几种胡敏酸还原容量的表征与比较

还原容量(RC)是衡量胡敏酸(HA)还原特性的重要指标。采用饱和H2振荡法和土壤溶液法对HA分别进行化学和微生物预处理,分别以硝酸铁(Fe(NO3)3)、柠檬酸铁(FeCit)作电子受体,测定了三种HA(上海巨枫SH,天津光复TJ,缙云山JY)的本底还原容量(NRC),化学还原容量(CRC),微生物还原容量(MRC)。对不同电子受体条件下、不同初始状态和不同种类的胡敏酸的RC进行比较。结果表明:三种HA中,以缙云山土壤提取的胡敏酸RC值最高,还原容量最大,分别为20.21±0.26 mmolc mol-1 C(NRC)、26.02±1.12 mmolc mol-1 C(CRC)和29.29±1.56 mmolc mol-1 C(MRC)。两种电子受体中,采用Fe(NO3)3得到的RC明显高于在FeCit条件下。另外,溶液态HA的RC明显高于固态。由此证明胡敏酸还原容量是一个相对量;其容量大小不仅和自身结构、性质有关,也受到HA初始形态和不同电子受体的影响。对比三个还原容量指标发现CRC和MRC显著大于NRC,而CRC和MRC之间无明确大小关系,因此用CRC来表征HA被微生物还原后的还原容量(MRC)还需作进一步验证。     

溶液体系中非生物因素对胡敏酸还原汞的影响

As a global pollutant process,the reduction of mercury(Hg)is especially important.One pathway is through an abiotic reduction with humic acids(HAs),which is controlled by different factors,including initial Hg and HA concentrations,pH,temperature and light.In this study,three humic acids were selected to illustrate the Hg~(2+)abiotic reduction mechanisms by HAs,and to identify the key limiting factors for reduction rates and amounts.In addition,the initial status of the HAs as a solid or in an aqueous solution were also compared,to help explain why HAs show different dominant characteristics(e.g.complexation or reduction)in the reaction process with Hg.Results indicated that HAs were able to reduce Hg abiotically.Higher initial Hg,higher HA concentrations and either high(8.1)or low(3.6)solution pH decreased the HA reduction capacity.In addition,Hg°production rates increased with increasing temperature,and the same trend was observed with light exposure.Humic acids added as an aqueous solution resulted in significantly greater Hg°production than addition as a bulk solid.Finally,the Hg reduction rate and capacity varied significantly(P0.05)with HAs from different sources.These findings helped to explain why HAs showed different dominant characteristics(e.g.complexation or reduction)in the reaction process with Hg,and evidentially demonstrated the existence of a possible pathway of Hg~(2+)reduction,which indicated that humic substances in natural environments,especially in water bodies,could act either as a sink or a source for Hg.     

土壤中水溶性有机质的结构特征及其与富里酸、胡敏酸的比较

采用元素分析、1HNMR和FTIR研究了黄泥土中水溶性有机质组成及结构特征,并与富里酸、胡敏酸进行比较。结果表明:胡敏酸含有大量的芳香族不饱和物质,烷基链烃多,支链长;富里酸以含有大量的羧基为主要结构特征;水溶性有机质主要由碳水化合物组成,含有大量的羟基,芳香族不饱和物质少。     

陕西省几种主要土壤胡敏酸能态及热分解特性的研究

氧弹量热计法测定不同土壤胡敏酸的热值(能态)表明,不同土壤胡敏酸具有不同的能态.土壤胡敏酸总能态高低与土壤有机质、全氮、胡敏酸含量呈显著正相关.DTA和TG法测定不同土壤胡敏酸的热分解特性表明,不同土壤胡敏酸的DTA、DTG曲线都有共同相似的热效应峰和失重峰.同时表明,与之相对应的焓变(△H)、重量损失百分数(W%),最大重量损失率-(dW/dT)m、活化能(E)、比速率常数(K₀)都有一定差异.红外光谱测定表明,不同温度下,不同胡敏酸热解温度上升到324-338℃时,主要是非核部分脂肪族侧链及氢链结合OH的裂解;当热解温度至444-464℃吋,主要是羧基和芳香核裂解;当热解温室达700℃以上吋,芳香核裂解趋于完全.     

