Mineralogy of Manganese Oxide Minerals in Iron Manganese Nodules of Several Main Soils in China

X-ray diffraction and selective chemical dissolution methods were used to investigate the composition of Mn oxide minerals in Fe-Mn nodules of several main types of soils in China. The changes of relative intensity of X-ray diffraction patterns were studied both before and after chemically selective dissolution. It was found that lithiophorite was a common Mn oxide in all examined Fe-Mn nodules. Todorokite, however, was a predominant Mn oxide in Fe-Mn nodules in caf-aquic Vertisols of Linyi, Shandong Province. The Fe-Mn nodules of arp-udic Luvisols in Wuhan and Zaoyang, Hubei Province, contained birnessite and vernadite. Hollandite was found in Fe-Mn nodules of alt-udic Ferrisols of Yizhang, Hunan Province; arp-udic Luvisols of Zaoyang, Hubei Province; and cal-aquic Vertisols of Linyi, Shandong Province. The Fe-Mn nodules in alt-udic Ferrisols of Guiyang, Hunan Province, had a few coronadites. Mineralogy of Mn oxide minerals in soil Fe-Mn nodules was related to soil environment, soil types and quantities of relevant cations.

Elemental Composition and Geochemical Characteristics of Iron-Manganese Nodules in Main Soils of China

Elemental composition and geochemical characteristics of iron-manganese nodules from nine main soils in China were studied by chemical and multivariate statistical analyses to better understand the reactions and functions of iron-manganese nodules in soils and sediment. Compared to the corresponding soils, Mn, Ba, Cd, Co and Pb had strong accumulation, Ni had moderate accumulation, while Ca, Cu, Fe, Na, P, Sr and Zn accumulated to a minor degree in the iron-manganese nodules. In contrast, Si, Al, K, Mg and Ti were reduced in the iron-manganese nodules. The contents of Ba, Cd, Co, Cu, Ni, Pb and Zn were positively and significantly correlated with that of MnO2 in the iron-manganese nodules, while the contents of Cr, Cu, Ni, Pb and Zn were positively and significantly correlated with that of Fe2O3 in soils. Based on a principle component analysis, the elements of iron-manganese nodules were divided into four groups: 1) Mn, Ba, Cd, Co, Cu, Li, Ni, Pb and Zn that were associated with Mn oxides, 2) Fe, Cr and P that were associated with Fe oxides, 3) Si, K, and Mg that were included in the elemental composition of phyllosilicate, and 4) Ca, Na, Al and Ti that existed in todorokite, birnessite, lithiophorite and phyllosilicate. It was suggested that accumulation, mineralization and specific adsorption were involved in the formation processes of soil iron-manganese nodules.

Effect of Casuarina Crushed Nodules, Rhizospheric Soil and Leaves Compost on Salt Tolerance of <i>Casuarina equisetifolia</i>L. and <i>Casuarina obesa</i>Miq.

Soil salinization is one of the major causes of land degradation. In Senegal, this phenomenon continues to grow, making soils unsuitable for agriculture. To rehabilitate salty lands, one of the recommended strategies is the use of salt-tolerant plants. Among them, plants of Casuarinaceae family form a relationship with symbiotic microorganisms such as arbuscular mycorrhizal fungi and nitrogen fixing bacteria. It has been shown that symbiotic microorganisms play an important role in the establishment of tolerant plants in saline conditions (Djighaly et al., 2018). They improve plant performance and reduce transplant shock under salt stress conditions (Diagne et al., 2014). These microorganisms can be used as biofertilizers. However, inocula containing symbiotic microorganisms are either too expensive or unavailable in many developing countries. The aim of this study is to test alternatively affordable and low-tech solutions to promote symbiotic interactions such as Casuarina crushed nodule, Casuarina rhizosphere soil and Casuarina leaves compost that may contain symbiotic microorganisms and also nutrients such as N and phosphorus. Two species of Casuarina (Casuarina equisetifolia L. and Casuarina obesa Miq.) were grown in the greenhouse on sterile soil to which an amendment was added (Casuarina crushed nodules, Casuarina Rhizospheric soil or Casuarina leaves compost). Plants were subjected to saline stress. After four months of cultivation, they were harvested and morphological and physiological parameters were determined. Results showed that inoculation with Casuarina crushed nodules, Casuarina rhizospheric soil and Casuarina leaves compost improved growth, total dry biomass, total chlorophyll and proline contents of C. equisetifolia and C. obesa plants in salt stress condition. These positive effects were more important in C. obesa plants amended with Casuarina leaves compost. This study shows that Casuarina leaves compost can play an important role in the rehabilitation of saline soils by improving Casuarina trees performance in saline conditions.

