黄壤颗粒表面离子吸附动力学中的离子特异性效应

基于考虑离子非经典极化作用的离子吸附动力学模型,以可变电荷黄壤颗粒为代表材料,研究了锂离子(Li+)、钠离子(Na+)和铯离子(Cs+)在黄壤颗粒表面的吸附动力学特征,进一步计算了离子在土壤/水界面的扩散距离与表面电化学参数。结果表明:(1)Li+、Na+和Cs+在黄壤颗粒表面吸附仅存在一级动力学过程并存在明显的离子特异性差异,这种差异随着电解质浓度降低而增大;(2)离子非经典极化与体积效应的共同作用决定了离子在固/液界面的扩散距离,在较高浓度电解质中,Na+和Li+的离子体积和极化效应基本平衡,导致Na+和Li+离子间差异不显著,但Cs+由于强烈的非经典极化作用,扩散距离表现为:Cs+Na+≈Li+;在低浓度电解质中,离子非经典极化作用占主导,扩散距离表现为:Cs+ Na+ Li+,表明离子扩散距离在低浓度下差异大,而高浓度下差异不显著;(3)离子扩散距离的差异导致固/液界面电位的不同,Stern电位、电荷密度和电场强度均受到离子扩散距离的影响,表面电位(绝对值)在各个浓度下均表现为:Li+ Na+ Cs+,说明表面电位仅受非经典极化作用的影响。本研究将对土壤/水界面反应理论的完善提供新思路。     

速冻青花菜预处理工艺研究

用响应面方法研究青花菜的不同烫漂温度和时间对青花菜品质的影响。试验中比较了在不同浓度CaCl₂处理后,速冻青花菜叶绿素含量和解冻后质构的变化,对现有的预处理生产工艺进行优化。中心组合优化后得出的速冻青花菜最佳预处理工艺为：烫漂温度96℃、烫漂时间2 min、CaCl₂浓度0.8%。优化前后数值比较：青花菜蕾质构强度提高26.9%;茎质构强度提高16.8%;叶绿素含量提高26.5%;过氧化物酶酶活降低到生产需要;维生素C、蛋白质和水分没有显著的变化。     

Ca(OH)2 预处理对水稻秸秆沼气产量的影响（英）

生物质材料经碱预处理后的发酵效率和甲烷产气量明显增加。为了提高预处理技术的经济效益及简化其工艺流程,利用自行设计的可控性恒温发酵装置,以秸秆为发酵原料,研究发酵沼液以及Ca(OH)2预处理对于水稻秸秆厌氧发酵产气量的影响。结果表明,与对照相比,沼液和Ca(OH)2预处理后的水稻秸秆木质素、半纤维素和纤维素含量显著降低,产气量明显提高。其中,Ca(OH)2预处理的产气量高于沼液预处理,8%浓度的Ca(OH)2下的秸秆产气量最高,为14374mL,比对照增加100.91%。该研究认为采用Ca(OH)2预处理水稻秸秆不仅简洁方便,成本低廉,而且具有较高的沼气产量,因此,可作为提高户用沼气产气效率的方法。     

A comparative evaluation of the Mississippi soil test method for determining available manganese,magnesium, and calcium

Abstract

Soil Samples (72) were collected from the Delta, Hill, and Northeast Blackland areas of Mississippi. Chemical analyses for manganese, magnesium, and calcium were made using the Mississippi Soil Test Solution (MSTS) and several other extracting solutions chosen for comparison. For the determination of available soil manganese, the MSTS proved to be as effective as either the Double Acid (0.025 N HCl in 0.05 N H₂SO₄) or 0.1 N H₃PO₄. The acid extractants removed more manganese than 1 N NH₄OAc (pH 7.0) and therefore included forms that are not exchangeable. The methods studied for magnesium determinations were equilibrium extraction with 1 N NH₄OAc, MSTS, Double Acid, 0.25 N CaCl₂, and leaching with 1 N NH₄OAc. All methods were highly correlated and therefore would be equally effective in determining available soil magnesium. Since MSTS and equilibrium extraction with 1 N NH₄OAc removed similar amounts of magnesium from the soil, the same calibration can be used. Calcium determinations were made using equilibrium extraction with 1 N NH₄OAc, MSTS, and Double Acid, and by leaching with 1 N NH₄OAc. All methods proved effective in measuring available soil calcium on acid soils.     

Surface water quality of factory-based and vegetable-based peri-urban areas in the Yangtze River Delta region,China

Detailed surveys of surface water in two contrasting peri-urban areas in the Yangtze River Delta region of China were conducted to determine the distribution of heavy metals, nitrogen (N) and phosphorus (P) as well as the speciation of N and P. A factory-based (FB) area was compared with a vegetable-based (VB) area during the dry season. The concentrations of heavy metals in the surface water in the FB area were higher than those in the VB area, suggesting modest contamination of surface water with Zn, Cu, Cr and Pb but not Cd, from discharge of factory effluent in the FB area but not the VB area. Although total N (TN) and total P (TP) levels in the surface water were high in both areas, the surface water in the VB area had significantly higher levels of nitrate N (NO₃–N), organic N (ON) and TN than those in the FB area. In both areas, the levels of water-soluble P (WP), organic P (OP) and TP were high in the river water that received municipal wastewater. The distribution of N and P species throughout the surface water system indicated that the NO₃–N and ON mainly came from vegetable fields, while ammonium N (NH₄–N), WP and OP were mainly from municipal wastewater. Treatment of municipal wastewater prior to discharge to reduce N and P by purification is recommended together with research and extension to develop more efficient use of N and P fertilizer by vegetable farmers.     

