贵州雷公山土壤发生学性状的垂直变化特征研究

为了解我国亚热带山地土壤发生学性状随海拔的垂直变化特点,选择位于亚热带常湿润气候区的贵州省雷公山作为研究对象,调查与采样分析了不同海拔高度的17个土壤剖面的理化性状及其与海拔的关系。结果表明,雷公山土壤的众多发生学性状与海拔高度存在显著的相关,随着海拔的升高,呈现土壤矿物质风化减弱而有机质和养分积累增强的变化趋势。表土层厚度、砾石、有机质、全氮和全磷含量、腐殖质的H/F比,土壤粉砂含量、粉黏比、CEC、ba值、氧化铁活化度、黏粒Sa值、黏粒矿物中蛭石和云母相对比例均随海拔的升高而增加;而土体厚度、表土胡敏酸E4/E6比值、土壤黏粒含量、游离氧化铁含量、氧化铁游离度和黏粒矿物中高岭石相对比例则随海拔升高而下降。研究土壤酸化明显,pH和盐基饱和度普遍较低,随海拔升高的变化趋势不明显。研究认为,雷公山地区土壤发生学性状主要受现代成土环境影响,随海拔变化的温度可能是控制这一地区土壤空间变异的主要因素。区内土壤主要发生学性状随海拔升高呈波动状变化,多数发生学性状具有协同变化的特征;不同地理发生学分类土壤带间发生学性状存在一定的差异。根据中国土壤系统分类,研究区土壤类型主要为淋溶土和雏形土,二者也不存在海拔上的明显分界,而呈现复合分布。     

梵净山垂直带土壤的发生学特性与系统分类研究

为了解贵州东北部山地土壤的发生学特性及土壤分布,选择梵净山地区采集了不同海拔高度的13个代表性土壤剖面,分析了其成土环境、土壤风化强度的垂直变化,鉴定了区内土壤的主要诊断层、诊断特性,并根据中国土壤系统分类对研究区土壤类型进行了分类。结果表明,随着海拔的增加,区内土壤温度状况由热性转变为温性,水分状况逐渐由湿润向常湿润转变。梵净山地区土壤风化较弱,土壤中存在较多的2∶1型矿物,土壤脱硅富铁铝化处于中下水平。土体厚度、土壤黏粒、全铁、游离氧化铁含量、铁游离度随海拔增加而下降,砾石含量、黏粒CEC、土壤ba值、黏粒Sa值随海拔增加而上升,部分土壤出现明显的黏化。区内土壤酸化明显,多数土壤的pH在5.5以下,部分土壤的铝饱和度超过了60%,土壤的平均铝饱和度随海拔增加而下降。研究区土壤黄化非常明显,土壤色调主要为10YR。共检出淋溶土、雏形土和新成土3个土纲,5个亚纲、8个土类和12个亚类,土壤类型主要由淋溶土和雏形土组成。亚纲在海拔高度变化上有一定的分布规律,随着海拔的上升,由湿润淋溶土、湿润雏形土向常湿淋溶土、常湿雏形土转变。     

模拟酸雨对果园土壤交换性阳离子迁移及其对土壤酸化的影响

采用短期室内淋溶的方法研究了模拟酸雨对供试果园土壤交换性Ca^2＋、Mg^2＋、K^＋、Na^＋、交换性盐基总量（BS）、阳离子交换量（CEC）、电导率（EC）等变化的影响。试验结果表明,土壤交换性Ca^2＋（pH2.5）、Mg^2＋、K^＋、Na^＋、BS（pH2.5）、CEC（pH≥3.5）含量较酸雨淋溶前增加,且随着剖面深度表现出较好的层次性;淋出液中Ca2＋、Mg^2＋、K^＋、Na^＋含量随着模拟酸雨酸度的增强而依次增加,其中pH2.5酸雨处理与其它淋溶处理间淋出液Ca^2＋、Mg^2＋、K^＋、Na^＋含量差异显著;以土壤交换性Ca^2＋、BS、CEC、盐基饱和度（BSP）与EC为指标衡量土壤的酸化,pH 2.5酸雨处理导致了淋溶土柱表层和中间土层的土壤酸化,其中交换性Ca^2＋、BS、BSP指标表征pH 3.5的酸雨处理引起了表层土壤酸化,而pH≥4.5的酸雨淋溶缓冲了土壤的酸化,土壤的酸度减弱。     

