栗钙土的年龄

在阐明粟钙土发生特性的基础上,本文运用放射性碳方法断定了玄武岩熔岩台地上栗钙土有机质和腐殖质组成中胡敏酸、胡敏素的年龄.结果表明,我国栗钙土与其它国家的软土系同一时期的产物,它们形成于大约6000年以前.栗钙土有机质诸部分的年龄序列是:胡敏酸>胡敏素>土壤有机质.     

漳州市农业土壤重金属现状、分析及防治

调查漳州市农业土壤重金属Hg、As、Cr、Cd、Pb背景值及污染现状,调查结果,漳州市农业土壤重金属背景值相对较低。其现状为,Hg、As、Cd、Pb含量高于背景值1~4倍(Cr除外),特别是Hg和As为高污染元素。按土壤类型划分,水稻土土类重金属含量高于赤红壤土类(Hg除外);按土地利用方式划分,水田>菜地>果园;按流域划分,九龙江流域农业土壤重金属含量高于非九龙江流域(Cr除外)。污染源以农业污染为主,工业污染相对较轻。     

A NOTE ON THE PLASTICITY LIMITS OF AGRICULTURAL SOILS

The plasticity limits of seventeen agricultural soil standards representing contrasting textures, were measured both by the standard methods and by the fall-cone penetrometer method (Towner, 1973). The results are compared with the Casagrande A-line in the plasticity chart. The plasticity limits obtained by the fall-cone method are given for twelve other soils. The plasticity indices for the soils tended to lie about a single curve. They lay above the Casagrande A-line at low values of liquid limit. There was some suggestion of an order according to texture along this curve.     

上海农田土壤重金属含量的空间分析

土壤环境中的污染物积累及其在食物链中的迁移转化是影响食品安全的重大科学问题。重金属污染因滞留持久、高富集等特性,易于通过食物链进入农产品中,影响农产品质量安全,危害人类健康[1,2]。因此,针对农田土壤中的重金属累积状况进行调查和评价,已是国内外广泛关注的问题。近年来,前人分别从不同的角度对土壤重金属空间分布特征进行了研究。从研究区上看,城乡结合部是土壤重金属污染研究的热点区域[3,4],如Zhao等[3]研究了无锡城市边缘区土壤重金属累积与空间分布特征。从研究尺度上看,Facchinelli等[5]从宏观尺度上研究了意大利Piemonte地区农田重金属污染的空间分异特征;刘付程等[6]从县域     

LEAD POLLUTION IN AGRICULTURAL SOILS

High concentrations of lead, copper, zinc and cadmium, are reported in agricultural soils of the southern Peak District in association with mining and smelting sites. A reliable background range of lead concentrations in non-contaminated soil was established and the relative topsoil enhancement (RTE) ratio was found to be a useful index of pollution. A wide range of amounts of lead was extracted from soils by dilute nitric acid; the higher end of the range may result from free lead oxides being present in some polluted soils. The amount of lead extracted also depended on the composition of the soil, a soil containing vermiculitic clay minerals maintained a very low lead concentration in solution. The effects of site history, weathering and redistributive processes are discussed.     

DISTRIBUTION AND PHYTOAVAILABILITY PREDICTION OF ZINC IN AGRICULTURAL CALCAREOUS SOILS

The extractability and distributions of zinc (Zn) were evaluated in calcareous agricultural soils from South-West Iran. Both single [diethylenetriaminepentaacetic acid (DTPA)] and sequential extraction procedures (Singh scheme) were applied to 20 representative soils. The DTPA extractable zinc levels were low (on average 3.34%). The sequential extraction procedures were also utilized for the study of zinc phytoavailability in maize plants (Zea mays L.) in a greenhouse experiment. The Singh scheme was significantly better than DTPA plus soil properties in phytoavailability prediction of zinc in soils. Significant correlations were found between the amounts of DTPA extractable zinc and the iron (Fe) oxides-bound (AFe and CFe) and residual fractions extracted by the Singh procedure. Zinc concentrations in plant samples (mean value of 27.49 mg kg^?1) were poorly correlated with the different extracted soil fractions (single and sequential). The Singh procedure provided better predictions of zinc uptake by plants than DTPA extraction method.     

多氯联苯污染农田土壤的细菌群落结构差异及其影响因素

应用PCR-DGGE技术分析多氯联苯长期污染农田土壤的细菌群落结构,并主要运用统计学方法探讨了多氯联苯总量和土壤理化因子对细菌群落结构的影响。结果显示:不同水平多氯联苯污染农田土壤中细菌群落结构存在差异,较高水平多氯联苯(64.0~484.5 ng g-1dw)污染土壤的细菌群落结构较为接近;相对于其他土壤理化因子(如有效磷、pH、有机质等),多氯联苯显著影响农田土壤中的细菌群落结构(p<0.05)。这表明在多氯联苯胁迫下土壤细菌整体群落结构发生改变,提示多氯联苯污染对土壤微生物生态的影响,这可能导致土壤生态环境质量发生变化,是潜在的生态风险因素。     

