黄河三角洲地区土壤水蒸发量计算的试验研究

对黄河三角洲地区土壤水蒸发量的计算进行了研究。在研究区典型点裸地、棉花地和芦苇地设立了 3个试验点 ,并利用陶管负压计TDR等仪器 ,获取各试验点不同深度土壤的土水势和含水量 ,应用定位通量法计算土壤水蒸发量。结果表明 ,观测期 ( 2 0 0 2年 9月 )棉花地蒸发量为 85 4mm ,裸地为 60 6mm ,芦苇地为 49 0 4mm。对计算结果以及芦苇地计算蒸发量小的原因进行了分析     

2005-2017年焉耆盆地平原区地下水时空演变规律及其与土地利用的关系

[目的]分析2005-2017年焉耆盆地平原区土地利用变化与地下水总溶解固体物TDS之间的关系,为地下水可持续利用和生态环境发展提供依据。[方法]利用GIS软件对焉耆盆地平原区2005,2014,2017年的Landsat-TM/ETM和Landsat 8的CNLUCC数据进行重分类,将土地分为耕地、林地、草地、水域、城镇建设用地和未利用土地6大类;通过对232组地下水水样的采集和分析,借助地统计和叠加分析模块研究焉耆盆地的TDS时空分区特征。[结果]焉耆盆地平原区以耕地、水域和未利用土地为主,占总面积的60%以上;2014年耕地TDS均值的含量最高为708.6 mg/L,林地TDS均值的含量最低为680.4 mg/L;2017年城镇建设用地TDS均值的含量最高为521.6 mg/L,未利用土地TDS均值的含量最低为477.4 mg/L。[结论]2017年各土地利用类型的TDS均值含量都低于2014年,是源于水域面积增加导致地下水补给量增加、耕地扩张的速度减缓及地下水径流积极循环带的淡化作用。     

华北平原典型土地利用类型下包气带土壤水稳定同位素变化特征

基于华北平原典型土地利用类型(梨园、农田)包气带(>18 m)土壤水同位素测定结果, 分析了华北平原深层土壤水稳定同位素(δD、δ18O)特征, 揭示了不同土地利用类型下包气带土壤水补给过程中蒸发和入渗的规律。结果表明, 研究区大气降水线δD =6.07δ18O-5.76(R2=0.86), 土壤水δD、δ18O值均落在大气降水线下方, 表明降水入渗补给土壤水过程中经历了强烈的蒸发作用；除梨园Ⅰ, 土壤水同位素值变异系数浅层＞中层＞深层, 表明浅层土壤水δD、δ18O波动较大, 主要由于其易受到降水和蒸发的影响, 随土壤剖面深度的增加, 蒸发和降水的影响逐渐变弱；梨园Ⅰ深层土壤水同位素变异系数较大, 表明该样点深层土壤水受到地下水波动的影响；梨园浅层土壤水氘盈余(d-excess)较农田大, 说明农田浅层土壤水蒸发强度大于梨园；0.25~0.5 m深处土壤水均出现δD、δ18O的明显富集, 主要受土壤质地分层影响导致土壤水入渗受阻, 同位素较为富集的土壤水在此深度层积聚；而梨园2~5 m出现δD、δ18O的贫化现象, 主要是梨树根系埋深使得降水以优先流形式补给至此土壤层。梨园和农田包气带土壤水δD、δ18O垂直剖面上差异显著，表明了华北平原不同土地利用方式的包气带土壤水入渗过程有明显差异, 梨园包气带土壤水入渗过程主要以优先流补给影响。本研究为深入了解华北平原农田区厚包气带水分运动、氮素迁移转化与地下水水质之间的关系提供了理论依据。     

土壤侵蚀模型研究综述

 近年来,人们对土壤水蚀形成过程及其模拟进行了广泛研究,并针对不同研究对象与目的,建立了土壤水蚀的经验预报模型、物理过程模型和分布式模型。在对国内外一些主要的土壤水蚀模型进行评述的基础上,讨论土壤侵蚀模型研究与GIS技术和BP神经网络理论结合的发展趋势,同时结合土壤水蚀模型的开发和应用情况,提出了土壤侵蚀预报模型研究亟待解决的一些问题和我国土壤侵蚀预报模型研究的设想。     

