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1.
炭化温度对沙蒿生物炭形貌特征和化学性质的影响   总被引:2,自引:0,他引:2       下载免费PDF全文
侯建伟  索全义  梁桓  韩雪琦  刘长涛 《土壤》2014,46(5):814-818
沙蒿是半灌木典型沙生植物,作为制炭物料具有其特殊性,而炭化温度决定生物炭形貌特征和化学性质。通过无氧炭化法制备了不同温度(300~900℃)的沙蒿生物炭,研究了炭化温度对沙蒿生物炭形貌特征、表面官能团种类、产率变化和有机组分含量的影响。结果表明:生物炭孔径随着炭化温度的升高而增大,700℃以后生物炭结构有一定程度的破坏;生物质炭化后C–O–C、–COOH、–CH3、–CH2、–OH和C=O逐渐消失;生物炭产率随着炭化温度的升高而降低,尤其是从300℃升高至400℃产率降低最为明显,这与纤维素及半纤维素的分解有直接关系;生物炭中有机组分的C元素含量增加,由701.7 g/kg增加到899.3 g/kg,增加了197.6 g/kg;而H、O和N元素含量则逐渐降低,分别降低了21.4、171.8和6.6 g/kg;生物炭中有机组分的原子比H/C、O/C和(N+O)/C都逐渐减小。总之,生物质升温炭化过程中,炭化温度与生物炭孔径及有机组分的C元素含量呈正相关关系而与生物炭产率、生物炭中有机组分的H、O和N元素含量呈负相关关系,低温和中温炭化时生物炭保留原有的骨架结构,而高温时对其有一定程度的破坏作用,沙蒿生物质含有丰富的官能团,升温裂解过程中多数官能团消失,无机组分Si–O–Si得以保留,此外,生物质升温裂解是一个芳香性逐渐增强,亲水性和极性逐渐减弱的过程。  相似文献   

2.
不同作物秸秆加工制成生物质炭的理化性质比较研究   总被引:1,自引:0,他引:1  
《土壤通报》2020,(1):130-135
为表征不同作物秸秆加工制成的生物质炭的理化性质差异,以玉米、水稻和油菜的秸秆为原料制备生物质炭,借鉴材料科学的方法,研究其形貌结构、表面特性和有机组分元素比等内容。结果表明:200℃→450℃作物秸秆样品失重量和失重速率最大,半纤维素和纤维素为主要燃失物质。玉米、水稻和油菜的秸秆生物质炭均为多孔结构,孔隙大小和形状各异。水稻秸秆炭的比表面积最大(2.65 m2g-1)、油菜秸秆炭次之(2.56 m2g-1)、玉米秸秆炭最小(1.84 m2g-1)。水稻、玉米、油菜秸秆炭的孔体积变化率分别在43 nm、62 nm、48 nm处达到峰值。油菜秸秆炭的H/C最小、为0.03,O/C和(O+N)/C最大、分别为1.15和1.19。因此,450℃更利于残留样品质量;生物质炭的孔隙结构决定其比表面积,油菜秸秆炭具有更强的芳香性、亲水性和极性。研究结果可为生物质炭的制取和应用提供参考依据。  相似文献   

3.
[目的]研究不同温度制备的玉米秸秆和污泥基生物质炭不同施加量对盐碱土壤基本理化性质的影响,为盐碱土改良及土壤污染物质的生态修复等方面的研究提供科学依据。[方法]以质量比5∶2的玉米秸秆和剩余活性污泥为原料,分别在300,350,400,450,500℃共5个不同温度条件下热解制备生物质炭,通过扫描电镜、元素分析和红外光谱对其性质及结构进行分析,并通过培养试验研究其对盐碱土壤基本理化性质的影响。[结果]随着热解温度的升高,生物质炭微观结构越发达,比表面积越大,表面官能团的种类和数量也产生了显著性变化;同时随着热解温度逐渐升高,生物质炭C含量不断增加,而O,H和N含量却逐渐降低;添加玉米秸秆和污泥共热解制备的生物质炭能够显著增加盐碱土壤中有机碳含量,而土壤中总氮、总磷、有效磷、速效钾含量变化幅度较小;水溶性盐含量降低明显;加入生物质炭后大幅度提高了土壤阳离子交换能力,添加量越大,阳离子交换量越大;但生物质炭对土壤pH值影响不大。[结论]玉米秸秆和污泥基生物质炭提高了土壤养分含量和肥力指标,降低了土壤盐碱性。玉米秸秆和污泥基生物质炭可用于盐碱土壤的改良。  相似文献   