Geotechnical properties of oceanic sediments in polymetallic nodules belts

Geotechnical data obtained from the polymetallic nodules investigation in 1994, in combi nation with the historical data concerned, are analyses comprehensively to study sediment types, geotechnical properties, soil strength and so on, in order to provide bases for design and construction of engineering facilities and the equipments raquired for the polymetallic nodules mining in the future.

不同水力集矿模型的矿粒采集及环境扰动特性数值研究

实现高效、低扰动海底集矿是深海多金属结核矿产资源开发面临的关键技术挑战.海底矿粒采集过程的力学行为十分复杂,是一个涉及三维紊动流动、离散粗颗粒运动与细颗粒土体破坏的流固土多物理场耦合过程.针对吸扬式、附壁射流式、射流冲采式3种主流的深海水力集矿方法,基于K-Epsilon两层模型和离散元模型分别模拟集矿液相湍流和固相矿粒,进行矿粒采集性能和环境扰动的数值模拟研究,分析集矿流量q m和集矿头拖曳速度v对矿粒采集率η、集矿流场湍动能k和海水-沉积物混合物体积分数φ的影响,探究集矿流场中流速、压力和矿粒的分布特征.结果表明:在相同q m和v下,射流冲采式模型获得的η最大,吸扬式模型获得的η最小;射流冲采式模型对近底流场扰动程度最大,深海沉积物扩散现象也最为明显,而吸扬式和附壁射流式模型造成的环境扰动程度较小,更有利于环保要求;附壁射流式模型的η对q m和v最不敏感,且该集矿模型可以较好地兼顾高效矿粒采集和低环境扰动.研究结果可为揭示集矿机理和设计研发高效低扰动集矿装置提供科学依据.

青海湖环湖地区燕麦与豆科饲草混播对根瘤及土壤养分的影响

在青海湖环湖地区开展燕麦与豆科饲草混播对根瘤生长特征及土壤养分的影响研究。结果表明:燕麦(Avena sativa L.)与蚕豆(Vicia faba L.)、豌豆(Pisum sativum L.)和绿豆(Vigna radiata(L.)R.Wilczek)的混播种植均对土壤的有机质、氮、磷、钾及有机碳等关键养分元素产生积极的增强效应,其中燕麦与蚕豆5:5的混播模式效果最为显著。

Cadmium isotope compositions of Fe-Mn nodules and surrounding soils: Implications for tracing Cd sources

