烟草果胶和纤维素含量13C MultiCP / MAS NMR同时测量

果胶和纤维素是烟草细胞壁的重要组成成分,其含量对烟草品质与安全性产生重要影响。传统分析方法难以实现果胶和纤维素的同时定量。本文在优化核磁共振波谱序列条件的基础上,采用固体¹³C 多重交叉极化/魔角旋转核磁共振波谱分析技术（¹³C MultiCP / MAS NMR）建立了烟草果胶和纤维素含量的同时测量新方法。方法以聚半乳糖醛酸和微晶纤维素为标准物质,以3-（三甲基甲硅烷基）丙酸-d₄钠盐（TMSP）做为内标物质,分别建立内标法标准曲线,相关系数R²为0.999 0和0.998 2。果胶测量的检出限和定量限分别为0.38和1.28 mg·g^-1 ,精密度（RSD,n = 5）小于3.05％。纤维素测量的检出限和定量限为1.01和3.32 mg·g^-1,精密度（RSD,n = 5）小于2.74％。应用本方法测量烟梗、烟草薄片和烟叶等不同类型样品中的果胶和纤维素含量,并对比烟草行业标准方法的测量结果,果胶含量的相对误差在－0.95％至4.51％之间,纤维素含量的相对误差在0.77％至2.46％之间。表明¹³C MultiCP / MAS NMR方法快速,准确,适合批量样品的分析测量,为果胶和纤维素等细胞壁类大分子的同时定量分析提供重要技术支持。     

用13C-核磁共振方法研究有机肥料对胡敏酸结构特征的影响

通过在棕壤上进行的田间试验和模拟试验,研究了施用有机肥胡敏酸（ＨＡ）＾１３Ｃ－核磁共振（ＮＭＲ）波谱的影响。结果表明,施用有机冯有使ＨＡ的碳骨架发生规律性的变化。一般表现为芳香碳（Ａｒ－Ｃ）和羰基碳（〉Ｃ＝Ｏ）含量减少;而烷基碳（Ｒ－Ｃ）和烷氧碳（ＲＣ－Ｃ）的含量增加。从恧地致ＨＡ的脂族化。研究表明,文中建立的土壤ＨＡ溶液＾１３Ｃ－ＮＭＲ方法,用于相对比较土壤有机增减肥后ＨＡ结构特征的变化规律是可     

长期施肥对土壤有机质δ13C值影响的初步研究

以黑土、棕壤、草甸土和水稻土为供试土壤,通过田间定位并结合室内培养试验,初步研究了不同施肥(包括施用化肥、有机肥以及有机肥配施化肥)条件下全土有机质和胡敏酸的δ13C值。结果表明:一般与未施肥的处理相比,田间施用有机肥以及有机肥配施化肥使全土有机质和胡敏酸的δ13C值均呈下降趋势;培养试验中,施用猪粪后全土有机质和胡敏酸的δ13C值也呈下降趋势,而施用玉米秸秆后则呈增加趋势。产生上述结果的可能原因,一方面是由于不同有机肥料的δ13C值不同,另一方面则是由于施肥改变了土壤有机质的数量与结构组成。初步分析表明,施肥后全土有机质和胡敏酸的δ13C,值与其有机碳数量及结构组成之间并不存在显著的相关性,而全土有机质的δ13C值与其有机碳数量的增加量和增加率之间则存在显著的相关性。     