4.
生物质炭对土壤结构改良、土壤肥力提升和农田温室气体排放具有重要意义。本研究以吉林省梨树县典型黑土为研究对象,通过培育实验,研究不同土壤水分含量(40%WHC和100%WHC)下,生物质炭种类(玉米秸秆生物质炭和稻壳生物质炭)和施加量(0%、1%和4%(w/w))对黑土N2O排放及硝化反硝化功能基因丰度的影响。结果表明,随着秸秆生物质炭施加量的增加,土壤N2O排放呈下降趋势,4%高量秸秆生物质炭添加下,土壤N2O排放量仅为1%低量秸秆生物质炭添加下的33.9%。同时土壤NO- 3-N也表现出一致性规律,4%高量生物质炭添加下土壤NO- 3-N含量显著低于1%低量生物质炭。在100%WHC土壤水分状况下,玉米秸秆生物质炭显著增加了土壤N2O排放,而稻壳生物质炭则显著降低了土壤N2O排放。高土壤水分显著促进了土壤N2O排放,进一步为实时荧光定量PCR结果所证实,高土壤水分通过增加nirS基因丰度进而促进了土壤反硝化作用过程,而4%高量稻壳生物质炭添加下nosZ基因丰度显著高于玉米秸秆生物质炭添加,表现出更强的N2O还原潜力。尽管amoA-AOA基因丰度在不同生物质炭添加量下并未发生显著变化,但amoA-AOB基因丰度在高量玉米秸秆生物质炭添加下显著下降。结果说明,土壤水分和生物质炭通过影响土壤硝化反硝化微生物的营养底物和代谢过程,进而影响土壤N2O排放特征。  相似文献   

5.
热解温度对生物质炭碳保留量及稳定性的影响   总被引:9,自引:4,他引:5  
以核桃壳为生物质炭生产原料,研究热解温度(200~700℃)对生物质炭产率、元素组成、表面官能团分布及其稳定性的影响,以期探明生物质炭基本性质随热解温度变化的规律,为全面了解生物质炭固碳减排效果提供理论参考。结果表明,生物质炭的C含量随温度升高而增加,H和O元素含量却随温度升高而降低。此外,生物质炭的H/C和O/C随着温度增加而减少。生物质炭的产率及碳保留量随着温度的升高而降低。红外光谱分析结果表明,经过热解核桃壳原材料分子中所含的-C-O和O-CH3基团消失,随着热解温度升高,生物质炭中的烷烃基团-CH逐渐减少,芳香化程度逐渐升高。500℃制备生物质炭的K2Cr2O7和KMn O4氧化碳损失量均最低,分别为10.4%和1.66%。相关分析表明,生物质炭的产率、碳保留量及稳定性与热解温度之间均具有显著相关关系。  相似文献   

6.
侯建伟  索全义  段玉  赵沛义  张君  景宇鹏 《土壤》2017,49(5):963-968
为明确不同炭化条件下沙蒿生物质炭的有机组分、炭化过程和降解特性。于不同炭化条件下无氧炭化制备沙蒿生物质炭并进行沙地封存。结果表明:H、O和N元素的质量分数及H/C、O/C和(N+O)/C均随炭化温度的升高和炭化时间的延长呈先降低后稳定的变化趋势,升温速率对其无显著影响。而C则呈相反趋势且均在炭化温度600℃、炭化时间60 min以后基本达定值,上述指标(H、O、N、H/C、O/C、(N+O)/C和C)的稳定值分别约为29.3 g/kg、79.8 g/kg、11.2 g/kg、0.40、0.07、0.08和879.7 g/kg。生物质炭的降解速率随着炭化温度的升高、炭化时间的延长和施用量的增大而降低,其半衰期为2~12年。综上,沙蒿的炭化既是有机组分富碳、去极性官能团的过程,同时也是芳香性增强、亲水性和极性减弱的过程,施用量和炭化温度是影响生物质炭降解的决定性因素。  相似文献   

