阴离子黏土上的吸附焓为2.85 kJ/mol,吉布斯吸附自由能改变量为-6.64～-5.90 kJ/mol,吸附自由能的变小是As（V）在阴离子黏土上吸附的推动力,吸附熵变为29.38 J/（mol.K）。 相似文献
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Although, much research has been done on arsenate adsorption by Al (oxy)hydroxides, relatively little is known about the kinetics of arsenate desorption from these (oxy)hydroxides, especially those formed in the presence of organic acids. The desorption kinetics of arsenate adsorbed on Al (oxy)hydroxides, formed under the influence of tannic acid, was investigated using 0.1 and 0.5 mM phosphate at pH 5.5 and an ionic strength of 0.01 M at 298 and 318 K. The kinetic data expressed as the mole fraction of the arsenate remaining adsorbed on the Al (oxy)hydroxides after different desorption periods indicated multiple rate characteristics; a fast reaction period from 0.083 to 3 h and a slow reaction period from 3 to 24 h. The second-order rate equation of the six kinetic models tested was chosen to compare the desorption rate of arsenate. The rate constants of arsenate desorption from the Al (oxy)hydroxides formed at different tannate/Al molar ratios (MRs) followed the order: tannate/Al MR of 0 > tannate/Al MR of 0.1 > tannate/Al MR of 0.01 > tannate/Al MR of 0.001 in the fast reaction period, and tannate/Al MR of 0.1 > tannate/Al MR of 0 > tannate/Al MR of 0.01 > tannate/Al MR of 0.001 in the slow reaction period both in 0.1 and 0.5 mM phosphate systems. The data indicate that the Al (oxy)hydroxides formed in the presence of small amounts of tannic acid (tannate/Al MR = 0.001 and 0.01) had a higher adsorption affinity for arsenate and resulted in slower desorption rates of the adsorbed arsenate compared with the Al (oxy)hydroxides formed in the absence of tannic acid. This is ascribed to the tannate-induced structural perturbation, development of microporosity, enhanced specific surface area, and reactivity of the Al precipitates. As the tannate/Al MR increased from 0.001 to 0.1, the rate constants of arsenate desorption steadily increased. This was attributed to the decrease in the point of zero salt effect (PZSE) of the Al precipitates with the increase of the tannate/Al MR and the resultant electrostatic repulsion from coprecipitated tannate which would weaken the binding of arsenate on the Al precipitates. The effect of temperature on the desorption rate of arsenate, which was governed by the activation energy and the pre-exponential factor (collision frequency), varied with the nature of the Al precipitates. The findings obtained in the present study indicate that the relative effects of tannate-induced structural perturbation, enhanced specific surface area, decreased PZSE, and development of micropore structure in the Al (oxy)hydroxides determine the overall impact of tannate on the kinetics of arsenate desorption from these Al (oxy)hydroxides. 相似文献
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磷和砷专性吸附对砖红壤胶体动电电位的影响 总被引：4，自引：0，他引：4
不同Na_2HPO_4和NaH_2AsO_4浓度及其配比的试验表明,磷酸根离子和砷酸根离子专性吸附都会显著地降低砖红壤胶体的ζ电位及其等电点(IEP),但后者的吸附对动电性质(ζ电位和IEP)的影响比前者的影响更大.磷和砷的专性吸附对砖红壤表面电荷的影响是很相似的. 相似文献
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Zhong-Jing Liu Xiao-Long Zhang Ji-Gang Bai Bang-Xia Suo Pei-Lei Xu Lin Wang 《Scientia Horticulturae》2009
In order to examine whether paraquat modifies the functioning of antioxidants and oxidative stress levels in drought-stressed plants, a cucumber cultivar (Cucumis sativus cv. Yuexiu no. 3) was grown hydroponically for 2 days. Drought stress, which was induced by polyethylene glycol (PEG), increased the contents of malonaldehyde (MDA), superoxide radical (O2−) and hydrogen peroxide (H2O2) in cucumber leaves, while pretreatment of paraquat decreased them. Under drought stress induced by PEG, we observed the decreased contents of MDA, H2O2 and O2− in paraquat-pretreated plants in comparison to unpretreated stressed plants. Drought stress and paraquat both increased the activities of antioxidants such as superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), guaiacol peroxidase (GPX, EC 1.11.1.7), ascorbate peroxidase (APX, EC 1.11.1.11), dehydroascorbate reductase (DHAR, EC 1.8.5.1), monodehydroascorbate reducatase (MDHAR, EC 1.6.5.4), glutathione reductase (GR, EC 1.6.4.2), reduced glutathione (GSH) and reduced ascorbate (AsA). But the combined effect of paraquat application and drought stress resulted in the highest activities of antioxidants. So paraquat is able to moderate the activities of scavenging system enzymes and to influence oxidative stress intensity under drought stress induced by PEG. 相似文献
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环境和食品中砷标准提高后,砷污染及其有关的食品安全问题更加受到广泛的关注。磷对植物吸收和累积砷的影响及其作用机制仍有很大争论。本文利用水培试验,研究了0.025~1.0 mmol L-1范围内7个供磷水平下50μmol L-1AsO43-胁迫对微型番茄生长、砷和磷的吸收及两个磷酸盐转运体基因(LePT1和LePT2)表达的影响。在0.025~0.4 mmol L-1的缺磷条件下,砷对番茄的生长有明显抑制作用。在缺磷状态下,增加磷供应能显著减少番茄体内砷的浓度。约58%的砷累积在番茄根部,根部砷的浓度较地上部高10倍以上。砷抑制番茄对磷的吸收只出现在严重缺磷(0.025~0.05 mmol L-1)条件下。此外,外界砷的存在对LePT1、LePT2基因的表达影响不显著。从本文的结果来看,番茄吸收过程中的磷砷相互作用在缺磷条件下更明显,提高供磷水平可降低番茄体内砷含量,缓解砷对番茄的胁迫作用。 相似文献
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