不同土壤对钾的选择吸附特性

用K Ca交换平衡法对砖红壤、红壤、土、黑土和水稻土K的选择吸附特性研究结果表明 :KG 和KV 系数随着K Ca平衡体系中吸附相中钾与钙比率的变化而改变 ,其曲线特征说明土壤胶体存在着对K亲和力不同的吸附点位。在低钾饱和度时 ,土壤对K的高选择吸附主要归于粘粒矿物楔形区域电荷点位吸附 ,五种土壤楔形区域相对吸附点位顺序为 :黑土 >土 >水稻土 >红壤 >砖红壤 ,该相对吸附点位顺序与土壤含有风化云母和蛭石有关。在高钾饱和度时 ,五种土壤对K的吸附主要发生于粘粒矿物的晶层表面电荷点位 ,粘粒矿物的晶层表面电荷起源也许起决定作用 ,此时KG 选择系数的大小顺序为 :砖红壤 >红壤 >黑土 >土 >水稻土     

玄武岩发育的几种红壤的矿物特征

本文主要研究不同生物气候条件下由玄武岩母质发育的红壤、赤红壤和砖红壤的理化性质及矿物组成。粘粒中氧化铁的含量都很高,为16.98±0.83%。砖红壤与赤红壤粘粒中高岭石与非晶物质的含量相近,它们之间的差异是赤红壤中没有三水铝石,而含有7—11%蒙皂石。红壤粘粒中高岭石和非晶物质的含量都低于砖红壤和赤红壤,而水云母和蒙皂石的含量较高,也没有三水铝石。粘粒含量、阳离子交换量、硅铝率、硅铁铝率、铁的游离度和风化淋溶系数等都反映了土壤风化程度上的差异,它与水热条件特别是年均温和积温有关,进一步说明生物气候因素引起的土壤性质及矿物组成变化比其它因素强烈。砖红壤与砖红壤性水稻土的差异是在氧化铁形态上;红壤与红壤性水稻土相比,后者粘粒中蒙皂石含量略高,水云母含量略低。     

不同利用年限红壤水稻土有机碳和养分含量的粒级分布变化

通过田间采样结合沉降法分级提取,研究了不同利用年限红壤水稻土有机碳和养分含量的粒级分布变化特征。结果表明,红壤水稻土有机碳和养分含量随土壤颗粒粒径的增大而下降,但在各粒级中的分布比例存在显著差异。<0.002mm、0.002～0.02mm、0.02～0.05mm、>0.05mm粒级的有机碳占全土有机碳的比例分别是29.2%、30.7%、11.9%、15.4%,氮的相应数值为36.7%、31.9%、10.2%、14.0%,磷为49.2%、26.5%、11.1%、12.4%,钾为36.9%、33.4%、12.9%、20.0%。总体来说,黏粒和粉粒中有机碳和养分的分布比例较高。红壤水稻土有机碳和养分含量及分布比例还随利用年限而有明显变化。开垦利用不到10a的水田土壤,有机碳和养分含量较低且主要集中在<0.002mm粒级中;而利用超过10a的水稻土,有机碳和养分在粉粒中(0.002～0.05mm)的比例大于50%。各利用年限的红壤水稻土多以0.02～0.05mm粒级的C/N为最高,并随利用年限延长而下降。红壤水稻土各粒级有机碳和养分含量及分布状况随利用年限的变化反映了土壤肥力熟化和养分有效性的提高过程。     

红壤旱土和水稻土团聚体中磷素的分布特点

为深入探讨红壤磷素有效性的控制机理,研究了典型红壤旱土和水稻土团聚体中磷的组分与分布特点。结果表明:旱土和水稻土以粒径>0.2mm的团聚体为主,且在该级土壤团聚体中磷素含量较高;两种土壤>0.2mm团聚体中吸附态无机磷以Fe-P为主,而<0.02mm团聚体以O-P为主;水稻土>0.2mm和<0.002mm团聚体的各组分有机磷总量亦显著高于旱土对应的团聚体。说明土壤磷的形态分布与团聚体粒级有密切关系,旱土有效磷含量较低可能与其团聚体游离氧化铁含量较高、且有机磷含量较低有关。     