不同利用年限茶园土壤矿化、硝化作用特性

茶叶（Camellia sinensis）是重要的经济作物，茶树具有耐酸耐铝毒等特性，适合在热带亚热带的酸性土壤种植。由于茶园的施肥管理，茶树凋落物归还土壤以及根系分泌物等原因，茶园土壤随着植茶年龄的增加，土壤理化性质会发生一系列变化。如土壤pH值下降，钙、镁等盐基离子和微量元素相对缺乏，而铝、氟和多酚类物质逐渐在茶园土壤中富集，形成了非常独特的茶园土壤生态系统。     

农田气象条件下阿特拉津在土壤中淋溶动态的数值模拟

阿特拉津(Atrazine)是我国华北地区夏玉米田常用的除草剂,而夏玉米生育期又是该地区的主要降雨时段,对这一时段Atrazine在田间尺度的淋溶风险进行评价,对保护浅层地下水环境具有重要意义。以北京市通州区永乐店试验站一块27 m×27 m的农田为背景,通过田间采样、测试分析土壤样品并收集2001年的气象数据,基于简化土壤水三维流场的柱模型假设,在同时考虑土壤水力学参数、Atrazine运移和吸附参数空间变异性的情况下,对该农药在农田尺度下淋溶动态的空间分布进行了数值模拟。在此基础上,对夏玉米不同生育期耕层20 cm深度处的土壤水负压、水流通量和Atrazine浓度的空间变异结构进行了地质统计学分析。结果表明,在整个夏玉米生育期内这三个参量的半方差模型基本上为球状模型,它们的变程多在8~10 m。本研究案例对布设农田尺度土壤水分和Atrazine动态监控网具有一定的参考意义。     

土壤硝化作用过程中亚硝态氮的累积研究

在实验室条件下比较了９种土壤硝化过程中ＮＯ２＾－的累积能力和ＮＯ２＾－在不同土壤中的稳定性,并在３种代表性土壤上检测了ＮＯ２＾－累积的动态变化。结果表明,红壤和黄棕壤在所有施氨（ＮＨ４＾＋－Ｎ）水平下均未出现ＮＯ２＾－的累积;但砂姜黑土、潮土、滨海盐士、潮棕壤、褐土、灌漠土和灰钙土等均出现不同程度的ＮＯ２＾－累积,且随着施ＮＨ４＾＋－Ｎ水平提高而增加ＮＯ３＾－在红壤和黄棕壤中的累积与施ＮＨ４＾＋－Ｎ水平无关,但在其它７种ｐＨ大于７的土壤中的累积受到浓度ＮＨ４＾＋的抑制。此外,试验还表明,ＮＯ２＾－在红壤和黄棕壤中不稳定,但在其它７种土壤中相当稳定。土壤硝化过程中产生ＮＯ２＾－累积的问题应引起重视。     

THE CONTENTS AND SORPTION OF CADMIUM IN SOME AGRICULTURAL SOILS OF ENGLAND AND WALES

Cadmium sorption was measured in 10 agricultural soils with pH ranging from 4.5 to 7.9, and total Cd content from 0.27 to 1.04 μg g^?1 dry soil. With initial Cd concentrations of 0.5 to 100.0 μM, sorption from 0.002 M CaCl₂ was described by the Freundlich adsorption equation but the gradients of the isotherms increased when the initial concentrations were below 0.5 μm. This indicates that there are specific sites of differing sorption energy; differences between soils in the gradients of the isotherms at low initial concentration could largely be accounted for by their contents of ‘free’ Fe₂O₃. When initial concentrations were below 0.5 μm there was a linear relationship between the quantity of Cd sorbed and the final concentration in solution. This relationship held with all soils except that of lowest pH from which there was a net loss of Cd to the solutions. Desorption was measured from three soils with contrasting pH. With the soil of lowest pH, over 80 per cent of sorbed Cd was desorbed to 0.002 m CaCl₂ and up to 30 per cent to 100 or 500 μm solutions of heavy metal chlorides. In contrast, only very small proportions (<1.25 per cent) were desorbed from the other soils with pH 6.7 and 7.8. The results indicate that Cd is strongly sorbed by soils of pH of above 6.0 when added in amounts comparable to additions in sewage sludges or phosphatic fertilizers, and illustrate the importance of liming as a means of reducing the mobility of this metal in soils.     

不同时期形成的铁质富铝土特性及其在发生上的意义

本文在其他成土因素相对一致的前提下研究时间因素对土壤性状的影响,并以此为依据探讨分类中的一些问题.随成土时间变长(Q₄-Q₁),土壤的微形态特征,化学性质和粘土矿物组成都发生较大变化.如原生矿物含量减少;三水铝石逐渐增多;高岭石结晶程度变高;粘粒硅铝率和交换量分别由1.91、57.5减至1.25、12.9;游离铁含量增加.分析资料的统计结果表明:成土时间对土壤性状的影响一般小于生物气候的影响;全新世火山灰发育的土壤的粘土矿物、交换量、游离铁含量等性状与红壤截然不同,不应归属于红壤而应在高级分类单元中加以区分;许多在发生上有意义的指标,如硅铝率等,由时间因素引起的变化(Q₃-Q₁)已超过了同一母质发育的不同土类间的变化,因此把Q₃-Q₁玄武岩发育的高富铝土归属于同一土属也是不妥的.     

