多效唑对水仙观赏效果的影响

水仙对多效唑比较敏感,无论浸泡法或叶面喷施法都具有明显的矮化效应,但当浓度≥200mg·l-1时又会产生药害,也有碍观赏;叶面喷施法对水仙矮化效应不如浸泡法,开花期亦迟10·15d;浸泡法的最佳处理浓度是50 mg·l-1;叶面喷施法以浓100-200mg·l-1效应最好,但此法费工费时,操作不便,生产上最好不采用。     

论中药的毒副作用

中药在临床的应用将日益广泛,但其毒副作用应当受到重视,本文就中药的毒副作用及其与毒副作用有关的因素,毒副作用对机体的影响等问题进行了论述.     

覆盖旱作水稻的生物效应及吸氮特征

研究了田间条件下旱作水稻半腐解秸秆覆盖、蚕豆秆覆盖、地膜覆盖、纸膜覆盖、生稻草覆盖 5种覆盖方式的吸氮特征 ;水稻水作与旱作的产量及其构成因素 ;水稻水作与旱作条件下灌溉水的利用效率。结果表明 ,旱作条件下水稻各部位的含氮量均大于水作 ;旱作水稻的氮素吸收、累积主要在拔节期以后 ,而水作水稻从移栽后就大量吸收氮素 ,灌浆期后很少吸收氮素 ;旱作水稻的产量以半腐解覆盖处理的最高 ,为 8415kg/hm2 ;旱作水稻耗水量只占水作耗水量的 7 14% ,旱作水稻的水分利用效率是水作的 12倍以上     

Cd-Pb复合污染在土壤-水稻系统中生态效应的研究

采用盆栽试验研究了重金属复合污染物在土壤 -水稻系统中迁移、积累规律及生态效应。结果表明 :Cd、Pb复合污染使水稻株高比对照的下降了 5～ 7cm ,水稻减产 2 0 % ,2元素交互作用特别是 5元素复合作用影响了水稻的正常生长发育 ;不同处理中重金属在水稻籽实的分配比例依次为 5元素 >2元素 >单元素 ;Cd -Pb 2元素交互作用时 ,Pb元素的存在促进了水稻对Cd元素的吸收 ,而Cd元素却抑制了水稻对Pb元素的吸收 ;Cd比Pb元素易向地上部迁移 ,Pb元素大部分积累于水稻根部     

Ozone and/or Water Stresses Could have Influenced the Betula ermanii Cham. Forest Decline Observed at Oku-Nikko, Japan

A serious forest decline of Betula ermanii Cham. has been observed at Mt. Mae-Shirane, Oku-Nikko, Japan, where high ozone (O₃) concentration and severe water deficiency have been measured. In order to consider the possibility whether O₃ and/or water stresses could have been the causes of the forest decline of B. ermanii, plant growth experiments were conducted in environment-controlled growth cabinets. Two-year-old seedlings of B. ermanii were exposed to either charcoal-filtered air (O₃ concentration <5 ppb) or 50 ppb O₃ (daily average, ranging between 20–100 ppb) for 123 days at 20.0/12.5 ± 1.0°C (day/night) and 70/80 ± 7% relative humidity (day/night). Simultaneously, seedlings were treated with three watering regime: 1.0 < pF < 1.8 (no water stress), 1.8 < pF < 2.5 (mild water stress) or 2.5 < pF < 3.0 (severe water stress). O₃ exposure significantly reduced the dry weights of leaf, root and the whole plant, while water stress significantly reduced the dry weights of each organ and the whole plant. Significant reductions of net photosynthesis, transpiration and stomatal conductance were also observed under O₃ and/or water deficiency treatments, while contents of RuBP carboxylase/oxygenase (Rubisco), chlorophyll _a+b and some essential nutrient elements (N, P, K, Mg and Ca) were not markedly changed. It was suggested that the decrease in net photosynthetic rate induced mainly by stomatal closure was the major cause of the growth reduction under O₃ and/or water stresses. No significant interactions between O₃ and water stresses were observed in terms of the depression of dry matter production, which suggested that simultaneous stress treatments of O₃ exposure and water deficiency could affect the tree growth of B. ermanii additively.     

Are Nitrogen-Fertilized Forest Soils Sinks or Sources of Carbon?

We developed a simple conceptual model that tracks nitrogen and carbon jointly through an N fertilized forest ecosystem. The stimulation of growth increases the litterfall and imports substrate for soil microorganisms. Microbial biomass forms according to the supply of C and N. The formation of microbial biomass is accompanied by respiratory C losses. The quantity of CO₂ efflux depends on the C use efficiency of microbes. When excess N is available, the microbial activity is accelerated and the demand for substrate is high. Litterfall supplies an insufficient amount of C to the soil. In such a case, labile soil C is mineralized and the net effect of N fertilization is a loss of soil C. A strong N fertilization effect on the aboveground biomass can offset the soil C loss. In the case of a low N dosage or high N losses due to leaching or emission of nitrogen oxides, the soil C loss is small. The conceptual model was applied to a case study. The field data, collected over a time span of several decades, could not support sound conclusions on the temporal trend of soil C because the spatial and temporal variability of the chemical data was high. The conceptual model allowed to give an evaluation of the fertilization effect on soil C based on reproducible principles.     