蒸发与降水入渗过程中不同水体氢氧同位素变化规律

为了研究土壤水蒸发与降水入渗非饱和带过程中不同水体氢氧同位素的变化规律,该文选用2种不同性质的土壤-砂土和黄土,设计了土壤水蒸发和降水入渗室内试验。结果表明:对于砂土,土壤水蒸发过程中剩余水体氢氧同位素分馏遵从瑞利模式;对于黄土,随着蒸发时间的延长,剩余土壤水氢氧同位素值越来越远离瑞利分馏关系线;在降水入渗非饱和带的初期,相对于风干砂土,风干的黄土颗粒对土柱出流水的氢氧同位素值产生了影响,并且出流水的氢氧同位素亦受到土壤原水同位素值的影响,只有入渗的降水达到了一定数量,土柱出流水才能与降水的同位素值相同。该研究可为运用氢氧同位素研究降水能否通过非饱和带补给地下水提供数据分析的依据。     

太行山坡地不同植物篱对表层土壤水盐分布影响研究

[目的]探究不同植物篱对太行山坡地表层土壤水盐分布影响，为太行山坡地布设最优植物篱和减少水土流失提供理论与实践依据。[方法]以太行山坡度13°、海拔152 m正南坡地的薄荷、白芍、泽兰、艾草、锦灯笼、鱼腥草植物篱小区为研究对象，以空白裸地小区为对照，采集各小区植物和带上、带中、带下0—20 cm土壤，比较分析植物生理特征和土壤水盐特征差异，并采用主成分分析、聚类分析对植物篱影响土壤水盐分布能力进行综合评价。[结果](1)植物篱生理特征存在差异。薄荷、白芍地上、地下、总生物量较高，锦灯笼、鱼腥草则较低；白芍根冠比最高(p<0.05);鱼腥草、锦灯笼植物含水率较高，白芍则最低。(2)植物篱影响坡地土壤水盐分。与空白裸地相比，植物篱带中、带下平均土壤容重降低了9.23%,7.22%;植物篱带中平均自然含水量、饱和持水量、毛管持水量、田间持水量分别增加了8.10%,14.98%,21.49%,19.78%;植物篱带下平均电导率则降低了9.97%。(3)植物篱类型与篱带位置对土壤水盐分布存在交叉影响，其中植物篱类型显著影响自然含水量、饱和持水量、毛管持水量、田间持水量、pH和电导率(p&l...     

控制暗管排水下土壤剖面水盐分布与变化特征

控制暗管排水可改变土壤水盐运移从而影响灌区盐渍化程度和土壤水分状况.为探讨土壤水盐分布与变化及其受控制排水与间距的影响,以河套灌区义长试验站暗管排水试区为对象,选取玉米生长期内典型灌溉周期开展研究.分析了控制排水及其间距变化下土壤水盐剖面静态分布与动态变化及灌水前后土壤水盐变异特性.结果表明:与自由排水比,控制排水提高...     

黑龙滩水库消落带植被恢复模式对土壤水稳性团聚体组成及其稳定性的影响

[目的] 为阐明水库消落带不同植被恢复模式对土壤水稳性团聚体组成及其稳定性的影响。[方法] 以川中丘陵区黑龙滩水库消落带人工恢复与自然恢复植被下的土壤为研究对象,利用湿筛法测定分析土壤水稳性团聚体组成特征及其稳定性指标。[结果] 消落带土壤＞0.25 mm水稳性大团聚体含量与未淹水对照相比降低4.21%,其中,自然恢复植被下土壤水稳性大团聚体含量较对照下降12.27%,人工恢复植被下大团聚体含量较对照增加3.84%;不同植被恢复模式下土壤水稳性团聚体组成差异显著(p＜0.05),人工恢复植被下土壤大团聚体含量(69.48%)显著高于自然恢复模式(43.20%);消落带土壤水稳性团聚体稳定性随水位高程增加而升高,团聚体稳定性指标＞0.25 mm水稳性团聚体含量(R_0.25)、平均重量直径(MWD)、几何平均直径(GMD)人工恢复模式下均大于自然恢复模式,团聚体分形维数(D)、土壤可蚀性因子(K)与团聚体破坏率(PAD)人工恢复模式小于自然恢复模式,表明人工恢复模式下土壤水稳性团聚体稳定性、土壤抗蚀性高于自然恢复模式。[结论] 黑龙滩水库消落带在淹水后土壤团聚体稳定性下降,但人工恢复模式能有效改善土壤团粒结构,研究结果可为黑龙滩水库消落带土壤结构稳定性评价及植被恢复提供科学依据。     

