Chemical characteristics and potential source of fulvic acids leached from the plow layer of paddy soil

To understand better the chemical characteristics and source of dissolved organic matter (DOM) leached from the plow layer of rice paddies, a lysimeter study was conducted, which simulated submerged paddy topsoil during rice growth. The fulvic acid (FA) fraction in the percolation water from the lysimeter was collected by adsorption onto insoluble polyvinylpyrrolidone (PVP), and the temporal variations in its elemental composition, molecular size distribution, IR spectra, ¹³C CPMAS NMR spectra, and δ¹³C values were investigated. The proportion of the FA fraction to bulk DOM varied greatly, but the chemical characteristics of the FA fraction did not change appreciably during the experimental period. Thus, it is considered that the changes in the DOM composition in percolation water were mainly due to the differing contributions of the FA fraction. Further, to investigate the source of the FA fraction in the leachate, the chemical characteristics of the FA fraction in the leachate were compared with those extracted from the plow layer soil. A sequential extraction of the FA fraction was conducted using a sequence of water, 0.25 M Na₂SO₄, 0.1 M Na₄P₂O₇ (pH 7.0), 0.1 M Na₄P₂O₇ (pH 10.5), and NaBH₄+0.1 M Na₄P₂O₇ (pH 10.5). It was found that the water- and 0.25 M Na₂SO₄-extractable fractions, which were most mobile, were not the only source of the FA fraction in the leachate. The small molecular size sub-fraction of the NaBH₄+0.1 M Na₄P₂O₇ (pH 10.5)-extractable FAs, most of which are probably bound mainly to iron oxides, are considered to be another source of the FA fraction leached from the plow layer of paddy fields.     

浅谈林业工作中常用的遥感影像及处理要点

在遥感影像定义的基础之上,讨论了遥感影像的四个基本特征.对林业工作中常用的中分辨率遥感影像Landsate TM5、中巴资源卫星以及常用的高分辨率遥感影像Spot5、Rapideye、Alos、QuickBird、WorldviewⅠ、WorldviewⅡ等进行了介绍并做了对比分析,总结各种遥感影像的优缺点;并讨论了遥感影像基础数据准备,DOM与DEM参考数据准备以及的遥感影像正射纠正,并以ALOS为例,对算法及图像增强等工作进行了探讨     

水稻土溶解性有机质与Cu2+结合过程及机制研究

农田土壤中Cu²⁺的迁移转化对生物体健康产生重要影响,然而,水稻土中的溶解性有机质（DOM）与Cu²⁺的结合过程和机制尚不清楚。本研究通过动态光散射、三维荧光、同步荧光以及X射线光电子能谱（XPS）等方法,探究水稻土中DOM的粒径、光谱和结构特征及其与Cu²⁺的结合过程及机制。结果表明,土壤DOM的SUVA₂₅₄值为（3.25±0.07）L·（mg·m）^-1,低于4 L·（mg·m）^-1,其亲水性较高同时芳香性偏低,并且其芳香结构中含有较多的含氧官能团。水稻土DOM的构成以类富里酸和类腐植酸为主,Cu²⁺与类腐植酸络合稳定常数（lgK_M=5.07）高于类富里酸（lgK_M=4.81）。表明稻田土壤DOM中的类腐植酸组分与Cu²⁺优先结合,尤其以短波类腐植酸中的酚基、羟基和酚羟基等含氧基团对Cu²⁺的添加表现得更为敏感。另外,DOM表面疏松的介孔结构、负电荷和羟基、酚羟基以及氨基等官能团对Cu²⁺吸附起到关键作用。     

基于DOM航空影像单木树冠提取

准确提取单木树冠边界是获取森林数量参数的重要基础，是高分辨率遥感图像林业应用的技术难题。基于DOM航空影像数据源，采用面向对象的方法对研究区内的2个树种的林分进行了单木树冠边界提取研究。首先利用桉树和杉木的空间分布矢量数据对DOM航空影像进行掩膜处理，在掩膜区域内进行多层次多尺度图像分割得到初步树冠分割结果，并剔除非树冠信息；再以树冠信息种子对象为基础，使用区域增长算法对树冠信息种子对象增长得到单木树冠范围；最后使用形态学滤波的方法优化单木树冠边界，完成林区内桉树和杉木两类树种的单木树冠边界提取。结果表明，由于不同树种的树冠存在尺度和形态差异，进行单木树冠分割时需要设置不同的参数才能到达较好的分割效果。本研究中桉树和杉木的单木树冠提取总体精度分别为86.75%与89.21%，可满足林业部门获取森林单木树冠的精度需求。     

