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1.
为探究锰矿物添加对微好氧堆肥过程腐熟、温室气体和臭气排放的影响,以由厨余垃圾、水稻秸秆、羊粪和尾菜组成的多元混合物料堆肥为研究对象,共设3个处理,采用间歇通风方式,将通风速率为0.14 L/（kg·min）设置为好氧堆肥对照（CK）,速率为0.06 L/（kg·min）为微好氧处理（T1）,添加二氧化锰（MnO2）的微好氧处理为T2。结果表明：多元废弃物好氧或微好氧堆肥在堆制70 d后均能腐熟,但T2处理腐熟度显著高于T1。微好氧处理T1、T2减少了26.47%～30.29%的NH3和33.19%～38.60%的N2O的排放,总温室效应减少了29.26%～31.38%。臭气的排放集中在前14 d,T1、T2处理的H2S和VOCs的释放量显著增加了320.35%～501.04%和39.82%～53.63%。因此,微好氧堆肥可达到减排目的,但却加剧臭气的排放;MnO2可提高促进堆肥腐熟,降低温室气体和臭气的排放。  相似文献   

2.
猪粪堆肥过程中NH3和H2S的释放及除臭微生物的筛选研究   总被引：1，自引：1，他引：1  
为了治理粪便臭气污染，测定了猪粪好氧堆肥过程中NH3和H2S的释放量以及堆肥温度、pH值、含水率、水溶性铵态氮等指标。结果表明，NH3在前20天释放量占总释放量的84.6%、H2S在前13天释放量占总释放量的100%。因此，在堆肥初期的前20天是控制臭气的最佳时期。并从畜禽粪便、垃圾、土壤和堆肥中分离、纯化了一些微生物，经过初筛得到能利用NH3的微生物41株，经过复筛得到脱除H2S较好的细菌一株，与对照相比其去除率达85.7%，经鉴定该菌是松鼠葡萄球菌。  相似文献   

3.
为解决规模化胡萝卜种植过程尾菜处理难的问题，在通风速率为0.05 m3/min的条件下，探讨不同添加比例的玉米秸秆对胡萝卜尾菜堆肥过程中腐熟度、气体排放和酶活性的影响。通过分析腐熟度、气体排放和酶活性之间的响应关系，确定最优辅料添加比例，以期实现胡萝卜尾菜无害化、资源化利用。结果表明：不同胡萝卜尾菜好氧堆肥产品均能满足种子发芽率指数≥70%的无害化标准；NH3和CO2排放集中在前7 d，排放速率主要受温度、pH值等理化性质影响，同时鸡粪的添加导致NH3 累积排放量增加，不添加任何辅料的胡萝卜尾菜单独堆肥处理（CK）其CO2 排放速率最高； 胡萝卜尾菜单独堆肥处理（CK）及7.5%秸秆添加处理（T1）在堆肥期间含水率较高，易产生渗滤液；通过相关性热图、冗余分析对5个处理的气体排放、腐熟度、酶活性进行显著性、相关性分析，进一步证实NH3、CO2的排放与温度呈正相关，与pH值呈负相关关系；同时过氧化氢酶与腐熟度指标有显著正相关关系，纤维素酶活性影响堆肥产品的腐熟度。因此，胡萝卜尾菜好氧堆肥过程中，添加15%玉米秸秆辅料（T2）可以提高C/N比、孔隙度，降低渗滤液产出，同时CO2 排放量较胡萝卜尾菜单独堆肥（CK）降低6.63%。该研究可为胡萝卜尾菜无害化和资源化利用提供技术支持。  相似文献   

4.
蚯蚓堆肥是废弃物资源化利用的有效途径,为明确规模化蚯蚓处理废弃物过程中碳(C)、氮(N)、磷(P)元素的物质变化规律与环境效益,以工厂化蚯蚓处理牛粪模式为对象,分析各环节物料的属性变化、气体排放规律和养分向堆体下方土壤迁移情况,并量化环境影响值。研究结果显示,蚯蚓处理过程中,固体物料全C、C/N和C/P均表现出降低的趋势,全N含量有所提高,pH和全P无明显变化;蚯蚓粪成品C/N、NH4+和NH4+/NO3-的范围均达到堆肥腐熟的标准。随着蚯蚓堆肥过程的进行,CH4和N2O的排放速率呈降低的趋势,CO2和NH3分别在蚯蚓处理中期和初期排放达到最高;C、N通过气体形式损失率分别为25.2%和10.9%。堆放牛粪后,土壤全N和全P含量主要在0～20 cm深度有所增加,平均增幅分别为23.8%和12.0%;NH4+和NO3-含量在不同土层均有所提高;有效P含量在0～10 cm深度增幅达到3倍以上。蚯蚓处理牛粪的全球变暖潜势、富营养化潜势、酸化潜势分别为181.1 kg CO2 eq/t、0.24 kg PO4 eq/t和1.29 kg SO2 eq/t,整体优于传统的好氧堆肥和厌氧发酵模式。研究结果可为蚯蚓处理过程中的品质控制、气体减排和污染防控提供理论参考,并为蚯蚓堆肥处理废弃物模式的工厂化应用推广提供  相似文献   