不同耕种年限红壤性水稻土理化性质的变化特征

以江西省余江县不同种植年限的红壤性水稻土为对象,研究了土壤有机质、pH、阳离子交换量(CEC)、游离氧化铁含量和氧化铁活化度随时间变化趋势;选择耕种7、22和80年的土壤剖面,研究了游离氧化铁和无定形氧化铁在剖面不同层次的分布。结果表明,耕层(0～20cm)土壤有机质含量随着水稻种植年限的增加而增加,淹水种稻导致土壤pH升高,但主要发生在种稻的前7年,7～80年间土壤pH变化不大。土壤CEC随着种植年限的增加而增加,在17年达到最大,然后随种稻时间的进一步增加而减小。土壤游离氧化铁含量随种稻时间呈下降趋势,但种稻后土壤氧化铁的活化度高于母土旱地红壤。对7年和80年水稻土,表层土壤游离氧化铁的含量低于底层土壤,说明铁在剖面中存在淋溶迁移。7年和22年水稻土表层土壤无定形氧化铁含量高于底层土壤,但对80年水稻土,土壤无定形氧化铁随采样深度的增加而增加。     

亚热带山地草甸土性态的变异及其在中国土壤系统分类中的地位

为了解我国亚热带地区山地草甸土性态的变化和成土特点,从福建、浙江、江西、安徽、湖南和贵州等省采集了20个代表性山地草甸土剖面,详细观察了土壤剖面形态特征,分析了土壤颗粒组成、有机质、阳离子交换量(CEC)、酸度、氧化铁形态和黏土矿物类型等指标,并从诊断分类的角度探讨了它们在中国土壤系统分类中的地位。结果表明:这一地区的山地草甸土表层有机质积累均非常明显,颜色普遍呈黑色和深褐色,土壤酸化明显,土壤氧化铁游离度多在40%以下,土壤CEC较高。但研究也发现,不同样点之间土壤的土体厚度、剖面构型、黏化状况、有机质垂直分布、氧化铁含量、矿物类型及其诊断层和诊断特性均有较大的差异。土体构型大致有Ah-C、Ah-Bw-C、Ah-Bt-C和Ah-G-C等4类。根据中国土壤系统分类的诊断标准,可把研究的20个剖面归并为均腐土、潜育土、淋溶土、雏形土和新成土等5个土纲,下续分为6个亚纲、10个土类和15个亚类。研究认为,在地理发生分类中笼统地把这些土壤归为一个土类存在边界不明确等问题。     

黄土高原淋溶土黏粒、氧化铁与颜色的关系及发生学解释——以山西土系调查的31个黏化层为例

以黄土高原山西省14个淋溶土剖面的31个偏红的黏化层(Bt)为研究对象,分析了其全铁、游离氧化铁、无定形态氧化铁的含量与土壤颜色参数、黏粒含量之间的相关性,并建立了定量关系模型。结果表明:Bt的黏粒含量与氧化铁含量之间呈极显著正相关(P<0.01);颜色的红度与全铁、游离氧化铁和无定形氧化铁含量之间均呈极显著正相关(P<0.01),其中游离氧化铁是最直接的土壤红色"染色剂";其他色调、明度与彩度等颜色参数与土壤全铁、游离氧化铁含量之间亦呈现出显著的相关性,这也间接说明了黏粒含量与土壤颜色具有一定相关性。野外观测发现,某些黏化层结构体表面颜色较结构体内基质颜色更红,证实了在土壤结构体表面氧化铁随着黏粒在土壤空隙中的迁移淀积。黄土高原淋溶土偏红的黏化层多是来自由于土壤侵蚀而出露地表或接近地表的第三纪保德红土和第四纪红黏土,其黏粒含量、土壤颜色等指标均表明第三纪的古气候条件较第四纪更为湿热。     