土壤水稳定同位素研究进展

本文从影响土壤水稳定同位素变化的因素、时空变化规律以及"土壤-植物-大气"界面水分转化和循环过程等方面综述了国内外土壤水同位素研究的主要成果,认为同位素方法在研究土壤水运移、降水入渗及土壤蒸发问题上优势比较明显,并且有助于从宏观和微观上阐明土壤水的特征及其运动规律;指出了当前土壤水分同位素研究存在的问题和今后研究的重点,并对同位素技术与方法在土壤水中应用前景进行了展望。     

中国西北戈壁地区12条河流水文水质调查

2014年9月对我国塔里木盆地南缘与柴达木盆地戈壁地区的12条典型河流进行实地调查,通过野外采集水样、测定流速、室内查阅资料和化验分析,获得了研究区河流的最新水文水质资料。结果表明:(1)戈壁地区修建的水库和防渗渠道,对河流正常发展产生了不利影响;(2)水样中的F-含量均超过1mg/L,不能满足人们直接饮用的要求,F-与Ca2+含量呈现负相关关系;(3)水样中阳离子浓度大小关系为Ca2+Na+Mg2+K+,水化学类型总体上为氯化物·硫酸盐·碳酸氢盐/钠质·钙质水;(4)水样的TDS变化范围在718.3~8 254.1mg/L,含量普遍偏高,水样pH变化范围在7.44~8.07,表现为弱碱性。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.     

Electron donor and pH relationships for biologically enhanced dissolution of chlorinated solvent DNAPL in groundwater

Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells.     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Increase in auxiliary photoprotective photosynthetic pigments in wheat seedlings induced by Azospirillum brasilense

Inoculation of wheat seedlings with the plant growth-promoting bacterium Azospirillum brasilense Cd was immobilized in alginate microbeads and, without applying any stress, significantly increased the quantity of several photosynthetic pigments, such as chlorophyll a, chlorophyll b, and the auxiliary photoprotective pigments violaxanthin, zeaxanthin, antheroxanthin, lutein, neoxanthin, and β-carotene. This resulted in greener plants with no apparent visible stress. After monitoring the quantity of photosynthetic pigments for 4 weeks, we observed that inoculated plants had higher quantities of pigments in shoot and stem. The greatest difference in the quantity of all pigments between inoculated and noninoculated plants occurred in the first week of growth. Regardless of treatment, the quantity of pigments in stems was three to four times less than the quantity of these pigments in shoots. Application of Azospirillum, either as liquid inoculant or as alginate microbeads, did not alter the positive effect of the bacteria on pigment production or the positive response of the plants towards A. brasilense Cd inoculation.     

In-situ enrichment and analysis of atrazine-degrading microbial communities using atrazine-containing porous beads

We examined the community composition of microbes that colonized atrazine-containing beads buried in agricultural soils that differed in atrazine treatment history. Bacterial abundance was 5-40-fold greater in atrazine-fortified beads. In beads containing 20 mg atrazine kg⁻¹ buried in soil with a history of atrazine application (conditioned soil), the abundance of Actinobacteria increased approximately 80-fold whereas in control soil, Actinobacteria were enriched only 10-fold and the gamma-Proteobacteria and Planctomycetes increased by 60- and 25-fold, respectively. The gamma-Proteobacteria were enriched by 120- and 230-fold in beads containing 200 mg atrazine kg⁻¹ in conditioned and control soil, respectively. The results demonstrate that BioSep^® beads are a suitable matrix for recruiting a diverse subset of the bacterial community involved in atrazine degradation.