红壤丘陵区林下灌木生物量估算模型的建立及其应用

以中国科学院千烟洲生态试验站林下常见的16种物种作为研究对象,构建了单一物种以植冠面积(Ac)为变量的二次方程和以植冠投影体积(Vc)为变量的乘幂方程来估算物种生物量,以及16种物种的混合模型来估算其生物量,并将最佳生物量估算模型应用于不同森林内灌木层生物量的估计.不同森林的灌木层生物量组成存在较大差异.以物种单一模型计算的落叶阔叶林、次生林、人工针叶林灌木层的生物量分别为4773、3175和733kg.hm-2;以物种混合模型估算的结果略低于单一模型,分别为3946、2772和840kg.hm-2.混合模型在未能对所有物种建立单一模型的情况下估算灌木层生物量时,具有简便、实用性的特点.     

Immediate and long-term nitrogen oxide emissions from tropical forest soils exposed to elevated nitrogen input

Tropical nitrogen (N) deposition is projected to increase substantially within the coming decades. Increases in soil emissions of the climate‐relevant trace gases NO and N₂O are expected, but few studies address this possibility. We used N addition experiments to achieve N‐enriched conditions in contrasting montane and lowland forests and assessed changes in the timing and magnitude of soil N‐oxide emissions. We evaluated transitory effects, which occurred immediately after N addition, and long‐term effects measured at least 6 weeks after N addition. In the montane forest where stem growth was N limited, the first‐time N additions caused rapid increases in soil N‐oxide emissions. During the first 2 years of N addition, annual N‐oxide emissions were five times (transitory effect) and two times (long‐term effect) larger than controls. This contradicts the current assumption that N‐limited tropical montane forests will respond to N additions with only small and delayed increases in soil N‐oxide emissions. We attribute this fast and large response of soil N‐oxide emissions to the presence of an organic layer (a characteristic feature of this forest type) in which nitrification increased substantially following N addition. In the lowland forest where stem growth was neither N nor phosphorus (P) limited, the first‐time N additions caused only gradual and minimal increases in soil N‐oxide emissions. These first N additions were completed at the beginning of the wet season, and low soil water content may have limited nitrification. In contrast, the 9‐ and 10‐year N‐addition plots displayed instantaneous and large soil N‐oxide emissions. Annual N‐oxide emissions under chronic N addition were seven times (transitory effect) and four times (long‐term effect) larger than controls. Seasonal changes in soil water content also caused seasonal changes in soil N‐oxide emissions from the 9‐ and 10‐year N‐addition plots. This suggests that climate change scenarios, where rainfall quantity and seasonality change, will alter the relative importance of soil NO and N₂O emissions from tropical forests exposed to elevated N deposition.     

薄层色谱法鉴定天麻胶囊中的天麻素

为了建立天麻胶囊中主要有效成分天麻素的快速鉴定方法,根据天麻素的理化特性,使用乙醇和甲醇提取天麻胶囊中的天麻素,使用薄层色谱法进行鉴定,并与高效液相色谱法的分析结果进行比较。结果表明,薄层色谱法的鉴定结果与高效液相色谱法的检测结果一致,能较准确地鉴别天麻胶囊的真伪。本研究结果表明薄层色谱法能快速简便、准确灵敏地检测天麻胶囊中的有效成分,可作为法定鉴定方法的补充,对天麻胶囊实施快速初筛。     

黄土旱塬区土壤水分状况与作物生长、降水的关系

土壤水分研究是统筹农业生产和生态环境建设的关键环节.本研究结合4年田间定位试验,通过对黄土高原南部长武旱塬冬小麦和春玉米2012—2015年土壤水分状况的研究,分析农田土壤干层形成情况、土壤水分对作物生长的影响、降水对土壤水库的影响以及作物对土壤水分状况的影响.结果表明: 降水年型是冬小麦地土壤干层形成的主导因素,年内降水分布不均是春玉米地土壤干层形成的主导因素.长武旱塬区冬小麦和春玉米一年一季的种植制度不会导致永久性干层的产生;相较于春玉米,冬小麦根系生长习性更符合黄土旱塬区土壤水分循环特征,黄土旱塬区土壤水分有效性可保证作物产量稳定;降水作用下,冬小麦土壤水库充、放水过程呈现收获期、休闲期和苗期连续充水、缓慢消耗期和大量消耗期连续失水相互交替的特点.0～300和300～600 cm土层土壤水库不一致性现象明显,以最大根深作为野外监测试验中土壤含水量的取样深度时,由于深层土壤水库负反馈作用,不同降水年型下,休闲期和苗期的蒸散均会被高估,缓慢消耗期和大量消耗期的蒸散均会被低估.冬小麦田间过渡层存在的范围为140～360 cm;作物生长的时间跨度影响土壤水库效应的发挥,土壤水库对冬小麦供水表现为年际间的调节作用,土壤水库对春玉米供水表现为季节间的调节作用.     

