紫色土可溶性有机碳的吸附-解吸特征

选择代表性的酸性、中性和石灰性紫色土为实验材料,采用平衡吸附和动力学吸附法研究了紫色土对可溶性有机碳（DOC）的吸附-解吸特征,分析了土壤理化性质与DOC吸附量之间的关系。结果表明,紫色土对DOC的吸附容量呈以下顺序：酸性紫色土〉中性紫色土〉石灰性紫色土。石灰性紫色土对DOC的解吸率明显高于酸性、中性紫色土,其迁移淋失问题值得重视。紫色土对DOC的吸附过程包括快速吸附和慢速吸附2个阶段,0~0.5 h内吸附速率最大,随后吸附速率逐渐减小,4~6 h内基本达到吸附平衡。土壤pH值、有机质、粘粒和活性铁铝氧化物含量是影响土壤DOC吸附量与解吸率的重要因素。通径分析表明,土壤理化性质对DOC吸附量的直接作用系数大小顺序为活性铝含量〉土壤pH值〉有机质,对DOC解吸率的直接作用系数大小顺序为活性铁含量〉粘粒〉有机质。多元线性回归模型能较好地预测土壤对DOC的吸附及解吸的变化。     

溶解性有机质对紫色土中锌形态分布的影响

溶解性有机质(Dissolved Organic Matter)作为有机质中生物活性和物理化学反应活性较为活跃的重要组成部分,对土壤中锌的形态分布有着重要影响,本文采用室内培养的方法,在相同的温度和湿度条件下,分析了两种不同来源的DOM在不同浓度梯度下对紫色土外源锌形态分布的影响,得出以下结论:(1)紫色土在添加DOM后,显著地促进了外源锌各形态之间的相互转化分布,酸性紫色土中DOM促进了外源锌由EX-Zn向其它形态转化,这对于减少土壤锌污染的植物毒性有一定的作用。石灰性紫色土中主要促进RES-Zn向其它形态转化,提高了锌对植物的有效性;(2)两种DOM对酸性紫色土的影响优于石灰性紫色土,影响效果DOM2>DOM1;(3)酸性紫色土形态间的相关关系程度显著,石灰性紫色土形态间的相关关系程度不显著。     

模拟硝田土壤铁和硫的形态转化特征及其影响因素

采用室内培养试验,在确定模拟硝田土壤硫酸钠含量的基础上,观测并探讨落干/淹水状况、有机物质种类与数量对模拟硝田土壤铁和硫形态转化特征的影响。结果表明:全铁(Fet)和游离铁(Fed)受落干/淹水状态和有机物质种类与数量的影响均不显著,而活性铁(Feo)、络合铁(Fep)、亚铁离子(Fe(II))及有效铁(Fea)受淹水及有机物质数量的显著影响,Fe(II)、Fea还受有机物质种类的显著影响;硫形态转化同时受淹水及有机物质种类与数量的影响;土壤铁、硫形态转化一方面通过有机物质与铁、硫的直接作用实现,一方面通过改变土壤氧化还原电位(Eh)及还原性物质总量(TARM)等氧化还原状况实现;铁与硫的形态转化也表现出一定的耦合关系。     

有机物料对紫色土有机磷含量及植物磷吸收的影响

采用盆栽试验,研究了4种有机物料对酸性、中性和石灰性紫色土有机磷含量及玉米幼苗磷的吸收与利用的影响。结果表明,等磷条件下,与化肥(HF)相比,猪粪沼渣(ZZ)使3种土壤有机磷含量显著提高,牛粪秸秆堆肥(NJD)和污泥堆肥(WD)的影响不显著,牛粪沼渣(NZ)的影响在酸性紫色土(APS)和中性紫色土(NPS)中不显著,但使石灰性紫色土(CPS)有机磷含量显著提高。有机物料降低了3种土壤的有效磷含量,对玉米幼苗根干重的影响不明显,却使除APS中NJD外的处理玉米幼苗地上部干重下降。除酸性紫色土的WD和NJD处理外,所有有机物料处理玉米幼苗磷的吸收量和表观利用率均低于HF处理。在所研究的有机物料中,WD和NJD处理土壤有效磷含量高于NZ和ZZ处理,玉米幼苗磷的吸收量和表观利用率以WD处理最高,NZ处理最低。研究还表明,酸性和中性紫色土有机磷含量与有机物料中的有机磷含量显著相关,在石灰性紫色土中则与土壤有机质含量显著相关,而土壤有效磷含量与物料中易溶性磷含量的高低一致。因而,施用有机物料时,不仅要考虑有机物料中的磷含量,还应关注有机物料中的磷形态及施用的土壤类型,并适当补充化肥。     

