土壤微量元素与人类活动强度的对应关系

本文以天津地区为例 ,在分析影响土壤中微量元素含量各种人为因素的基础上 ,利用天津地区人类活动强度对土壤微量元素含量变化的联系、不同土地利用方式土壤微量元素含量的变化规律 ,探讨土壤微量元素含量变化与人类活动强度之间的联系。研究发现 ,Hg、Cd、Se元素是最敏感的地球化学因子 ,能够反映天津地区土壤环境受人类活动的影响程度 ,利用土壤环境中Hg、Cd、Se的变化特征 ,可以确定本地区土壤环境受人类影响程度的大小     

Variability of CO2 and N2O emissions during freeze‐thaw cycles: results of model experiments on undisturbed forest‐soil cores

The amounts of N₂O released in periods of alternate freezing and thawing depend on site and freezing conditions, and contribute considerably to the annual N₂O emissions. However, quantitative information on the N₂O emission level of forest soils in freeze‐thaw cycles is scarce, especially with regard to the direct and indirect effect of tree species and the duration of freezing. Our objectives were (i) to quantify the CO₂ and N₂O emissions of three soils under beech which differed in their texture, C and N contents, and humus types in freeze‐thaw cycles, and (ii) to study the effects of the tree species (beech (Fagus sylvatica L.) and spruce (Picea abies (L.) Karst.)) for silty soils from two adjacent sites and the duration of freezing (three and eleven days) on the emissions. Soils were adjusted to a matric potential of –0.5 kPa, and emissions were measured in 3‐hr intervals for 33 days. CO₂ emissions of all soils were similar in the two freeze‐thaw cycles, and followed the temperature course. In contrast, the N₂O emissions during thawing differed considerably. Large N₂O emissions were found on the loamy soil under beech (Loam‐beech) with a maximum N₂O emission of 1200 μg N m^–2 h^–1 and a cumulative emission of 0.15 g N m^–2 in the two thawing periods. However, the sandy soil under beech (Sand‐beech) emitted only 1 mg N₂O‐N m^–2 in the two thawing periods probably because of a low water‐filled pore space of 44 %. The N₂O emissions of the silty soil under beech (Silt‐beech) were small (9 mg N m^–2 in the two thawing periods) with a maximum emission of 150 μg N m^–2 h^–1 while insignificant N₂O emissions were found on the silty soil under spruce (0.2 mg N m^–2 in the two thawing periods). The cumulative N₂O emissions of the short freeze‐thaw cycles were 17 % (Sand‐beech) or 22 % (Loam‐beech, Silt‐beech) less than those of the long freeze‐thaw cycles, but the differences between the emissions of the two periods were not significant (P ≤ 0.05). The results of the study show that the amounts of N₂O emitted in freeze‐thaw cycles vary markedly among different forest soils and that the tree species influence the N₂O thawing emissions in forests considerably due to direct and indirect impacts on soil physical and chemical properties, soil structure, and properties of the humus layer.     

中国黄土地区土壤中天然放射性元素的生物地球化学

本文叙述了我国黄土地区主要类型土壤中天然放射性元素的含量水平、迁移积聚和剖面分布情况。研究结果表明，本地区土壤放射性元素的含量、比值和离散程度均接近其黄土母质，但各土类间仍表现出一定的分异，在弱碱性的土壤环境里，以（ＵＯ２）＾２＋存在的铀比较活跃。碳酸盐能促使铀的淋滤，而有机质的存在却有利于铀的积聚。钍和镭集中积蓄在富含粘粒的土层中，但在林地土壤中钍有淋移的迹象。从各核素的剖面分布看，土壤在发育过     

镍污染对小麦幼苗矿质营养元素吸收与累积的影响研究

试验研究Ni胁迫对小麦幼苗茎叶中Cu、Zn、Fe、Mn、Ca和Mg营养元素吸收及累积的影响结果表明 ,Ni胁迫下随土壤施Ni量的增加而小麦幼苗生长受抑 ,生物产量下降 ,小麦幼苗Cu、Fe、Ca和Mg累积量呈下降趋势 ,而Zn、Mn累积量呈增加趋势。小麦幼苗 6种营养元素累积率与其累积量的规律较吻合 ,表明作物受Ni毒害与营养元素代谢平衡失调有关     

菊花营养价值的初步研究

分析测定了野生菊(Mantianxing),药用菊(Hangbaiju),栽培菊(Huangjingqiu),三个菊花品种的还原糖、总糖、维生素C,氨基酸及钙,磷、铁、铜、锌、锰等矿质元素的含量。结果表明:野生菊的维生素C、总糖、还原糖、氨基酸总量分别比药用菊和栽培菊高,药用菊的铁、锌、铜、锰的含量分别比野生菊和栽培菊高。栽培菊的钙、磷则分别比野生菊和药用菊高。从而为进一步开发利用我国丰富的菊花资源提供了依据。     

