基因型及播种密度对冬小麦分蘖期生长、生物量分配及产量的影响

采用双因素随机区组设计,研究了分别来自干旱与湿润区的4个小麦品种6个播种密度对冬小麦生长、生物量分配及产量的影响.结果表明,在本试验条件下,生长指标、生物量积累各指标及籽粒产量均主要受基因型和播种密度互作(g×d)影响,而成穗数、穗粒数主要受播种密度(d)的影响,基因型(g)则是引起小麦籽粒产量、千粒重及穗长变化的主要因素.白粒三号和川麦39最佳播种密度为315×104 hm-2,籽粒产量达到5 863.8 kg hm-2和5 882.1 kg hm-2;西农2000与陕麦139产量最佳播种密度为195×104 hm-2,籽粒产量分别为6 422.4 kg hm-2和7 062.4 kg hm-2.陕西小麦品种籽粒产量高出四川小麦约12.90%~18.62%.相关分析表明,籽粒产量与成穗数、千粒重呈极显著正相关(r=0.859 7**,r=0.499 3**),而与穗长、地上部干重及根系长度呈极显著负相关,与穗粒数及其它生长、生物量指标无显著相关.研究表明,干旱区小麦在湿润地区种植表现出较大的增产潜力,此外,在生产中应重视基因型和播种密度二者互作所表现出来的优势.表5参31     

不同制图比例尺土壤数据库对旱地磷储量估算的影响

陆地生态系统中的磷元素在土壤肥力保持和生态环境保护方面起着重要的作用,但以往国家或区域尺度磷储量估算并没有考虑不同尺度土壤数据库所造成的差异。文章以江苏北部29个县（市）390多万hm2旱地为例,分析了17 000多个图斑和963个剖面组成、能详尽反映土壤属性空间异质性的1∶50 000数据库与目前国内同类研究使用最多的1∶1 000 000和1∶4 000 000土壤数据库对磷储量估算的影响。结果表明,不同制图尺度土壤数据库估算的全磷密度和储量差异很大,1∶50 000土壤数据库下的全磷密度和储量分别为1.34 kg.m-3和10.52 Tg,而1∶1 000 000和1∶4 000 0002个土壤数据库下磷密度和储量分别为0.79 kg.m-3和6.02 Tg、0.77 kg.m-3和6.26 Tg,远小于1∶50 000土壤数据库的全磷密度和储量。从不同土壤类型看,褐土受制图比例尺影响最大,1∶1 000 000和1∶4 000 000土壤数据库下与1∶50 000土壤数据库全磷密度和储量相对偏差分别在80%~90%和7%~130%之间,面积最大的潮土在1∶1 000 000和1∶4 000 000土壤数据库下与1∶50 000全磷密度和储量相对偏差也分别达到38%~39%和21%~23%。从各个县（市）来看,1∶1 000 000和1∶4 000 000土壤数据库下与1∶50 000土壤数据全磷密度和储量相对偏差大多超过40%。这也说明使用不同制图尺度土壤数据库将对旱地磷储量和磷密度的估算结果造成很大的影响。因此,在今后的国家和区域尺度全磷密度和储量估算研究中使用更详细的土壤数据库是非常必要的。     

滨海不同生境下盐地碱蓬生物量分配特征研究

盐地碱蓬是黄河三角洲重要的先锋植物,抗盐能力强,分布范围广,对维持该地区生态系统稳定和演替发挥着重要作用。通过野外取样测定,研究了潮间带和潮上带盐地碱蓬种群的形态及生物量分配特征。在个体大小上,潮间带盐地碱蓬在株高和地径上显著低于潮上带盐地碱蓬;潮上带盐地碱蓬密集分布的株高高于散生分布,而生物量低于散生分布。在生物量分配特征上,潮间带盐地碱蓬Ⅰ以发展花、叶为主,潮上带盐地碱蓬Ⅱ的密集分布以优先发展茎为主,潮上带盐地碱蓬Ⅲ的散生分布以发展枝为主,属于种群发展的稳定阶段。因此,盐地碱蓬通过形态特征及生物量分配特征的调节,以适应潮间带和潮上带的不同生境特征,从而达到种群维持和土壤改良的目的。     