长期施用有机肥对黑土胡敏素结构特征的影响——固态13C核磁共振研究

 【目的】研究连作玉米农田长期施用有机肥（猪粪）对黑土胡敏素（HM）结构特征的影响,比较不同施肥量和施肥年限间的差异,为阐明HM在土壤肥力上的作用提供理论依据。【方法】以1980年建立的国家黑土肥力与肥料效益监测基地的长期肥料试验为平台,采集定位12年和25年的3个试验处理（①不施肥CK;②施低量有机肥,施猪粪30 t?hm-2?a-1;③施高量有机肥,施猪粪60 t?hm-2?a-1）土样,在NaOH-Na4P2O7分离和HF-HCl脱灰处理的基础上,应用固态13C交叉极化魔角自旋核磁共振（13C CPMAS NMR）方法对HM进行结构表征。【结果】与不施肥相比,施用有机肥后HM的有机碳含量增加,烷基C比例增加,烷氧C和芳香C比例下降,烷基C/烷氧C、脂族C/芳香C和疏水C/亲水C比值增加,上述规律性随有机肥施用量的提高和施用年限的延长表现得更加明显。不施肥处理随年限延长,HM的有机碳含量降低,而烷基C、烷氧C和芳香C比例以及烷基C/烷氧C、脂族C/芳香C和疏水C/亲水C比值均表现出与施肥处理相同的变化规律,但其变化幅度小于施肥处理。【结论】长期施用有机肥使土壤HM的结构向着烷基化和疏水性程度增加的方向发展,这对于土壤肥力的保持是有利的。     

应用脉冲标记粗枝云杉和四川红杉幼苗的13C分配特征研究

【目的】探究针叶树种对光合碳同化产物在器官-土壤中的分配规律。【方法】以粗枝云杉(Picea asperata)和四川红杉(Larix masteriana)5 a生幼苗为试验对象,通过盆栽实验,利用脉冲标记法对处于生长期的幼苗进行4次¹³C同位素脉冲标记,以期揭示粗枝云杉和四川红杉光合碳同化产物在器官-土壤中的分布规律。【结果】两种幼苗各器官和土壤δ¹³C值在标记前后均存在显著差异,且标记后¹³C富集量表现为：四川红杉>粗枝云杉。标记后四川红杉根、枝、叶和土壤的δ¹³C值范围分别为：25.33‰～171.64‰、36.68‰～206.84‰、79.40‰～230.91‰和-16.49‰～-11.28‰,具体表现为叶>枝>根>土壤;粗枝云杉根、枝、叶和土壤的δ¹³C值范围为-23.02‰～63.97‰、-23.72‰～18.52‰、-20.09‰～14.09‰和-20.27‰～-15.71‰,表现为根>叶>枝>土壤。【结论】基于     

核磁共振波谱法研究玉米植株残体培肥对土壤胡敏酸的影响

用核磁共振波谱法研究了施人玉米秸秆和根茬后土壤胡敏酸（HA）的变化。结果表明，玉米植株残体施用后，土壤HA的烷基链变短且多分支；土壤HA的芳香度降低，芳香碳减少，而烷基碳和烷氧碳增加，HA的脂肪族特性增强，氧化程度降低；发生变化最大的时期在施人玉米植株残体60d左右，且玉米秸秆对土壤胡敏酸的影响要大于根茬的影响。     

黄泥土中胡敏酸对芘的吸附及作用机理研究

采用高效液相色谱法测定了3种不同利用方式下黄泥土中胡敏酸对芘的吸附效应，并利用元素分析、FTIR图谱分析对其吸附机理进行研究。吸附试验表明，桑园、水田、水杉土壤中胡敏酸对芘的吸附在低浓度范围近似线性，而浓度较高时，吸附曲线的非线性增强，三者呈相似的非线性吸附。不同利用方式下黄泥土中胡敏酸对芘的吸附等温线用Freundlich等温方程拟合效果很好，均达到显著相关。元素分析与FTIR图谱分析结果表明，10年时间的不同利用方式对土壤中胡敏酸元素组成影响较小；桑园、水田、水杉土壤中胡敏酸对芘的吸附分配系数有一定差别，推测脂肪族类物质对吸附起着重要的影响。由胡敏酸吸附前后的FTIR图谱变化主要集中在3400、2920cm^-1附近，进一步推出两者结合机制是胡敏酸中脂肪族类物质作用的结果。     