长吻鮠人工催产及脑垂体促性腺激素细胞的超微结构的变化

通过对催产和未催产的长吻鮠脑垂体中腺垂体促性腺激素分泌细胞（ＧＴＨ 细胞） 的分泌活动分析,证实了用促黄体素释放激素类似物（ＬＲＨ－ Ａ） ５０μｇｋｇ 加ＤＯＭ５ｍｇｋｇ 混合注射催产长吻鮠,能有效地促使ＧＴＨ细胞分泌促性腺激素,诱导卵母细胞成熟和排卵,催产效果显著。超微结构的进一步观察,揭示了长吻鮠脑垂体ＧＴＨ 细胞中存在两种分泌颗粒,即分泌小球,直径１２００～２０００ｎｍ ,电子密度低;分泌颗粒直径３００ ～５００ｎｍ ,电子密度高。分泌小球释放与卵母细胞的发育成熟有关,分泌颗粒的释放则与排卵相关。     

Absorption of dissolved and dispersed nutrients from sea-water by Panulirus japonicus phyllosoma larvae

This study examined the capacity of Japanese spiny lobster Panulirus japonicus phyllosoma larvae to absorb nutrients directly from the surrounding water. For this purpose, 48-, 81-, 124-, 160-, and 264-day-old intermoult larvae were starved for 48 h, held for 30 min to 4 h in 0.05 g L^–1 solutions or dispersions of cholesterol, peanut oil, saccharose and horseradish peroxidase in seawater, and subsequently examined by histological and ultrastructural methods. Lipids, carbohydrate, and protein were detected in either the lumen of the midgut gland tubules, the midgut gland cells, the haemolymph or in the cells of the epidermis of all larvae examined after each experimental period, with general improvement of the cell and tissue characteristics over unfed controls. The lipids were also found in the cuticle. Thus, the results provide evidence of nutrient absorption via the digestive tract, and possibly also via the integument. Structural adaptations that may be involved in the process of absorption were tentatively identified. Our observations suggest the possibility that particulate organic matter (POM) and dissolved organic matter (DOM) can be utilized by the P. japonicus phyllosoma larvae, perhaps as supplementary sources of nutrients to macroscopic diets.     

Kinetics of the release of dissolved organic matter (DOM) from air‐dried and pre‐moistened soil material

In this study, the kinetics of soil organic matter (SOM) dissolution from soil samples in different states of moisture was investigated, using a continuous extraction method. The investigation distinguished three processes of SOM dissolution. They include an initial, fast process (probably hydrophilic dissolved organic matter) and two slow, rate limited processes, which probably correspond to hydrophobic dissolved organic matter (DOM). The second process indicates a slow, continuous release of DOM, whereas the third process is determined by a power law. The rate of the third process strongly depends on temperature and state of moisture. It is diffusion limited, with the diffusion control probably being located in the solid soil organic matter. This was explained by a gel structure, which slowly forms in the hydrating SOM and allows diffusion of mobile particles of SOM. The results show the importance of considering the moisture state of SOM for the kinetics of DOM dissolution.     

微咸水膜下滴灌条件下绿洲棉田土壤盐分的时空变化规律试验研究

在相同灌水量条件下,以不同比例混合地下咸水(3.56 g/L)和地表淡水(0.4 g/L),采用膜下滴灌方式充分灌溉棉田,探求土壤盐分的时空变化规律.研究表明,棉花生长期间土壤盐分的变化主要受土壤水分运移和地面植被覆盖度的影响;表层土壤盐分波动大,深层土壤盐分波动小;监测层在总合盐量上比未灌水处理前低,但所有微成水处理的都比淡水对照的大;膜下滴灌棉田盐分的变化主要受灌溉水和蒸散发的影响.     

滇池金线鲃全人工繁殖研究

用人绒毛膜促性腺激素(HCG)+促黄体素释放激素类似物(LRH-A2)+马来酸地欧酮(DOM)组成的混合催产剂对滇池金线鲃催产获得成功,单独用人绒毛膜促性腺激素或鲤鱼脑垂体(PG)+人绒毛膜促性腺激素的混合催产剂均催产失败。采取2次注射催产效果明显,第1次用2μg/kgLRH-A2催熟,第2次用8μg/kgLRH-A2+3mg/kgDOM+1000IU/kgHCG催产,能获得88.5%的催产率。催产成功后,采取遮光孵化,孵化率明显提高。