钇覆盖Si@Al_（12）团簇的贮氢性能

利用密度泛函理论系统地研究了Y_mSi@Al_（12）（m=1—3）团簇及其贮氢性质.结果表明,在所研究的尺度范围内,钇原子未在Si@Al_（12）团簇上团聚;每个钇原子按18电子规则吸附氢分子,其中Y_3Si@Al_（12）团簇可以吸附16个完整氢分子,贮氢质量分数为5.0%,平均吸附能处于0.324—0.527 eV之间,较为理想的吸附能说明在室温条件下吸氢和脱氢是可行的.     

Competition between the Rotifers Brachionus patulusand Euchlanis dilatata:Effect of Algal Food Level and Relative Initial Densities of Competing Species

We tested the effect of different algal (Chlorella vulgaris) levels and inoculation densities on the outcome of competition between the rotifers Euchlanis dilatata and Brachionus patulus. The experiment was performed in 36 transparent jars, each with 20 ml of a test medium. We used three Chlorella levels: 0.75 × 10⁶, 1.5 × 10⁶, and 3.0 × 10⁶ cells/ml. For each algal level, we used five different ratios of initial inoculation density. The population growth experiments were terminated after 19 days. Regardless of inoculation densities, an increase in food level resulted in an increased population abundance of both rotifer species. Regardless of food concentration,E. dilatatawas able to outcompete B. patulus at all inoculation densities when grown together. However, when Chlorella was offered in low concentration and there was a higher ratio of Brachionus to Euchlanis at the onset of the experiment, both rotifer species coexisted in more or less equal densities until the end of the experiments. When the food level was enhanced, E. dilatata totally eliminated B. patulus. The rate of population growth ranged from 0.002 to 0.578 for B. patulus and from 0.006 to 0.447 for E. dilatata. The results are discussed with respect to the factors influencing the outcome of competition between species.     

Enhanced ozonation of dichloroacetic acid in aqueous solution using nanometer ZnO powders

Nanometer zinc oxide (ZnO) powders were used as a catalyst to enhance the ozonation for the degradation of dichloroacetic acid (DCAA) in aqueous solution. The batch experiments were carried out to investigate the e ects of key factors such as catalyst dosage, ozone dosage, solution pH and tert-butyl alcohol (t-BuOH) on the degradation e ciency of DCAA. Density functional theory (DFT) was adopted to explore the mechanism of generating hydroxyl radical (.OH) on the ZnO surface. The results showed that adsorption and ozonation processes were not e ective for DCAA removal, and the addition of ZnO catalyst improved the degradation e ciency of DCAA during ozonation, which caused an increase of 22.8% for DCAA decomposition compared to the case of ozonation alone after 25 min. Under the same experimental conditions, the DCAA decomposition was enhanced by increasing catalyst dosage from 100 to 500 mg/L and ozone dosage from 0.83 to 3.2 mg/L. The catalytic ozonation process is more pronounced than the ozonation process alone at pH 3.93, 6.88, and 10. With increasing the concentration of t-BuOH from 10 to 200 mg/L, the degradation of DCAA was significantly inhibited in the process of catalytic ozonation, indicating that ZnO catalytic ozonation followed .OH reaction mechanism. Based on the experimental results and DFT analysis, it is deduced that the generation of .OH on the ZnO surface is ascribed to the adsorption of molecule ozone followed by the interaction of adsorbed ozone with active sites of the catalyst surface. It is also concluded that ZnO may be an e ective catalyst for DCAA removal, which could promote the formation of .OH derived from the catalytic decomposition of ozone.     