Cadmium (Cd) pollution in agricultural soils has become a severe threat to food security and human health in recent years. Stable Cd isotopes are a potentially powerful tool for identifying the sources of Cd in soils. However, many Earth surface processes, including adsorption, leaching, and biogeochemical cycles in plants, may generate Cd isotope fractionation, which can complicate the potential application of Cd isotopes in tracing the sources of Cd pollution in soils. In this work, the Cd isotope compositions of typical Fe-Mn nodules (FMNs) and surrounding soils in two different soil profiles are investigated. Our results show that the FMNs in lower layers (i.e., C and W horizons) are isotopically lighter than the surrounding soils by –0.114‰ to –0.156‰ (Δ114/110CdFMN-soil). We interpret this fractionation as the result of preferential adsorption of isotopically light Cd onto the surface of goethite. In the upper layers (i.e., P and A horizons), the Δ114/110CdFMN-soil values are more negative in the P horizon (–0.213‰ to –0.388‰) but more positive in the A horizon (0.061‰ to 0.204‰). We interpret these fractionations as the result of natural biogeochemical processes (i.e., leaching and biological cycling) during soil development. Soil leaching preferentially releases isotopically heavy Cd into the underlying soil (i.e., P horizon), shifting the topsoil towards lower δ114/110Cd values but the underlying soils towards higher δ114/110Cd values. Moreover, biological cycling contributes isotopically heavy Cd to the topsoil, probably shifting the topsoil towards higher δ114/110Cd values. Our study demonstrates that the formation of Fe oxyhydroxides, leaching, and biological cycling can considerably modify the soil Cd isotope signature, highlighting the need to consider natural biogeochemical processes when using Cd isotopes to trace heavy metal pollution in soils.

Elevated Carbon Dioxide and Soil Moisture on Early Growth Response of Soybean

Interactions between elevated [CO2] and soil water availability have the potential impact on crops and future food security of the world. The study was conducted to investigate vegetative growth response of soybeans under two [CO2] (380 and 800 μmol mol-1) with three soil moisture levels in controlled environment. Slow growth rate and altered crop phenology of soybeans were observed under elevated [CO2] at early stage (V-3/V-4), but showed positive physiologically response at later stage (R3) indicating adoptive mechanism of plants to high [CO2]. Elevated [CO2] decreases the number of leaves by 23% and 14% and reduces in leaf areas by 11.7% and 9.7% compared with ambient [CO2] at 29 and 44 days after planting (DAP), respectively. Adaptive mechanism of plants to high [CO2] produced 39% and 83.7% greater leaf number and leaf areas, respectively at later stage (R3) of the crop growth (59 DAP). There was a reduction in a specific leaf area (SLA) at 29 DAP (22.2%) but an increase at 44 DAP (1.4%) and 58 DAP (8.5%) under elevated [CO2]. Dry matter production of plants was increased significantly for elevated [CO2]. Increase in leaf C (<1%) and reduction in N concentration (6.0% - 9.5%) increased the C:N ratio of soybean leaves (4.4% - 12.98%) under elevated [CO2]. Elevated [CO2] with normal soil moisture condition produced a maximum number of pods (54.8% - 122.4%) and an increase in dry weight of pods (29.8% - 56.6%). Plants under elevated [CO2] produced significantly greater numbers of root nodules per plant by 114% compared with plants under ambient [CO2] at 44 DAP. These results show a direct and interactive effect of elevated [CO2] and soil moisture on plant growth that will affect not only the global food security but also nutritional security.

African Traditional Vegetables as Agents of Integrated Soil Fertility ManangementmCrotalaria and Amaranth Farming

The knowledge and understanding of African leafy vegetables has diminished over time, but in the recent past year there is more interest in their research for their nutritive and medicinal values. Of value are those that have the potential to ameliorate soil nutrient levels. This is with the background that despite inorganic fertilizers （IF） have a dramatic impact on agriculture in the world, the economic situation in Sub-Saharan African calls for alternative methods to reduce soil fertility degradation. The use of leguminous vegetables may be a solution. The study looks at the potential contribution of a leguminous traditional vegetable-- Crotalaria brevidens to soil nitrogen under various treatments. During the study which was conducted over two seasons, C. brevidens was grown under two treatments of IF and organic fertilizer （OF） with a control in which there was no fertilizer （NF） applied. A non-leguminous vegetable--Amaranthus dubious （Amaranth） was grown under the same treatments for comparison purposes. Soil analysis was done before and after planting in the treatment subplots. Growth parameters were measured every fortnight and these included leaf number, shoot length, dry weight and nodule number for Crotalaria. Results indicated that the leguminous vegetable was not affected by external inputs and there were no significant differences between treatments and control. The non-leguminous vegetables responded well to both IF and OF treatments in all the measured parameters. This underlines the potential for improving soil nitrogen levels using leguminous vegetables, especially as intercrops with the non-leguminous types.

