Responses of soil enzyme activity and microbial community compositions to nitrogen addition in bulk and microaggregate soil in the temperate steppe of Inner Mongolia

In order to explore the responses of soil enzyme activities and microbial community compositions to long-term nitrogen (N) addition in both bulk soil and microaggregate of chestnut soil, we conducted a 7-year urea addition experiment with N treatments at 6 levels (0, 56, 112, 224, 392 and 560 kg N ha^–1 yr^–1) in a temperate steppe of Inner Mongolia in China. Soil properties and the activities of four enzymes involved in carbon (C), nitrogen (N) and phosphorus (P) cycling were measured in both bulk soil and microaggregate, and phospholipid fatty acids (PLFAs) were measured in bulk soil. The results indicated that: 1) in bulk soil, N addition significantly decreased β-1,4-glucosidase (BG) and leucine aminopeptidase (LAP) activities at the treatment amounts of 224, 392 and 560 kg N ha^–1 yr^–1, and obviously suppressed β-1,4-N-acetylglucosaminidase (NAG) activity at the treatment amount of 560 kg N ha^–1 yr^–1. N addition enhanced total PLFAs (totPLFAs) and bacterial PLFAs (bacPLFAs) at the treatment amounts of 392 and 560 kg N ha^–1 yr^–1, respectively, but fungal PLFAs showed no response to N addition. The activities of BG, NAG and LAP were positively correlated with soil pH, but negatively correlated with the concentration of NH ₄⁺-N; 2) in microaggregate (53–250 μm), the activities of BG, NAG and AP showed no response to increased addition of N, but the significantly decreased LAP activity was observed at the treatment amount of 392 kg N ha^–1 yr^–1. These results suggested that enzyme activities were more sensitive to N addition than PLFA biomarkers in soil, and LAP activity in microaggregate may be a good indicator for evaluating N cycle response to long-term N addition.     

影响大蒜精油提取得率的工艺参数研究

研究了大蒜精油提取条件，包括反应温度、反应pH值、反应时间和蒸馏时间对大蒜精油提取得率的影响，初步确定了采用鲜蒜提取风味物质的最适工艺条件。     

冻融期积雪覆盖下土壤水热交互效应

为了研究季节性冻土区土壤水热时空分异特征,揭示冻融过程中的水热相互作用机理及其复杂性。在松嫩平原黑土区,以野外实测试验数据为基础,分别建立裸地、自然降雪、积雪压实和积雪加厚覆盖处理条件下20 cm土层土壤含水率和温度的耦合模型,并通过对比模型的预测效果研究土壤水热变化的复杂程度,采用差异性分析和基于小波变换的分形理论方法定量研究含水率与温度序列的变异波动性和分维指标,进而验证不同覆盖处理条件对于土壤水热空间变异复杂性的影响。结果表明:冻结期,积雪阻碍了环境因素对于土壤水热迁移过程的影响,土壤含水率和温度的耦合效果较好,并且预测值与实测值能够较好的吻合,裸地、自然降雪、积雪压实、积雪加厚处理条件下的相对误差分别为0.42%、0.31%、0.13%和0.06%,随着积雪厚度的增加和密度的增大,含水率和温度的差异性减弱,复杂程度逐渐降低;融化期,积雪覆盖区的融雪水入渗抑制了土壤温度稳定提升,含水率出现骤然升高的现象,自然降雪、积雪压实、积雪加厚条件下的含水率变化分别为14.31%、15.90%和16.91%,土壤温度变化范围分别为-5.9~5.3、-3.6~6.9和-3.1~3.8℃,二者的互作效应减弱,并且随着积雪覆盖量的增加,土壤的水热时空迁移复杂程度逐渐增强。同时,采用基于小波变换的分形理论研究土壤含水率和温度的时间序列复杂性精度较高、结果可靠。该研究对于揭示冻土区土壤水热迁移动态规律,准确预测春播期土壤温度和墒情,合理高效地利用松嫩平原的土壤水资源具有重要的理论价值和现实意义。     

农业生态系统养分循环再利用作物产量增益的地理分异

根据3个地点中长期田间试验联网比较研究发现，保持养分循环再利用可明显减少作物产量的年际波动，使作物具有较好的产量稳定性。农业生态系统养分循环再利用的产量增益与化肥施用和所处气候区的热量因素有关。在无化肥的前提下，保持80％循环率养分循环再利用的平均粮食增产量从北向南分别是：海伦262 kg·hm^-2(14年平均)，沈阳956 kg·hm^-2(12年平均)，桃源3 063 kg·hm^-2(11年平均)；在施用N、P化肥基础上保持养分循环再利用     