土壤胡敏酸的温和水解及分组研究 Ⅱ.胡敏酸水解产物中的醇类化合物

采用温和水解及薄层层析等分组方法 ,并应用气—质联机技术对土壤胡敏酸 (HA)水解产物中的醇类化合物进行了初步研究。结果表明 :HA水解产物中醇类含量顺序是饱和醇 >甾醇 >非饱和线性醇。饱和醇中主要是C12～ 3 0 中的偶数碳和C15,非饱和线性醇主要是C2 0 -1π、C2 0 -2π和C19-4π。C3 和C4植物条件下形成的HA有一定的差异 ,C3 -HA含有较多的非饱和醇 ,而C4-HA含有更多的饱和醇特别是C12 和C2 6。     

几种胡敏酸和富里酸分子结构模型的三维可视化与特性研究

针对已提出的几种胡敏酸和富里酸的二维分子结构模型,应用HyperChem软件转换为三维结构并进行几何优化,计算了这些三维模型的能量以及定量构效关系(QSAR)参数。结果表明:几种模型在三维结构和特性上都各不相同,这为从空间角度更直观地认识腐殖物质的分子结构提供了可能性。     

施用有机肥料对土壤胡敏酸结构特征的影响──胡敏酸的光学性质

本工作通过田间试验和模拟试验研究了施用有机物料对棕壤、草甸土和水稻土中胡敏酸光学性质的影响。结果表明，施用有机物料后使土壤胡敏酸的吸光值和相对色度下降，色调系数升高，甚至发生类型改变。还使胡敏酸紫外２８５ｎｍ和红外２９２０ｃｍ＾－１吸收增强，１７２０ｃｍ＾－１和萤光强度减弱，激发光谱最大强度波长紫移。说明胡敏酸的分子结构变得脂族化，简单化和年轻化。两种有机物料相比，玉米秸杆对胡敏酸的木质素特征作用     

蒙脱石对不同施肥处理土壤胡敏酸及其级分的吸附特征Ⅰ.蒙脱石对胡敏酸的吸附特征

以17年不同施肥处理土壤胡敏酸为材料,研究了不同性质胡敏酸与钙饱和蒙脱石的 吸附特征。结果表明,钙饱和蒙脱石对土不同施肥处理胡敏酸的吸附曲线可用单表面Langmuir方程、双表面Langmuir方程以及Freundlich方程来描述。由单表面Langmuir方程计算的有机肥处理（厩肥、秸秆）胡敏酸的吸附量和吸附强度大于无肥、化肥处理。温度升高各处理胡敏酸吸附量增加,但吸附强度下降。双表面Langmuir揭示,蒙脱石对胡敏酸的吸附呈现高低两种能位的吸附。高能点位的吸附以化学吸附为主,是吸热反应,低能点位的吸附以物理吸附为主,是放热反应。有机肥处理和无肥、化肥处理相比,高能点位吸附相对减弱,低能点位吸附相对增强。     

胡敏酸的酒精分级沉淀法分级

本文利用酒精分级沉淀法，将胡敏酸分成１２个级分，并对各级分的结构进行了表征。结果表明，随着溶液中乙醇浓度的增大，各级分胡敏酸的腐殖化程度大体上逐渐由强变弱，分子量逐渐变小，全氮，水解性总氮和氨基酸氮的含量逐渐增大，而氨基糖氮和铵态氮逐渐减少 ，同时还讨论了本法与凝胶分级法所获得的结果不同的可能原因。     

论胡敏酸和胡敏酸盐与二、三氧化物相互作用产物的本性和性质

取生荒地表层黑土,用酒精-笨浸提脂蜡质,和0.1NH_2SO_4脱钙后,用0.1NNaOH 提取出胡敏酸,再重复净化而进行电滲析,所得胡敏酸的 pH 3.41,灰分含量为1.79%。以此胡敏酸与 FeCl_3、Fe_2(S04)3和 Al_2(SO_4)3溶     

溶液培养条件下腐殖酸对铁异化还原的影响

腐殖酸对土壤和水体环境中铁(Fe)的还原过程有重要影响。本文采用从山西大同风化煤、河南巩县褐煤、云南昆明滇池底泥中提取制备的腐殖酸,通过布置培育试验并接种土壤悬液,研究了不同来源的腐殖酸对无定形氧化铁异化还原的影响。结果表明:单独添加腐殖酸对氧化铁的还原几乎没有影响;而当同时添加腐殖酸与葡萄糖时,培养基质中氧化铁的还原过程显著加强;腐殖酸浓度越高对氧化铁还原的促进作用越明显。不同来源的腐殖酸因其复杂程度和结构不同,对氧化铁还原的促进作用有明显差异,其中山西大同风化煤提取的腐殖酸促进作用最大,云南昆明滇池底泥和河南巩县褐煤提取的腐殖酸之间则无显著差异。     

