Vineyard evaporative fraction based on eddy covariance in an arid desert region of Northwest China

Studying farmland evaporative fraction (EF) plays an important role in interpreting the components of energy budget and evapotranspiration (ET). The present study examines the pattern of vineyard EF after monitoring energy components by eddy covariance for 2 years, and estimates the crop ET by EF in the arid desert region of Northwest China. Main results indicate that EF during daytime is nearly constant on sunny days when the available energy exceeds 200 W m⁻², but EF becomes relatively unsteady when the available energy is lower than 200 W m⁻². Furthermore, daytime average EF is relatively low in the early growth stage, nearly constant in the mid-later stage, and significantly reduced in the later stage; Moreover, mean EF in different periods of daytime is in good agreement with daytime average EF, mean EF during 10:00–15:00 h is relatively close to daytime average EF and mean EF during 14:00–15:00 h is approximately equal to daytime average EF. The estimated daytime ET from mean EF during 14:00–15:00 h is highly correlated to the measured ET by Bowen ratio-energy balance though the value is partially underestimated. This study demonstrated that daytime ET can be estimated from midday EF and the relationship can be used to guide irrigation practice in the arid region.     

Evaluating eddy covariance method by large-scale weighing lysimeter in a maize field of northwest China

Accurate determination of evapotranspiration (ET) is useful to develop precise irrigation scheduling. Although eddy covariance (EC) is a direct method which is widely used to measure ET, its performance in arid region of northwest China is not clear. In this study, ET measured by EC (ET_EC) was compared with that by large-scale weighing lysimeter (ET_L) during the whole growing season of maize in 2009. Energy balance ratio was 0.84 for daytime fluxes, indicating that lack of energy balance closure occurred, so daytime ET_EC was adjusted by Bowen-ratio forced closure method. Compared to the corresponding ET_L, half-hourly daytime ET_EC was underestimated by 21.8% without the adjustment and 4.8% with the adjustment. Furthermore, nighttime ET_EC was adjusted using filtering/interpolation method. Mean error between half-hourly nighttime ET_EC and ET_L decreased from 30.2% without the adjustment to 10.3% with the adjustment. After such adjustment of day and night measurements, daily ET_EC was underestimated by 6.2% compared to ET_L. These results indicated that the adjusted ET_EC well matched with the ET_L. Moreover, the discrepancy of adjusted total ET_EC and ET_L was decreased to 3.2% after subtracting the overestimated ET by lysimeter resulting from irrigation and heavy rainfall events. Thus, after appropriate adjustments of observations, eddy covariance method is accurate in estimating maize ET in the arid region of northwest China.     

Behavior of Natural Estrogens in Reservoir: Investigations Based on Continuous Flow Experiments and Model Analysis

The behavior of estrone (E1) and 17??-estradiol (E2) in relatively closed water environment was studied by continuous flow experiment using sediments from a freshwater reservoir. For this, four sediment columns (two oxic ones and two anoxic ones) were employed, which were structured by packing 30?cm of undisturbed sediment and 60?cm of overlying water collected from two sites within a reservoir. A mass balance model that considered the influent flux, the effluent flux, mass transfer, sorption, and biodegradation was proposed to describe the behavior of E2 and E1 in the columns. The results indicated that the water?Csediment partition coefficient of E1 $ \left( {K_{\text{d}}^{\text{E1}}} \right) $ was higher than E2 $ \left( {K_{\text{d}}^{\text{E2}}} \right) $ . The degradation rate of E1 (k _E1) was smaller than E2 (k _E2). Under both oxic and anoxic conditions, E1 was formed from E2. Furthermore, to clarify the impact of the model parameters such as the hydraulic retention time (HRT), K _d, and k on the behavior of E2 and E1, variance analysis was performed based on the results of model simulations. The results showed that the concentrations of E2 and E1 in the column effluent were controlled most significantly by the sorption capacity of the natural estrogens onto sediment particles, with the determined contributory ratios changing in the order of sorption > HRT > degradation.     

超微粉碎对桑叶粉理化性质的影响

为拓展超微粉碎技术在食品添加剂和药品开发中应用,以桑叶为原料,分别对桑叶粗粉进行干法超微粉碎2 、4、6、8 h,得到4种不同粒径大小的桑叶超微粉,并对桑叶粗粉与4种超微粉的理化性质进行比较。研究结果表明,超微粉碎能明显减小桑叶粗粉的颗粒粒径（P＜0.05）,随着超微粉碎时间的增加,超微粉的粒径减小,粉体的粒径分布范围变窄,比表面积和体积密度显著增加（P＜0.05）,休止角、滑角和膨胀性显著降低（P＜0.05）,水溶性/持水力、持油力、蛋白质的水溶性和多糖的水溶解性均有不同程度的增加,但多酚含量变化不显著（P＞0.05）。扫描电镜结果显示,粗粉经超微粉碎后,其颗粒呈零散的分布形态。说明超微粉碎可改善桑叶粉的部分理化性质,可将这些性质应用于食品添加剂和常规食品开发与加工中。所得研究结果将为超微粉碎技术在桑叶食品中工业化应用提供数据支持和理论依据。     

