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1.
高温处理与添加物料对蚓粪基质培育辣椒壮苗的影响 总被引：8，自引：2，他引：6
蚓粪是蚯蚓处理有机固体废弃物的产物,具备替代泥炭作为蔬菜育苗基质材料的优良性质。蚓粪高温处理（120℃）后加入蛭石、 尿素等物料复配成育苗基质,通过温室育苗和室内分析的手段,分析蚓粪中活性有机物和GA3、 IAA的含量变化以及蚓粪基质培育辣椒幼苗的系统发育特征。结果表明, 蚓粪高温处理过程增加了蚓粪中GA3含量,使活性有机物裂解成具有相同母核类极性更大的水溶性衍生物。无论是否高温处理,蚓粪育苗基质都有利于辣椒幼苗茎粗、 株高、 展宽、 叶片数、 根长、 根表面积、 根体积、 根尖数、 鲜（干）重和壮苗指数的提高,但会导致辣椒幼苗叶片叶绿素含量的减小。蚓粪添加蛭石和高温处理后育苗能够增大辣椒幼苗根直径。高温处理蚓粪中添加蛭石（蚓粪∶蛭石=4∶1,V∶V）和尿素（0.50 kg/m3）有利于提高辣椒幼苗成苗率,增加鲜干物质累积,促进茎叶和根系的系统发育,增大壮苗指数。可见,蚓粪高温处理后与蛭石按4∶1体积比均匀混合后用于辣椒育苗,最能提升辣椒幼苗的各项指标,形成壮苗。 相似文献
2.
以蚯蚓消解半腐熟后的牛粪和蘑菇渣所得的蚯蚓粪为主要原料,与蛭石按照不同比例混合作为番茄的育苗基质,研究蚯蚓粪复合基质对番茄幼苗生长发育的影响,以利于蔬菜穴盘育苗新型基质的开发,为蔬菜工厂化育苗提供性能可靠、廉价、取材广泛的育苗基质。结果表明:各个处理基质容重在0.43～0.79 g/cm3之间,总孔隙度在65.32%～72.95%之间,大小孔隙比在1∶1.53～1∶2.02之间,pH值在5.45～8.75之间,EC值在0.91～1.38 mS/cm之间,除了pH值以外其他理化特性都在较适宜的范围;相较对照,蚯蚓粪复合基质有较高的pH值,但没有对番茄最终出苗情况产生影响;蚯蚓粪复合基质促进了番茄幼苗生长发育,其作用效果与基质混合比例有关,蚯蚓粪∶蛭石=2∶1(V∶V)育苗效果较佳,与对照相比,其株高、茎粗、地下部干重、全株干重、壮苗指数分别显著增加23.12%、11.76%、57.14%、38.24%、60.34%(P0.05)。 相似文献
3.
为探究椰糠替代草炭用作人参穴盘育苗基质的可行性,将椰糠、草炭、蛭石按体积进行不同比例复配,研究不同配比基质对人参种苗生长及生理指标的影响。结果表明:随椰糠在基质中占比的减少,基质通气孔隙度上升,持水孔隙度下降,有效磷、速效钾含量显著高于CK(草炭 ∶ 蛭石=5∶3),其中T3处理(椰糠 ∶ 蛭石=2∶1)在茎粗、根长、鲜重、干重、根冠比、壮苗指数、叶绿素含量、过氧化物酶(POD)活性、过氧化氢酶(CAT)活性、丙二醛(MDA)含量与CK相比无显著差异,尤以T4处理(椰糠 ∶ 蛭石=1∶1)最优,叶面积、地下干重和鲜重、根冠比、壮苗指数、可溶性蛋白、SOD活性、POD活性、MDA含量显著优于CK(P<0.05),隶属函数综合分析得分(0.936)高于CK(0.775)。综上所述,T4处理为最适的椰糠配比基质,能够替代以草炭为主的人参育苗基质配方。 相似文献
4.
该试验分别以烘干鸡粪、尿素和硫酸铵为氮源发酵的玉米秸基质为原料，采用玉米秸基质∶蛭石=6∶4(体积比)为育苗基质，以草炭∶蛭石=2∶1(体积比)为对照，进行春季番茄育苗试验，研究了不同氮源及配比发酵的玉米秸基质对番茄育苗效果的影响。结果表明：采用25%烘干鸡粪氮+75%化学肥料氮发酵生产的玉米秸基质，在番茄日历苗龄35 d、40 d时，其幼苗平均株高与对照基质相近，平均茎粗、平均根体积、平均最大根长均高于对照；日历苗龄40 d时，番茄幼苗地上部、地下部平均单株干重均略高于对照，采用该氮源配方发酵生产的玉米秸基质可以替代草炭用于番茄育苗。 相似文献
5.
