华北土石山区植物群落多样性特征分析

根据12个样地的调查资料，分析了八达岭地区天然林植物群落物种多样性的特征，群落内部各层次物种多样性指数的顺序依次为：草本层＞灌木层＞乔木层，但在糠椴（Tilia mandshurica）林和核桃楸（Juglans mandshurica）林中由于特殊的生境表现为：灌木层＞草本层＞乔木层。白梨（Pyrus bretschneideri）山丁子（Malus baccata）林和核桃楸林群落中Sorenson指数最小，共有种最少，群落间多样性最大。     

冀北山区三种典型森林类型枯落物水文效应研究

枯落物层在森林生态功能中具有十分重要的作用。在冀北山区北沟林场搜集了3种典型森林群落枯落物,研究其储量和持水特性。结果表明：3种林分类型枯落物半分解层的储量均大于未分解层;枯落物最大持水量总和为：油松蒙古栎混交林（155.31t/hm2）〉山杨桦树混交林（105.62t/hm2）〉落叶松桦树混交林（88.17t/hm2）;枯落物有效拦蓄量半分解层均大于未分解层,排序为：油松蒙古栎混交林（128.15t/hm2）〉山杨桦树混交林（82.27t/hm2）〉落叶松桦树混交林（69.22t/hm2）;总的有效持水量为：油松蒙古栎混交林（132.01t/hm2）〉山杨桦树混交林（89.39t/hm2）〉落叶松桦树混交林（74.95t/hm2）;枯落物各层持水量与浸泡时间呈很好的对数关系。总之,油松蒙古栎混交林保持水土效果最佳。     

北方典型区域果园表层土壤农药类POPs残留特征分析

在我国典型果业生产区域的黄土高原、胶东半岛和北京郊区选择11个采样区的99个果园,利用GPS定位仪共采集0~20cm表土样品99份,测定了DDT、六氯苯、七氯、氯丹、狄氏剂、异狄氏剂、灭蚁灵和艾氏剂等8种主要POPs残留量,对土壤POPs残留的环境安全性、土壤残留差异性以及区域分布特点进行了分析研究。结果表明：（1）果园表层土壤8种POPs残留浓度符合国家土壤环境质量标准,属于环境安全残留;（2）滴滴涕是果园土壤残留分布最广泛和残留量较高的POPs,其次是六氯苯、氯丹和七氯,再其次是狄氏剂、异狄氏剂、灭蚁灵和艾氏剂;（3）果园土壤POPs残留种类多、广泛残留与高残留量地区的共同特征是建园早、园龄长、自然条件好和农业经济较发达。     

不同防护措施下流沙地表层温湿度的日变化特征

[目的] 探讨不同防护措施下流沙地表层温湿度变化规律及其影响机理,为沙漠区植被恢复提供理论依据。[方法] 采用野外大田试验,设置5种防护措施（单管防护、管裹反光膜、管壁开孔、管内覆秸秆和双管防护）,3种管件直径（75,90,110 mm）和3种露地高度（10,15,20 cm）,以无防护流沙地表为对照,依托土壤温湿度记录仪对地表层温湿度日变化特征进行研究。[结果] 5种防护措施均能起到降温作用,其中双管防护降温效果最好;同一防护措施下,06：00时刻管内地表层温度随管件直径的增大而增大,其他时段则随管件直径的增大而降低,而全天时段管内地表层温度随露地高度的增大而降低;管内地表层温度随流沙地表层温度的增大而增大,两者具有良好的线性关系（R²≥0.830）;与无灌溉相比,灌溉在白天时段（06：00—21：00）起降温作用,而夜间时段（21：00—06：00）起保温作用;管内地表层水热存在耦合效应,地表层含水率越高,其温度越低。[结论] 双管防护+灌溉措施最有利于流沙地表层控温保水,其中最佳管件参数是管件直径110 mm和露地高度20 cm。     

弱光下种植密度对冬小麦冠层温湿度及籽粒灌浆的影响

2016年在小麦拔节?成熟期用透光率为50%的白色尼龙网模拟遮阴环境,遮阴和自然光条件下分别设置450（M1）、525（M2）、600（M3）、675（M4）、750万株·hm?2（M5）5种种植密度,进行双因素裂区田间试验,观测对比冬小麦冠层空气温度、湿度以及小麦籽粒灌浆特性的变化过程。结果表明：与自然光相比,遮阴处理下冬小麦冠层温度明显降低、中午高温持续时间明显缩短,冠层湿度明显升高,中午冠层湿度低谷持续时间明显缩短,籽粒灌浆速率降低;遮阴显著降低了冬小麦的有效穗数、穗粒重及千粒重。遮阴条件下,可以通过适当降低种植密度,改善冠层温湿度,提高冬小麦籽粒灌浆速率,增加穗粒数和千粒重,从而获得高产。     