5.
通风量对蔬菜和花卉废弃物混合堆肥的影响   总被引：14，自引：3，他引：11  
试验在2 m3的静态好氧堆肥中试装置中进行,以蔬菜和花卉废弃物为原料,采用0.005,0.0075和0.01 m3/(kgVS·h) 3个水平的通风量,分析了不同通风量对堆肥过程中堆体温度、有机质含量、含水率、pH值、体积等指标随时间的变化特征。通风量为0.01 m3/(kgVS·h)条件下,堆肥降解蔬菜和花卉废弃物的效果最好,其中又以堆温80℃以上的“超高温”条件下为最佳;堆体含水率均呈下降趋势,堆肥后期堆体温度和水分下降较快,不利于有机质的降解;堆体体积在堆肥初期快速下降,5 d后基本保持稳定。3个水平的通风条件下,堆体pH值、含水率变化的趋势一致,相互之间的差别不明显。  相似文献   

6.
探讨有机物料还田对冬小麦田温室气体排放特性的影响,对提高经济效应和环境效应有积极意义。本研究应用静态箱-气相色谱法对秸秆还田（J）、秸秆还田+牛粪（JF）和秸秆还田+菌渣（JZ）3种有机物料还田下分别施氮肥243 kg （N）·hm-2（减氮10%,N1）、216 kg （N）·hm-2（减氮20%,N2）对冬小麦农田N2O、CO2和CH4的排放通量进行监测,探讨了不同施肥措施对麦田温室气体累积排放量、增温潜势的影响。试验期间同步记录每项农事活动机械燃油量、施肥量和灌溉量,测定产量,地上部生物量,估算农田碳截留。结果表明,冬小麦农田土壤N2O和CO2是排放源,是CH4的吸收汇,氮肥施入、灌溉以及强降水促进了土壤N2O和CO2的生成,却弱化了CH4作为大气吸收汇的特征。牛粪+秸秆（JF）处理N2O和CO2排放总量最高,分别为3.5 kg （N2O-N）·hm-2和19 689.67 kg （CO2-C）·hm-2,但CH4的吸收值最大,为5.33 kg （CH4-C）·hm-2,均显著高于菌渣+秸秆（JZ）和秸秆（J）处理（P<0.05）;各处理N2O和CO2的总量随施氮量的增加呈升高趋势,CH4的总量随施氮量的增加而呈降低趋势。JFN2、JN2和JZN2处理农田综合增温潜势（GWP）均为负值,表明有机物料还田且减氮20%条件下农田生态系统为大气的碳汇,麦季净截留碳1 038~2 024 kg·hm-2,其他处理GWP值均为正。JZN2处理小麦产量为8 061 kg·hm-2,显著高于JFN2处理（P<0.05）。综上所述,JZN2处理不仅能够保证小麦产量,且对环境效应最有利,为本区域冬小麦较优的施肥管理模式。  相似文献   

7.
应用静态明箱-气相色谱法对4 个施氮肥水平N0 [0 kg(N)·hm-2]、N200 [200 kg(N)·hm-2]、N400 [400kg(N)·hm-2]、N600 [600 kg(N)·hm-2]的夏玉米-冬小麦季轮作体系2008~2010 年的土壤温室气体(CH4、CO2 和N2O)排放通量进行研究, 同时观测5 cm 土层土壤温度并记录降水量。结果表明: 太行山前平原冬小麦-夏玉米轮作农田生态系统为CH4 吸收汇, CO2 和N2O 排放源。随着氮肥施入量的增加土壤对CH4 的吸收速率降低, 而CO2 和N2O 的排放速率增加。冬小麦季施氮处理土壤对CH4 的吸收速率显著低于无氮肥的N0 处理, 而N600处理土壤CO2 和N2O 排放速率显著高于N0 处理(P<0.05)。施肥和灌溉会直接导致土壤CO2 和N2O 的排放通量增加, 同时土壤对CH4 的吸收峰值减小。土壤温度升高和降水量增加以及干湿交替加剧均会造成N2O 和CO2排放速率增加。同时在持续干燥和低温条件的冬季不施氮处理观测到土壤对N2O 的吸收现象。N0、N200、N400 和N600 处理土壤CH4 年排放总量(kg·hm-2·a-1)分别为-1.42、-0.75、-0.82、-0.92(2008~2009 年)和-2.60、-1.47、-1.35、-1.76(2009~2010 年), N0、N200、N400 和N600 处理土壤CO2 年排放总量(kg·hm-2·a-1)分别为15 597.6、19 345.6、21 455.9、29 012.5(2008~2009 年)和10 317.7、11 474.0、13 983.5、20 639.3(2009~2010年), N0、N200、N400 和N600 处理土壤N2O 年排放总量(kg·hm-2·a-1)分别为1.05、2.16、5.27、6.98(2008~2009年)和1.49、2.31、4.42、5.81(2009~2010 年)。  相似文献   