基于升流式厌氧污泥床反应器的微生物燃料电池的研究

构建了一种基于升流式厌氧污泥床反应器（UASB）的微生物燃料电池（MFCs）,利用UASB高效去除COD能力及连续进样方式,获得稳定电能输出。考察了水力停留时间、进液方式、电极材料、离子交换膜种类、溶液离子强度等因素对于MFCs性能的影响。实验结果表明：在水力停留时间6h、连续进液、高纯石墨板电极以及均相阳离子交换膜条件下,连续运行3个月,放电功率稳定在145mW／m^2,开路电压0．78V,放电电流最高可达321mA／m^2。     

二噁英结构与正辛醇-水分配系数相关性的密度泛函理论

为精确描述二噁英分子的电子结构及其定量结构/性质相关关系(QSPRs),运用密度泛函理论,在B3LYP/6-311G**水平上,分别对多氯二苯并对二噁英(PCDDs)和多氯二苯并呋喃(PCDFs)进行了优化计算.相应量子化学参数,即平均分子极化率(α),熵(S),极化率和四极矩的张量分量(αxx,αyy,αzz和Qxx,Qyy,Qzz)用于该类化合物辛醇-水分配系数的QSPR研究,构建了2个单变量和1个双变量模型,其决定系数R2分别为0.962、0.950和0.951;其显著性检验因子F分别为509.759、379.498和186.234.PCDD/Fs在辛醇相-水相间的分配性质主要与分子体积因素有关,而电性因素的影响较小;不同模型预测值间的差异与模型中预测变量本身性质和实验值的有限性有关.经比较,本研究中所建立的3个QSPRs模型尽管只有1个或2个变量,但其结果与复杂的偏最小二乘分析(PLS)相近.     

林线树种太白红杉碳储量估算

林线对气候变化十分敏感,有关环境如何影响林线植被碳储量分布的研究鲜见报道.采用野外调查、遥感影像解译和生物量模型计算相结合的方法,对秦岭主峰太白山林线树种——太白红杉(Larix chinensis)碳储量、碳密度及其分布进行了估算.结果表明:太白红杉林总碳储量为5.290×105 t,其中南坡碳储量为1.765×105 t,北坡碳储量为3.525×105 t,南北坡碳储量分布不均与太白红杉分布面积和海拔有很大的关系;太白红杉林碳密度为0～17.40 kg/m2,平均值为(7.65±4.15)kg/m2,与年均温度呈正相关,与海拔和年降水量呈负相关,温度是影响太白红杉林碳密度的关键因素.     

Fractal analysis of polyferric chloride-humic acid (PFC-HA) flocs in di erent topological spaces

The fractal dimensions in di erent topological spaces of polyferric chloride-humic acid (PFC-HA) flocs, formed in flocculating di erent kinds of humic acids (HA) water at di erent initial pH (9.0, 7.0, 5.0) and PFC dosages, were calculated by e ective densitymaximum diameter, image analysis, and N2 absorption-desorption methods, respectively. The mass fractal dimensions (Df) of PFC-HA flocs were calculated by bi-logarithm relation of e ective density with maximum diameter and Logan empirical equation. The Df value was more than 2.0 at initial pH of 7.0, which was 11% and 13% higher than those at pH 9.0 and 5.0, respecively, indicating the most compact flocs formed in flocculated HA water at initial pH of 7.0. The image analysis for those flocs indicates that after flocculating the HA water at initial pH greater than 7.0 with PFC flocculant, the fractal dimensions of D2 (logA vs. logdL) and D3 (logVsphere vs. logdL) of PFC-HA flocs decreased with the increase of PFC dosages, and PFC-HA flocs showed a gradually looser structure. At the optimum dosage of PFC, the D2 (logA vs. logdL) values of the flocs show 14%–43% di erence with their corresponding Df, and they even had di erent tendency with the change of initial pH values. However, the D2 values of the flocs formed at three di erent initial pH in HA solution had a same tendency with the corresponding Df. Based on fractal Frenkel-Halsey-Hill (FHH) adsorption and desorption equations, the pore surface fractal dimensions (Ds) for dried powders of PFC-HA flocs formed in HA water with initial pH 9.0 and 7.0 were all close to 2.9421, and the Ds values of flocs formed at initial pH 5.0 were less than 2.3746. It indicated that the pore surface fractal dimensions of PFC-HA flocs dried powder mainly show the irregularity from the mesopore-size distribution and marcopore-size distribution.