稻草还田和冬种绿肥对华南双季稻产量及稻田CH4排放的影响

以常规稻合丰占为材料,开展田间裂区试验,主因素设稻草不还田和全部稻草还田2种处理,副因素设冬闲和冬种绿肥并全部还田2种处理,研究稻草还田和冬种绿肥及其互作对华南双季稻产量和稻田CH4排放的影响,以期为华南双季稻低碳高产栽培提供指导。结果表明:稻草全量还田显著提高水稻产量,平均增产4.8%,主要原因是稻草还田促进水稻的干物质积累,增加了每穗粒数,但稻草还田极显著增加稻田CH4排放量,平均增幅为41.8%;冬种紫云英绿肥显著提高水稻产量,平均增产3.6%,同时稻田CH4排放量也增加,但差异没有达到显著水平。无论是对水稻产量还是稻田CH4排放,稻草还田和冬种绿肥处理之间的互作效应均不显著,表明二者的作用是相互独立的。综合考虑水稻产量和CH4排放的表现,冬种紫云英绿肥可作为华南双季稻低碳高产栽培的重要措施。     

蚯蚓作用下不同C/N秸秆还田对土壤CO2及N2O排放的影响

为探讨蚯蚓作用下不同C/N秸秆还田对土壤CO_2及N_2O排放的影响,利用室内培养实验,选取不同C/N的四种秸秆(油菜饼、玉米叶、水稻秸、玉米秆)为材料,以无秸秆的处理为对照,比较有、无蚯蚓(Metaphire guillelmi)作用下不同秸秆施入土壤后的CO_2及N_2O排放规律。为期60 d的培养显示,无论添加何种秸秆,土壤CO_2和N_2O的累积排放量均不同程度增加,且CO_2排放系数(EFs-C)与秸秆C/N呈显著的负相关关系(R2=0.827 3)。蚯蚓活动刺激了土壤CO_2和N_2O的产生,接种蚯蚓后的油菜饼、玉米叶、水稻秸、玉米秆和对照处理CO_2累积排放量较相应的无蚯蚓处理分别增加了0.3、0.5、0.9、1.0、1.8倍,N_2O累积排放量较相应的无蚯蚓处理分别增加了1.4、1.7、1.7、1.4、9.5倍。然而,进一步的分析显示,蚯蚓提高了低C/N油菜饼处理的N_2O排放系数(EFs-N),却降低了其他秸秆处理的EFs-N。此外,低C/N油菜饼混入土壤后在培养前期即产生了较高含量的无机氮和可溶性碳,而其余秸秆混入土壤后却导致无机氮含量低于对照处理;虽然接种蚯蚓在培养后期缓慢增加了高C/N秸秆处理的无机氮,但仍低于无秸秆的蚯蚓对照处理。研究表明,接种蚯蚓和施入秸秆均能促进土壤CO_2及N_2O的排放,但蚯蚓作用下不同秸秆施用对EFs-N的影响却可能因秸秆C/N的不同而产生差异。     

利用13C CP/MAS测定葛根淀粉晶体结构

对淀粉颗粒粒度分布、热力学性质、微观结构、淀粉晶型以及双螺旋含量和相对结晶度的测定等表征葛根淀粉的物理性质和物理化学性质进行系统性探究,并以马铃薯淀粉作为对照。结果表明,葛根淀粉颗粒粒度大小的分布模式呈双峰型;起始糊化温度为64.32℃,糊化焓为1.77 J·g~(-1)。通过固体核磁可以测定葛根淀粉的晶体结构含淀粉的晶型,双螺旋含量和相对结晶度,其中,通过对NMR图谱中化学位移在94~110 nm处的C1区进行分峰,产生了2个副峰表明了葛根淀粉为Cb型晶体,同时利用X晶体衍射(X-ray diffraction,XRD)对葛根淀粉颗粒进行,衍射角在5.7°、15.3°、17.2°和17.5°时出现明显尖峰,证明葛根淀粉晶型为C型。13C CP/MAS固体核磁和XRD对葛根淀粉相对结晶度含量的测定结果分别为28.7%和19.18%,且通过13C CP/MAS得到葛根淀粉双螺旋含量为41.21%。     