稻萍鱼体系中红萍供氮的特点

应用~(15)N示踪技术,研究了稻萍鱼共生体系中红萍氮素的循环利用效率。试验结果表明,红萍作饵针对尼罗罗非鱼生长有良好效率,早、晚季稻田的鱼体增重率分别为47.9％和52.1％。鱼体排泄物对水稻生长有益,其稻谷产量与等量红萍压施作肥料的结果相近。早、晚季稻田罗非鱼对~(15)N-红萍的利用率分别为21.73％和23.76％,早、晚季水稻对鱼体排泄物中~(15)N利用率分别为18.90％和16.59％,其~(15)N总利用率分别达40.63％和40.35％。而红萍直接压施作肥料,早、晚季稻株对萍体氮素的利用率分别为28.84％和24.30％。     

三江源区不同高寒草地植物矿物元素含量特征及分析

本试验对三江源区不同高寒草地植物中6种矿物元素（钾K,钙Ca,钠Na,镁Mg,锌Zn,铁Fe）的含量进行了测定和分析,结果表明：植物中K元素含量为7.314～12.803 g·kg^-1之间,Ca元素含量为2.851～6.823 g·kg^-1之间,Na元素含量为64.404～185.553 mg·kg^-1之间,Mg元素含量为1.272～2.655 g·kg^-1之间,Zn元素含量为14.718～51.387 mg·kg^-1之间,Fe元素含量为161.056～531.677 mg·kg^-1之间;豆科（Leguminosae）植物和杂类草（Forbs）矿物元素含量显著高于禾本科（Gramineae）和莎草科（Cyperaceae）植物;植物中K元素与Mg元素、Ca元素与Na元素、Ca元素与Zn元素、Na元素与Zn元素含量之间呈极显著正相关关系（P<0.01）,Ca元素与Fe元素、Mg元素与Fe元素之间呈显著正相关关系（P<0.05）;根据美国国家研究理事会（National research council,NRC）绵羊日粮矿物元素需求标准,三江源区各草地植物中Na,Zn元素相对缺乏,其它4种元素均能满足放牧藏羊的矿物营养需求。     

Effect of Salinity Stress and Surfactant Treatment on Physiological Traits and Nutrient Absorption of Fenugreek Plant

Salinity is considered as a major abiotic stress affecting crop production in arid and semi-arid regions in the world. Surfactants can improve water-use efficiency in saline soils and improve crop yield. This study was conducted to evaluate the effect of salinity stress and surfactant treatments on photosynthetic pigments and nutrition elements of fenugreek in the Crop and Soil Science greenhouse at the Pennsylvania State University (University Park, PA, USA) in 2013. The experiment was conducted using a 5 × 3 factorial randomized complete block design with three replications. Factor A consisted of five salinity levels [0, 4, 6, 8, and 10 ds m^–1 sodium chloride (NaCl)] while factor B consisted of three nonionic surfactant levels (0, 1, and 3 ppm). The results indicated a stepwise reduction in photosynthetic pigments of fenugreek as salt stress increased, however, Peroxidase and polyphenol oxidase activity increased in fenugreek leaves as salinity stress increased. Levels of surfactant application had different effects on nutrient uptake. Some nutrient elements such as sodium, phosphorus, copper, manganese, and zinc content increased while others decreased at high salinity conditions. Surfactant application rate of 3 ppm at moderate and high salinity levels and 1 ppm at lower salinity levels had a good performance in enhancing the total photosynthetic and carotenoid activities in fenugreek.     

赣南不同土壤类型脐橙园叶片营养状况研究

从赣南10个区县的沙质红壤、黏性红壤、紫色土和黄壤共131个果园采样测试了叶片营养元素含量，分析营养丰缺状况。赣南脐橙园普遍存在叶片N、K过量和Mg、Zn同时缺乏的问题。叶片N、P、K、Ca、Mg、Fe和 Mn在不同土壤类型的果园间存在显著性差异（P<0.05）：沙性红壤果园P、Fe更为丰富。黏性红壤果园N含量最高，K的过量程度和 Mg的缺乏程度都最轻。黄壤果园P更丰富，Ca更缺乏，Mn最容易过量。紫色土果园N、P含量最低，K最易过量，Ca较丰富，Mg最缺乏，有部分pH较高的果园植株缺Fe。叶片S、Zn、Cu、B和Mo 在不同土壤类型的果园间差异不显著（P>0.05），但有相当比例的脐橙园叶片缺Cu，少量果园叶片缺B，所有果园叶片S和Mo在适宜范围内。赣南脐橙园叶片N、K过量和Mg、Zn缺乏的情况较为普遍，不同土壤类型的脐橙园叶片N、P、K、Ca、Mg、Fe和 Mn营养丰缺状况存在显著性差异（P>0.05）。     

Leaf chlorophyll content as a possible diagnostic mean for the evaluation of plant nitrogen uptake from the soil

The influence of temperature, irradiance, and soil humidity on the nitrogen (N) concentration in some organs, chlorophyll in the leaves, N uptake and accumulation of dry matter in plants of winter wheat was investigated. In the plants grown under equal initial N supplement but in contrasting conditions of the evironment, the correlation between concentration of total N and chlorophyll in the leaves was absent. No interrelationship was found between concentration of total N in the leaves and accumulation of N and dry matter in the whole plants. There is a close correlation between chlorophyll in the leaves, accumulation of total N, and dry matter of the whole plant. It was concluded that chlorophyll is a more stable informative parameter for the estimation of the N uptake from the soil under different growth conditions than leaf N concentration.