钙质钝化材料对四川盆地6种主要旱作土壤Cd的钝化效应

为针对性、定量化地利用钝化处理实现不同类型Cd污染土壤的安全利用,以四川盆地6种主要旱作土壤为研究对象,采用室内培养试验和土培试验探讨了6个剂量水平下,钙质钝化材料对土壤pH、CEC、有效Cd含量、Cd形态、小白菜生物量和Cd含量的影响。结果表明:(1)钙质钝化材料可提升6种土壤的pH和CEC,土壤CEC随用量的增加而持续增加,而土壤pH在提升至微碱性水平后,不再随用量的增加而增加;(2)6种土壤有效Cd含量随钝化材料用量的增加先显著降低,后趋于平稳,用量＞2.5%后均无显著变化。该添加量下,有效Cd含量降幅为典型黄壤(63.32%)＞酸性紫色土(46.65%)＞漂洗黄壤(38.51%)＞中性紫色土(34.97%)＞石灰性紫色土(18.03%)＞灰潮土(16.60%);土壤中可交换态Cd主要向碳酸盐结合态、铁锰氧化物结合态和残渣态形态转化;(3)除石灰性紫色土外,钙质钝化材料可显著提升其余5种污染土壤中小白菜的生物量并显著降低其可食部位Cd含量。用量为2.5%时,典型黄壤、漂洗黄壤和酸性紫色土中小白菜Cd含量降幅高达84.28%,79.90%,69.87%,显著优于中性紫色土、灰潮土和石灰性紫色土(5%用量时降幅仅为40.27%,31.13%,17.98%)。该研究揭示钙质钝化材料对6种Cd污染旱作土壤的剂量-效应差异,并在典型黄壤、漂洗黄壤和酸性紫色土中钝化效率较优,为不同土壤条件下钙质钝化材料的合理使用提供科学依据。     

紫色土施氮对莴笋营养效应的研究

3种紫色土施用化学氮肥盆栽莴笋的研究结果表明,石灰性紫色土莴笋生长状况最差,施中、高氮明显降低其株高、根重和茎、叶产量,而中性紫色土施氮的生物效应最佳。酸性紫色土莴笋叶片((NO3--N)/(TN)100)值最低、((AAN)/(TN)100)值最高;植株氮素表观利用率为中性土酸性土石灰性紫色土。中性、酸性和石灰性紫色土施氮分别为133、67、67mg/kg土时,莴笋3个生长期叶片N/P、N/K、K/P值变异系数(C.V％)小,生物量高。施氮显著提高中性和石灰性紫色土莴笋叶片NRA(r值0.9275*～0.9956* *),降低CAT活性和Vc含量,使茎中(△NO3-)/(△FN)值高于酸性紫色土2～5倍,但却提高酸性紫色土莴笋水溶性氨基酸、粗蛋白和可溶性糖含量,改善其食用价值。     