水稻土及其提取腐植酸组分对邻苯二甲酸二丁酯（DBP）的吸附解吸研究

采用批处理试验研究邻苯二甲酸二丁酯(DBP,1~12 mg·L-1)在水稻土及其提取腐植酸组分中的吸附-解吸行为。结果表明,DBP在水稻土及其腐植酸组分中的吸附分别在48 h和24 h内达到平衡,吸附动力学过程均符合拟二级动力学方程(R20.997),是涉及表面扩散和颗粒内扩散吸附过程。不同温度条件下(15、25、35℃)吸附等温线均符合Freundlich方程(R20.901)。吸附过程属于熵增的自发吸热物理吸附过程,其中腐植酸组分(K_(oc)值为925~7691 m L·g-1)对DBP的吸附性能强于水稻土(K_(oc)值为524~3565 m L·g-1),这与其有机质含量较高有关。解吸实验(25℃)显示,水稻土及其腐植酸组分也符合Freundlich方程(R~20.870),其中水稻土对DBP的解吸存在明显滞后现象,但其腐植酸成分对DBP解吸的滞后现象不显著,即其吸附的DBP较易再次释放。     

稻秆及稻秆生物炭添加对稻田红壤有机碳组分及CH4和CO2累积排放量的影响

为明确稻秆生物炭添加对稻田红壤有机碳组分及CH₄和CO₂累积排放量的影响过程与机制,本研究以稻田红壤为对象,通过室内培养试验,按土壤质量的1%等碳添加量设置对照(CK)、稻秆(RS)及300、400℃和500℃下制备的稻秆生物炭(RSB300、RSB400、RSB500)5个处理,对比分析了稻秆及稻秆生物炭添加0、30 d与120 d时,稻田红壤中可溶性有机碳(DOC)、总有机碳(TOC)、游离态粗颗粒有机碳(fcPOC)、游离态细颗粒有机碳(ffPOC)、闭蓄态颗粒有机碳(oPOC)、游离态矿物结合态有机碳(fMOC)及闭蓄态矿物结合态有机碳(oMOC)的变化差异,并探讨了稻田红壤CH₄和CO₂累积排放量与各有机碳组分含量的相关关系。结果表明:稻秆生物炭添加后稻田红壤中DOC、TOC、fcPOC、ffPOC、oPOC和fMOC含量均显著增加;其中,oPOC与oMOC含量随着培养时间的增加而显著增加,但fcPOC与fMOC含量则显著降低(P<0.05)。与CK处理相比,RS处理的稻田红壤中CH₄和CO₂的累积排放量均显著且持续增加;RSB各处理的稻田红壤中CO₂的累积排放量显著降低;只有RSB300和RSB400处理的稻田红壤中CH₄的累积排放量显著增加,且在培养120 d时分别增加了188.5%和32.7%(P<0.05)。相关性分析表明,添加稻秆及稻秆生物炭的稻田红壤中CH₄和CO₂累积排放量虽与DOC、ffPOC和fcPOC含量均呈极显著正相关关系,但其中DOC和fcPOC含量起主导作用(P<0.01)。研究表明,添加稻秆生物炭可以有效提高稻田红壤中各有机碳组分的含量与稳定性,且500℃热解制备的稻秆生物炭添加对稻田红壤中CH₄、CO₂累积排放量抑制效果最好。     

The effects of co-utilizing green manure and rice straw on soil aggregates and soil carbon stability in a paddy soil in southern China

