干燥和重新湿润过程引起土壤CO_2激发释放的模拟研究

应用短期培养实验研究了干燥和重新湿润引起的土壤CO2激发释放及其动力学过程.结果表明,不经干燥和重新湿润处理土壤CO2释放速率基本不随时间变化,其CO2释放过程可以用零级反应动力学方程(y=k0t)描述;干燥和重新湿润处理过程能够引起明显的土壤CO2激发释放,这是干燥和重新湿润引起的土壤呼吸激发效应(一级反应)和土壤基本呼吸(零级反应)相互叠加的结果,可以用两库叠加模型y=at+Ao(1-e-kt)很好描述.本实验条件下扰动、干燥和重新湿润引起的(蝼)土CO2净激发释放量为23.05～59.90 mg CO2-C·kg-1,主要与不同培肥措施长期实施造成的土壤性质和肥力差异,特别是有机质数量和质量的差异有密切关系.     

冲水洗盐对滨海盐碱地盐分变化的影响

【目的】改良盐碱地。【方法】通过引水冲刷的方法,研究盐碱地盐分因子的时空变化,采用常规理化分析方法对样点土壤的盐碱度进行分析,并比较土壤的阴阳离子和生态离子之间的相关性。【结果】随着冲洗的次数增多,土壤中SAR从11.87 mmol/L降到3.02 mmol/L,pH值(从8.47降到8.25,夏季盐碱因子量最低,而秋季为返盐期盐碱因子小幅增加;盐度量随着月份的增加而增加,10月份最大为8.30‰;EC和TDC呈先减小后增加的趋势,分别从982.67μS/cm到1 037.67μS/cm和491.33 mg/L到523.67 mg/L;上、中、下层土在不同月份间有差异。本试验盐碱离子主要是Na+、CL-构成,表现为CL->Na+>Mg2+>SO42->Ca2+>HCO3->K+>CO32-,SAR与Na+极显著正相关。【结论】减少土壤中Na+量对治理盐碱地具有极大的作用。     

姬松茸60Co辐射诱变菌株J5与原菌株J1蛋白质

采用非生物学评价法对姬松茸60Co辐射诱变菌株J5和其原菌株J1不同潮次菇蛋白质的营养价值进行评价.结果表明:J5子实体的必需氨基酸指数、生物价、营养指数、氨基酸比值系数分、化学评分和氨基酸评分分别比J1高1.02％、2.26％、2.93％、11.72％、9.35％和5.13％;以上6项蛋白质评价指标中,J5第1、第2...     

沈阳市降雨径流初期冲刷效应

研究探讨城市降雨径流的初期冲刷效应对于城市水环境治理和水污染防治具有重要意义。以沈阳市典型区域为例,对坡顶屋面、平顶屋面和路面3种典型下垫面的降雨径流进行了监测,分析的污染物包括总悬浮颗粒物(TSS)、总氮(TN)、总磷(TP)、化学需氧量(COD)和主要重金属(Cd、Cr、Cu、Ni、Zn)。利用M(V)曲线和污染物初期冲刷率(MFF₃₀),分析了不同降雨径流事件的初期冲刷强度和发生强冲刷、弱冲刷的概率。结果显示:研究区较易产生初期冲刷现象,约有50%-90%的降雨事件能产生初期冲刷现象。3种下垫面发生初期冲刷的强度依次是:平顶屋面>坡顶屋面>路面。降雨历时和干期长度与初期冲刷效应具有正相关关系,降雨量和降雨强度与初期冲刷先是正相关关系,但当稀释效应大于冲刷效应时,呈现负相关关系。重金属污染物较容易发生初期冲刷现象,而TN易发生强初期冲刷。     

Carbon and nitrogen mineralization as affected by drying and wetting cycles

Drying and rewetting of soil is an important process in soil aggregation, soil organic matter (SOM) decomposition, and nutrient cycling. We investigated the source of the C and N flush that occurs upon rewetting of dry soil, and whether it is from microbial death and/or aggregate destruction. A moderately well drained Kennebec silt loam (Fine-silty, mixed, superactive, mesic Cumulic Hapludoll) was sampled to a 10 cm depth. Soil under constant water content (CWC) was compared with soil subjected to a series of four dry-wet (DW) cycles during the experimental period (96 d) and incubated at 25 °C. Mineralized C and N were measured during the drying and rewetting periods. Aggregate size distributions were studied by separating the soil into four aggregate size classes (>2000, 250-2000, 53-250, and 20-53 μm) by wet sieving. Repeated DW cycles significantly reduced cumulative N mineralization compared with CWC. The reduction in cumulative mineralized C resulting from DW compared with CWC increased as the DW treatments were subjected to additional cycles. The flush of mineralized C significantly decreased with repeated DW cycles. There was no significant effect on aggregate size distributions resulting from to the DW cycles compared with CWC treatment. Therefore, the flush of mineralized C and N seemed to be mostly microbial in origin in as much as aggregate distribution was unaffected by DW cycles.     