不同立地条件下沙棘土壤水分分布特征及动态生长研究

为探究不同立地条件下沙棘土壤水分分布特征和生长情况,采用样地试验,设置2种坡向（阴坡、阳坡）和3种坡位（坡顶、坡中、坡底）进行研究。研究表明：（1）各样地内的土壤水分季节变化可划分为消耗期（5—6月）、快速补充期（6—7月）和消退期（7—9月）,天然降水对土壤含水率影响较大;（2）各样地内的土壤水分垂直分布为土壤水分显著变化层（Cv>0.2）、土壤水分次变化层（0.2>Cv>0.1）和土壤水分相对稳定层（Cv<0.1）;（3）不同立地条件对土壤水分及植株的生长具有显著影响。阴坡土壤水分明显高于阳坡,土壤水分由坡顶向坡底呈递减趋势;沙棘的生长指标及存活率表现为阴坡>阳坡,不同坡位表现为坡底>坡中>坡顶。研究结果可为玛纳斯县前山地带沙棘造林提供参考和理论依据。     

卵丘细胞对牛卵母细胞体外成熟和体外受精的影响

本试验探讨了卵母细胞周围不同类型的卵丘细胞对牛卵母细胞体外成熟、受精及其随后的胚胎发育的影响。卵母细胞周围一般都含有多层卵丘细胞。按卵丘细胞的层数及形态将卵母细胞大致分为５类：（１）无卵丘细胞；（２）有２～３层卵丘细胞；（３）有４～５层卵丘细胞；（４）有６层以上卵丘细胞；（５）异常者（即卵母细胞外周有较厚的透明胶状物而无正常卵丘细胞）。以上５种卵母细胞经体外成熟培养并受精后，其卵裂率（分别为：４８．８％，７０．９％，８４．４％，８２．１％，６８．２％）及囊胚发育率（分别为：０．０％，１７．８％，３３．３％，５４．６％，２５．０％）除异常者外均随着卵丘细胞层数的增加而提高（Ｐ＜０．０５）。对含有２～６层卵丘细胞的卵母细胞成熟后进行不同程度的剥离处理。然后按剥离程度分为３组：（１）全部剥离；（２）仅剩放射冠；（３）放射冠外有２～３层卵丘细胞。受精后３组间的卵裂率无显著差异（分别为：８１．７％，８５．２％，８４．４％）。而囊胚发育率（分别为：１６．８％，２３．８％，２３．４％），全部剥离组明显低于其他两组（Ｐ＜０．０５）。试验结果表明卵丘细胞对卵母细胞的体外成熟有促进作用，从而影响随后的受精及胚胎发育。     

基于CT扫描的不同粒形滤料孔隙结构特征

滤层孔隙结构直接影响过滤过程中的颗粒沉积和运移效果。为了掌握砂石过滤器不同粒形滤料组成滤层的内部孔隙结构特征，该研究以粒径为1～1.18 mm的普通石英砂（QS1）、天然海砂（SS2）、改性玻璃（MG3）和玻璃微珠（GB4）4 种滤料为研究对象，采用CT 扫描技术对滤层孔隙模型进行了三维重构，利用VGStudio MAX、Image J等计算机图像处理软件，分析了 4 种滤层的孔隙率、孔径大小及孔隙形状参数，并结合分形理论确定了 4 种滤层孔隙结构的计盒分形维数。结果表明：4种滤层的表观孔隙率范围分别为0.397～0.446（QS1）、0.385～0.423（SS2）、0.407～0.456（MG3）、0.351～0.380（GB4），对应体积孔隙率分别为0.422、0.412、0.441、0.366；对应孔径范围分别为75～960、80～760、70～1 050、85～930 μm，圆度值区间分别为1.59～1.78、1.35～1.54、1.65～2.03、1.20～1.36，扁平度值区间分别为2.62～2.75、2.05～2.20、3.04～3.21、1.94～2.04，计盒维数均值分别为1.621、1.566、1.661、1.446。该研究定量表征了滤层孔隙结构特性，得出不同粒形滤料细观孔隙结构的差异：滤层表观孔隙率呈现"上高下低"分布规律，孔径分布规律表明滤层内均是小孔隙占多数，大孔隙占少数，且孔隙以狭长型为主。随着滤料棱角度增加，表观孔隙率分布越分散，体积孔隙率越大，大孔隙占比也相应增加，最大达到17.24%（MG3），孔隙形状更加偏离球形，表征孔隙结构复杂性的计盒维数相应增加，且分形维数与孔隙率呈负相关关系。滤层孔隙结构研究可为后续研究滤层内颗粒沉积和运移规律奠定基础。     