水耕人为土时间序列铁氧化物与磁化率演变特征

以我国亚热带地区不同母质起源的水耕人为土时间序列为研究对象,分析不同形态铁氧化物和磁化率随成土时间的动态演变特征及其影响因素。结果表明,石灰性母质起源的水耕人为土0~120 cm土体中全铁(Fet)、游离铁(Fed)和游离度(Fed/Fet)随时间序列演变均逐渐增加,0~50 a内Fet、Fed和Fed/Fet增加速率分别为3.2 t hm~(-2) a~(-1)、1.2 t hm~(-2) a~(-1)和0.04%a~(-1),50~1 000 a内Fet、Fed和Fed/Fet增加速率分别为0.1 t hm~(-2) a~(-1)、0.15 t hm~(-2) a~(-1)和0.01%a~(-1);而酸性母质起源的水耕人为土0~120 cm土体中Fet、Fed和Fed/Fet随时间序列演变均逐渐下降,0~60 a内Fet、Fed和Fed/Fet下降速率分别为0.2 t hm~(-2) a~(-1)、0.5 t hm~(-2) a~(-1)和0.03%a~(-1),60~300 a内Fet、Fed和Fed/Fet下降速率分别为0.9 t hm~(-2) a~(-1)、1.2 t hm~(-2) a~(-1)和0.06%a~(-1)。土壤pH、Eh、以及外源铁输入与土体内铁淋失的相对强度是控制不同母质水耕人为土中铁氧化物转化速率与途径的主要因素。石灰性母质起源的水耕人为土中不同磁学指标随时间演变分为三个阶段:0~50 a内表现为质量磁化率(MS)、饱和等温剩磁(SIRM)和软剩磁(IRMs)的急剧降低;50~300 a内表现为MS、SIRM和IRMs的持续、缓慢降低以及硬剩磁(IRMh)的相对稳定发展;300~1 000 a内表现为MS、SIRM和IRMs的持续、缓慢降低以及IRMh的快速下降。酸性母质起源的水耕人为土0~20 cm和20~120 cm土壤中磁学指标演变呈现截然不同的两个阶段:0~60 a 0~20 cm内MS,SIRM和IRMs的急剧降低,IRMh具有明显增加;而20~120 cm内MS、SIRM和IRMs缓慢下降,IRMh明显降低。60~300 a 0~20 cm内不同磁学指标变化幅度均很小,而20~120 cm内IRMh相对比较稳定,MS、SIRM和IRMs在种稻150 a后快速下降。淹水还原条件下亚铁磁性矿物的破坏是不同母质水耕人为土演变过程中磁性衰减的主要机制。     

缓释复合肥料在不同pH值紫色土中氨挥发特性（简报）

采用“通气法”室内培养试验,研究了非包膜缓释复合肥（SRF）施入不同pH值紫色土壤后的氨挥发损失状况和动力学特性。结果表明,土壤pH值对SRF氨挥发有极显著影响,随着土壤pH值升高,氨的挥发损失增加,以石灰性紫色土＞中性紫色土＞酸性紫色土。与大粒尿素（PUR）相比,SRF的氨挥发速率和损失量显著降低。在石灰性紫色土中SRF氨挥发分别减少14.2%和7.18%,中性紫色土中SRF氨挥发分别减少32.3%和24.1%,酸性紫色土中SRF氨挥发分别减少76.8%和10.7%。3种紫色土中,SRF的氨挥发动力学特性可用一级动力学方程、E1ovich方程和抛物线扩散方程定量描述,根据这些模型可在给定时间内预测SRF的氨挥发量。SRF能大大减少在不同pH值土壤中因施肥造成的氮肥损失,从而减轻对环境的污染。     

重庆市紫色土系统分类高级单元划分研究

依据中国土壤系统分类的原则和方法,对重庆市境内的41个紫色土典型剖面进行鉴别、检索和分类定名,并与其发生分类进行参比。结果表明,41个紫色土典型剖面分别被划归为4个土纲(人为土、淋溶土、雏形土和新成土)、6个亚纲、12个土类和19个亚类等系统分类高级单元,被划归为雏形土土纲的剖面最多,其次为新成土土纲,仅有9个剖面被划归为紫色湿润雏形土或紫色正常新成土;雏形土土纲和新成土土纲均分别对应紫色土发生分类的3个亚类(酸性紫色土、中性紫色土和石灰性紫色土),而淋溶土土纲则仅与酸性紫色土1个亚类相对应;地形、海拔、母岩和人为活动与紫色土的土壤水分状况、剖面发育、颜色以及其他理化性质等关系密切,是影响重庆市紫色土系统分类高级单元划分的重要因素;针对多数紫色土个体达不到紫色砂、页岩岩性特征的色调标准以及铁质湿润雏形土的下设亚类不能充分反映紫色土属性(如石灰性、酸性等)差异等问题,建议适当放宽紫色砂、页岩岩性特征的颜色要求或增设石灰铁质湿润雏形土和酸性铁质湿润雏形土2个亚类。     