Absorption spectra of humic acids

For the purpose of explaining the forming process of soil humic acids, the author determined the absorption spectra of various humic acids. From soils and peats which were pretreated with 5% HCl at 70°C for 30 minutes or from those which were not, humic acids were extracted by treating with 0.5% NaOH at boiling temperature for 30 minutes. In these humic acids, the one which is extracted after acid pretreatment is provisionally designated as SrL humic acid and the other as L humic acid. The supernatant alkaline solutions obtained by centrifuging the above mentioned extracts were acidified with hydrochloric acid, and precipitated humic acids were filtered and washed with water until Cl' free. Humic acids were dissolved in 0.1% NaOH and ultrafiltered using collodion membrane. The filtrates were acidified with hydrochloric acid and humic acids were collected by centrifuging, transferred on the filter paper, washed with dilute hydrochloric acid and water successively, then air-dried and pulverized.     

Characterization of humic acids extracted from sewage sludge-amended oxisols by electron paramagnetic resonance

In tropical soils, the high turnover rate and mineralization of organic matter (OM) associated with intensive agricultural use, generally leads to faster soil degradation than that observed in temperate climatic zones. The application of sewage sludge to the soils is one proposed method of maintaining soil organic matter, and is also an alternative method of disposing of this waste product. As well as containing large quantities of OM, sludge is also a significant source of supplementary nitrogen, phosphorus and other essential nutrients for plant growth. However, it is necessary to understand the qualitative and quantitative changes that take place in the OM in soil treated with sewage sludge. The approach of the present study was intended to identify possible structural changes caused by sewage sludge applications on soil humic acids (HAs). The HAs extracted from a Typic Achrortox under sewage sludge applications were characterized by electron paramagnetic resonance (EPR) spectroscopy. The soil samples were collected from a field experiment designed to evaluate the effects of different doses of sewage sludge on corn growth and development in Brazil. The sewage sludge originated from urban waste treated at the sewage sludge treatment station in the city of Franca, state of Sao Paulo, Brazil. The following soil treatments were studied: control (non-cultivated soil under natural vegetation (NC)), control soil amended with NPK (conventional corn fertilization) and four treatments N1, N2, N4 and N8 with applications of 3.5, 7, 14 and 28 Mg ha⁻¹ of sewage sludge (dry matter), respectively. HAs were extracted from the surface layer using the methodology of the International Humic Substance Society (IHSS). Fe³⁺ and VO²⁺ ions complexed with HAs, and also semiquinone-type free radical (SFR) at concentrations of approximately 2.0 × 10¹⁸ spins g⁻¹ HA were identified in EPR spectra. The levels of SFR were lower for treatments where the applied sewage sludge doses were equivalent to four and eight times the normal doses of N mineral fertilization, reaching values of 1.7 × 10¹⁸ and 1.24 × 10¹⁸ spins g⁻¹ HA, respectively. The observed decrease in SFR content as sewage sludge dose was increased, was probably associated with the incorporation of less aromatic components into HAs originating from the sewage sludge.     

Characterization of fungal melanins and soil humic acids by chemical analysis and infrared spectroscopy

Summary Humic acids from two Brazilian topsoils under savanna grassland and five soil fungal melanins were characterized by elemental, functional group and infrared analysis. C, N, total acidity, COOH, and phenolic OH contents were within the ranges reported for several other fungal melanins and soil humic acids. Compared with the soil humic acids, the infrared spectra of the fungal melanins showed greater detail, indicative of higher aliphaticity. They were similar to the type III infrared spectra of humic acids, which are characteristically high in proteinaceous material and polysaccharides. The infrared spectra of the humic acids from the two Brazilian soils studied were classified as type I, which includes most soil humic acids. Notwithstanding the greater detail, in some areas the fungal melanin spectra were similar to those reported for other fungal melanins and humic acids of different origins. The probable contribution of the melanic fungi to the formation of soil humic polymers is discussed.     