7.
何娴  徐仁扣 《土壤》2022,54(5):1016-1023
选择稻草、玉米秸秆和油菜秸秆作为制备生物质炭的原料,分别用H2O2和HNO3/H2SO4对生物质炭进行改性处理,以未改性的生物质炭和HCl处理的生物质炭作为对照。按土重3%的比例向采自安徽郎溪的酸性水稻土中添加上述生物质炭,在经历一个干湿交替周期后,进行Cd(Ⅱ)吸附/解吸实验,研究添加生物质炭对水稻土吸附Cd(Ⅱ)的影响及其机制。结果表明,两种改性方法均有效增加了生物质炭表面的质子结合位点数,且HNO3/H2SO4改性对生物质炭表面羧基官能团的扩增效果更显著。官能团的增加使得添加了HNO3/H2SO4改性生物质炭的水稻土对Cd(Ⅱ)的专性吸附能力显著增强。因此,添加HNO3/H2SO4改性生物质炭可以作为酸性水稻土吸附固定重金属Cd的一种新型方法。  相似文献   

8.
生物质炭是由生物质在缺氧或无氧的情况下,经高温慢速热解产生的一类难熔的、稳定的、高度芳香化的、富含碳素的固态物质,在能源、农业、环境和材料领域有广阔的应用前景。该文以纤维素、半纤维素和木质素为原料,采用程序控温管式炉,在不同的热解温度条件下(250、350、450、550、650、750和850℃)制备生物质三组分炭材料,并利用元素分析仪、量热仪、傅里叶变换红外光谱仪(FTIR)、X射线衍射仪(XRD)、核磁共振波谱仪(13C NMR)、热重分析仪(TG)和扫描电镜(SEM)等仪器对其物理化学性能进行表征,研究热解温度对生物质三组分炭材料理化性能的影响。结果表明:随着热解温度增加,生物质三组分炭的质量产率和能量产率都呈下降的趋势,纤维素炭、半纤维素炭和木质素炭的质量产率分别从94.23%、63.06%和87.14%减少至17.01%、20.67%和41.40%,能量产率分别从94.23%、55.7%和77.82%减少至58.69%、12.91%和31.09%。随着热解温度增加,生物质三组分炭中C元素的含量逐渐增加,而H元素、O元素、H/C、O/C的含量逐渐减少,尤其在250~450℃范围内下降最为显著。随着热解温度增加,FTIR分析表明-OH、-CH3、-CH2、C=O、C=C、苯环骨架、C-O、C-H等官能团含量显著下降,并且在高温热解时红外曲线几乎变为直线。随着热解温度增加,XRD分析表明生物质三组分炭中的三斜晶系(Iα)和单斜晶系(Iβ)衍射峰的强度逐渐降低,而石墨化微晶碳的002衍射峰和101衍射峰的强度逐渐增加;13CNMR分析表明生物质三组分炭中的烷基碳、含氧烷基碳和羧基碳含量逐渐减少,而芳基碳的含量则显著增加,证明高温有利于类石墨化结构形成。随着热解温度的增加,纤维素炭和半纤维素炭的热失重率逐渐下降,而木质素炭的热失质量率逐渐增加,三组分炭的热失质量峰值往高温一侧移动。随着热解温度的增加,生物质三组分炭的颜色逐渐加深,其中纤维素炭发生皱缩现象,其直径不断减小,半纤维素炭发生熔融和发泡现象,变为薄片状的炭材料,木质素炭的孔结构变得更加发达,并且出现球状的金属结晶体。该文研究结果可为生物质炭的制备和应用提供基础数据。  相似文献   