侧挂式电动移栽机系统开发

现有的大田使用的蔬菜苗移栽机,体积庞大,作业半径较大,动力一般为内燃机,作业时有废气排出,很难直接应用于温室内作业。侧挂式电动移栽机系统采用水平侧挂结构,尺寸小,转弯灵活;以直流电动机作为移栽动力,无废气排出,不会对温室内空气环境造成污染;更适合温室内移栽作业,不仅可以提高种植效率,也有利于降低劳动强度和劳动成本。      

两种大豆蛋白-磷脂酰胆碱纳米乳液粉末化特性研究

将超声处理及高压均质后的纳米乳液,直接利用真空冷冻干燥法制备了大豆蛋白-磷脂酰胆碱的乳化粉末,并进一步通过扫描电子显微镜、激光粒径分析仪、红外光谱等手段对真空冷冻干燥粉末以及复原乳液的物理化学等特性进行研究。研究发现冻干粉末复原乳液水复溶性良好,基本保持了与原始乳液相同的纳米级粒径。扫描电子显微镜及冻干粉末的粒径分布显示超声和高压均质制备的纳米乳液粉末结构致密均匀,表面无裂缝和孔隙,且高压均质制备粉末的表面更为平整,粒径分布总体呈现单峰分布,粒径平均值仅为6.13μm。使用超声和高压均质制备的纳米乳液冻干粉末的包埋产率和效率均达到90%以上,同时超声制备的纳米乳液冻干粉末更有利于β-胡萝卜素的包埋,更好地防止β-胡萝卜素损失。采用红外光谱学实验验证后发现,高压均质制备纳米乳液粉末的蛋白α-螺旋与β-折叠结构含量较低。与大豆蛋白-磷脂酰胆碱纳米乳液相比,真空冷冻干燥粉末的储藏稳定性及货架期显著提高。     

赣南苏区松材线虫病防控现状与策略

赣南苏区是我国南方地区重要的生态屏障,生态地位非常重要,本文结合该区域森林资源特点和生态保护要求,分析当前松材线虫病防控形势,提出松材线虫病防控策略.     

26种乡土树种苗木生长规律及育苗技术的系统研究

通过对省沽油科圆齿野鸦椿、壳斗科8种、木兰科2种、冬青科2种、山茶科4种、蔷微科2种、桃金娘科的赤楠、八角科的莽草、槭树科的五裂槭、交让木科1种、金缕梅科3种等26种亚热带乡土树种的种子预处理、种子主要播种品质参数测定、对苗木的苗高、地径、主根长、大于5cmI级侧根数、根幅、冠幅、鲜叶重、鲜干枝重、鲜根重的测定,以及对苗木物候、苗木生长节律进行研究,从而得出上述树种的较为系统的育苗技术。     

降压草的组织培养技术研究

以白城市林业科学研究院选育的新品种降压草2号为试材,利用其带芽茎段进行组织培养,筛选降压草组织培养程序及培养基配方。结果表明:适宜的腋芽诱导培养基为MS+6-BA0.5mg L-1+NAA0.1mg L-1,适宜的增殖培养基为MS+6-BA1.0mg L-1+NAA0.5mg L-1+IAA0.1mg L-1。     

Atmospheric deposition and leaching of nitrogen in Chinese forest ecosystems

Data have been compiled from published sources on nitrogen (N) fluxes in precipitation, throughfall, and leaching from 69 forest ecosystems at 50 sites throughout China, to examine at a national level: (1) N input in precipitation and throughfall, (2) how precipitation N changes after the interaction with canopy, and (3) whether N leaching increases with increasing N deposition and, if so, to what extent. The deposition of dissolved inorganic N (DIN) in precipitation ranged from 2.6 to 48.2 kg N ha⁻¹ year⁻¹, with an average of 16.6 kg N ha⁻¹ year⁻¹. Ammonium was the dominant form of N at most sites, accounting for, on average, 63% of total inorganic N deposition. Nitrate accounted for the remaining 37%. On average, DIN fluxes increased through forest canopies, by 40% and 34% in broad-leaved and coniferous forests, respectively. No significant difference in throughfall DIN inputs was found between the two forest types. Overall, 22% of the throughfall DIN input was leached from forest ecosystems in China, which is lower than the 50–59% observed for European forests. Simple calculations indicate that Chinese forests have great potential to absorb carbon dioxide from the atmosphere, because of the large forest area and high N deposition.