不同程度重金属污染对水稻土团聚体组成的影响

以太湖地区长期受重金属污染的稻麦轮作条件下的水稻土为研究对象,分别采取水稻收获期和小麦收获期不同重金属污染水平的土壤和临近非污染土壤(对照土壤),利用低能量超声分散分离技术将原状土进行团聚体分级,并结合土壤碳库分析,研究不同程度重金属污染对水稻土团聚体组成的影响。结果表明:随着重金属污染程度的增加,小麦收获期土壤2~0.2 mm与0.2~0.02 mm粒级的团聚体含量呈显著降低趋势,0.02~0.002 mm与0.002 mm粒级团聚体含量显著增加,但这种趋势在水稻收获期表现不显著;重金属污染降低了水稻季团聚体平均重量直径(MWD),从而降低了土壤的团聚程度,但这在小麦季并未表现出显著的降低作用;而小麦季重金属污染对原土及团聚体中有机碳含量没有显著影响,水稻季重金属污染则显著增加了土壤有机碳的含量。这些结果表明不同重金属污染程度对土壤团聚体组成的影响在不同的作物收获期表现不同,这可能与土壤团聚体周转过程受农田水分管理等措施影响有关,尚需深入研究。     

连续污泥农用对土壤微团聚体及有机质组分中 重金属分布的影响

采用物理和化学相结合的分组方法,将土壤逐级分离成不同粒径后再分出以有机无机复合体存在的重组,研究施加不同污泥后土壤中不同粒径颗粒、不同重组结合态腐殖质组分中铜锌镉的分配特征。结果表明,土壤重金属浓度随其粒径减小呈不断升高趋势,但施用污泥增加了土壤细砂粒级组分中的重金属所占比例,且随施用污泥中重金属浓度上升而增率升高。施加污泥后,不同粒径土壤颗粒中松结态腐殖质比例明显增加,紧结态腐殖质所占比例下降。施加污泥后土壤细砂颗粒松结态腐殖质中铜锌镉所占比例上升,紧结态腐殖质中铜锌镉所占比例下降。粉砂粒级松结态腐殖质中铜镉比例上升,紧结态腐殖质中铜镉所占比例下降。细粉砂和胶体粒级不同结合态腐殖质中铜锌镉比例没有明显变化。不同粒径组分土壤颗粒中重金属比例变化不仅与不同结合态腐殖质的比例有关,还与土壤颗粒大小和土壤性质有关。     

连续污泥农用对土壤微团聚体及有机质组分中 重金属分布的影响

采用物理和化学相结合的分组方法,将土壤逐级分离成不同粒径后再分出以有机无机复合体存在的重组,研究施加不同污泥后土壤中不同粒径颗粒、不同重组结合态腐殖质组分中Cu、Zn、Cd的分配特征。结果表明:土壤重金属浓度随其粒径减小呈不断升高趋势,但施用污泥增加了土壤细砂粒级组分中的重金属比例,且随施用污泥中重金属浓度上升而增加。施加污泥后,不同粒径土壤颗粒中松结态腐殖质比例明显增加,紧结态腐殖质所占比例下降。施加污泥后土壤细砂颗粒松结态腐殖质中Cu、Zn、Cd所占比例上升,紧结态腐殖质中Cu、Zn、Cd比例下降。粉砂粒级松结态腐殖质中Cu、Cd比例上升,紧结态腐殖质中Cu、Cd比例下降。细粉砂和胶体粒级不同结合态腐殖质中Cu、Zn、Cd比例没有明显变化。不同粒径组分土壤颗粒中重金属比例变化不仅与不同结合态腐殖质的比例有关,还与土壤颗粒大小和土壤性质有关。     