不同氮源发酵的玉米秸基质对番茄育苗效果的影响 总被引：1，自引：0，他引：1
该试验分别以烘干鸡粪、尿素和硫酸铵为氮源发酵的玉米秸基质为原料,采用玉米秸基质∶蛭石=6∶4(体积比)为育苗基质,以草炭∶蛭石=2∶1(体积比)为对照,进行春季番茄育苗试验,研究了不同氮源及配比发酵的玉米秸基质对番茄育苗效果的影响。结果表明:采用25%烘干鸡粪氮 75%化学肥料氮发酵生产的玉米秸基质,在番茄日历苗龄35 d、40d时,其幼苗平均株高与对照基质相近,平均茎粗、平均根体积、平均最大根长均高于对照;日历苗龄40 d时,番茄幼苗地上部、地下部平均单株干重均略高于对照,采用该氮源配方发酵生产的玉米秸基质可以替代草炭用于番茄育苗。 相似文献
6.
生物质炭醋糟复配物代替草炭对辣椒幼苗生长的影响 总被引：1，自引：1，他引：0
生物质炭的农业利用日益受到关注。针对草炭资源日益耗竭的问题,以药渣炭、木屑炭和猪粪炭为试验对象,配比一定量的醋糟,分析了不同配比生物质炭复合基质对辣椒幼苗生长的影响,探讨了生物质炭复合基质代替草炭基质的可能性。试验结果表明:生物质炭在与醋糟按4∶2、3∶3、2∶4等不同配比混合后,基质的pH大多数在6.0~7.5,基质的通气孔隙有所提高。综合整个幼苗生育期,含20%生物质炭的各复合基质处理的辣椒幼苗株高、茎粗、叶面积、地上部生物量均显著优于对照草炭基质;含20%、40%药渣炭的基质处理的幼苗根表面积、根体积表现较好,在前期与草炭基质无显著差异,后期显著高于草炭基质。药渣炭和木屑炭与醋糟混配基质的壮苗指数优于草炭处理,其中B1A2(药渣炭∶醋糟∶蛭石∶珍珠岩=4∶2∶3∶1)、B1A4(药渣炭∶醋糟∶蛭石∶珍珠岩=2∶4∶3∶1)、B2A4(木屑炭∶醋糟∶蛭石∶珍珠岩=2∶4∶3∶1)处理的壮苗指数均显著高于其他处理。综合评价各生长指标,B1A2和B1A4处理基质的表现最好,可代替草炭基质在辣椒育苗上应用。 相似文献
7.
以有机废弃物为主的辣椒无土育苗基质配方研究 总被引：1，自引：0，他引：1
筛选以有机废弃物为主的辣椒无土育苗基质配方。以辣椒品种‘陇椒2号’为材料,采用完全随机设计,用T1:(玉米秸杆∶炉渣∶沼渣;V/V=1∶2∶1;体积比,下同);T2:(沼渣:炉渣:牛粪;V/V=1.5∶2∶0.5);T3:(玉米秸杆∶炉渣∶牛粪;V/V=1∶2∶1);T4:(菇渣:炉渣:牛粪;2∶1∶1);T5:(玉米秸杆∶炉渣∶牛粪∶菇渣;V/V=1∶1∶1∶1)和山东寿光绿尔旺育苗基质为对照,分析6种配方基质的理化性质,以及对辣椒幼苗生长的影响。结果表明:T4配方基质的容重为0.52 g cm-3,总孔隙度为59.7%,持水孔隙度为46.9%,通气孔隙度为12.8%,水气比为3.7,pH为8,电导率为0.21 mS cm-1,各项理化性质接近对照;T4配方基质的‘陇椒2号’株高为20.88 cm,茎粗为0.23 cm,根长为7.88 cm,全株鲜重2.48 g,全株干重为0.405 g,茎叶干重为0.280 g,根干重为0.125 g,壮苗指数为0.44,根冠比为0.45,叶绿素含量为0.58 mg g-1 FW,其中全株鲜重、根干重、壮苗指数虽不及对照,但与对照间差异不显著,其它指标接近对照。在草炭匮乏的地区,辣椒无土育苗时可选用T4和T5配方。 相似文献
8.
