污水灌溉条件下Cu在农田土壤中的运移及其模拟研究

通过土柱模拟试验,分析污水灌溉条件下Cu在我国7种典型农田土壤中的迁移趋势及其对浅层地下水的污染风险.试验用添加含有Cu(20 mg·L-1)的人工污水以相当于水作4年、旱作10年的灌溉量(20 L)进行土柱淋溶实验,并应用Hydrus-1D软件对Cu在土壤中的运移进行模拟分析.结果表明:黑土、黄潮土和黄绵土对Cu的吸附性能很强,淋出液中Cu浓度低于地下水水质Ⅱ类标准,污水灌溉风险较低,进入土壤中的Cu主要积累在0～5 cm表层,确定性平衡模型(DEM)可以对Cu在黑土、黄潮土和黄绵土土壤剖面中的分布进行拟合;红壤、灰潮土和2种水稻土对Cu的吸附能力相对较弱,进入土壤的Cu含量超过了土壤对它的吸持固定能力,Cu在较短时间里即可穿透土体,对地下水及环境造成潜在危害,污水灌溉风险较大,化学非平衡两点模型(TSM)对Cu在红壤、灰潮土和2种水稻土中的运移有较好的拟舍效果.从Cu在不同农田土壤中的迁移分布及拟合过程来看,土壤对Cu的吸附性能是决定Cu在土壤中迁移的最重要因素,它从宏观上决定了Cu在土壤中迁移、积累的全过程,也是导致污水灌溉条件下Cu在7种农田土壤中迁移差异性的根本原因.     

利用 ｍｔＤＮＡＤ-ｌｏｏｐ序列为遗传标记分析槟榔江水牛的群体遗传特征

槟榔江水牛是近年在云南西部发现的中国第一个本土河流型水牛群体,具有较高种用价值,但其重要遗传背景信息还不清楚。本文采用 ＰＣＲ产物直接测序法对 ８６头槟榔江水牛 ｍｔＤＮＡＤ-Ｌｏｏｐ序列进行了突变检测,并以 ＧｅｎＢａｎｋ上已发表的 ７０条河流型和 １１２条沼泽型水牛 ｍｔＤＮＡＤ Ｌｏｏｐ序列为对照,对所得数据进行群体遗传和系统发育分析。结果在槟榔江水牛中检测到 ３３种单倍型,１１２个多态位点。其中单一变异位点 １４个,简约信息位点 ９８个。槟榔江水牛 ｍｔＤＮＡＤ Ｌｏｏｐ序列 Ｔ,Ｃ,Ａ,Ｇ的平均含量分别为 ２８.４３％,２４.８２％,３１.９６％,１４.７９％,单倍型多样度为 （０.９４８±０.０１２）,核苷酸多样度为 （０.０３８１±０.００１６）,序列间平均核苷酸差异数为３３.２８８,群体内平均遗传距离为 （０.０４３±０.００５）。系统发育、中介网络图和群体遗传关系分析表明,槟榔江水牛含有两个差异显著的母系世系组分,其中一个为河流型世系,在群体中占 ６１.６３％;另一个为沼泽型世系,在群体中占３８３７％,而其沼泽型世系可进一步分为 Ａ,Ｂ,Ｃ３个支系,其中,Ｃ为在水牛中新发现的支系,其频率极低。结果揭示了槟榔江水牛群体遗传多样性丰富,但该群体存在一定的沼泽型水牛基因渗入。     

Plasma levels of vitamin D3 metabolites during parr-smolt transformation of Atlantic salmon Salmo salar L.

Plasma vitamin D and vitamin D metabolites were measured in Atlantic salmon parr during smoltification and after transfer to seawater. The fish were fed commercial feed for 5 months under natural light, and Na⁺/K⁺ ATPase was measured as an indicator of the smoltification status. No significant differences were recorded in the level of plasma vitamin D metabolites. However, a tendency of increasing plasma concentration of 25OHD₃ and also a temporary increase in plasma 1,25(OH)₂D₃ and 24,25(OH)₂D₃ were recorded prior to seawater transfer. The minor changes in plasma levels of the metabolites indicate a role of the vitamin D metabolites during parr–smolt transformation, although we do not know whether the increased levels are caused by increased synthesis of the metabolites or by decreased binding to receptors or decreased excretion.     

Effects of dietary vitamin E level on growth and tissue lipid peroxidation of soft-shelled turtle, Pelodiscus sinensis (Wiegmann)

A feeding trial was conducted to determine the effect of dietary vitamin E supplementation on growth, liver lipid peroxidation and liver and muscle vitamin E level of soft‐shelled turtle, Pelodiscus sinensis. Eight experimental diets analysed to contain 0–457 IU vitamin E kg^?1 were fed to juvenile soft‐shelled turtle of 4.8 g initial body weight for 12 weeks. Weight gain (WG) of the turtles fed the diet containing no vitamin E was significantly lower than those fed diets containing 83–457 IU vitamin E kg^?1 (P<0.05). Feed conversion ratio and protein efficiency ratio showed similar trends to that of WG. No significant difference (P>0.05) was found in whole‐body composition among turtles fed the different diets. Dietary vitamin E requirement using WG as the response and estimated using the broken‐line regression model is approximately 88 IU kg^?1. Liver and muscle vitamin E content increased when dietary vitamin E level increased. Ascorbate‐induced lipid peroxidation in liver tissue of turtles fed diets containing 0 and 17 IU vitamin E kg^?1 was significantly (P<0.05) greater than those fed diets containing high vitamin E (≥35 IU kg^?1).     