长期施肥下不同种植年限碱化草甸土水稳性团聚体及有机碳分布

以松嫩平原碱化草甸土为研究对象,通过长期施用有机肥,对不同种植年限碱化草甸土水稳性团聚体及有机碳的粒径分布特征进行了研究。结果表明,随着种植年限的增加,土壤较大粒级水稳性团聚体(>1mm)含量减少,而0.25~0.5mm粒级水稳性团聚体含量明显增加随种植年限的增加,各粒级碱化草甸土有机碳平均含量呈增加趋势。2~5mm粒级土壤有机碳平均含量最高,随粒级的减小,有机碳含量逐渐减少,0.25~0.5mm粒级水稳性团聚体含量与有机碳含量呈现显著正相关关系种植4a后,碱化草甸土土壤水稳性团聚体及有机碳含量开始呈现稳中有升的趋势。     

再生水灌溉下紫色水稻土颗粒态有机质中重金属的富集特征

颗粒态有机质(POM)属于活性较高的有机碳库,为了解在长期再生水灌溉条件下,灌区土壤POM是否会富集更多的重金属而对作物生长造成不利影响,研究比较6个不同灌溉年限(2,3,5,8,10,12年)的再生水灌溉区紫色水稻土中POM分布规律及重金属铜(Cu)、铅(Pb)和镉(Cd)的富集特征,以探明再生水灌溉条件下POM中重金属的动态变化过程及影响因素。结果表明,灌区紫色水稻土中1～0.05mm是POM的主要分布粒级,该粒级POM所占比例超过78%,>1mm的POM所占比例较低。灌区紫色水稻土中POM对重金属有较明显的富集作用,对Cu、Pb和Cd的平均富集系数分别为6.58,5.78和4.03,富集的Cu、Pb和Cd分别占土壤重金属总量的8.22%,7.27%和7.65%。随着再生水灌溉年限的增长,灌区紫色水稻土的重金属含量未超出土壤重金属环境质量二级标准,土壤有机质含量显著提高,而POM中重金属的富集系数呈下降趋势。POM中重金属的富集系数与灌溉时间的关系可用Elovich方程表示。     

土壤磁化率-温度(κ-T)曲线测定中的影响因素研究

土壤磁化率-温度曲线(κ-T)可用于鉴定土壤中磁性矿物类型。以水稻土、红壤、黄壤和砖红壤为对象,采用BaringtonMS2κ-T磁化率/温度系统,测定了不同土壤类型中磁性矿物种类。结果表明:水稻土κ-T曲线在300℃出现矿物相变点,黄壤、红壤和砖红壤在350℃出现相变点;水稻土和黄壤κ-T曲线呈现出磁铁矿的居里点(580℃),表明土壤磁性载体以磁铁矿为主;红壤和砖红壤的κ-T曲线呈现赤铁矿的居里点(680℃)。将水稻土和红壤分别制成2 mm、1 mm、0.30mm和0.15 mm的颗粒大小,称取相同质量土样(1 g)研究不同颗粒大小对土壤κ-T曲线测定的影响;称取过2 mm筛土样0.5 g、1 g、1.5 g和2 g,研究不同称样量对κ-T曲线测定的影响。结果表明:不同土壤类型,颗粒大小和称样量对κ-T曲线的测定有一定影响,但不会改变土壤中磁性矿物的相变点。它们对红壤和砖红壤的κ-T曲线测定影响甚少,对水稻土和黄壤的影响较大。实验证明在颗粒大小上选择过0.30 mm筛的土样,称样量上选择大于1 g的土样可以得到较明显的κ-T曲线,不会掩盖矿物的相变点。     

平原区水田改林地后土壤黏土矿物及氧化铁的变化

近年来水田改为林地在我国南方地区非常普遍,为了解这种转变对土壤矿物(黏土矿物和氧化铁)演变的影响,在浙江省平原地区构建了4个水田改林地系列土壤,采用野外调查和室内分析相结合的方法,研究水田改林地后土壤剖面中氧化铁形态和黏土矿物类型的演变规律。结果表明,改林地后,土壤剖面中全铁含量变化不明显,耕作层和犁底层土壤游离氧化铁有轻微增加趋势。改林地15～20 a后,4个系列土壤耕作层活性铁和活化度降幅分别在18.0%～38.4%和24.7%～48.9%;耕作层土壤铁氧化物的晶胶比增幅在0.73倍～1.62倍;耕作层土壤亚铁含量明显下降,降幅最高达95.8%,变异系数达到143.9%;耕作层络合铁降幅在21.3%～36.2%,并与有机质呈极显著正相关(P0.01)。改林地后,犁底层土壤中绿泥石相对含量及其与高岭石的比值都呈降低趋势,其他黏土矿物相对含量变化规律不明显,土壤有机质显著下降,土壤明显酸化。土壤铁氧化物形态和数量的变化对土壤结构以及土壤重金属的迁移转化等产生重要影响。     

