Microbial dynamics in an anaerobic soil slurry amended with glucose, and their dependence on geochemical processes

Under anoxic conditions, microbial activities interact closely with geochemical reactions and consequently affect soils, underlying aquifers, and the atmosphere. Recent studies have noted the relationships between microbial biodiversity and environmental conditions, but the dynamics of numerous coexisting microbial groups in connection with soil biogeochemical processes has never been investigated. In this work, we investigated the dynamics of anaerobic microbial populations using a new method combining PCR-SSCP and epifluorescent direct counts, and analysed these results in the light of biogeochemical changes. Batch incubations were performed over an 8-day period on a calcic cambisol (WRB) incubated anaerobically, either without amendment (treatment C) or after adding glucose (treatment +G). In treatment +G, the predominant microbial processes included (i) NO₃⁻ and NO₂⁻ reduction during the first 12 and 24 h of incubation respectively, (ii) fermentations during the first 6 days with non-symbiotic N₂ fixation between days 1 and 6, enabling bacterial growth during this period, and probably (iii) reduction of FeIII by H₂ oxidation throughout the incubation period. In treatment C, microbiological and geochemical measurements revealed no prominent microbial activities, and the PCR-SSCP method led to complex bacterial density profiles without prominent peaks. In treatment +G, 78 microbial groups were distinguished; these were divided into seven sets (A to G) according to their dynamics. Bacteria belonging to sets A, E and F grew during the period of intense fermentation and were probably able to fix N₂, as is the case with Clostridium butyricum (set A). Bacteria belonging to sets B, D, and G were probably able to reduce FeIII to FeII with concomitant oxidation of H₂ into H₃O⁺, but unable to fix N₂. Two microbial groups in these sets were closely related to Clostridium favosporum (set B) and the genus Bacillus (set B). Bacteria belonging to class C were probably only able to reduce N oxide(s). Lastly, we obtained two similar estimates of the gross increase in microbial biomass by taking into account either (i) the sum of gross increases for the 78 microbial groups, or (ii) the energy yield of catabolic reactions minus the energy requirement for N₂ fixation.     

澧阳平原末次冰期-早全新世气候环境演变研究

通过对澧阳平原野外考察、典型剖面YC自然沉积剖面的系统采样、室内地球化学元素Li、Rb、Sr、Ba和Li/Ba、Rb/Sr比值的分析,以及沉积物年代样品的OSL和AMS14C年代测定,探讨了长江中游地区澧阳平原末次冰期-早全新世的气候环境变化过程。结果表明,MIS3阶段晚期(31.80~23.80 ka BP)暖湿期记录明显,对应的沉积物含大量黑色铁锰膜和铁锰结核,地球化学元素Li含量、Rb含量、Rb/Sr比值、Li/Ba比值出现峰值,而Sr含量、Ba含量出现低谷,表明此时期冬季风减弱,夏季风增强,降水量增大,温度上升,风化作用显著增强。澧阳平原YC剖面很好的记录了56.00~6.96 ka BP的气候环境演变过程,大致经历了冷干期(56.00~31.80 ka BP)、相对暖湿期(31.80~23.80 ka BP)、冷湿期(23.80~10.60 ka BP)、暖湿期(10.60~6.96 ka BP)4个气候变化阶段。     

坝上地区马铃薯种植地球化学区划——以尚义县为例

尚义县为国家级贫困县,为了从根本上脱贫致富,因地制宜地进行马铃薯生产及生态环境规划,河北省地矿局出资对尚义县坝上地区开展了农业生态地质环境调查。结果表明：马铃薯优势区土壤Si、K和Na含量相对偏高,Mg、Cl、B、Ca、Cu、As等元素含量偏低,为沙质风积沉积环境;灌溉水水质较好且富Sr,呈弱碱性。通过建立地质地球化学模型对马铃薯种植进行区划,区划结果能有效地提高耕地的产能,发挥土壤内在质量优势,指导土壤平衡施肥,同时为土地利用规划修编、农作物种植结构调整提供可借鉴依据。     

尚义坝上地区莜麦种植区划

通过对尚义县坝上地区开展农业地球化学调查,获取了研究区土壤27项指标、灌溉水12项指标、莜麦子实及其根系土共计12项指标的原始数据。对比分析莜麦优势区土壤、灌溉水相关指标与全区平均值的含量关系发现:莜麦优势区土壤中有机碳(SOC)、N、P含量明显高于全区平均值,是优势区的主要标志,Si和Na含量相对较高,Mg、Cl、S、Ca等常量元素含量偏低,反映的是偏沙壤性土壤环境;灌溉水水质较好,同时富Sr和Se。通过建立地质地球化学模型进行莜麦种植区划,总结种植规划建议,为该县因地制宜地进行农业生产及生态环境规划提供技术支撑。     

