浙江萧山“一刀切”萝卜产地土壤地球化学特征

浙江“萧山萝卜干”肉质鲜美、产量高、抗逆性强,易于种植和加工。这些优良品质除了与品种有关外,还与其产地的土壤地质和地球化学背景密切相关。与浙江平原土壤元素平均值对比,产地的MgO、B、P、CaO、Mn含量较高,N、K、Mo、Fe、Zn含量较低;从该区土壤养分和微量元素有效态分析结果来看,碱解氮、Fe、Mn、Cu含量丰富,速效磷、有机质和Zn含量一般。由于产地土壤成熟度不高,加上该区复种指数高等问题,造成土壤N、K流失和B、Mo缺乏,影响和制约了萝卜产量和质量。建议及时追加微肥和有机肥,做到科学养地。     

土壤环境中化学定时炸弹的研究现状与展望

土壤环境中的化学定时炸弹对生态环境乃至人类自身危害极大,国内外均有大规模发生化学定时炸弹的实例,但是,由于其不易发现而常常被忽略,这将造成更为严重的后果。化学定时炸弹的分类问题比较复杂,目前较为妥当的做法是对各种分类方案进行有益的探索。化学定时炸弹的触爆机制研究十分重要,是进行地球化学灾害评价、预测和防治的基础;地球化学工程技术是将来预防和治理化学定时炸弹最主要手段。从科学的严密性和严肃性考虑,化学定时炸弹的概念应该由具有更深刻内涵和更广泛外延的“缓变型地球化学灾害”来替代。     

试论黄土高原的生态环境与“土壤水库”──重塑黄土地的理论依据

值今西部开发如火如荼之际, 黄土高原生态环境的重建又在全国生态环境建设总体 布局中被列为最严峻的问题来对待。可见谋求一个为各家共识的治黄对策已刻不容缓。笔者 愿就５０年来的研究所得, 对黄土高原的形成及其演变规律和“土壤水库”确是其中关键等问题 的机理作一比较系统的介绍, 以广求共识和加强各家协作共事, 从而使“顺天时, 得地利, 促人 和”的“黄土高原国土整治２８字方略”能够顺利有序地实施。一个山川秀美、举世无双的黄土 高原可望在下个世纪初重现于中国大陆。     

半干旱半湿润地区土壤盐分平衡情势评价方法及应用

了解土壤盐分平衡情势对于预警土壤盐渍化和指导农业生态环境调控具有实际意义。从地下水、气候、土壤理化性质和土壤初始盐源状况四方面考虑,构建了半干旱半湿润地区土壤盐分平衡情势的评价指标体系;采用综合指数法,以环渤海低平原区为典型区进行了评价应用。评价结果表明：环渤海低平原区土壤盐分平衡情势“良”级区分布面积占总面积的0.8%,“中”级区26.8%,“差”级区58.9%,“劣”级区13.5%,总体维持土壤盐分平衡的能力较弱。通过效验,评级结果与实际情况基本吻合,证明了评价方法的适用性。     

“巫山黄土”元素地球化学特征及成因和物源意义

为了探讨“巫山黄土”的成因及物源,对剖面73个样品进行了常量元素测试和分析,并与已知典型的黄土剖面的元素地球化学特征进行了比较．结果表明:（1）“巫山黄土”主要化学成分以SiO₂、Al₂O₃和TFe₂O₃(TFe₂O₃=Fe₂O₃+FeO)为主,三者的平均含量之和为84.84%,与上部陆壳(UCC)（86.2%）、洛川黄土（85.34%）、镇江下蜀土（86.76%）均非常接近。（2）“巫山黄土”常量元素质量百分含量与洛川、甘孜黄土和西风红黏土的均比较接近,显示了具有相同或相近的沉积环境和类型。（3）“巫山黄土”的TiO₂/Al₂O₃-K₂O/Al₂O₃的数据点主要分布区域与镇江下蜀土与川西的甘孜黄土大致相同,经UCC 标准化后的“巫山黄土”分布曲线与其它风成黄土也显示了较好的相似性,从而说明“巫山黄土”具有风积成因的特点。（4）元素比值分析显示“巫山黄土”与甘孜黄土、洛川黄土均十分相近,在Mg/Mn、Al/Mg、Fe/K方面与甘孜黄土更为接近,而在Mg/Ca 、Si/Al方面与洛川黄土更为一致,可能与两处黄土同源。     