中国东南部某些水稻土的矿物学

Limited information is available concerning the mineralogy of paddy soils in the southeastern China. Using chemical methods in conjunction with X-ray diffractometry, we studied the mineral composition of three paddy soils: Jinghua (paddy soil on Quaternary red clay), Fuyang (Hapl-percogenic loamy paddy soil), and Shaoxing (gleyic clayey paddy soil). All the soils contained quartz, mica, vermiculite, chlorite and kaolinite, and the distribution of these minerals varied with soil particle size fractions. The clay fraction of the Fuyang and Shaoxing soils also contained smectite. Although X-ray data did not show the presence of smectite in the Jinghua soil, this mineral was identified by the chemical method, suggesting a transitional property of the mineral in the soil. Hydroxy-Al interlayered minerals were also present in the clay fraction. The amount of smectite in the soils was 31.6 (Shaoxing), 16.5 (Fuyang), and 21.4 (Jinghua) g kg^-1; for vermiculite it was 33.3 (Shaoxing), 16.5 (Fuyang), and 8.5 (Jinghua) g kg^-1. Smectite was only found in the clay fraction. In contrast, amounts of vermiculite in soil particle size fractions were 3.0~11.4 (sand), 2.1~6.0 (coarse silt), 4.6~18.9 (medium silt), 0.9~40.0 (fine silt), and 17.0~108 (clay) g kg^-1. The amount of noncrystalline aluminosilicates in the soils in g kg^-1 decreased in the order: Shaoxing (2.4) > Jinghua (1.9) > Fuyang (1.7). This study has provided useful mineralogical information that is fundamental in future development of management strategies of the soils.     

水稻子实对不同形态重金属的累积差异及其影响因素分析

在分析成都平原核心区土壤重金属(Cd、Cr、Pb、Cu、Zn)全量、各形态含量及相应点位种植的水稻子实重金属含量的基础上,通过统计分析、空间插值及线性回归方程的模拟,研究了土壤Cd、Cr、Pb、Cu、Zn全量的空间分布状况、各形态重金属含量统计特征,以及水稻子实对重金属各形态的累积差异及其影响因素。结果表明,成都平原水稻土重金属污染较轻,除Cd外,均低于国家土壤环境质量二级标准。土壤中重金属的可交换态含量均较低,Cd主要以铁锰氧化态存在,Cr、Cu、Zn、Pb主要以残渣态存在。水稻子实对5种重金属的累积效应顺序为:Cd>Zn>Cu>Pb>Cr。与水稻重金属累积关系密切的重金属活性形态(可交换态、碳酸盐结合态、铁锰氧化物结合态和有机物结合态)主要有:Cd的碳酸盐结合态、Cr的可交换态、Pb的有机物结合态和Cu的碳酸盐结合态含量;Zn各活性形态对水稻子实含量的影响不明显。土壤理化性质对不同活性形态重金属元素的影响效应各不相同。活性态Cd主要受有机质、pH和容重的影响;活性态Cr与pH、有机质、CEC和容重密切相关;活性态Pb与有机质、容重、中细粉粒、砂粒等均有密切的关系;Cu的活性主要受粘粒、有机质含量的影响;Zn的有效性主要受pH、有机质、砂粒、容重的影响。总的看来,对土壤Cd、Cr、Pb、Cu、Zn各活性形态含量影响效应较强的是有机质、pH、容重,而与土壤吸附性能密切相关的颗粒组成、CEC的影响不甚明显。     