几种木材表面化学成分分布特征的XPS分析

本文利用XPS表面分析技术,分析了意杨、红橡、色木、柚木和红檀五种树种木材的表面化学成分特征。结果表明:⑴不同树种木材表面的化学成分存在差异;⑵意杨、红橡、色木、柚木和红檀5个树种木材表面都存在四种结合方式的C;⑶不同树种木材表面的O/C比值和C1/C2比值存在一定的差异。     

玉米自交系幼胚愈伤组织诱导的条件优化

本研究以铁7922、H99、丹598和丹988四个玉米自交系的幼胚为材料,对影响愈伤组织诱导和继代的几个重要因素进行研究。结果表明,2mg/L的2,4-D有利于胚性愈伤组织的形成,基因型、培养基、胚龄和4℃冷存时间对其也有明显影响。此外,添加KT、Ca2+和AgNO3,H99和丹988的胚性愈伤率明显提高,而铁7922的胚性愈伤率则有所下降。此外,Ca2+的添加对丹598的胚性愈伤率没有明显影响。     

用于连续制备乳清蛋白ACE抑制肽的酶膜反应器运行条件优化

采用中空纤维膜连续型酶膜反应器制备血管紧张素转移酶(angiotensin converting enzyme,ACE)抑制多肽。在传统酶解工艺条件的基础上,设计出能高效连续制备ACE抑制肽的酶膜反应器,并对此酶膜反应器的运行参数进行了优化,得到能高效制备ACE乳清蛋白源抑制肽的运行条件是:循环流速22.4 L/h,底物质量分数5%,跨膜压力0.07 MPa,酶膜反应器能稳定运行12 h以上,得到乳清蛋白酶解产物的ACE抑制率为30%￣50%。     

新疆15个引进梨品种果实贮藏性研究初报

以新疆当地品种库尔勒香梨果实为对照,从果实感官品质、硬度、好果率、可溶性固形物含量等方面研究从内地引进新疆的15个优良梨品种果实的贮藏性。结果表明,在温度-1.5～-0.5℃、湿度90%～95%条件下,黄冠等9个品种的梨果实不宜较长时间贮藏;玉露香等6个品种较耐贮藏,可贮藏8个月左右。     

Research on treatment efficiency of deep sequence constructed wetlands

According to the problems that traditional constructed wetlands have low nitrogen removal performance and large areas, deep sequence constructed wetlands(DSCW) is proposed and the influences of depth of wetland, filler particle size and operational states of DSCW on treatment efficiency are investigated. The experimental results show that when the depth of wetland is increased from 0.5 m to 2 m, it has no significant influent on its treatment efficiency. The running condition has influence on its treatment efficiency. When the water temperature is 20~25 ℃ and operating condition of DSCW is inlet water 8 min-reaction 12 h-outlet water 8 min-idle 12 h, the removal rate of COD, NH+4-N, TN, PO3-4-P is 83.8%, 54.1%, 48.1%and 63.9% respectively by DSCW with the depth of 2 m. The area load for COD, TN, PO3-4-P is 128, 17.6, 1.49 g/(m2·d) respectively, raised 2.4 times, 2 times and 1.71 times respectively compared with traditional constructed wetlands. Land occupation for processing 1 m3 wastewater is 1.87 m2, decreasing 3~5 times commendably. Compared to DSCW system of particle size of gravel of 20~30 mm, the removal rate of COD, NH+4-N, TN and PO3-4-P of DSCW system of 5~10 mm is increased by 3.8%, 7.9%, 3.8% and 7% respectively. The filler particle size exhibits some influences on DSCW efficiency.     

壳聚糖添加助剂保鲜草莓的效应

壳聚糖（Chitosan, 缩写CTS）是甲壳素脱去乙酰基的多糖类生物大分子，具有安全无毒、成膜抑菌、营养保健等多种功能，已被广泛应用于医药、食品、饲料、环保等多个领域。近年来，随着人们对化学保鲜剂毒性的担忧，壳聚糖在食品保鲜方面的开发应用受到国际社会的高度重视，研究十分活跃。我们依据壳聚糖的成膜抑菌能力与分子量的大小密切相关，将两种分子量的壳聚糖配合并适当添加食品级助剂，以探讨壳聚糖对草莓的保鲜效应。……