Do artificial waterholes influence the way herbivores use the landscape? Herbivore distribution patterns around rivers and artificial surface water sources in a large African savanna park

It has been argued that the wide-scale provision of artificial surface water in semi-arid savannas may result in homogenisation of foraging regimes, compromising biodiversity and ecosystem resilience. This is the first landscape-scale study investigating to what degree artificial waterholes and natural rivers influence the distribution of large herbivores, and hence foraging patterns, in the Kruger National Park, South Africa. This is explored by examining consistencies within and differences between distribution patterns of herbivore feeding groups on different geologies. Seven years of dry season aerial census data of thirteen large herbivores were analysed in a GIS. It was found that different herbivores exhibit different distribution patterns around rivers and waterholes. It was found that most grazer species were associated with artificial waterholes, whereas browsers and mixed feeders were indifferent to waterholes and were associated with the main rivers. This has important management implications for artificial water provision in the KNP and potentially for other semi-arid African savanna conservation areas. Man-made waterholes are therefore features in the landscape that can change the distribution of herbivores, even in a landscape where natural water is available, transforming patterns of landscape use. Furthermore, it was also found that the underlying geology interacts with water distribution in shaping herbivore distributions, with artificial waterholes and rivers acting as stronger nodes of herbivore activity on nutrient-rich basaltic soils than nutrient-poor granitic soils. The results from this paper may be useful for designing surface water policies and management plans for Kruger and other savanna reserves in Africa in order to maximise biodiversity conservation.     

温,湿度条件及不同种子处理对棉籽吸胀冷害的影响

棉籽在4－5℃条件下吸水，发生吸胀冷害的程度随吸水速度的加快而减轻，随吸水时间的延长而加重；在10-12℃、18－20℃的水中吸水分别超过16小时、12小时，会因吸水时间过长使部分棉籽的种子活力降低，而使正常发芽率降低。经温汤浸种和预冷处理的棉籽能耐72小时0－5℃的低温，且耐较长时间低温的能力强于干籽与晾干籽；干籽、晾干籽能耐24小时0－2℃的低温，且干籽耐短时间低温的能力强于湿籽。     

Effect of snow amount on runoff,soil loss and suspended sediment during periods of snowmelt in southern West Siberia

Surface runoff, soil loss, suspended sediment concentration (SSC), texture of eroded soils and suspended sediment were determined on slightly eroded chernozems (mouldboard fall-ploughed) during years with different amounts of snow in three areas of southern West Siberia (Predsalairye, Priobye and Kuznetsk hollow). These areas have different geomorphological and climatic characteristics and soils. Observations were made from 1969 to 2007. The soil loss during very low-snow and low-snow years did not exceed 2 t ha^− 1. After winters with normal amounts of snow, the runoff led to slight soil loss (2–5 t ha^− 1). Soil losses in high-snow and very high-snow years varied from slight to severe (4.8–15.8 t ha^− 1) depending on studied area. The main sediment exported during intensive snowmelt and the 1 mm of runoff transported from 35 to 150 kg ha^− 1 of soil material. The removal of soil particles < 0.01 mm (especially clay) prevailed during the initial and final stages of snowmelt. Clay removal by meltwater from the ploughed layer in high-snow and very high-snow years varied from 3300 to 4200 kg ha^− 1 and, in the initial and final stages of snowmelt clay removal, accounted for 1260–1,500 kg ha^− 1. Among the three studied regions, Predsalairye had decreased soil erosion resistance and was the area with the greatest danger of erosion.     

预处理对微波联合气流膨化干燥黑毛豆仁品质的影响

通过对黑毛豆仁的水分含量、硬度、脆度、花色苷含量以及色泽等指标的测定,研究烫漂、冷冻、NaCl浸渍以及辐照4种不同的预处理方式对微波联合气流膨化干燥黑毛豆仁品质的影响。结果表明,适度的烫漂预处理可以钝化过氧化物酶,减少豆腥味的产生,降低膨化产品的水分含量,有利于保持产品色泽;冷冻预处理可使膨化产品的硬度降低,酥脆性提高...     

Tracking the structural and functional development of a perennial pepperweed (Lepidium latifolium L.) infestation using a multi-year archive of webcam imagery and eddy covariance measurements

The continued spread of invasive weeds is threatening ecosystem health throughout North America. Understanding the relationships between invasive weeds’ key phenological phases and structural and/or functional canopy development is an essential step for making informed decisions regarding their management. We analyzed a three-year image archive obtained from an inexpensive webcam overlooking a perennial pepperweed (Lepidium latifolium L.) infestation in California to explore the ability of red (R)-green (G)-blue (B) color space information to track the structural and functional development of the pepperweed. We characterized structural and functional canopy development through surface roughness length (z_0m; a proxy for canopy height and leaf area index) and canopy photosynthesis (F_A), respectively, both of which we derived from eddy covariance measurements. Here we demonstrate the use of cross-correlation functions to determine the temporal lags between chromatic coordinates and two color indices, all calculated from RGB brightness levels, with z_0m and F_A. We found that these color metrics fail to represent the structural and/or functional state of the canopy. In contrast, relative luminance (CIE Y) appears to be a better indicator for z_0m and especially for F_A. We calculated CIE Y from pepperweed RGB brightness levels in relation to hypothetical horizontal reference RGB brightness levels. We obtained the latter by applying the ratio between horizontally measured and hypothetical incoming solar radiation on a vertical surface to RGB brightness levels of a vertically oriented reference of invariant light-grey color. We conclude that webcam image archives may provide an inexpensive tool for making informed decisions regarding the timing but not for assessing the effectiveness of invasive plant control measures such as mowing.