Distribution of applied cadmium in different size fractions of soils after incubation

The size fraction of soils is one of the important factors that influence the retention of heavy metals. The sorptive properties of soils for heavy metals are principally associated with clay and silt-size fractions. Phosphate fertilizers that are applied to highly weathered tropical soils contain a wide concentration range of cadmium (Cd) as an impurity. Tropical soils contain kaolinite and oxides of Al, Fe, and Mn, which have the ability to sorb Cd. However, the distribution of Cd in different size fractions and the chemical speciation of particulate-bound Cd in the clay size fractions when introduced to soil and allowed to incubate at field moisture capacity merits attention. Cadmium was, therefore, applied to selected surface Kenyan soils varying widely in physicochemical properties to investigate its distribution in different soil particle size fractions and the speciation of particulate-bound species in clay size fractions after incubation. The Cd content in different particle fractions was analyzed by graphite furnace atomic absorption technique after HF-HClO₄ digestion. The particulate-bound Cd species were investigated using chemical sequential extraction method. The study showed that clay size fraction of the natural and the Idaho monoammonium phosphate (MAP)-fertilizer or the Cd perchlorate-added MAP chemical reagent-treated soils contained the highest amount of the total Cd. However, silt and sand fractions of the treated soils also retained appreciable amounts of Cd. Speciation studies revealed that metal-organic complex-bound Cd was the most predominant compared to other particulate-bound Cd species in the clay size fractions of the soils treated with Idaho MAP fertilizer or the Cd perchlorate-added MAP chemical reagent. The distribution of total Cd in the different soil particle size fractions and the speciation of particulate-bound Cd in the clay size fractions varied with the soil type. The results indicate that clay size fractions can retain Cd making it less available; however, the influence of farming practices, which affect Cd mobility, should not be overlooked.     

Relationship between mineral composition or soil texture and available silicon in alluvial paddy soils on the Shounai Plain,Japan

Abstract

To evaluate the relationship between the amount of available Silicon (Si) in paddy soils and their mineral properties on the Shounai Plain in Japan, which is formed from several parent materials, we evaluated the amount of available Si, the particle size distribution, the oxide composition of crystalline minerals and the amount of oxalate-extractable Si (Si_o), iron (Fe_o) and aluminum (Al_o) in the soil. The amount of available Si in the soil and the oxide content of the crystalline minerals differed among four soil groups that were distinguished by their clay mineral composition. There was no difference in the particle size distribution among the soil groups. The amount of available Si was positively related to the SiO₂/Al₂O₃ ratio of clay, the CaO concentration of silt and fine sand, and the amounts of Si_o, Fe_o and Al_o in the soil. The amount of available Si in the soils was negative correlated with the Na₂O and K₂O concentrations of silt, the K₂O concentration of fine sand, and the coarse sand content. These results suggest that the amount of available Si in soils is affected by the weathering resistivity of their minerals and that the particle size distribution and mineral composition are related to the available Si of the soils. Mineralogical properties, including the particle size distribution and mineral composition such as the SiO₂/Al₂O₃ ratio × clay fraction content and the amounts of CaO and MgO in silt-sized particles, were positively correlated with the amount of available Si in the soil, but these correlations were not found for fine sand-sized particles. The Si_o, Fe_o and SiO₂/Al₂O₃ ratio × clay fraction contents contributed approximately 50% to the amount of available Si in the soils. The amount of available Si in the soil was divided into two groups according to the location of the paddy field. The amount of soil-available Si in the alluvial plain was affected by the geology upstream through the mineral composition.     

绰墩遗址古今水稻土黏土矿物特征比较研究

在江苏绰墩山遗址考古发掘中,发现了在剖面不同深度埋藏的距今约6000年的史前水稻土层、距今约3 000年的商周史前的古水稻土层和现代水稻土层.本研究为了比较古今水稻土黏土矿物特征的差异,以土壤剖面P01(包含史前古水稻土、商周史古水稻土和现代水稻土)与P03(仅含商周时期古水稻土和现代水稻土)为对象,测定其各种形态铁锰...     