黄土高原典型土壤剖面土壤颗粒组成分形特征

采集从北向南依次分布的干润砂质新成土（神木）、黄土正常新成土（延安）和土垫旱耕人为土（杨陵）等典型土壤剖面0～200 cm土层土样,通过测定土样颗粒体积分形维数及基本性质,以期阐明黄土高原典型土壤颗粒体积分形特征及其与土壤基本性质间的相关性。结果表明,从南到北,土壤颗粒体积分形维数呈下降趋势,而不同土层土壤颗粒体积分形维数差异不显著。土垫旱耕人为土、黄土正常新成土和干润砂质新成土表层（0～10 cm）颗粒体积分形维数分别为2.723±0.024、2.609±0.077和2.589±0.025,表层以下（10～200 cm）颗粒平均体积分形维数分别为2.729±0.034、2.584±0.054和2.558±0.034;颗粒体积分形维数与＜0.01 mm的物理性黏粒及＜0.002 mm的黏粒体积百分含量呈极显著正相关关系,与0.002～0.05 mm的粉粒和＞0.05 mm的砂粒体积百分含量呈极显著负相关关系,与粉粒的显著性较小,而土壤中物理性黏粒体积百分含量与土壤全氮、有机碳及矿物固定态铵均达到极显著正相关关系,而砂粒体积百分含量与上述土壤基本性质均呈极显著负相关关系。     

罗浮山土壤发生特性与系统分类研究

为了解我国南亚热带山地土壤的发生特性及其在中国土壤系统分类中的归属,以罗浮山不同海拔高度的10个代表性剖面为研究对象,分析土壤发生特性,确定诊断层和诊断特性,对土壤进行系统分类,并在高级分类单元级别上进行了中国土壤系统分类、美国土壤系统分类和世界土壤资源参比基础之间的参比研究。研究表明:土壤干态色调主要为10YR,质地属壤土大类,粉黏比为0.42 ~ 2.62,多数剖面土壤粉黏比小于1.0;土壤酸性强（水浸提pH 3.69 ~ 4.94）,CEC为4.43 ~ 25.68 cmol (+) kg?1,盐基饱和度（2.27% ~ 16.25%）低,交换性酸（1.35 ~ 6.41 cmol (+) kg?1）以交换性Al3+为主,多数土层铝饱和度超过了80%;土壤矿质元素以Si、Al、Fe为主,黏粒硅铝率（Sa）、黏粒硅铁铝率（Saf）均小于2.0,各剖面B层Al、Fe、P、Ti在黏粒中富集明显,Fe富集率稍大于Al;在土壤垂直带谱上,湿润富铁土一般分布于800 m以下,常湿富铁土介于800 ~ 1200 m,常湿雏形土在1200 m以上。罗浮山土壤具有明显的脱硅富铁铝化特性,具有有机碳累积明显、酸性强、盐基饱和度低、铝饱和度高等特点;归属为2个土纲、3个亚纲、4个土类和6个亚类。     

渭北旱塬区不同坡向土地利用类型对土壤性质的影响

为了研究不同坡向土地利用类型对土壤性质的影响,以渭北旱塬区5种土地利用类型(不同坡向)为研究对象,系统分析该区不同坡向土地利用类型剖面土壤物理、化学和生物性质的差异。结果表明:(1)除土壤pH和土壤颗粒组成外,5种土地利用类型土壤含水量、总孔隙度、有机质、全氮、微生物量碳和氮含量总体随土层加深呈下降趋势,土壤容重则相反。(2)0-30cm土层,阳坡农用地土壤含水量、黏粒含量和pH最高,粉粒和全氮含量最低;人工草地砂粒和全氮含量最高,黏粒含量最低;人工林地土壤总孔隙度、土壤有机质、微生物量碳和氮含量最高,土壤含水量、土壤容重和pH最低;天然草地土壤容重和粉粒含量最高,总孔隙度和砂粒含量最低;退耕地有机质、微生物量碳和氮含量最低。阴坡农用地土壤含水量、粉粒含量和pH最高,黏粒和全氮含量最低;人工草地土壤容重、黏粒和微生物量氮含量最高,土壤总孔隙度、粉粒、砂粒和有机质含量最低;人工林地有机质含量和微生物量碳含量最高;天然草地土壤总孔隙度、砂粒和全氮含量最高,土壤容重和pH最低;退耕地土壤含水量、微生物量碳和氮含量最低。(3)5种土地利用类型中,土壤容重、细黏粒、粗黏粒、细粉粒、粗砂粒、土壤pH和有机质(退耕地除外)表现为阳坡阴坡,土壤含水量(退耕地和农用地除外)、总孔隙度、粗粉粒、细砂粒、土壤质地粗化度、全氮(人工草地除外)、土壤微生物量碳和氮含量则为阴坡阳坡。     