林洪生教授“固本清源”理论治疗肺结节经验思想

随着CT影像学手段应用不断推广和人们健康意识的提高,肺结节的检出率较前有明显的提高。目前各项指南对其的建议以CT复查随访及手术切除为主,如何运用中医药的优势防治肺结节的发生发展是当前热点问题。林洪生教授从事恶性肿瘤中西医结合诊疗数十年,将“固本清源”引入临床治疗,取得较好的临床及科研成果。现从肺结节的病因病机、辨证用药等方面,阐述“固本清源”理论指导下中医治疗对肺结节患者的思路与方法,为中医防治肺结节提供参考。

GEOCHEMICAL CHARACTERISTICS OF Fe-Mn NODULES AND CRUSTS FROM THE MARIANA RIDGE AND THE WEST PHILIPPINE BASIN

I. INTRODUCTIONA lot of work on marine Fe-Mn nodules has been done. However, few reports about the study of Fe-Mn nodules in the Mariana Ridge and the West Philippine Basin are known. The purpose of this note is to report in detail the geochemical characteristics

掌叶木幼苗根瘤形成及土壤石砾含量对根瘤形成的影响

为探究掌叶木(Handeliodendron bodinieri)幼苗根瘤形成及土壤石砾含量对根瘤形成的影响,以掌叶木幼苗为研究对象,采用石蜡切片技术,结合体视显微镜,观察掌叶木幼苗根瘤形成及发育过程;设置不同的土壤石砾含量,分别为0%(CK)、20%、40%、60%和80%,探讨土壤石砾含量对根瘤形成的影响。结果表明,掌叶木幼苗根瘤属内源性根瘤,起源于中柱鞘细胞,多为圆形或椭圆形;幼嫩根瘤呈黄白色或淡黄色,表面光滑有光泽;衰老根瘤多呈深红棕色或褐色,质地较硬,有矿化或腐烂现象;部分新瘤叠生于老瘤之上,呈串珠状或叠生状;根瘤上有瘤毛。土壤石砾含量对掌叶木幼苗根瘤形成影响显著。随土壤石砾含量增加,根瘤数量和重量均呈先升后降的趋势;石砾含量为60%时,根瘤数量最多,最重。随土壤石砾含量增加,根瘤长度呈先升后降再升的趋势;石砾含量为80%时,根瘤最长。随土壤石砾含量增加,根瘤宽度呈先升后降的趋势;石砾含量为60%时,根瘤最宽。综合评价表明,掌叶木幼苗根瘤各形态指标在土壤石砾含量为60%时得分最高,说明适当增加土壤石砾含量,有助于掌叶木幼苗根瘤形成。

中国暖湿地区土壤Fe-Mn结核形成的气候与元素阈值

暖温带-亚热带-热带地区Fe-Mn结核是温、湿气候下土壤发育的重要特征,但是土壤Fe-Mn结核出现的明确气候意义仍然有待厘定。本研究通过集成暖温带-亚热带-热带地区154个研究点位(43个Fe-Mn结核点、65个含Fe-Mn结核土壤剖面、46个不含Fe-Mn结核土壤剖面)912个样品的主量元素数据,对提供Fe-Mn结核的点位在气候要素(温度和降水)上的空间分布特征作了分析,对含/不含Fe-Mn结核的土壤化学蚀变指数(CIA)与铁锰元素的关联进行了比较,结果表明暖湿地区土壤Fe-Mn结核形成的气候阈值为年平均温度>15℃且年平均降水量>800 mm,元素阈值为土壤TFe2O3>5%且MnO>0.1%,此时CIA平均值也大于80。据此阈值,本研究可以推论,高温气候背景下,当土壤Fe-Mn结核普遍发育时,该区域的气候条件即符合年平均降水量大于800 mm且年平均温度达到15℃。这一结果为深入理解土壤Fe-Mn结核的形成机理及其气候指示意义提供了重要线索,也为不同温暖时期的古气候重建提供了一个重要的气候约束。