中国北方某城市近郊土壤中重金属污染现状及潜在危害

通过中国北方某城市近郊土壤环境质量的系统调查发现,本区土壤中重金属污染物的化学组成主要为Hg、Cu、Pb、Zn、Se、Cd等;该城近郊土壤的重金属污染是一种典型的大面积、低含量的散漫型污染,局部存在着一些高含量的热点污染。污染物存在形式的研究显示,本区土壤中很有可能存在着潜在的重金属"化学定时炸弹"。     

构造活动区特征源汇体系及古地理重建:以塔里木块体北缘记录“泛非”事件的碎屑锆石分析为例*

完整认识盆山沉积系统,这是古地理重建研究的必然趋势,其中从构造稳定区到构造活动区的特征源汇体系解析是重要环节。塔里木块体北缘活动区存在与“泛非”造山事件有关的岩浆和变质记录,但与这一特征构造-热事件有关的碎屑沉积记录以往在塔里木块体北缘及邻区却鲜有报道。主要针对塔里木块体北缘泥盆纪-石炭纪砂岩样品,文中开展了碎屑锆石原位地质年代学分析,结果表明下石炭统野云沟组砂岩碎屑锆石U-Pb年龄以新元古代中-晚期为主体,与“泛非”造山事件的持续时间较为一致,且此类沉积记录在该地区也是首次大量发现。相应的碎屑锆石的ε_Hf(t)值几乎全为负值,是古老陆壳熔融的产物。而野云沟组之下和之上的砂岩碎屑锆石均无“泛非”造山事件的明显信息。研究认为,泥盆纪南天山洋向南俯冲,导致塔里木块体北缘发育岛弧体系;至早石炭世维宪早期南天山洋盆闭合,相关块体拼贴-碰撞作用致使该区构造古地理转变,与“泛非”造山作用有关的结晶基底隆升和剥露,并成为野云沟组主要物源。晚石炭世随海平面上升和沉积超覆,塔里木块体北缘与“泛非”造山事件有关的结晶基底剥露终止。综合对比区域碎屑锆石U-Pb年代学数据发现,研究区其他显生宙地层中(除上奥统桑塔木组外)均未记录到明显的与“泛非”造山事件物源相关的碎屑沉积,可能说明现存的塔里木块体受“泛非”造山构造-热事件影响的范围有限,另一方面也说明相关基底岩石的剥露主要出现在早石炭世以及晚奥陶世。这些信息的揭示对于认识塔里木块体北部古生代古地貌、碎屑源汇体系与构造古地理具有重要意义。     

试论南昌—莲塘一带土壤环境地球化学特征及其环境质量

通过对南昌——莲塘一带沉积环境、成土母质、土壤化学组分及酸碱性、土壤类型等特征的综合研究,指出区内土壤的成土母质存在一定的相近性,但受人为因素的影响,表土中大部分元素的分布、分配是不均匀的,可将本区划分为“一高两低”三个环境地球化学区;同时查明了该区土壤环境现状,对土壤环境质量进行了初步评价,认为区内土壤环境污染主要与人类活动有关,城区污染重于郊区,菜地污染重于农田。最后提醒人们应广泛关注该区的土壤环境质量,尽早采取有关举措,排除“化学定时炸弹”给人类造成的极大伤害。     

北京五环线两个土壤包气带中Hg和As累积层位的研究与分析--警惕北京地下的"化学定时炸弹"

通过对不同深度土壤中Hg和As含量的测试、污染状况的分析与调查,了解Hg和As元素在不同深度土壤中的累积层位、垂直迁移过程,进而探索Hg和As元素的转移可能对环境造成的潜在危害(即形成"化学定时炸弹"的可能性).对北京东南郊南苑土壤钻孔剖面研究发现,在深度为13.66～16.00 m之间的土壤层,pH剧烈变化,As元素含量明显增高,初步判断该层位是污染物的主要累积层位.     