岷江上游干旱河谷海拔梯度上的土壤发生特征

了解岷江上游干旱河谷的土壤发生特征对区域植被恢复有着指导意义,为此选择不同海拔梯度上7个典型土壤剖面进行土壤发生特性分析。结果表明,受区域成土环境影响,土壤化学风化和成土作用弱;土壤质地较粗,土壤机械组成以粉砂为主,黏化作用不强。土壤全Fe含量和Fe游离度一般<50g/kg和<30%;交换性盐基组成在土壤剖面中无明显分异。随海拔升高,土壤黏粉比、全Fe含量、Fe游离度增加。土壤表土有机碳同位素δ13C值随海拔升高偏负,反映区域植被类型由低海拔半干旱气候条件下的C4型灌丛植被向高海拔凉润气候条件下C3型针阔叶林自然过渡。基于干旱河谷地区土壤特征,其植被恢复应以提高土壤质量为基础,并应遵循海拔梯度上自然植被分布特征进行植被恢复和生态重建。     

基于图像技术的温室光分布研究

温室内光照环境对作物生长有重要影响,然而受温室形状、方位、覆盖材料、天气等各因素的影响,温室内光分布一直是研究的难点。该文提出基于计算机视觉技术和基于图像的光照技术来采集温室内真实环境的光分布,通过高动态范围图像的制作,以及从图像中的光源信息的提取,得到温室内光分布的辐射度图,该图能够真实反映不同天气情况下以及一天中不同时刻、不同方向的光照强度分布,能较好地模拟场景周围的自然光照。该研究将为温室内复杂光源分布的获取和作物冠层顶部入射辐射的研究提供准确的光照模型。     

Horizontal distribution of main hydroxyanthraquinones in soil

Six hydroxyanthraquinones (chrysophanol, chrysotalunin, microcarpin, physcion, 7,7′-biphyscion, and hinakurin) present in the samples of 26 surface soils were quantitatively analyzed, and the contents of HAQs in soil types were compared. The soil samples had been collected from 19 Umbric Andosols and seven Distric Cambisols, and the Andosols were further subdivided into those with allophanic soil materials (exchange acidity (y ₁<5 mL 100 g^-l) and nonallophanic soil materials (y _l≧5 mL 100 g^-l). The following results were obtained. (1) It was determined quantitatively for the first time that chrysotalunin was the major hydroxyanthraquinone in many soils. (2) The amounts of major dime ric hydroxyanthraquinones (chrysotalunin, 7,7′-biphyscion, and microcarpin) in non-allophanic soil materials were significantly larger than those in allophanic soil materials. As the contents of chrysotalunin in Andosols were positively correlated with y _l, which was reported to be positively correlated with aluminum toxicity and exchangeable aluminum in soil, it is suggested that toxic aluminum may be involved in the production of soil hydroxyanthraquinones.     

Water distribution and microstructure in enhanced pork

Water characteristics and meat microstructure of NaHCO3-enhanced pork were compared with NaCl- and Na4O7P2-enhanced pork using low-field proton NMR relaxometry, advanced microscopy techniques, and traditional meat quality measurements. Porcine samples were enhanced at 4 degrees C for 48 h with sodium salts individually and in the following combinations: (i) 5% NaCl, (ii) 5% Na4O7P2, (iii) 3% NaHCO3, (iv) 5% NaCl and 5% Na4O7P2, (v) 5% NaCl and 3% NaHCO3, (vi) 5% Na4O7P2 and 3% NaHCO3, and (vii) 5% NaCl, 5% Na4O7P2, and 3% NaHCO3. Independently of the marinade used, the water-binding capacity was improved, cooking loss was reduced, and the yield was enhanced compared with nonmarinated pork samples. This was also reflected in the water mobility within the samples measured by proton NMR relaxometry. Visualization of samples by confocal laser scanning microscopy (CLSM) revealed salt-dependent microstructural changes in the green pork samples treated with NaHCO3, giving rise to nearly complete disintegration of overall structures. High-resolution visualization by atomic force microscopy (AFM) further suggested that a higher cooking loss in sodium chloride-enhanced samples could be ascribed to less solubilization and higher heat-induced protein denaturation compared with phosphate- and bicarbonate-enhanced samples.     