9.
生物质炭的性状与原料中木质纤维含量密切相关,为探明不同原料生物质炭对土壤腐殖质组成的影响,选取玉米秸秆和紫茎泽兰分别作为纤维类和木质类原材料制备生物质炭,向酸性紫色土分别添加5%玉米秸秆生物质炭(MB)和5%紫茎泽兰生物质炭(EB),测定90 d室内培养期间土壤胡敏酸(HA)、富里酸(FA)、胡敏素(HM)含量以及HA光学性质和元素组成变化。结果表明:MB和EB的比表面积分别为2.32 m2·g-1和0.72 m2·g-1,总孔体积分别为42.71 mm3·g-1和12.59 mm3·g-1,碳与氢元素摩尔比(C/H)分别为1.91和1.46,氧、硫之和与碳元素摩尔比[(O+S)/C]分别为0.09和0.16,玉米秸秆生物质炭的吸附能力更强、有机质成分的缩合度更大且氧化度更小。与对照(不添加生物质炭,CK)相比,培养结束后,施入生物质炭的土壤HA、FA和HM含量分别显著增加(P<0.05)65.59%~102.82%、85.87%~118.54%和137.25%~161.23%,MB处理对这3种腐殖质含量的增加效应较EB处理更明显。培养结束时添加生物质炭的土壤HA/土壤有机碳(SOC)降低13.53%~27.06%,FA/SOC降低6.81%~18.03%,其中EB处理的降低效应达显著水平;HM/SOC则增加4.58%~11.40%,其中MB处理的增加效应达显著水平。添加生物质炭的土壤HA色调系数(ΔlgK)增加2.40%~5.60%,HA的缩合度(C/H)降低3.51%~11.81%,(O+S)/C增加1.51%~8.74%。总体来看,施入生物质炭均能相对增加腐殖质各组分含量,降低C/H,提高HA的氧化度[(O+S)/C],且纤维类原料(玉米秸秆)生物质炭的效果更明显。纤维类原料(玉米秸秆)生物质炭显著提高了稳定性较高的土壤胡敏素碳比例(HM/SOC),但降低了土壤HA的稳定性[HA的C/H降低,(O+S)/C增加];木质类原料(紫茎泽兰)生物质炭显著降低土壤胡敏酸碳比例(HA/SOC)和富里酸碳比例(FA/SOC),对HM/SOC增加效益不显著,反之提高了土壤易分解有机碳比例。  相似文献   

10.
利用玉米秸秆炭、木醋液与化肥等原料制成生物质炭基肥,通过盆栽试验研究生物质炭与木醋液复配制肥对玉米苗期农艺性状、氮素利用率的影响。结果表明,与常规炭基肥比较,添加20%、40%木醋液的炭基肥氮素利用率分别提高13.87%和23.49%。炭基肥处理对玉米苗期各农艺性状有显著(P 0.05)提高作用,其中木醋液添加量在40%的炭基肥处理最大叶面积较常规炭基肥显著提高10.24%,地下部生物量比其他处理提高9.16%~22.76%。在玉米生长过程中,炭基肥各个处理土壤铵态氮和硝态氮含量均高于化肥,20%和40%高木醋液含量的炭基肥处理玉米植株茎和叶的硝酸盐含量分别比常规炭基肥提高14.95%、17.45%和60.98%、75.61%。因此,复配木醋液的生物质炭基肥在提高肥料利用率、促进植物生长方面具有很好潜力。  相似文献   

11.
低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响   总被引:2,自引:2,他引:0  
【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。  相似文献   

12.
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.  相似文献   

13.
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,  相似文献   

14.
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.  相似文献   

15.
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.  相似文献   

16.
李聃枫  朱春梧 《土壤》2020,52(3):561-566
自20世纪60年代"绿色革命"以来,育种技术和农耕技术的发展促进了农作物产量的大幅提升,然而作物的营养品质出现下降趋势。在相似的遗传背景下,大气CO_2浓度升高会使单位体积农作物产品的营养元素含量下降,因此"绿色革命"至今,农作物产品的营养元素下降可能受大气CO_2浓度升高影响。通过植物生长箱模拟"绿色革命"初期和目前的大气CO_2浓度水平(310μmol/mol和400μmol/mol),针对主要C_3作物水稻、小麦和大豆,研究"绿色革命"以来大气CO_2浓度升高对其籽粒的C、N、Fe、Zn元素含量的影响,结果表明:CO_2浓度升高对3种作物籽粒的C元素含量几乎没有影响,变化幅度在±1.5%之间;籽粒的N、Fe、Zn元素含量普遍呈现下降趋势,但均未达到显著水平。  相似文献   

17.
Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity.  相似文献   

18.
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.  相似文献   

19.
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.  相似文献   

20.
We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass, soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration, N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially (<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils, indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea.  相似文献   

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