以番茄品种“豫艺金粉二号”、黄瓜品种“豫艺201”为试验材料,采用穴盘育苗的方式,以草炭∶蛭石∶珍珠岩=1∶1∶1 (体积比)为栽培基质。通过根施用不同浓度(0、25%、50%、75%、100%)的砻糠灰浸提液,研究其对基质的理化性质、番茄和黄瓜幼苗生长的影响。试验结果显示:与对照相比,根施75%浓度的砻糠灰浸提液显著提高了育苗基质的持水孔隙、通气孔隙,改善了基质的理化特性;随着砻糠灰浸提液浓度的增加,2种育苗基质中微生物数量的变化趋势基本一致,其中细菌和真菌数量均呈下降趋势;与对照相比,根施砻糠灰浸提液可显著提高番茄和黄瓜幼苗株高、茎粗、根冠比和壮苗指数,幼苗叶片叶绿素含量、净光合速率、气孔导度和蒸腾速率也显著提高,以75%砻糠灰浸提液浓度为最佳;此外,根施75%砻糠灰浸提液还可以显著提高幼苗叶片可溶性总糖、蔗糖含量,提高碳水化合物代谢关键酶活性。由此可见,砻糠灰浸提液可以有效改善基质理化性质,促进植株生长和光合作用能力的提高,以提升幼苗碳水化合物的代谢能力,并以75%砻糠灰浸提液浓度的效果最好。 相似文献
9.
为了明确不同类型氮肥在穴盘基质育苗中的效果,向中药渣废弃物育苗基质中施用不同类型氮肥进行番茄育苗,研究育苗完成后成苗生长指标参数。结果表明,施用氨基酸氮肥和化学氮肥均显著增加叶绿素SPAD值(6.4%和8.4%)和幼苗茎粗(2.5%和3.8%)。氨基酸氮肥较不施肥对照和化学氮肥显著增加了成苗的地下部干重(17.9%和22.2%)、地上部干重(17.4%和18.7%)以及壮苗指数(16.4%和20.1%);显著增加了根表面积(13.3%和18.5%)、平均直径(38.9%和25.0%)、根长(10.4%和31.5%)和根体积(6.3%和13.3%)。与对照相比较,施用化学铵态氮肥对幼苗地上部、地下部干重和壮苗指数没有显著影响,但降低了根表面积和单位体积根长。此外,施用氨基酸氮肥较对照显著增加了细根相关参数在相应参数总值中的占比,细根表面积增幅22.9%,根长增幅20.8%,根体积增幅49.6%。由此可见,在育苗基质中应用氨基酸氮肥能够改变根系形态结构并实现壮苗目标,值得进一步研究并在规模生产中推广应用。 相似文献
10.
为探究蚯蚓粪、椰糠复配基质对三七种苗生长的影响,采用单因素随机区组试验设计,分为蚯蚓粪组(处理T1～T4)、椰糠组(处理T5～T8)、蚯蚓粪+椰糠组(处理T9～T11),传统育苗基质草炭∶蛭石=2∶1(体积比)为对照组(CK),共12个处理,结合相关性和隶属函数法综合评价,客观有效地筛选出适合三七苗生长的基质配方。结果表明:椰糠组容重较小,孔隙度较大,大小孔隙比接近最优值0.5(T5为0.5),pH在三七种苗生长适合范围内,有机质含量高,全氮、全磷、有效磷、碱解氮与CK相近。T5、T6、T7、T8的隶属函数值综合排名均高于CK,其中T5排名最高,其根鲜重、地上部鲜重、根冠比、壮苗指数、G值均优于其他处理,分别较CK提高了34.84%、12.50%、14.58%、84.05%、37.50%。说明T5[椰糠∶草炭∶蛭石∶生土=0.5∶1.5∶1∶1 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.
Kyle Devey Michael Mucalo Gordon Rajendram Joseph Lane 《Communications in Soil Science and Plant Analysis》2015,46(4):72-80
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.
《中国生态农业学报》2014,(8)
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.
M.A. Callaham Jr. J.M. BlairT.C. Todd D.J. KitchenM.R. Whiles 《Soil biology & biochemistry》2003,35(8):1079-1093
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.
I.L. Boyd 《Biological conservation》2010,143(7):1664-1674
“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options. 相似文献
16.
Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage 总被引：1，自引：0，他引：1
Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate. 相似文献
17.
Grete Skrede Berit Karoline Martinsen Anne-Berit Wold Stein-Erik Birkeland Kjersti Aaby 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(3):193-208
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
18.
《Communications in Soil Science and Plant Analysis》2012,43(7):865-877
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. 相似文献
19.
Electron donor and pH relationships for biologically enhanced dissolution of chlorinated solvent DNAPL in groundwater 总被引：3，自引：0，他引：3
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.
Yoav Bashan Bernardo Salazar Ma. Esther Puente Macario Bacilio Robert Linderman 《Biology and Fertility of Soils》2009,45(6):585-594
To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse
trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus
were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB;
the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons
reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened
later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons
growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants,
no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi,
enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant.
In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after
30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination
only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity
to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as
compost or PGPB can either amplify the effect or else attenuate it. 相似文献