桉树林和针阔混交林对植物多样性的影响比较

为了系统评价桉树林和针阔混交林对生物多样性的影响,采用立地条件控制及空间代替时间法,对南亚热带桉树林（2代和1代）和针阔混交林（10～11 a生和5～7 a生）乔木层、灌木层和草本层生物多样性进行了比较。结果表明,针阔混交林Ⅰ（10～11 a生）有68种植物,隶属38科62属,桉树林Ⅱ（桉树2代）有41种,隶属26科39属,针阔混交林Ⅲ（5～7 a生）有53种植物,隶属30科48属,桉树林Ⅳ（桉树1代）有55种植物,隶属33科51属。针阔混交林乔木层重要值较大的科为杉科、樟科、金缕梅科、大戟科、山茶科、木兰科和楝科,灌木层为五加科和大戟科,草本层以禾本科、鳞始蕨科和乌毛蕨科为主。桉树林乔木层重要值较大的科为桃金娘科、芸香科、樟科、大戟科和漆树科,灌木层为冬青科、樟科、大戟科和芸香科,草本层以禾本科和里白科为主。4种试验林间乔木层、灌木层和草本层物种丰富度指数（S）、Shannon-Wiener指数（H’）、Simpson优势度指数（D）、Pielou均匀度指数（E）差异不显著（P > 0.05）。针阔混交林Ⅰ乔木层和灌木层H’指数、D指数及E指数显著高于草本层（P < 0.05）,桉树林Ⅱ乔木层、灌木层和草本层间H’指数、D指数及E指数均存在显著差异（P < 0.05）。针阔混交林乔木层均匀度指数（E）均大于桉树林。与针阔混交林Ⅲ相比,针阔混交林Ⅰ乔木层物种S,H’,D及E指数呈上升趋势,而灌木层和草本层呈下降趋势。与1代桉树林Ⅳ相比,2代桉树林Ⅱ灌木层和草本层S,H’和D指数呈下降趋势。研究结果为桉树人工林物种多样性保护和可持续经营提供科学依据。     

La与UV-B辐射胁迫对大豆叶片细胞叶绿体超微结构的影响

采用水培法研究了稀土La（Ⅲ）对紫外辐射（UV-B：0.15Wm^-2,0.45Wm^-2）胁迫下大豆（Glycine max）叶片细胞超微结构尤其是对叶绿体结构的影响。结果表明：La（Ⅲ）处理下叶绿体中的类囊体片层排列整齐、有序、清晰;UV-B辐射胁迫下叶绿体内类囊体片层紊乱、膨胀甚至模糊不清,高强度UV-B辐射（T2）对叶绿体的影响大于低强度辐射（T1）;而La（Ⅲ）能够影响UV-B辐射胁迫下叶绿体在细胞环境内的空间分布,减轻UV-B辐射对叶绿体外膜的破坏,使叶绿体内类囊体片层变得有序清晰,且对低强度UV-B辐射（T1）的缓解效果优于高强度（T2）。     

Analysis of free and esterified ergosterol in tomato products

A new extraction and chromatographic procedure to quantify free and esterified ergosterol in tomato products was devised. The extraction solution was composed of a dichloromethane/methanol mixture in a 2:1 (v/v) ratio. This extraction solvent allowed for higher ergosterol recovery from tomato products (an average of 25% more) compared to hexane, which is frequently employed for ergosterol extraction. Both free and esterified ergosterol were determined by HPLC reverse-phase chromatography employing a Nova-Pak C-18 column (300 x 3.9 mm), filled with 4 mm average particle size and a guard column of the same material. The elution was performed at a flow rate of 1 mL. min(-1) with a linear gradient of solvent A (methanol/water, 80:20, v/v) and solvent B (dichloromethane). The gradient, starting at sample injection, was from 0 to 50% B for 20 min for the free ergosterol analysis and additional 15 min at 50% B to analyze the ergosterol esters. This technique has proven to be more sensitive for ergosterol determination than other reported chromatographic procedures. Moreover, ergosterol esters, extracted from various fungal sources, separated well and were easily quantified.     