两种黄芪属植物的根瘤特性比较及与土壤因子关系研究

豆科植物在氮素匮乏的荒漠生态系统中大量存在,也是这一区域的先锋物种。本研究选择古尔班通古特沙漠广泛分布的弯花黄芪(Astragalus flexus)和镰荚黄芪(Astragalus arpilobus)的根瘤为对象,研究两种植物在不同生长期的根瘤固氮酶活性(Nodule nitrogenase activity,NNA)、根瘤固氮潜力(Nodule nitrogen fixation potential,NNFP)、根瘤重量(Weight of nodule,WON)及土壤因子关系。结果表明:两种植物在不同生长期的NNA,NNFP,WON均存在显著性差异(P<0.05),且在6月上旬均达到最高。在5月上旬,电导率(EC)、全磷(TP)分别是弯花黄芪NNA,NNFP的促进因子,而有机质(SOM)是两种植物NNFP及弯花黄芪WON的限制因子;在5月下旬,全氮(TN)是镰荚黄芪NNFP的限制因子;有机碳(SOC)和TN分别是6月上、下旬镰荚黄芪NNA的限制因子。结果为新疆干旱区对高效利用黄芪属植物及通过调控土壤因子来提高共生固氮提供了借鉴。

农业土壤铁锰结核对铅的吸附特性

铁锰结核是土壤环境的重要成分,能够影响土壤组分的迁移转化,对土壤重金属有很强的结合能力。目前,对土壤铁锰结核吸附重金属的相关研究尚不完善。以农业土壤铁锰结核为研究样本,通过单因素和正交试验分析其对铅(Pb)的吸附行为。结果表明:铁锰结核对Pb的单位吸附量随反应时间的延长快速增加,60 min时的吸附量为5.84 mg·g^(-1),之后增幅变缓;温度和溶液初始pH对反应过程影响很小,但升高Pb溶液浓度、减小铁锰结核粒径都能促进Pb的吸附去除;增加铁锰结核量对Pb的单位吸附量影响不大;不考虑各因素交互作用时,铁锰结核吸附Pb的影响因素主次顺序依次为铁锰结核粒径、反应时间、Pb溶液浓度和溶液初始pH。

东北黑土区大豆生长、结瘤及产量对氮、磷的响应

氮肥和磷肥显著影响大豆的结瘤和产量。然而在土壤肥力较高、速效养分有效性差的东北地区,有关氮肥和磷肥施用量对大豆结瘤和产量影响的研究较少。本试验采用裂区田间试验,设置3个氮(N)水平(0、20和50kg/hm2)和3个磷(P)水平(0、20和40 kg/hm2),研究氮、磷及其交互作用对大豆生长发育、结瘤特征及产量的影响。结果表明:单施氮肥大豆生物量和产量随着施氮量的增加而增加,而根瘤数量、干重、大小和结瘤指数呈逐渐下降的趋势。单施磷肥促进大豆生物量、产量、根瘤数量、干重、大小和结瘤指数的增加,但其增幅低于施氮处理下的增幅。氮×磷对大豆生长和产量促进作用高于单施氮和单施磷处理,但差异不显著;氮×磷处理下的根瘤数量、干重、大小和结瘤指数低于单施磷处理;氮×磷处理下N2(N 50 kg/hm2)处理下的大豆根瘤数量、干重、大小和结瘤指数高于N1处理(N 20 kg/hm2)下的,随着施磷量的增加大豆根瘤数量、干重、大小和结瘤指数增加,施磷能够抵消氮对大豆根瘤产生和形成的抑制。氮、磷及其交互作用对大豆根瘤的影响都是直接的,并且不是通过促进大豆生长间接促进的。因此氮和磷均是限制东北地区大豆结瘤和产量的因素,但氮是主导因素。若要获得大豆高产,氮肥施用量需要控制在50 kg/hm2,磷肥在40 kg/hm2;但若想最大的发挥大豆的结瘤固氮功能,那么应该不施或者减少氮肥的施用量到20 kg/hm2,磷肥仍在40 kg/hm2。