低温季节生物栅对富营养化河水净化试验研究

文章介绍和分析了低温季节不同工况条件下生物栅净化池对富营养化河水的处理效果。结果表明,11月中旬到12月底期间,江南地区的气温和河道水温都较低,生物栅池中水生植物(水花生)处于休眠和枯死阶段,生物膜上微生物活性也较低,因此河水在池中的净化主要由过滤、沉淀和吸附等物化作用完成的,停留时间为10h时生物栅池对河水中COD、NH4+-N、TN和TP的平均去除率为16.7%～38.8%、30.0%～41.7%、14.1%～35.0%和15.4%～44.4%。随着气温和水温的进一步降低(A阶段到B阶段),河水中污染物的去除率也逐渐下降(下降幅度为2%～10%),低温导致污染物沉淀和吸附速度及生物膜活性降低可能是其中的主要原因。低温季节富营养化河水的DO含量较高,温度越低,填料类型、曝气与否、植物有无对污染物去除率的影响也越小。     

印染废水处理的磁混凝-高梯度磁分离协同作用

混凝过程作为工业废水的预处理技术普遍受到重视,在混凝过程中降低污泥产生量并提高污泥分离速度是该技术发展的方向,基于上述目标,通过将磁粉引入絮体使之磁化并在自行研制的高梯度磁分离装置中实现磁混凝与磁分离的协同作用.以高浊度的印染废水作为试验废水,以色度、COD及SS作为考核指标,重点考察了磁混凝反应及磁分离的影响因素.当印染废水的色度约为900倍、COD约为595 mg/L、SS约为500 mg/L时,在pH=8.5、FeSO4500 mg/L、PAM3.5 mg/L、磁粉400 mg/L的适宜磁混凝反应条件下,相应指标去除率比传统混凝法分别高出17.3%、21.7%及24.2%,此时絮团沉降速度增大了64.3%,污泥体积减少了61%,污泥压缩比为0.39.在电流强度8 A、流速2.5 L/min和介质填充率1%的操作条件下,该磁性絮体流经高梯度磁分离装置时的水力表面负荷达到61.0 m3/m2·h,处理出水达到国家二级排放标准.     

固液相离子吸附体系中吸附剂浓度效应与Langmuir方程的适用性

以蛭石吸附Zn2 和Cd2 为例,探讨Langmuir方程在固液相离子吸附体系中的适用性,结果表明:传统吸附等温线随吸附剂浓度W0增大而下降,吸附量qe不仅仅由液相平衡浓度Ce所决定,而是Ce和W0两个变量的函数;以Langmuir方程的线性形式对实验数据进行拟合,在给定吸附剂浓度水平下的实验数据与Langmuir方程拟合的相关性很好,但方程中的两个参数随吸附剂浓度增大而降低而且差异显著,表明Langmuir方程仅适用于给定吸附剂浓度的体系,采用单一参数的Langmuir方程难以准确描述试验检测范围内Zn2 和Cd2 的吸附规律.     

乙草胺对小麦生理机能的影响与生物标记物识别

对乙草胺胁迫下小麦幼苗叶片的超氧化物歧化酶（SOD）、过氧化物酶（POD）活性、可溶性蛋白含量、丙二醛（MDA）以及叶片中叶绿素含量的变化进行了研究.结果表明,乙草胺处理小麦幼苗1 d后,叶片MDA含量显著增加,说明了乙草胺处理诱导有毒活性氧（AOS）生成,但随着处理时间的延长,不同浓度处理与对照的差异逐渐减小.对小麦叶片中POD活性变化的研究表明,在乙草胺胁迫的开始阶段,植物有能力抵抗低浓度乙草胺污染所产生的氧化胁迫,但是,随着暴露时间的延长和污染物浓度的增加,这种抵抗能力将会消失.对小麦SOD活性的研究表明,小麦叶片中POD酶活的上升可能与其它途径而不是SOD诱导产生的H₂O₂有关.小麦叶片中MDA含量和POD活性不能作为土壤乙草胺污染的生物标记物.小麦叶片中SOD酶活性有着作为乙草胺污染土壤生物标记物的潜力,但还需要进一步研究.小麦叶片叶绿素含量和可溶性蛋白含量可以作为乙草胺污染胁迫的生物标记物,并且小麦幼苗叶片可溶性蛋白含量与土壤乙草胺浓度之间具有较好的剂量-效应关系.