Fractionation and distribution of selenium in soils

Abstract

A modified selenium (Se) fractionation procedure was used to study Se distribution in three soils (two silt loams and one silty clay). This sequential procedure consisted of: i) 0.2 M potassium sulfate (K₂SO₄)‐soluble fraction, ii) 0.1 M potassium dihydrogen phosphate (KH₂PO₄)‐exchangeable fraction, iii) 0.5 M ammonium hydroxide (NH₃H₂O)‐soluble fraction, iv) 6 M hydrochloric acid (HCl)‐extractable fraction, and v) residual fraction digested with perchloric (HClO₄) and sulfuric (H₂SO₄) acids. The fractionation procedure had high recovery rates (92.5 to 106%). The Se distribution in soil was controlled by soil properties, such as pH, oxide, clay, and calcium carbonate (CaCO₃) contents. In the untreated soil samples, residual Se fraction was dominant. In the Se‐enriched soils, the silty clay had significantly more Se in the NH₃H₂O and residual fractions while in the two silt loams the largest were KH₂PO₄ and residual fractions. The Se availability in the two silt loams was higher than in the silty clay. The Se availability pattern in the untreated soils was: unavailable (HCl + residual fractions) >> potentially available (KH₂PO₄ + NH₃H₂O fractions) > available (K₂SO₄ fraction), while in the Se‐enriched soils it was potentially available > unavailable > available.     

Particle-size distribution in soils of West Antarctica

The particle-size distribution in soils sampled near Russian polar stations in West Antarctica has been studied. It is shown that the soils of the Subantarctic zone (the Bellingshausen Station on King George Island) are characterized by a higher content of silt and clay in the fine earth fraction and by a higher content of the fine earth fraction in comparison with the soils of the proper Antarctic tundra barrens near the Lenin-gradskaya Station and the Antarctic cold desert near the Russkaya Station. In the latter soils, the content of rock fragments is higher than that in the soils of the Antarctic tundra barrens. In the soils of the tundra barrens, a considerable accumulation of fine earth may take place in large cavities (hollows) on the stony bedrock surface. Desert pavements are formed in both types of Antarctic landscapes.     

Cadmium accumulation and distribution in sunflower plant

Cadmium (Cd) accumulation and distribution was studied in sunflower (Helianthus annuus L., public line HA‐89) plant. From an uncontaminated sandy loam brown forest soil with 162 μg kg^‐1 HNO₃/H₂O₂ extractable Cd the HA‐89 sunflower public line accumulated 114 ug kg^‐1 Cd in its kernels under open field conditions. This value is rather low as compared to data found by others. Sandy loam brown forest soil was treated with 0, 1 or 10 mg kg^‐1 of Cd to study the interaction of this heavy metal with young sunflower plants in a greenhouse pot experiment. The fresh weight and dry matter accumulation of sunflower plant organs (roots, shoots, leaves or heads) was unaffected by cadmium treatment of soil. The nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), copper (Cu), iron (Fe), manganese (Mn), or zinc (Zn) uptake of sunflower plant organs was not influenced by lower or higher Cd‐doses, except sunflower heads where 10 mg kg^‐1 of Cd treatment of soil significantly reduced the uptake of Ca, Fe, and Mn. Although Cd reduced the Zn uptake of roots, its rate was statistically not significant. Cadmium was accumulated prevalently in roots (1.21 mg kg^‐1,4.97 mg kg^‐1, or 13.69 mg kg^‐1 depending on Cd‐dose), and its concentration increased also in shoots or leaves. In spite of the short interaction time, elevated concentrations of cadmium (0.78 mg kg^‐1, 1.34 mg kg^‐1, or 3.02 mg kg^‐1 depending on Cd‐dose) were detected in just emerged generative organs (heads) of young sunflower plants.     