Abundance of rare earth elements in rice paddy soils from three regions of Sri Lanka

Very few studies deal with the rare earth element (REE) content within paddy soil systems. This paper presents, for the first time, the distribution of REEs in paddy soils from three different regions in Sri Lanka. Seventy samples from the Kalutara and Kandy regions located in the Wet Zone and Anuradhapura region in the Dry Zone were selected for this study. ICP-MS measurements were performed on the soil samples to determine their respective REE concentrations. The sum content of all the REEs (REE) in these three regions were 182, 186 and 132 g/g, respectively. The mean concentrations for the 70 soil samples in µg/g were 35(La), 77 (Ce), 7.6 (Pr), 27.6 (Nd), 4.8 (Sm), 0.87 (Eu), 4.1 (Gd), 0.54 (Tb), 2.91 (Dy), 0.56 (Ho), 1.57 (Er), 0.21(Tm), 1.44 (Tb), and 0.23 (Lu). The chondrite-normalized REE patterns of the paddy soils from the three study areas were similar, which may be a reflection of comparable parent materials. Kalutara soils, which are richer in organic matter and kaolinite, showed a higher lighter REE content and lower heavy REE content with a more pronounced negative Eu anomaly with respect to the other regions. Whilst this may be a result of subtle differences in soil parent materials, it could also reflect secondary processes related to clay mineral and organic matter adsorption of REEs in paddy soils     

重庆芙蓉洞洞穴滴水地球化学初探

2005年10月至次年4月的6个月内对重庆芙蓉洞滴水地球化学过程的监测发现：芙蓉洞2个观测点滴水均是矿化度很低的重碳酸盐水型,而地球化学过程受季节变化影响较大,人为影响相对较小;滴水中的pH、电导存在明显的季节变化;而2个观测点水化学组分的差异以及变化趋势的延迟,也可以初步判断出2个观测点可能由于水类型的不同而使其组分有所差异.     

浙江省及邻近地区名茶形成的土壤地质环境分析

名茶产地的成土母质主要有石英砂岩、花岗岩、酸性凝灰岩与片麻岩等 ,它们在浙江被两条地质深大断裂分隔为三区 ,而各区的母质又各有特点。从新构造运动看 ,名茶多分布在强烈上升的山地区和沿海的升沉过渡丘陵区。从局部环境看 ,名茶产地附近多有湖、海等巨大水体。各类成土母质对茶品质的影响可用地球化学性质来解释 ,有关的元素有Si、K、Fe、Al、Ca、Mg、Mn等。文中还从已发现的名茶产地地质学规律出发 ,提出了全省的名茶发展战略     

土壤水分和养分利用效率几种定义的比较

本文在综述了水分和养分利用效率的各种定义的基础上 ,提出了作者对利用效率的观点 ,并对几种常用的土壤水分和养分利用效率的不同定义作了比较 ,分析了它们的不同内涵 ,并用实例进行了分析 .建议今后在应用中应根据研究目的 ,明确所需用的利用效率的内涵和计算方法 ,并给以恰当的名称     

豫中黄土地区全新世黄土剖面成壤作用与古气候研究

通过对河南豫中黄土地区黄土剖面化学元素的深入研究认为:在该地区全新世中期风化成壤过程中,Al、Fe、K、Ti、Rb、Ba等元素在古土壤中相对富集,表现出残留富集的特征;而Si、Ca、Na、Sr等元素则在风化剖面中淋失。而Al、Na在成壤过程中因具有不同的地球化学行为,从而产生显著的分异现象,并且随着成壤作用的增强分异加剧。因此,Al/Na值在黄土剖面中的变化反映了风尘堆积物成壤强度的变化,能够作为成壤作用、气候变化的替代指标。     

江苏海涂土壤盐分地球化学特征的初步研究

根据江苏海涂地区所做的大量分析数据,应用数理统计方法,对滨海盐土的盐分地球化学类型及其变化规律进行了定量的研究,分别提出盐分离子组成规律和盐分变化中几种离子当量比的特征值,为滨海盐土的分类和利用改良提出了依据。