Removal of trichloroethylene from aqueous solution by pyrolyzed Japanese cedar bark

The bark of Japanese cedar (Cryptomeria japonica D. Don) was heated in an N₂ atmosphere at 300–900C for 3h to investigate the surface properties of the pyrolyzed residuces and their ability to remove trichloroethylene (TCE) from aqueous solutions. The specific surface areas (S _N) and total pore volumes (V _N) of the pyrolyzed barks steadily increased with rising pyrolysis temperature; no significant differences in the average pore diameters (D _N) were observed at higher temperatures (600–900C). The adsorption capacities of the pyrolyzed residues for TCE were determined under batch mode conditions using an aqueous solution containing 500g TCE dm^–3. The adsorption data were well fitted to the Freundlich equation. The adsorption capacity of the bark pyrolyzed at 900C was about five times larger than that of commercial activated carbon.This study was presented at the 10th International Symposium on Wood and Pulping Chemistry, Yokohama, June 1999     

基于ATV平台的全地形立体草原防火系统

提出以ATV(全地形车)为移动平台,搭载各种灭火、通讯装备,组成一种反应迅速的草原消防灭火系统,并将复杂地形移动技术、灭火技术和遥控通讯技术有机地融合在一起.对系统方案做了详细介绍,该系统有助于实现草原防火“早发现、早扑灭”的目标,可大大减少火灾损失.     

八角缺素症状的形态特征及处理方法

通过对八角植株体内11种营养元素失调症状诊断的描述,判断其体内的营养状况,并针对所出现的各种特征通过施肥进行处理,让广大种植经营者能够通过简易目测方法,了解与掌握八角栽培过程中树体营养元素缺乏后的形态表现,从而调整施肥的品种、方法和用量,使八角的营养元素含量保持合理水平,提高经营管理水平,促进八角速生丰产稳产。     

Adoption of improved fallow technology for soil fertility management in Zambia: Empirical studies and emerging issues

In the subsistence-agricultural region of eastern Zambia, less than 10% of the households have adequate supply of maize (Zea mays L.), the staple food, throughout the year. A major constraint to increasing crop production in the region is poor fertility status of the soil. In order to address this problem, improved fallow has been introduced as a technology for improving soil fertility within a short span of two to three years. Farmers have been testing the technology and a number of empirical studies have been undertaken over the years to identify the factors influencing farmers' decision to adopt the technology. This paper presents a synthesis of the results of adoption studies and highlights generic issues on the adoption of improved fallows in Zambia. The synthesis indicates that farmers' decision on technology adoption does not have a simple directed relationship of some technological characteristics only, but constitutes a matrix of factors including household characteristics, community level factors, socioeconomic constraints and incentives that farmers face, access to information, local institutional arrangements and macro policies on agriculture. The adoption of improved fallows is not strictly speaking a binary choice problem but a continuous process in which farmers occupy a position along a continuum in the adoption path. Further, adoption of improved fallows may not take place in a policy vacuum but needs to be facilitated by appropriate and conducive policy and institutional incentives. Several questions and issues that require further study emerge from the synthesis. These include determination of the relative importance of the factors in the adoption matrix, identification of the conditions under which farmers use a combination of inputs and their profitability under changing price scenarios, exact definition to delineate between `non-adopters', `testers' and `adopters' of agroforestry technologies, and understanding the impact of cash crop farming in farmers' adoption decisions of improved fallows (where off farm opportunities exist). Further, there is a need to determine the inter-relationship between household poverty, labor availability and the adoption of improved fallows and, to evaluate a combination of policy interventions at both national and local level to promote the adoption of agroforestry-based soil fertility management. This revised version was published online in June 2006 with corrections to the Cover Date.     

基于注意力机制及多尺度特征融合的番茄叶片缺素图像分类方法

针对番茄早期缺素性状不明显及各生长期特征差异较大所导致的特征区域尺寸不一致、难提取、难辩别等问题,提出了一种基于注意力机制及多尺度特征融合卷积神经网络的番茄叶片缺素图像分类方法（Multi-Scale Feature Fusion Convolutional Neural Networks Based On Atte ntion Mechanism,MSFF-AM-CNNs）。首先根据番茄叶片缺素特点提出了多尺度特征融合结构（Multi-Scale Feature Fusion Module,MSFF Module）;其次在DenseNet基础上,结合浅层网络主要提取纹理、细节特征,深层网络主要提取轮廓、形状特征的特点分别提出具有针对性的特征提取方法,通过不同形式引入注意力机制及多尺度特征融合结构,使全局多尺度信息融合多个特征通道、选择性地强调信息特征并达到对特征精准定位的功能;同时引入Focal Loss函数以减少易分类样本的权重。试验结果表明,MSFF-AM-CNNs的平均召回率、平均F1得分、平均准确率较原模型DenseNet-121均大幅提升,其中缺氮和缺钾叶片的准确率分别提高了8.06和6.14个百分点,召回率分别提高了6.31和5.00个百分点,F1得分分别提高了7.25和5.55个百分点,平均识别准确率可达95.92%,具有较高的识别准确率及广泛的适用性,能够满足番茄叶片缺素图像的高精度分类需求,可为植物叶片缺素识别提供参考。