Cadmium accumulation and distribution in cucumber plant

An experiment developed in soilless culture was used to study the cadmium (Cd) accumulation, and distribution of Cd in cucumber (Cucumis sativus var. peonero‐mixfl) plant. Four treatments were established (0, 5, 10, and 20 mg Cd⁺² L^‐1). Uptake, and transport of Cd were increased with time, and Cd concentration in the nutrient solution. Fruit accumulation of Cd varied from 16 to 92 mg kg^‐1 depending on the treatments. The fresh weight, and dry matter accumulation of cucumber plant organs (roots, stem, leaves, and fruits) was affected by cadmium treatment. A decrease of the total, a, and b chlorophyll increasing Cd concentration in nutrient solution, and time of experiment were observed. The incidence of this metal on the content of chlorophyll b seem to be faster than chlorophyll a. Cucumber plant could be a feasible plant for pollution experiments due to their high sensibility, and transport efficiency.     

Sulphur distribution and metabolism in waterlogged peat

About 90% of total S in a peat profile from a valley mire was associated with organic matter, and in the anaerobic zone, most of the remaining S could be distilled as H₂S (steam-volatile H₂S). [³⁵S]SO^2?₄ was rapidly incorporated into both organic and steam-volatile H₂S pools, with preferential labelling of organic matter at the surface of the peat (? 10 cm depth) and of steam-volatile H₂S at greater depth (? 10 cm depth). Less than 2% of the steam-volatile H₂S could be accounted for as H₂S in solution in the pore water, and evidence suggesting FeS as the source of this fraction is presented. Less than 2% of the total S in the profile was present as FeS₂ or S°, and S₂O^2?₃ and S₄O^2?₆ could not be detected. Measurements of total S content of the peat and estimates of the age of the deposit indicate a rate of S accumulation of 4.76–6.06 g S m^?2yr^?1. The results are discussed in the context of the mechanisms of S transformations and uptake by other mire systems.     

Pore size distribution measurements in swell-shrink soils

A method for the determination of pore size distribution in swell-shrink soils was described. Undisturbed core samples, saturated and drained at 1.5 MPa suction, were filled with a non-polar liquid (xylol), and its retention at suctions lower than 1.5 MPa was measured. Oven dry samples were analyzed in the same way. Derived pore size distributions were compared with those obtained by water desorption. Pore size distributions and their relative changes as a function of water content were related to some soil constituents and properties. Stability factor and sum of montmorillonite and vermiculite significantly influenced the pore size distribution by water release, A higher stability factor resulted in lower relative changes (ratios) in the pore size classes <10 μm and 0.2–10 μm when the samples were drained from saturation to 1.5 MPa suction, however, at extreme dryness, the relative changes were positively correlated to the sum of montmorillonite and vermiculite.     

Minerals controlling arsenic distribution in floodplain soils

As a consequence of intensive mining of the western Erzgebirge since medieval times, floodplain soils of the Mulde river contain large concentrations of arsenic (As) (>50 mg kg⁻¹). Arsenic in soil is often bound to poorly crystalline Fe and Mn (hydr)oxides, which may dissolve under reducing conditions. Part of the As may also exist in primary minerals, predominately sulphides, or in secondary minerals formed upon weathering. In order to better understand the impact of seasonal flooding, we surveyed As‐bearing mineral phases, especially of iron (Fe) (hydr)oxides. Because Fe (hydr)oxides are clay‐sized, soil samples were fractionated into six particle‐size fractions. The fractions were digested with aqua regia for determination of total element concentrations, extracted with hydroxylammonium chloride (NH₃OHCl; selective for Mn (hydr)oxides and NH₄ oxalate), and analysed by X‐ray diffraction and scanning electron microscopy. The largely similar distribution of As and lead (Pb) suggested the potential co‐existence of the two elements in primary or secondary mineral phases. However, neither As–Pb minerals nor any other As mineral were detected. Association with Mn oxides was negligible. The predominant As‐bearing phases were poorly crystalline Fe (hydr)oxides, which also incorporated large amounts of Pb and were affected by redox dynamics.