Chemical studies on soil humic acids

Abstract

Relationships between elementary compositions and types of humic acids or the "degrees of humification were studied statistically using 39 humic acids prepared from various types of soils. Mean values of C%. H%. N%, 0%, H/C, N/C, and O/C of the different types of humic acids (A. B. Rp(l), Rp(2). and Po) were compared. The elementary compositions of various types of humic acids were proven by variance analyses to be significantly distinct. Linear regression analyses of C%, H%, N%. 0%, H/C, N/C, or O/C on RF or AlogK values were also carried out on 35 humic acids excluding the P_+~+++ type humic acids. The linear associations were found to be significant between C%-RF (5% level), H%-RF, H%-?logK, H/C-RF and HIC-?logK (0.1% level), N/C-RF(O.1% level). N%-RF(l% level), N%-?logK N/C-?logK(5% level), and ?logK (1% level), while no significant relationship was found with regard to C%;-?logK, 0%-?logK (both 5% level) and O/C-RF and O/C-?logK (l0% level). Carbon and oxygen contents of humic acids may be apt to reflect the different conditions of soils. The deeper the visible light absorption of humic acids and so the higher the degrees of humification, the lower the hydrogen contents of humic acids were. Though nitrogen content showed a trend similar to the trend of hydrogen content against RF values as a whole. the nitrogen content of less humified humic acids (Rp type) varied from very low to very high values. suggesting the enrichment of nitrogen into humic acid molecules in the early stage of humification. In the H/C versus O/C diagram, humic acids occupied an area reserved for the oxydation products of lignins. The area was fairly wide and “J”-shaped, that is, in the early to the middle stage of humification humic acids were arranged in the direction of dehydrogenation or demethanation, and in the later stage they were arranged in the direction of dehydration.     

Fe2+与胡敏酸的络合特征及其抗氧化性和生物有效性研究

在研究不同来源胡敏酸性质的基础上,研究了Fe2+与胡敏酸的络合特征以及络合态Fe2+的抗氧化性和生物有效性。结果表明,来源于土的胡敏酸属于A型,而来源于腐解秸秆、粪肥的胡敏酸属于RP型。A型胡敏酸与Fe2+络合能力大于RP型。HA-Fe2+络合物的络合稳定常数越大,络合物中Fe2+抗氧化性越强,玉米叶片中全铁含量也越高,但存在活性铁含量和全铁含量不一致现象。     

不同施肥处理土壤胡敏酸及其级分 与 Fe2+的络合特征 Ⅰ.胡敏酸原样与 Fe2+的络合特征

采用 17年不同施肥处理 (无肥、化肥、秸秆、厩肥 )土耕层土样 ,在对土壤胡敏酸性质研究的基础上 ,着重研究不同施肥处理土壤胡敏酸与Fe2+的络合特征 ,揭示络合作用与胡敏酸性质以及环境条件的关系。结果表明 ,不同施肥处理土壤胡敏酸与Fe2+的络合能力不同。和无肥处理相比 ,化肥处理胡敏酸的络合能力加强 ,logk值 (络合稳定常数 )增大 ,有机肥处理则使胡敏酸的络合能力下降 ,logk值减小。logk值大小与胡敏酸的羧基、酚羟基以及总酸度有关。pH值、温度、离子强度是影响络合稳定常数大小的环境因素 ,pH值由 4到 7,各处理胡敏酸的logk值增大 ,络合配位数也有增加趋势。温度升高 ,离子强度增大 ,logk值降低。胡敏酸与Fe2+络合反应是一个自发的放热反应 ,络合后整个体系的有序性增强 ,熵值减小。     

Effect of humic acid on growth and crop nutrient status of wheat on two different soils

The effect of plant-derived humic acid (PDHA) and coal-derived humic acid (CDHA) on wheat growth was tested on two alkaline calcareous soils in pots. Humic acid derived from plant and coal materials was applied at the rate 0 (control), 50 and 100 kg/ha to wheat in pots carrying two soils viz. clayey loam soil and sandy loam soil separately. Data was collected on plant growth parameters such as spike weight, grain and straw weight, and plant nutrients (macronutrients and micronutrients). Results showed that spike weight increased by 19%, 15%, and 26%, and 11% with application of PDHA at the rate of 50 and 100 mg/kg in clayey loam and sandy loam soil, respectively. Grain yield show an increase of 21% and 11% over control with application of PDHA and CDHA at the rate of 50 mg/kg on both soils, respectively, and 10% and 22% with application of PDHA and CDHA at the rate of 100 mg/kg on both soils.     

不同施肥处理土壤胡敏酸及其级分与Fe2+络合特征Ⅱ.胡敏酸级分与Fe2+络合特征

采用酒精沉淀法对不同施肥处理胡敏酸进行分级 ,在研究胡敏酸级分组成变异以及各级分性质变化的基础上 ,研究了胡敏酸各级分与Fe2+的络合特征。结果表明 ,胡敏酸各级分随级分数的增大芳构化度逐渐降低 ,分子结构趋于简单。在所分离的 7个级分中 ,均以级分 3与Fe2+的络合能力最强。从级分 1到级分 3络合能力逐渐增强 ,级分 3到级分 7络合能力逐渐降低。胡敏酸A型级分的络合能力一般大于P型。但若A型级分芳构化度过高 ,也存在A型级分小于P型现象。Rp型级分的络合能力明显比A型、P型级分小。不同施肥处理胡敏酸原样与Fe2+络合能力差异与其级分组成变异以及各级分的络合能力有密切关系