石灰性土壤中铁肥的形态转化及其供铁机理研究

通过土培试验的方法 ,研究了复混铁肥、硫酸亚铁两种肥料在石灰性土壤中的形态转化、对土壤因子的调控作用及在有效性上的差异。结果表明 ,与硫酸亚铁相比 ,复混铁肥具有更强的调控土壤因子的能力 ,并提高了铁在有效和较有效形态中的分配 ,显著增加了有效铁的供给。结果也表明 ,交换态铁、碳酸盐结合态铁和氧化锰结合态铁是石灰性土壤中有效铁的主要供给形态。土壤pH值、有机质与土壤铁动态密切相关     

EGCG溶液浓度与酸碱度对黄壤Al、Fe和Mn形态的影响

植物多酚可通过络合作用改变元素的存在形态。采用双因素完全随机试验设计,通过浸提试验研究表没食子儿茶素没食子酸脂(EGCG)溶液浓度、酸碱度、浓度与酸碱度互作对黄壤可溶态、游离态、无定形态和络合态铝(Al)、铁(Fe)和锰(Mn)的影响。结果表明:EGCG溶液浓度对黄壤可溶态和络合态Al、Fe、Mn及无定形态Al、Fe均产生极显著影响,EGCG溶液酸碱度对黄壤可溶态及无定形态Al、Fe、Mn均产生显著或极显著影响,EGCG溶液浓度与酸碱度对黄壤可溶态Al、Fe、Mn,无定形态和络合态Al也有极显著或显著的互作效应。相关分析结果显示,土壤中3种元素的无定形态氧化物含量与对应的可溶态氧化物含量呈显著或极显著负相关,表明EGCG溶液主要通过改变氧化物形态,特别是无定形态氧化物含量,影响元素活化,进而改变其可溶态含量;Al和Mn的活化会使土壤滤液pH降低,在pH降低幅度较大时,可能导致土壤酸化。本试验一方面为研究酸性茶园土壤酸化的来源提供了方向,另一方面也可为植物Al/Mn毒害的防治提供参考,但在利用植物多酚类物质防治土壤Al/Mn毒害的同时要处理好土壤酸化与治理毒害的关系。     

由石灰性冲积物发育而来的排水不良和排水良好的土壤中游离氧化物的分布

A study on the distribution of free iron and manganese oxides was conducted in soils developed on calcareous alluvial deposits under subhumid climatic conditions, in Western Greece. Soil samples from two well drained soils and from two poorly drained soils, classified as Alfisols, were collected and used in this study. After certification of soil homogeneity the acid ammonium oxalate and dithionite-citrate-bicaxbonate methods were used to extract free iron and manganese oxides from the samples. Iron oxides extracted by the dithionite-citrate-bicarbonate method (Fed) were significantly higher than the iron oxides extracted by the ammonium oxalate method (Feo), indicating that a considerable fraction is present in crystalline forms, independent of drainage status. A confirmation of free iron oxides and fine clay was detected. The ratios Feo/Fed and (Fed-Feo)/total Fe (Fet) could not be used to distinguish the well drained soils from the poorly drained soils. Manganese movement in a soluble form is independent of the fine clay.     

Low‐molecular‐weight organic acids enhance desorption of polycyclic aromatic hydrocarbons from soil