生态环境对根瘤菌竞争结瘤影响的研究进展

影响根瘤菌竞争结瘤能力的生态因素有土壤条件 ,肥力水平 ,土著根瘤菌的数量和类型 ,其它微生物 ,根瘤菌的接种方式和时间等。在土壤条件方面研究较多的是土壤类型、pH值。肥力水平主要指氮水平和有机质含量。

几种土壤中铁锰结核的重金属离子吸附与锰矿物类型

土壤与水体中的锰氧化物对某些重金属离子有强烈的富集作用 ,本研究表明我国几种土壤铁锰结核中锰氧化物的重金属离子 (Pb、Cu、Zn、Co、Ni和Cd)吸附量占结核吸附这些离子总量的 60 %～ 1 0 0 %。结核中所含锰矿物类型不同 ,对重金属离子吸附的能力不一样。山东砂姜黑土中含钙锰矿和锂硬锰矿 ,其锰氧化物的重金属离子吸附量最高 ;其次是湖北黄棕壤和黄褐土中铁锰结核的锰氧化物 ,它们为锂硬锰矿与水钠锰矿组合 ;吸附量最低的是湖南红壤中铁锰结核的锰氧化物 ,它们仅为锂硬锰矿。上述几种锰矿物构造上的差异和结晶程度不同是导致不同土壤铁锰结核中锰氧化物吸附重金属离子量不一样的重要原因。Co2 +在吸附过程中被氧化及试样中氧化锰含量和Mn(Ⅳ )百分率不同也是影响其铁锰结核中Co吸附量变化的原因。

黎塘岩溶区土壤铁锰结核的地球化学特征研究

对黎塘岩溶区土壤铁锰结核的地球化学特征研究表明:与土壤相比,铁锰结核的化学组成中仍以SiO2、Al2O3和Fe2O3为主,但Fe2O3的含量明显增加,成为铁锰结核中含量最多的氧化物,MnO含量也有一定程度增加,它们富集系数分别为5.19和3.40;铁锰结核对重金属具有明显的富集效应,其富集顺序为Cr()>Pb>Co>Zn>Ni>Ba>Li,它在土壤中的含量受成土母质及浅层地下水活动的影响。元素的相关分析及因子分析表明,铁锰结核在形成过程中还具有成核富集效应、专性吸附效应和成核易淋溶效应。

两个大豆品种在暗棕壤和黑土中的根系形态和根瘤性状

选取黑龙江省2种主要农田土壤类型(暗棕壤和黑土)和2个大豆品种(滴2003-1和合丰25),采用盆栽试验,分别于大豆第5片复叶展开期、初花期、结荚初期、结荚盛期、鼓粒初期、鼓粒期和完熟期取样,进行根系形态(根干质量、根长、根表面积和平均根直径等)和根瘤性状(根瘤数、根瘤鲜质量和单个根瘤质量)的动态分析,以研究品种和土壤类型对大豆根系形态特征的影响.结果表明:土壤类型对大豆根系形态及结瘤性状均有显著影响,在第5片复叶展开期和初花期,暗棕壤的根系干质量、根长和根表面积低于黑土,而在鼓粒初期后高于黑土,暗棕壤的平均根直径在鼓粒初期后也高于黑土,但土壤类型对根冠比的影响不大;暗棕壤的根瘤数在初花期后明显低于黑土,但根瘤鲜质量和单个根瘤质量高于黑土.不同品种的根系性状在2种土壤上的差异程度不同,与合丰25相比,滴2003-1的根系性状受土壤条件的影响较大.在鼓粒期,根干质量(P<0.05)、根表面积(P<0.05)、根瘤数(P<0.01)及单个根瘤质量(P<0.001)在不同品种与土壤类型间表现出显著的互作效应.