Effects of Applying Potassium,Zeolite and Vermiculite on the Radiocesium Uptake by Rice Plants Grown in Paddy FieldSoils Collected from Fukushima Prefecture

Abstract

Radionuclides were released into the environment as a consequence of the Fukushima Daiichi Nuclear Power Plant accident that occurred on 11 March 2011. Radiocesium at an abnormal concentration was detected in brown rice produced in paddy fields located in northern part of Fukushima Prefecture. We examined several hypotheses that could potentially explain the excessive radiocesium level in brown rice in some of the paddy fields, including (i) low exchangeable potassium content of the soil, (ii) low sorption sites for cesium (Cs) in the soil, and (iii) radiocesium enrichment of water that is flowing into the paddy fields from surrounding forests. The results of experiments using pots with contaminated soil indicated that the concentration of radiocesium in rice plants was decreased by applying potassium or clay minerals such as zeolite and vermiculite. The obtained results indicated that high concentrations of radiocesium in rice are potentially a result of the low exchangeable potassium and sorption sites for Cs in the soils. Application of potassium fertilizer and clay minerals should provide an effective countermeasure for reducing radiocesium uptake by plants. Radiocesium-enriched water produced by leaching contaminated leaf litter was used to irrigate rice plants in the cultivation experiments. The results indicated that the radiocesium concentrations in rice plants increased when the radiocesium-enriched water was applied to the potted rice plants. This indicated the possibility that the radiocesium levels in brown rice will increase if the nuclide is transported with water into the rice paddy fields from surrounding forests.     

Characterization and evaluation of chabazite- and mordenite-rich tuffs,and their mixtures as soil amendments and slow release fertilizers

In the present study, zeolite tuffs of diverse chemistry, mineralogy and origin were characterized and tested for their efficiency as slow release fertilizers (SRF) through a series of leaching tests. Mixtures of zeolite tuffs were created and tested as loamy soil additives, in order to evaluate any synergistic effect on their cation exchange capacity (CEC) and SRF properties. The studied materials were a chabazite-rich tuff (SOR), a mordenite-rich tuff (KIM), 3 mixtures of them (SOR/KIM 30/70, 50/50 and 70/30) and a commercial clinoptilolite-rich tuff (BLG). CEC (sodium acetate method) was 95.7 for BLG, 100.9 for KIM and 92.2 cmol kg^?1 for SOR, while their mixtures displayed intermediate values. SRF values vary, with the SOR/KIM 30/70 exhibiting the slowest NH₄⁺ release in 29 days (1.7%) compared to the control sample (19%). Zeolites promoted PO₄^?3 release, while their selectivity for Mg²⁺ and K⁺ was clearly affected by their different structure and chemistry. BLG exhibited the strongest selectivity for Mg²⁺, having the lowest release (39%). The results demonstrate that mixtures of zeolite tuffs could have a potential use in agricultural processes, by improving parameters like: chemistry, mineralogy, CEC and SRF efficiency, and resulting in the production of a competitive and functional soil additive.     

沸石添加对番茄幼苗素质的影响

以草碳、蛭石 (2V∶1V)为基本基质添加不同比例的沸石 ,就其对番茄幼苗生长的影响进行了研究。结果表明 ,幼苗茎粗、叶面积、干物质量和壮苗指数随沸石量的增加而增加。同时基质中添加沸石对叶片的光合色素含量、光合参数和根系生长等方面也有不同程度的影响。     