8.
城市生活垃圾堆肥过程中腐熟度指标及控制参数   总被引：11，自引：1，他引：11  
以日处理400 t经马家楼筛分处理后的15～60 mm生活垃圾的北京南宫堆肥厂垃圾堆肥过程为研究对象，对堆肥过程中垃圾的理化性质、腐熟度指标与控制参数进行了研究。结果表明，堆肥过程中水分含量是下降的；不同季节堆肥pH值的总体变化均呈上升趋势；电导率(EC)降到了作物受抑制的限定值以下，不会对作物产生盐分毒害；堆肥水浸提的腐殖酸E4/E6值随着垃圾堆肥腐熟度升高呈增加趋势；24 h和96 h的发芽率指数(GI)表明垃圾堆肥时间可以从8周缩短到5周；有机碳、总氮和C/N比随着堆肥时间的增加均呈下降趋势；C/N比与E4/E6值和GI(24 h和96 h)值呈显著负相关关系，EC值与E4/E6值和GI(24 h和96 h)值呈极显著负相关，而E4/E6值与GI(24 h和96 h)值呈极显著正相关。  相似文献   

9.
不同施肥处理稻田甲烷和氧化亚氮排放特征   总被引：48，自引：14，他引：48  
采用静态箱－气相色谱法对长期不同施肥处理(NPKS、CK、NPK和NKM)的稻田CH4和N2O排放进行了观测。结果表明，稻田CH4和N2O排放季节变化规律明显不同，二者排放通量季节变化呈显著负相关(p<0.01)。与单施化肥和CK相比，施用有机肥显著促进CH4排放，排放量最高的NPKS处理早晚稻田排放量分别是：526.68 kg/hm2和1072.92 kg/hm2。对于N2O排放，早稻田各处理间差异不显著，NPK处理排放量最大，为1.48 kg/hm2；晚稻田各处理差异极显著(p<0.01)，NPKS处理排放量最大，为1.40 kg/hm2。晚稻田CH4排放通量和10 cm土层温度及土壤pH值相关极显著(p<0.01)，并与二者存在显著的指数关系。没发现N2O排放通量与温度及pH值间存在显著相关。稻田CH4和N2O排放受多种因素影响，但对全球变暖的贡献率CH4远大于N2O。NPKS处理的增温潜势最大，NPK处理的最小。  相似文献   

10.
为了研究耕作措施对双序列轮作农田土壤温室气体的排放及影响, 采用CO2分析仪、静态箱 气相色谱法在陇中黄土高原半干旱区对传统耕作不覆盖、免耕不覆盖、免耕秸秆覆盖和传统耕作+秸秆还田4种耕作措施下豆麦双序列轮作农田土壤温室气体(CO2、N2O和CH4)的排放及影响因素进行了连续测定和分析。结果表明: 测定期内4种耕作措施下农田土壤均表现为CO2源、N2O源和CH4净吸收汇; 除传统耕作不覆盖措施, 其他3种耕作措施不同程度地减少了2种轮作序列土壤的N2O排放通量, 并显著增加了土壤对CH4的吸收。CO2和N2O的排放通量分别与地表、地下5 cm处、地下10 cm处的土壤温度呈极显著和显著正相关关系, 相关系数分别为0.92**和0.89**、0.95**和0.91**、0.77*和0.62*; 而CH4吸收通量与不同地层的温度之间无明显的相关关系; CO2和CH4的通量与0~5 cm、5~10 cm的土壤含水量均呈显著正相关关系, 相关系数分别为0.69*和0.72*、0.77*和0.64*, 而与10~30 cm土壤含水量无明显相关关系; N2O排放通量与各层次的土壤含水量之间均呈不显著负相关关系。对2种轮作序列各处理下土壤中排放的3种温室气体的增温潜势计算综合得出: 4种耕作措施中, 免耕不覆盖处理可相对减少土壤温室气体的排放量, 进而降低温室效应。  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.
“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   

15.
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   

16.
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   

17.
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.
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.
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.
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   

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