土壤样品中多环芳烃分析方法研究进展

概述了国内外土壤样品中多环芳烃(PAHs)测定方法的研究状况,其中提取方法包括加速溶剂萃取方法、固相微萃取方法、超临界流体萃取方法、亚临界水萃取方法和流化床提取方法等,测定方法有HPLC法、GC法和免疫分析法等。重点介绍了PAHs的提取过程,同时总结了各种方法的优缺点。     

Chemical confirmatory tests for ochratoxin A, citrinin, penicillic acid, sterigmatocystin, and zearalenone performed directly on thin layer chromatographic plates

Published tests have been improved and a new procedure is described for chemical confirmation of mycotoxins directly on thin layer plates. After extraction and preliminary cleanup chromatography with n-hexane or chloroform, the mycotoxins ochratoxin A, citrinin, penicillic acid, sterigmatocystin, and zearalenone were easily separated by thin layer chromatography (TLC) using toluene-ethyl acetate-90% formic acid (6 + 3 + 1) developing solvent. In chemical confirmatory methods, the developed chromatogram was exposed to vapors of pyridine, acetic anhydride, or a mixture, or the mycotoxins were over-spotted. With this treatment, ochratoxin A, citrinin, penicillic acid, and zearalenone were converted to new fluorescent compounds, and observed under 365 nm light after re-chromatography with the same developing solvent. Sterigmatocystin was confirmed chemically using TLC plates impregnated with 0.6N H2SO4 or 10% oxalic acid in methanol. The described procedures are satisfactory for confirming mycotoxins present in standards, artificially contaminated grain samples (barley, corn, oat, rye, and wheat), and extracts from both fungal cultures and naturally contaminated grain samples.     

Assessing the Potential of Organic Solvents on Total Petroleum Hydrocarbon Extraction from Diesel-Contaminated Soils

The total petroleum hydrocarbon (TPH) extraction potential of organic solvents including dichloromethane (DCM), pentane, hexane, methanol, ethanol, propanol, and acetone was investigated along with the effect of water content in solvents for their efficiency of extraction. The extent of TPH extraction was analyzed using various extraction schemes (i.e., solvent/solid ratio, treatment time, extraction method, solvent/water ratio) to better understand the physical and chemical factors controlling TPH release from contaminated soils. More TPH was extracted with increasing solvent/solid ratio and increasing time. The extent of TPH extracted also varied depending on the extraction method, solvent type, and solvent/water ratio, but was highest when using the total extraction method and 100% DCM. However, the efficiency of TPH extraction decreased dramatically with the increase in the water content in organic solvents. The results also showed that TPH extraction using DCM was the best option for achieving cost-effective, eco-friendly outcomes along with remediation goals. DCM used in solvent extraction to remediate diesel-contaminated soils showed low toxicity, low cost, high recycling potential, and high efficiency compared to the other solvents tested in this study.     

盐碱地膜下滴灌技术参数的确定

覆膜种植是一种新型的农业种植技术，而滴灌是一种农业节水灌溉技术，将覆膜种植技术与滴灌技术有机结合起来形成一种开发利用盐碱地的新方法。该文根据膜下滴灌过程中土壤水盐运移特征，对利用膜下滴灌技术开发利用盐碱地的有关技术要素进行了深入探讨。     

Effects of methanol concentration and solvent:peanut ratio on extraction of aflatoxin from raw peanuts

Aflatoxin B1 was extracted by a water slurry process using methanol concentrations of 55, 60, 65, and 70% in water and solvent:peanut ratios of 3, 4, 5, and 6 mL/g. Results failed to show that methanol concentration had an effect on amount of B1 extracted; however, the amount of B1 extracted increased with an increase in solvent:peanut ratio. Aflatoxin B1 was also extracted by the official AOAC method II, using methanol concentrations of 55, 60, 65, and 70% in water and solvent:peanut ratios of 2, 3, 4, and 5 mL/g. Results showed that the amount of B1 extracted increased with percent methanol at low solvent:peanut ratios but not at high ratios. Also, the amount of B1 extracted increased with solvent:peanut ratios at all methanol concentrations.     

