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.     

椰壳粉与蛭石不同配比基质对黄瓜幼苗生长的影响

研究椰壳粉与蛭石不同配比基质对黄瓜幼苗生长的影响。结果表明 ,椰壳粉与蛭石混合的基质理化性状优于单纯蛭石和椰壳粉 ,孔隙度为 81.4 2 %～ 85.4 5% ,最大持水量为157.2 0 %～ 398.90 %。混合基质明显促进黄瓜幼苗的生长 ,椰壳粉含量为 50 %和 75%时 ,地上部鲜样质量显著增加 ,分别为蛭石的 2 .0 1、2 .0 6倍 ,地下部鲜样质量均增大 84 .38% ;地上部干样质量明显提高 ,而地下部干样质量差异不大。随椰壳粉含量的增加 ,叶片可溶性糖含量增大 ,而根系活力与叶片叶绿素含量降低。由此认为 ,椰壳粉与蛭石等体积混合后可明显改善基质理化性状 ,利于黄瓜生长发育 ,为最佳基质配比。     

棕壤和蛭石对外源钾的固定和释放特征

在外源钾施入量为2800mgkg-1条件下,供试耕地棕壤的固钾容量高达1450mgkg-1。在试验条件下,棕壤对钾素的固定量随外源钾施入量的增加而增加。蛭石对钾素的固定量具有随外源钾的施入量增加而呈线性增大的规律,其中0.3mm~0.1mm粒级蛭石对于钾素的固定量要高于1mm~0.3mm和<0.1mm两粒级蛭石对钾素的固定量。蛭石和棕壤对外源钾的固定率表现为随固钾量的增加而趋于降低的规律,但钾素释放量却随之提高。     

Steepland resources: characteristics, stability and micromorphology

Steeplands of Central America are a major land resource, but due to population pressures they are rapidly being deforested leading to landscape instability. Microwatersheds of Southern Honduras were examined to correlate soil type, landform, slope gradient and slump potential. Soils most susceptible to slumping were moderately deep (0.5–1 m) Haplustalfs and Haplustepts. These soils occupy about 25% of the landscape, and have slope gradients of 45–90%. Soils are developed on plagioclase-rich andesitic parent material, are loam to clay loam in texture and have high base status. However, due to weathering of parent material, sand and silt fractions are dominated by quartz with smaller amounts of plagioclase, vermiculite and kaolinite. The A and B horizons have an open porphyric related distribution with plagioclase as the coarse fraction in a fine-grained groundmass. The andesitic parent rock contains abundant hydrothermally altered plagioclase phenocrysts in a single-spaced porphyric-related (c/f_5μm ratio of 4:1) distribution. Some feldspars are partially to completely altered to clay pseudomorphs, probably vermiculite. Microfabric analysis of soil and pararock did not show any striated b-fabric indicative of shear failure. However, microfabrics do confirm translocated clay into the subsoil as typic pore coatings indicating long-term landscape stability prior to deforestation.     

不同栽培基质对菌根化枳实生苗生长和矿质元素含量的影响

以蛭石、珍珠岩、椰糠、泥炭作为介质,与土壤按照体积比1:1混合作为栽培基质,比较Glomus mosseae接种的枳Poncirus trifoliata实生苗在这些基质栽培下生长、菌根侵染率和矿质营养状况。结果表明,土+蛭石作为栽培基质最有利于菌根的侵染(73.58%)和苗木的生长(地上部干重、地下部干重和整个植株干重),土+椰糠混合的表现最差。以土+蛭石基质下菌根化枳实生苗叶片具有显著最高的磷、钙、锌、铁含量。因此,土+蛭石混合是一种高效的柑桔苗木菌根化栽培基质。     

不同基质配比对温室黄瓜生长的影响

[目的]为进一步加大对醋糟资源的开发和利用提供理论指导和技术依据。[方法]利用醋糟与菇渣、蛭石等基质的不同配比,研究其对温室黄瓜生长的影响。[结果]结果表明:采用醋糟+60%的蛭石的基质配比,营养液施用量为正常用量的50%,黄瓜在株高、叶龄、叶面积、叶绿素含量以及产量等各项指标上都呈现较好结果,在有些指标上超过了采用全肥灌溉的珍珠岩基质(对照CK)。而与菇渣配比中,以60%菇渣配比的处理,黄瓜在各项指标上表现都最差。[结论]在与醋糟配比过程中,菇渣比例不应过高,以20%为宜。     

大红袍花椒组培苗蛭石介质生根技术试验

切取高度1.5 cm以上大红袍花椒优系‘兴秦二号’增殖丛生苗，蛭石为介质，生根培养液为1/2MS+食用糖5 g/L +IBA0.4 mg/L+IAA0.8 mg/L，培养温度26±2 ℃, 光照时间12 h/d, 光照度2 200 Lx，15 d后瓶壁可见不定根，光照度增到3 000~3 500 Lx，与光照时间同步施放CO_{2浓度900~1 000 mg/L，培养瓶盖上扎1~2个针孔，22~30℃变温培养，加大主动换气量，待生根苗高度多数触及瓶盖，即可搬到调控温室，进行炼苗培养，泥炭土4份、珍珠岩1份基质，穴盘移栽，成苗率达94%以上。}