The co-utilization of green manure (GM) and rice straw (RS) in paddy fields has been widely applied as an effective practice in southern China. However, its effects on soil aggregate and soil organic carbon (SOC) stability remain unclear. In the present study, the effect of GM, RS, and co-utilization of GM and RS on particle size distribution of soil aggregates and SOC density fractions were measured in a field experiment. The experiment included six treatments, i.e., winter fallow (WF) without RS return (Ctrl), WF with 50% RS return (1/2RS), WF with 100% RS return (RS), GM without RS return (GM), GM with 50% RS return (GM1/2RS) and GM with 100% RS return (GMRS). The results showed that the proportion of small macro-aggregates (0.25–2 mm) and the mean weight diameter (MWD) of aggregates in the GMRS treatment was greater (by 18.9 and 3.41%, respectively) than in the RS treatment, while the proportion of silt+clay particles (<0.053 mm) was lower (by 14.4%). The concentration of SOC in microaggregates (0.053–0.25 mm) and silt+clay particles was higher in the GMRS treatment than in GM and RS treatments individually. The concentration and proportion of free light organic carbon (fLOC) in aggregates of various particle sizes and bulk soil was greater in the GMRS treatment than the RS treatment, whereas the concentration and proportion of mineral-associated organic carbon in small macroaggregates, microaggregates, and bulk was lower in the GMRS treatment than in the RS treatment. The proportion of intra-aggregate particulate organic carbon (iPOC) was greater in the GMRS treatment than in GM treatment. The GMRS treatment had strong positive effects on iPOC in small macroaggregates, suggesting that SOC was transferred from fLOC to iPOC. In conclusion, co-utilizing green manure and rice straw cultivated the SOC pool by increasing the concentration of fLOC and improved soil carbon stability by promoting the sequestration of organic carbon in iPOC as a form of physical protection.     

Effects of long-term straw return on soil organic carbon fractions and enzyme activities in a double-cropped rice paddy in South China

Long-term straw return is an important carbon source for improving soil organic carbon(SOC) stocks in croplands, and straw removal through burning is also a common practice in open fields in South China. However, the specific effects of long-term rice straw management on SOC fractions, the related enzyme activities and their relationships, and whether these effects differ between crop growing seasons remain unknown. Three treatments with equal nitrogen, phosphorus, and potassium nutrient inputs, including straw/ash and chemical nutrients, were established to compare the effects of straw removal(CK), straw return(SR), and straw burned return(SBR). Compared to CK, long-term SR tended to improve the yield of early season rice(P=0.057), and significantly increased total organic carbon(TOC) and microbial biomass carbon(MBC) in double-cropped rice paddies. While SBR had no effect on TOC, it decreased light fraction organic carbon(LFOC) in early rice and easily oxidizable organic carbon(EOC) in late rice, significantly increased dissolved organic carbon(DOC), and significantly decreased soil p H. These results showed that MBC was the most sensitive indicator for assessing changes of SOC in the double-cropped rice system due to long-term straw return. In addition, the different effects on SOC fraction sizes between SR and SBR were attributed to the divergent trends in most of the soil enzyme activities in the early and late rice that mainly altered DOC, while DOC was positively affected by β-xylosidase in both early and late rice. We concluded that straw return was superior to straw burned return for improving SOC fractions, but the negative effects on soil enzyme activities in late rice require further research.     

有机物料培肥对风沙土结合态腐殖质中富里酸与胡敏酸的影响

通过不同的试验设计 ,三年间对风沙土进行秸秆等有机物料培肥 ,研究其结合态腐殖质中富里酸与胡敏酸含量的变化。结果表明 ,不同的有机物料培肥均能提高风沙土松结态、稳结态富里酸的含量 ,处理间胡敏酸含量的变化不十分明显 ,但胡敏酸与松结态、稳结态腐殖质的比值 ,随着培肥年限的增加 ,与 CK处理比较 ,有降低的趋势。松结态、稳结态腐殖质中胡敏酸与富里酸的比值 ,与 CK处理比较 ,也呈降低趋势。经统计分析表明 ,以处理低量麦秸 +泥炭全肥 +泥炭效果最好。     

Fractionation of soil organic carbon in a calcareous soil after long-term tillage and straw residue management