Effects of leaf shape plasticity on leaf surface temperature

干旱区植物叶片形态可塑性是植物适应高温干旱环境的重要生存策略, 但目前仍缺乏直观的数据予以证明。该研究应用热成像技术和图像分析技术, 同步测定真实叶片与模拟叶片的叶温、形态及风速、辐射和温度等环境参数。研究结果显示: 在干旱、高温环境下, 除了蒸腾, 叶片形态变化也是调控叶温的重要因子。干旱区植物叶片变小, 有利于加速叶片与环境的物质及热量交换, 从而达到降低叶温的目的。样地数据显示, 在高温、低风速环境下, 叶片宽度每减少1 cm, 叶片表面温度降低约2.1 ℃, 而模拟叶片叶宽度每减少1 cm, 叶片表面温度降低0.60-0.86 ℃。该研究对深入理解植物生存策略与环境适能力具有重要意义。     

典型功能层带-填埋场覆盖层中四氯化碳代谢机制及功能微生态响应

垃圾填埋场是四氯化碳(carbon tetrachloride, CT)污染的重要来源,明晰覆盖层功能层带中CT的转化机制对其污染控制尤为重要。本研究通过构建模拟覆盖层系统,开展了CT沿程生物降解及微生态研究。覆盖层理化特性分析表明,长期生物氧化使覆盖层形成了稳定存在的厌氧层(>45 cm)、缺氧层(15–45 cm)和好氧层(0–15 cm)功能层带,各特征层带氧化还原电位、微生物群落结构差异显著,为CT降解提供了生物资源和有利条件。降解结果显示,CT在厌氧层和缺氧层脱氯产生氯仿(chloroform,CF)和二氯甲烷(dichloromethane,DCM)及氯离子(Cl–),副产物在30 cm处浓度最大,好氧层中CF和DCM迅速发生好氧降解;CT降解速率为13.2–103.6μg/(m2·d),随填埋气通量增大而增大。多样性测序结果表明,不同层带功能菌属差异显著,中慢生根瘤菌(Mesorhizobium)为好氧层CT潜在降解菌属,硫杆菌(Thiobacillus)和间孢囊菌(Intrasporangium)为厌氧层和缺氧层潜在功能菌属;覆盖土中6种脱氯菌属和18种甲烷氧化菌...     

啤酒酵母多糖的提纯、化学组成及抗氧化性质鉴定

以啤酒酵母为材料,通过化学抽提法得到水溶性提取物Mal;经薄层层析分析表明：Mal主要含有甘露糖;经检测分析,Mal含有蛋白成分,为蛋白多糖;氨基酸自动分析仪分析表明Mal含有多种氨基酸,包括7种必需氨基酸和9种非必需氨基酸;邻苯三酚自氧化法检测发现多糖能够抑制邻苯三酚自氧化,具有抗氧化能力。     

分子探针定量和定位分析种子吸涨早期活性氧的生成

借助活性氧发光分子探针,利用荧光光谱和激光共聚焦扫描显微技术,在不同年份的玉米种子吸胀早期,对其胚、淀粉和糊粉层细胞活性氧生成进行了定量和亚细胞定位分析.结果表明:胚细胞产生的活性氧最多,糊粉层细胞次之,淀粉细胞几乎不产生活性氧;而且胚细胞产生的活性氧主要定位在细胞内,细胞膜上不产生:糊粉层细胞产生的活性氧主要定位在细胞膜.这一种子吸涨早期活性氧生成机制的揭示,为化学发光检测种子活力提供了生理依据.     

High-Areal-Capacity and Long-Cycle-Life All-Solid-State Lithium-Metal Battery by Mixed-Conduction Interface Layer

The rapid growth of lithium dendrites has seriously hindered the development and practical application of high-energy-density all-solid-state lithium metal batteries (ASSLMBs). Herein, a soft carbon (SC)-nano Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) (with high ionic conductivity and diffusion coefficient) mixed ionic and electronic conducting interface layer is designed to promote the rapid migration of Li⁺ at the interfacial layer, induce the uniform deposition of lithium metal on nanoscale (nano) LLZTO ion-conducting network inside the interface layer, effectively suppress the growth of lithium dendrites, and significantly improve the electrochemical performance of ASSLMBs. LiZrO₂@LiCoO₂(LZO@LCO)/Li₆PS₅Cl(LPSCl)-nano LLZTO/Li ASSLMB achieves high current density (12.5 mA cm⁻²), ultra-high areal capacity (15 mAh cm⁻², corresponding to LZO@LCO mass loadings of 111.11 mg cm⁻²), and ultra-long cycle life (20 000 cycles). Therefore, the introduction of SC-nano LLZTO mixed conducting interface layer can greatly improve the interfacial stability between solid-state electrolyte (SSE) and lithium metal anode to enable dendrite-free ASSLMBs.