The impact of low‐molecular‐weight organic acids (LMWOAs) on desorption of phenanthrene and pyrene as representative polycyclic aromatic hydrocarbons (PAHs) from a contaminated soil was investigated by using a laboratory batch experiment. Three LMWOAs were used in this study and were citric, oxalic and malic acids. The LMWOAs in aqueous solution promoted desorption of PAHs from soil significantly and demonstrated an increasing trend as the concentration of LMWOAs increased. When compared with desorption of phenanthrene and pyrene from soil to water, the addition of LMWOAs enhanced desorption of test PAHs by up to 285 and 299%, respectively. Among the three LMWOAs studied, citric acid demonstrated the greatest efficiency in promoting PAH desorption from soil. Solutions of LMWOA continuously promoted PAH removal from soil during the multiple cycles of desorption. Overall, the experimental results suggest that LMWOAs in aqueous solution could disrupt soil organic matter (SOM)–metal cation–mineral linkages in soils, resulting in the release of SOM from soil and simultaneous increase of dissolved organic carbon (DOC) in solution. The loss of SOM from soil and increase of DOC in solution are responsible for the enhanced PAH desorption from soil. The positive correlation between DOC in solution and desorbed PAHs from soil suggests that the loss of SOM from soil plays an important role in LMWOA‐enhanced desorption of PAHs from soil.     

珠江三角洲平原不同种植年限土壤铁氧化物特征研究

珠江三角洲平原具有上千年的围垦历史,其土壤发生演变过程深受人为作用影响,开展此区域不同种植年限土壤中铁氧化物形态特征和分布规律的研究,能够揭示人为耕种下土壤发生演变过程。以珠江三角洲平原不同种植年限的土壤剖面为对象,研究了滨海沉积物、河流冲积物和三角洲沉积物发育的土壤及黏粒中全铁、游离铁含量变化及其影响因素。结果表明:随着种植年限的增加,河流冲积物、三角洲沉积物发育土壤中游离铁(Fe_d)向土体下部淀积深度逐渐增加,黏粒中游离铁(Fe_(d(clay)))含量在水耕氧化还原层中呈减小趋势,而滨海沉积物发育的土壤Fe_d含量及淀积深度均有所减小。随着种植年限的增加,滨海沉积物发育的土壤全铁(Fe_t)和游离铁(Fe_d)在黏粒中的富集程度呈增大趋势,而河流冲积物、三角洲沉积物发育的土壤Fe_t和Fe_d富集程度逐渐减小。土壤Fe_d与Fe_t、黏粒游离铁(Fe_(d(clay)))与黏粒全铁(Fe_(t(clay)))均呈极显著正相关;全铁富集率(Fe_(t(clay))/Fe_t)、游离铁富集率(Fe_(d(clay))/Fe_d)均与Fe_(t(clay))、Fe_(d(clay))、黏粒铁游离度(Fe_(d(clay))/Fe_(t(clay)))呈极显著正相关,与Fe_t、Fe_d、土壤铁游离度(Fe_d/Fe_t)、黏粒含量呈极显著负相关,且Fe_(t(clay))/Fe_t与Fe_(d(clay))/Fe_d呈极显著正相关,表明土壤铁氧化物在黏粒中的富集以Fe_d为主,且铁氧化物的富集程度受土壤黏粒含量的影响。     

低分子量有机酸对石灰性潮土无机磷形态转化的影响

无菌培养条件下,模拟缺磷胁迫时植物根系分泌的低分子量有机酸种类和数量,采用石灰性土壤无机磷分级方法,研究了低分子量有机酸对石灰性潮土无机磷形态转化的影响。结果表明:①在石灰性潮土中无机磷主要以有效性较低的磷酸钙盐(Ca10-P等)形式存在,而有效性较高的形式(Ca8-P等)含量较少,Ca2-P就更少。②有机酸通过结合土壤中可以使磷固定的Ca、Fe及Al,致使根际范围酸化,促进磷酸盐的形态转换,增加磷的有效性。这种促进能力因有机酸种类和性质的不同而异,其促进能力大小顺序为草酸>柠檬酸>酒石酸。     

Geochemistry of Aluminium and Iron in Mine Soils from As Pontes,Galicia (N.W. Spain)