Organic compounds of different extractability in total solvent extracts from soils of contrasting water repellency

Previous studies examining organic compounds that may cause water‐repellent behaviour of soils have typically focussed on analysing only the lipophilic fraction of extracted material. This study aimed to provide a more comprehensive examination by applying single‐ and sequential‐accelerated solvent extraction (ASE), separation and analysis by GC/MS of the total solvent extracts of three soils taken from under eucalypt vegetation with different degrees of water repellency. Water repellency increased in all the soils after extraction with DCM/MeOH (95:5), but was eliminated with iso‐propanol/ammonia (95:5). Quantities of major lipid compound classes varied between solvents and soils. Iso‐propanol/ammonia (95:5) solvent released saccharides, glycerol, aromatic acids and other polar organic compounds, which were more abundant in fractionated extracts from the single extraction and the third step sequential ASE extraction, than in the extracts from the DCM/MeOH ASE solvent. Dominant compounds extracted from all soils were long‐chain alkanols (>C₂₂), palmitic acid, C₂₉ alkane, β‐sitosterol, terpenes, terpenoids and other polar compounds. The soil with the lowest repellency lacked >C₁₈ fatty acids and had the lowest concentrations of alkanols (C_26,C₂₈ and C₃₀) and alkanes (C₂₉, C₃₁), but a greater abundance of more complex polar compounds than the more repellent soils. We therefore speculate that the above compounds play an important role in determining the water repellency of the soils tested. The results suggest that one‐stage and sequential ASE extractions with iso‐propanol/ammonia and subsequent fractionation of extracts are a useful approach in providing a comprehensive assessment of the potential compounds involved in causing soil water repellency.     

A screening method for protein characterization and differentiation.

A circular paper chromatographic method was developed for the separation of the amino acids in proteins into 7 subgroups. Butanol-acetic acid water (4+1+1) was used as the developing solvent. Eluted ninhydrin-stained aminograms gave rise to graphic profiles or numerical indexes based on absorbance percentages. The profiles can be used to compare protein-containing samples. Twenty different samples were studied through 190 comparisons of graphic profiles and coefficients of correlation, with only 4% misleading results. The method showed excellent reproducibility for the identification or differentiation of proteins and has the advantage of being performed with low-priced apparatus and reagents.     

Determination of the odor threshold concentrations of iodinated trihalomethanes in drinking water

Iodinated trihalomethanes (ITHMs) have been usually considered the disinfection byproducts suspected of causing medicinal odor episodes in treated water around the world. The odor threshold concentration (OTC) of mixed ITHMs (bromochloroiodo-, bromodiiodo-, chlorodiiodo-, dibromoiodo-, and dichloroiodomethane) which were previously synthesized -- because commercial standards are not available-- were determined by using two sensory techniques: flavor profile analysis (FPA), performed by an experienced panel trained in identifying odors and tastes in water; and gas chromatography coupled with olfactometry (GCO). FPA results gave a theoretical OTCs range from 0.1 to 8.9 microg/L and ITHMs were described as sweet, solvent, and medicinal products. The lowest experimental value (OTC(exp)) obtained from the six ITHMs, 0.03 microg/L, corresponded to iodoform.     

Interactions Between Sediments and Water Summary of the 7th International Symposium

The interactions between sediments and water have received increased emphasis over the last two decades, leading to a greater understanding of physical, chemical and biological processes in a wide range of aquatic systems including river, lake, estuarine and coastal systems. This new understanding has fostered research and assessment projects, and focused awareness on the implications of sediment/water interactions for policy and regulation. The international symposium on “The Interactions Between Sediments and Water” held in Baveno, Italy from 22–26 September 1996 was the seventh in a series of symposia held since 1976. All focused on issues relating to processes which occur near the sediment/water interface as well as responses to interactions between sediments and water. Previous symposia were held in Amsterdam in 1976, Kingston (Canada) in 1982, Geneva in 1984, Melbourne in 1986, Uppsala in 1990 and Santa Barbara in 1993. Almost 200 oral and poster presentations were made by attendees representing 27 nations, including dozens of participants from developing countries. The scientific sessions were organized around the following themes: sediment/water dynamics, contaminant interactions, sediment/nutrient relationships, sediments as historical records of deposition, sediment/water science in remote areas, sediment/organism interactions, and novel methods and analytical quality control. This paper attempts to summarize the key highlights of the various sessions.