Mineral Composition and Weathering of Soils Derived from Xiashu Loess

Mineralogical, physical and chemical analyses of the soils derived from Xiashu loess were carried out. The primary minerals of these soils were found to be mainly composed of light minerals, such as quartz, feldspar and mica, with traces of heavy minerals. Clay minerals, more complicate in composition, were dominated by hydromica, accompanied by smectite, vermiculite, chlorite, kaolinite, 2:1/1:1 randomly interstratified minerals and small amounts of quartz, goethite, lepidocrocite and hematite, Clay minerals were characterized by low crystallinity and fine particle size. In light of the quartz/feldspars ratio of the 0.01-0.05mm silt fraction, and the clay mineral composition, the freeness of iron oxide, and the silica/sesquioxide and silica/alumina ratios in < 0.002mm clay fraction, it is concluded that the weathering intensity of these soils was lower than those of red soil and yellow earth, but higher than that of brown earth, and that the soil allitization, depotassication and hydroxylation of cl     

Selected enzyme activities as affected by free iron oxides and clay particle size

Abstract

The effect of soil clay size phyllosilicates, particle size, and iron oxides on the activities of α‐ and β‐glucosidases, phosphomonoesterases, and urease were examined. The two clay fractions (0.2–2 and <0.2 μm) of selected soils had similar mineralogy and were illitic, kaolinitic, and smectitic in composition. In general, enzyme activities were reduced in the presence of clay size phyllosilicates. The montmorillonitic samples were the most effective inhibitors. Activities were generally lower in the presence of the finer clay fractions. The effect of iron oxides on enzyme activities varied. Acid phosphatase activity was significantly influenced by phyllosilicate type, iron oxides, and particle size. The inhibitory effect of phyllosilicates on acid phosphatase activity increased when iron oxides were removed from the clay fraction. Removal of iron oxides, on the other hand, enhanced the activity of alkaline phosphatase. Unlike β‐glucosidase, α‐glucosidase was deactivated in the presence of montmorillonitic and illitic samples regardless of clay particle size. The activity of urease was significantly reduced in the presence of iron oxides.     

利用粘粒矿物修复重金属污染农业土壤研究进展

Heavy metal contamination of agricultural soils poses risks and hazards to humans.The remediation of heavy metal-polluted soils has become a hot topic in environmental science and engineering.In this review,the application of clay minerals for the remediation of heavy metal-polluted agricultural soils is summarized,in terms of their remediation effects and mechanisms,influencing factors,and future focus.Typical clay minerals,natural sepiolite,palygorskite,and bentonite,have been widely utilized for the in-situ immobilization of heavy metals in soils,especially Cd-polluted paddy soils and wastewater-irrigated farmland soils.Clay minerals are able to increase soil pH,decrease the chemical-extractable fractions and bioavailability of heavy metals in soils,and reduce the heavy metal contents in edible parts of plants.The immobilization effects have been confirmed in field-scale demonstrations and pot trials.Clay minerals can improve the environmental quality of soils and alleviate the hazards of heavy metals to plants.As main factors affecting the immobilization effects,the pH and water condition of soils have drawn academic attention.The remediation mechanisms mainly include liming,precipitation,and sorption effects.However,the molecular mechanisms of microscopic immobilization are unclear.Future studies should focus on the long-term stability and improvement of clay minerals in order to obtain a better remediation effect.     

蒸腾潜能的模型研究及估算中国土壤湿度状况

The morphologies of goethites in latosol,red soils,yellow-brown soil and the paddy soils developed from red soils were studied in comparison with the morphology of synthetic goethite by means of the X-ray diffration,transmission electron microscopy and energy dispersive X-ray analysis.The synthetic goethite displayed acicular particles elongated in the c-direction.The goethites in the latosol,red soils and yellowbrown soil were platy particles stretched in two directions or isodimensional particles,and those in the paddy soils from red soils were acicular,short columnar,palty or isodimensional particles,Various morphologies of the goethites probably suggested their different dominant crystal faces,surface charge distribution and surface adsorption characteristics.