利用稻壳气化残渣制备K—ZSM—5分子筛的研究

以生物质稻壳气化残渣（RHA）为原料,通过KOH溶液高温水热反应制取RHA硅溶胶,采用水热合成法制备K—ZSM—5分子筛。考察了热水反应时间对Si溶出率的影响,分析了RHA硅溶胶的复杂物质组成。研究了RHA硅溶胶复杂合成体系中,模板剂种类、硅铝摩尔比、晶化温度和晶化时间等因素对K—ZSM—5分子筛成核与生长过程的影响规律;并采用XRD、SEM、ICP、TG、N2吸附脱附等手段表征分子筛晶体。结果表明：直接以RHA硅溶胶为原料合成K—ZSM—5分子筛时,对有机模板剂的结构导向作用要求较高;采用乙醇类的弱有机模板剂无法合成出分子筛晶体;采用低含量的TPABr强有机模板剂,可以在一定硅铝摩尔比范围内合成出晶形较为完备的K—ZSM—5分子筛晶体,但存在合成体系可调范围比较窄,晶形杂乱且粒度较大,合成温度较高,合成时间较长等劣势。实验还发现,煅烧方式对所合成的大粒度K—ZSM—5分子筛晶体的孔道结构影响较大,直接550℃高温煅烧容易形成积碳,须在350℃中温热解3h后,再550℃高温煅烧才能获得纯净的K—ZSM—5分子筛产品。     

施用沸石对烤烟生长效应的研究

盆栽试验结果表明:每千克风干土中施入2~3g沸石能明显促进烤烟植株生长,使烟株比对照增高8.6%~9.8%;茎围增粗3.9%~5.8%;烟叶干重提高5.4%~6.9%;烟叶中钾含量提高0.81~1.83个百分点,氯含量降低0.07~0.12个百分点。     

人工沸石复合湿地技术控制面源污染应用研究

通过研究滇池流域一区域段的暴雨径流特征,探索人工沸石复合湿地技术应用于区域农业面源污染控制的可行性。研究结果表明,以人工沸石复合湿地技术为核心的组合湿地系统对氮、磷具有稳定的去除效果,且在处理暴雨径流期间,表现出短时间内对氮、磷较强的截留率。     

膨润土和沸石对重金属镉的吸附性研究

通过等温吸附试验,研究了粘土矿物膨润土和沸石对Cd~(2+)的吸附状况,并与土壤对Cd~(2+)的吸附状况进行了对比。结果表明:随溶液中Cd~(2+)浓度的增大,膨润土、沸石和土壤对Cd~(2+)的吸附量增大,对Cd~(2+)的吸附率随Cd~(2+)浓度的增大而降低,其中膨润土的降低的较慢,沸石次之,土壤的降低最快。膨润土、沸石和土壤对Cd~(2+)的吸附等温曲线符合Langmuir方程,三者对Cd~(2+)的最大吸附量膨润土>沸石>土壤。粘土矿物膨润土和沸石对Cd~(2+)有很好的吸附作用,可用于重金属污染土壤的治理。     

沸石联合硫酸铝处理生活污水技术初探

[目的]探讨沸石联合无机絮凝剂硫酸铝处理生活污水的最佳投加比例。[方法]将沸石和硫酸铝联合起来处理生活污水,通过分析絮凝率的变化,研究二者联合使用的最佳投加比例。[结果]沸石和硫酸铝联合使用的最佳投加比例为1∶1,此时絮凝率高达98%以上。沸石联合硫酸铝处理生活污水不仅可以提高污水的处理效果,而且降低了化学絮凝剂的用量,从而减少了化学絮凝剂的二次排放,并降低了经济成本。[结论]该研究为今后生活污水的有效处理提供了理论依据。     

日粮中添加沸石对蛋鸡生产性能的影响

本试验选用本校牧场39周龄体健海兰商品蛋鸡1000只,随机分为五个组Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ,每组设四个重复,试验Ⅰ组为不含沸石的对照组,试验Ⅱ、Ⅲ、Ⅳ、Ⅴ组分别在其日粮中用1%,3%,5%,7%的沸石代替玉米或豆粕,每组200只鸡在同一鸡舍笼养(温度、湿度、光照均满足正常生产需要)。试验结果表明,除第Ⅴ组外,所有试验组的产蛋率分别高于对照组0.02%、3.09%、0.36%,饲料利用率分别提高0.84%、5.42%、2.50%。经统计分析,添加3%、5%沸石的两组产蛋率和料蛋比与对照组相比,差异极显著(P<0.01)。试验结果表明,产蛋鸡日粮中添加3%的沸石,生产性能和经济效益最佳。