No-tillage (NT) and straw return (S) collectively affect soil organic carbon (SOC). However, changes in the organic carbon pool have been under-investigated. Here, we assessed the quantity and quality of SOC after 11 years of tillage and straw return on the North China Plain. Concentrations of SOC and its labile fractions (particulate organic carbon (POC), potassium permanganate-oxidizable organic carbon (POXC), microbial biomass carbon (MBC), and dissolved organic carbon (DOC)), components of DOC by fluorescence spectroscopy combined with parallel factor analysis (PARAFAC), and the chemical composition of SOC by ¹³C NMR (nuclear magnetic resonance) spectroscopy were explored. Treatments comprised conventional tillage (CT) and NT under straw removal (S0), return of wheat straw only (S1), or return of both wheat straw and maize residue (S2). Straw return significantly increased the concentrations and stocks of SOC at 0–20 cm depth, but NT stratified them with enrichment at 0–10 cm and a decrease at 10–20 cm compared to CT, especially under S2. Labile C fractions showed similar patterns of variation to that of SOC, with POC and POXC more sensitive to straw return and the former more sensitive to tillage. Six fluorescence components of DOC were identified, mainly comprising humic-like substances with smaller amounts of fulvic acid-like substances and tryptophan. Straw return significantly decreased the fluorescence index (FI) and autochthonous index (BIX) and increased the humification index (HIX). No-tillage generally increased HIX in topsoil but decreased it and increased the FI and BIX below the topsoil. Relative abudance order of the chemical composition of SOC was: O-alkyl C>alkyl-C>aromatic-C>carbonyl-C. Overall, NT under S2 effectively increased SOC and its labile C forms and DOC humification in topsoil and microbially-derived DOC below the topsoil. Return of both wheat and maize straw was a decisive factor in promoting SOC in the plow layer. The stratification of SOC under NT may confer a long-term influence on carbon sequestration.     

珠三角地区稻田土壤和谷粒中邻苯二甲酸酯(PAEs)的分布特征及人体健康暴露风险

选择珠三角地区(东莞、惠州、广州、番禺)4个水稻种植区,采集土壤(30个)和水稻谷粒(37个)样品,通过超声提取进行样品前处理,利用气相色谱-质谱仪(GC-MS)分析9种邻苯二甲酸酯(PAEs)化合物的含量,研究PAEs的污染特征和人体健康暴露风险。结果表明,4个地区稻田土壤中PAEs总含量(∑PAEs)为3.25~8.05 mg·kg-1(平均为5.25 mg·kg-1),水稻谷粒的∑PAEs为1.77~4.13 mg·kg-1(平均为2.93 mg·kg-1),两者均以东莞的平均值最高,分别为(6.26±1.45)mg·kg-1和(3.13±0.71)mg·kg-1。土壤和水稻谷粒中PAEs均以邻苯二甲酸正二丁酯(DBP)、邻苯二甲酸双(2-乙基己基)酯(DEHP)和邻苯二甲酸二异丁酯(DIBP)为主,三者的累计含量占∑PAEs的85%以上。水稻谷粒对PAEs化合物的生物富集系数在0.37~1.27之间,部分DBP、DIBP、DEHP的大于1。大米和谷壳中∑PAEs分别为1.33~3.22 mg·kg-1(平均为2.17 mg·kg-1)和0.81~2.61 mg·kg-1(平均为1.43 mg·kg-1)。若人体食用这些大米,成人和儿童对DBP和DEHP的日均摄入量均小于10μg·kg-1bw·d-1,低于美国环保局推荐的日允许摄入量(DBP:100μg·kg-1bw·d-1,DEHP:20μg·kg-1bw·d-1),健康暴露风险较小。但人体通过食用大米的长期低剂量暴露不容忽视。     

不同碳氮比物料有机肥中腐殖酸含量、 化学组成与结构特征研究

采用重铬酸钾容量法、元素分析、傅立叶变换红外光谱和固体¹³C核磁共振技术对不同碳氮比物料有机肥中腐殖酸含量、化学组成和结构特征进行了初步研究。结果表明,4种不同碳氮比物料配方有机肥中腐殖酸主要为游离腐殖酸,占98%以上;随着碳氮比提高,总腐殖酸和游离腐殖酸含量增加,水溶性腐殖酸降低,但碳氮比25～30:1之间差异很小。4种有机肥腐殖酸主要由C、H、O、N等元素组成;其结构都主要由脂肪碳、含氧脂肪碳、芳香碳和羧基碳、羰基碳等组成。不同碳氮比物料配方有机肥中腐殖酸在官能团上存在差别,20:1有机肥中碳水化合物（或多糖）和羧酸等含氧基团要明显多于其他比例有机肥。