山洪及泥石流灾害空间预报技术研究

通过荒溪调查与分类 ,在分析北京山区山洪及泥石流灾害发生的历史、影响因子、灾害特点的基础上 ,建立了北京山洪及泥石流灾害空间预报信息系统 ,并对北京山区山洪及泥石流灾害空间分布进行了预报。建立的空间预报信息系统能查询、更新、管理各类荒溪危险区分布及基本情况 ,能准确预报山洪及泥石流灾害发生的位置及分布范围。其成果已用于危险区内居民的迁移工作     

The number of leaves required for floral induction and translocation of the florigenic promoter in mango (Mangifera indica L.) in a tropical climate

Mango flowering appears to be determined by a temperature-regulated florigenic promoter (FP) synthesized in leaves and translocated to buds in phloem. The number of leaves required for flowering was investigated in ‘Keitt’ and ‘Tommy Atkins’ mango trees exposed to tropical conditions in Colombia. Data were compared with a previous study conducted under cool, floral-inductive conditions in Florida (Davenport et al., 2006). Leaf-number treatments consisted of 0, 1/8, 1/4, 1/2, 1, 2, 3, or 4 leaves on each of 20–40 stems per branch. The long distance translocation experiment consisted of a terminal donor stem and five defoliated receiver stems on each treatment branch. Treatments were 0, 1, 3, or 5 leaves on the donor stem. Every treatment branch in both experiments was girdled to isolate it from the rest of the tree, and developing panicles were removed to stimulate lateral shoot initiation at a time when conditions were right for floral induction in those buds. Treatment stems bearing no leaves produced only vegetative shoots in both cultivars in both experiments. The minimum number of leaves per stem (1/8 of a leaf and 1/4 of a leaf) was sufficient to induce 6% and 1% reproductive shoots with 94% and 99% vegetative shoots in Tommy Atkins’ and ‘Keitt’ stems, respectively. Branches bearing 4 leaves per stem in ‘Tommy Atkins’ trees produced the maximum mean flowering response with 45% reproductive shoots and 55% vegetative shoots. The maximum ‘Keitt’ response was 22% reproductive and 78% vegetative shoots with 4 leaves per stem. The donor stem of the 1-leaf treatment and the donor and first receiver stem of the 3-leaf treatment in the translocation experiment were induced to flower in ‘Tommy Atkins’ trees. The more distal receiver stems from the donor were vegetative. The 5-leaf donor treatment-induced reproductive shoots as far as the third leafless receiver stem located 52 cm from the donor. Proportions of flowering shoots decreased with distance from the donor, and the level of the FP was apparently insufficient to reach the fourth and fifth receivers since their shoot responses were vegetative. Only vegetative shoot responses were obtained in the translocation experiment conducted in ‘Keitt’ trees. The leaf number and translocation experiment results support the hypothesis that far less FP is synthesized in both ‘Tommy Atkins’ and ‘Keitt’ leaves during warm, tropical conditions than is synthesized in ‘Keitt’ leaves exposed to cool, subtropical conditions.     

植物生长调节剂对库尔勒香梨产量与品质的影响

为了明确植物生长调节剂在库尔勒香梨(Pyrus brestschneideri Rehd.)生产中的施用效果,该田间试验以20 a树龄库尔勒香梨为研究试材,研究植物生长调节剂PBO(增效醚,包含细胞分裂素BA与生长素衍生物ORE)、PP333(15%多效唑)和复硝酚钠对库尔勒香梨果实产量及内外部品质的影响,分别设置不同生长调节剂、不同浓度、清水及空白喷施处理,共计17个处理,每处理3次重复。结果表明:喷施植物生长调节剂可以显著提高库尔勒香梨产量,可以降低果皮厚度、果实硬度、果实总酸含量,还可以提高果实脱萼率、红晕果率、果实还原糖含量和维生素C含量,其中以喷施PBO 300倍液效果最佳。与对照处理相比,喷施PBO 300倍液处理的库尔勒香梨产量、红晕果率、脱萼果率及果实还原糖含量分别提高了63.41%、42.01%、38.97%和22.22%,而果皮厚度、果实硬度及果实总酸含量分别降低了26.44%、13.42%和31.3%。     

快速城市化地区小流域降雨径流污染特征

降雨径流污染对快速城市化地区的水环境安全造成巨大威胁.在对深圳市石岩水库6条入库支流的4次降雨径流事件进行水文水质监测的基础上,选择CODcr、NH3-N、TN、TP、SS和BOD5 6种常见水质测试指标对该区域的降雨径流污染的水质状况、空间差异和初始冲刷效应等基本特征进行了分析.结果表明,研究区降雨径流中耗氧性污染物...