The geochemical processes influencing iron and aluminium mobilization and immobilization processes in mine soils are discussed. The study was carried out on 11 soils from the As Pontes mine dump, in the process of reclamation. The soils differ in age, spoils nature, reclamation tasks and type of vegetation, covering a wide range of physico-chemical conditions. Oxalate and pyrophosphate extractable Al and Fe (Alo, Alp, Feo, Fep), and dithionite extractable Fe (Fed) were analysed. These fractions were related to the solution Al and Fe forms and contents and to other soil properties (Eh, pH, sulfides, organic matter, cation exchange capacity, and composition of the soil solution). Alo ranged between 2.2 and 111.2 cmolc kg-1; 5 to 80% of this Alo was organic aluminium (Alp). Fed ranged between 8.5 and 215.6 cmolc kg-1; 20 to 70% was poorly-criystalline iron (Feo). The solution concentrations of Al and Fe ranged between <0.1 and 319.2, and between <0.1 and 46.7 mg L-1, respectively. The results showed that the spoil nature (mostly carbonaceous clays and slates differing in sulfide content) and the reclamation tasks undertaken (topsoiling, liming with fly ash) determine the forms and contents of Al and Fe in the solid phase as well as in the soil solution and also its distribution between the solid and liquid phases.     

Impact of low-molecular-weight organic acids on the availability of phenanthrene and pyrene in soil

The impact of low-molecular-weight organic acids (LMWOAs) on the availability of phenanthrene and pyrene was investigated using laboratory batch assays. Experiments were conducted with two types of soil with different organic contents. The LMWOAs used were citric and oxalic acid. A mild solvent extraction procedure and a sorption-desorption experiment were used to predict the availability of phenanthrene and pyrene. Results showed that the extractable amounts of phenanthrene and pyrene in both soil types increased with increased citric or oxalic acid concentration. Citric acid addition promoted phenanthrene and pyrene extraction to a greater degree than oxalic acid. Compared with freshly spiked soils, the extractable amounts of phenanthrene and pyrene with the addition of LMWOAs decreased significantly after 60 days of cultivation. Soils with higher values of soil organic carbon content (f_oc) showed decreased phenanthrene and pyrene availability after the addition of LMWOAs. The sorption and desorption results also demonstrated the enhanced availability of PAHs with LMWOA addition. Phenanthrene sorption could be described using a linear model, regardless of the addition of LMWOAs. The simulated distribution constants (K_d) for phenanthrene sorption decreased significantly with the addition of LMWOAs. In contrast, phenanthrene desorption clearly increased with the addition of LMWOAs. These results suggest that the availabilities of phenanthrene and pyrene can be increased with the addition of suitable LMWOAs.     

Distribution of iron and manganese oxides in Haploxeralfs and Rhodoxeralfs and their relation to the degree of soil development and soil colour

The status and the distribution of iron and manganese oxides were studied in six soil profiles from Thrace region (Greece), classified as Rhodoxeralfs and Haploxeralfs. The acid ammonium oxalate and the dithionite-citrate-bicarbonate methods were used to extract the free iron and manganese oxides from the soils. In both great groups the Fed and Mnd values are higher than Feo and Mno values, respectively, indicating that a considerable fraction is present in crystalline form. Both Feo/Fed and Fed-Feo values suggest that, in the study area, Haploxeralfs are less developed soils than Rhodoxeralfs. The manganese oxides present in crystalline forms (Mnd-Mno) were more in Rhodoxeralfs than in Haploxeralfs, suggesting that the crystallinity of manganese oxides increases, with the degree of soil development. Significant correlations were found of Redness Rating to Fed-Feo and to Feo/Fed ratio, positive and negative respectively, leading to the conclusion that soil red colouration increases with the degree of soil development.     

海南岛北部玄武岩上土壤发生研究Ⅱ.铁氧化物特征

研究了海南岛北部玄武岩上发育的不同风化成土年代土壤系列的铁氧化物特征。研究表明,随风化成土时间增加,土壤发生过程中形成的游离铁（Fed）以及铁游离度（Fed/Fet）增大,铁活化度（Feo/Fed）降低。穆斯堡尔谱分析显示风化成土时间从9×104a、64×104a至 181× 104a,土壤黏粒中形成的赤铁矿含量占铁氧化物的比例从16％、25％增至 48％。风化成土时间越短,土壤中针铁矿结晶程度越差。X-射线衍射结果表明土壤细土和黏粒中赤铁矿含量与风化成土时间呈正比增加。同时,土壤有磁铁矿含量减少、磁赤铁矿增加的趋势。