湖北省几种农业土壤自生固氮菌生态地理分布的研究

这项工作的主要目的,在于研究湖北省几种农业土壤中,自生固氮茵的类型、数量及其生态地理条件。     

AN EXAMINATION OF THE FALL-CONE METHOD FOR THE DETERMINATION OF SOME STRENGTH PROPERTIES OF REMOULDED AGRICULTURAL SOILS

Measurements of unconfined shear strengths were made over a range of moisture contents on seven remoulded agricultural soils which covered a range of textures, and these were used to calibrate the Swedish fall-cone device. It was found that the calibration factor, usually regarded as constant in engineering literature, was dependent on soil texture, but constant over a range of moisture contents for a given soil texture. From the assumption that the liquid and plastic limits correspond to two fixed specified strengths, it is shown that one can use the fall-cone device to determine these limits by making measurements of cone penetrations over a range of moisture contents. It is suggested that a modified plasticity chart, which can be obtained very simply from measurements of cone penetrations made over a restricted range of moisture contents, may be used for characterizing soil behaviour.     

遵义东南部地区农业土壤重金属分布特征及风险评价

对贵州省遵义东南部地区农业土壤重金属As、Pb、Cd、Cr、Hg污染现状进行调查和分析,结果表明,该地区重金属平均含量分别为:As 11.39mg/kg,Pb 38.75mg/kg,Cd 0.34mg/kg,Cr 40.45mg/kg,Hg0.21mg/kg。主要污染物为Cd,单项污染指数是1.13,单项生态危害系数是50.85,为中等生态危害级,遵义县污染指数最高为1.43,单项生态危害系数为64.35。同时通过污染指数与生态危害系数比较,表明Cd、Hg在构成土壤环境污染的同时,也造成了相应的生态危害。     

POLYCARBOXVLIC ACIDS EXTRACTED BY WATER AND BY ALKALI FROM AGRICULATURAL TOP SOILS OF DIFFERENT DRAINAGE STATUS

Water-ex tractable poly carboxy lie acids and alkali-extractable humic acids and fulvic acids, were isolated from agricultural top-soils of two soil associations. Samples from four soil series from each association were selected with drainage status varying from well-drained to very poorly-drained. The amounts of atkali-extractable humic acid and water-ex tractable polycarboxylic acids were highest in the very poorly-drained soils whilst the amounts of alkali-extractable fulvic acid were generally similar in all the soils, although the fulvic acid accounted for a lower proportion of the total organic matter in the poorly-drained soils. Oxalate-extractable aluminium decreased with increased drainage impedance, whilst no such trend was observed for oxalate-extractable iron. It is suggested that the fulvic acid-like polycarboxylic acids are removed from the soil solution by adsorption onto sesquioxides; so that the lower content of aluminium oxides in the very poorly-drained soils results in depressed levels of fulvic acid and increased concentrations of water-extractable polycarboxylic acids.     

陕西扶风新集黄土剖面中的稀土元素

本工作用仪器中子活化法(INAA)测定了陕西新集近40米厚的黄土剖面中5个埋藏古土壤层的10个稀土元素。结果表明,其20个不同层次的土样中稀土总含量在157—231.68ppm之间,平均为199ppm,接近北美页岩。各层土壤稀土含量有差别,可能是碳酸钙在各层中起着稀释剂作用的缘故。消除它的影响后,各层稀土含量很接近。黄土系陆相沉积类型,富含Ce族元素,各层甲稀土元素的配分模式很相似,没有显著的分馏异常现象,反映了黄土在来源区和堆积区的漫长岁月里处于相似的弱碱性界质和较干燥通气良好的条件下,淋溶不太强烈。     

工业型城乡交错区农业土壤Cu、Zn、Pb和Cd的空间分布及影响因素研究

在江苏省无锡市工业型城乡交错区，选择8km2区域，采集119个土壤样品，对土壤Cu、Zn、Pb,Cd及其有效态含量的空间分布和影响因素进行探讨。结果表明：该区土壤Cu、Zn、Pb、Cd含量和变异系数都明显增加，土壤有效态重金属含量与相应的全量重金属含量具有显著相关性。土壤Cu、Zn、Cd空间变异主要受到工业影响，但由于该区工业类型的多样性和工厂分布的分散性，Cu、Zn、、Cd空间分布模式并不相同。本区土壤Pb的分布与工厂分布的相关性不大，但随与城市距离增加而降低。公路和土地利用与土壤重金属含量的关系表现不明显。该区工业污染对土壤重金属空间变异的影响可能掩盖了公路和土地利用等的影响，建议在城乡交错区合理安排工业布局以控制土壤受重金属污染的范围。