三峡库区重庆段土壤某些重金属污染的矿物学方法评价

分析了三峡库区重庆段51件土壤样品的矿物组成,结果表明,石英、斜长石和钾长石是土壤中主要矿物,大部分样品中石英的含量高,主要粘土矿物是伊利石,其次是蒙脱石,其他矿物含量较低。同时,参比国家水质标准,根据土壤对金属离子的临界吸附量公式计算了样品重金属污染的阈值,对样品进行了Cd、Hg、Pb、Cu的污染状况评价。结果表明,土壤中污染元素的含量与生态效应评价值并不一致;Cd和Hg的污染尚未达到临界值,危险性较小,但不能因此忽视地球化学定时炸弹的风险;Pb和Cu的污染严重。由于包括母岩在内的样品的评价结果显示污染,可能反映研究区的地球化学背景,需要采取有效措施改善和预防目前和将来的污染危害。     

农田土壤固碳潜力研究的关键科学问题

农田生态系统在陆地生态系统碳循环中扮演着重要的角色。增加农田土壤有机碳的固定不仅可减少大气CO2含量,而且对保障国家粮食安全具有举足轻重的作用。近年来评估土壤固碳潜力已成为国际科学界研究的热点和难点。但由于不同研究者对“潜力”范畴的界定不同,全球或区域尺度农田土壤固碳潜力的估算还存在很大的不确定性。所谓固碳潜力,即土壤碳的饱和水平或土壤所容纳碳的最大能力。这一能力受区域气候、土壤类型、农业管理措施的综合影响。故此,合理地评价固碳潜力,应综合考虑气候、土壤和农业措施诸因素,并将宏观尺度与微观尺度的研究结合起来。从固碳潜力概念范畴及研究方法出发,阐述了农田土壤固碳潜力的研究现状,并结合生物潜力和物理化学潜力的研究,提出区域农田土壤固碳潜力的计量方案,并就该研究领域亟需回答的科学问题进行了探讨。     

福建沿海土壤地球化学分类及基准值研究

利用多目标区域地球化学调查成果,探讨了福建沿海土壤地球化学分类的方法,提出了分类命名方案和诊断标准,将研究区土壤按SiO₂含量划分为铁铝土、硅铝土、铝硅土、硅土4个大类,其中硅铝土又分为一般硅铝土、铁质硅铝土、钾质硅铝土、硫铁质硅铝土4个亚类,铝硅土分为一般铝硅土和钾质铝硅土2个亚类;提出了在各种统计量中,中值比较客观地反映元素含量背景,适合作为基准值;给出了研究区各类土壤的分布图和52种元素及pH的基准值,分析了其成因和农业利用情况。     

The liquefaction of clayey soils under cyclic loading

This paper seeks to investigate the liquefaction of clayey soils, a phenomenon that has been the trigger for many natural disasters in the last few decades, including landslides. Research was conducted on artificial clay-sand mixtures and natural clayey soils collected from the sliding surfaces of earthquake-induced landslides. The undrained response of normally consolidated clayey soils to cyclic loading was studied by means of a ring-shear apparatus. For the artificial clay-sand mixtures, it was found that the presence of a small amount of bentonite (≤ 7%) would cause rapid liquefaction, while a further increase in bentonite content (≥ 11%) produced the opposite effect of raising soil resistance to liquefaction by a significant degree. It was demonstrated that the bentonite-sand mixture was considerably more resistant to liquefaction than the kaolin-, and illite-mixtures, given the same clay content. The test results of plastic soils revealed the significant influence of plasticity on the liquefaction resistance of soil. The microfabric of clayey soil was investigated by means of a scanning electron microscope. The analysis showed that the liquefaction potential of soil was strongly related to certain particle arrangements. For example, soil vulnerable to liquefaction had an open microfabric in which clay aggregations generally gathered at the sand particle contact points, forming low-strength “clay bridges” that were destroyed easily during cyclic loading. On the other hand, the microfabric of soil that was resistant to liquefaction appeared to be more compact, with the clay producing a matrix that prevented sand grains from liquefying. In the case of the natural soils, the obtained results indicated that their cyclic behavior was similarly influenced by factors such as clay content, clay mineralogy and plasticity. The relation between the liquefaction potential of natural soil and its microfabric was thus also established. On the basis of the obtained results, the authors posited an explanation on the mechanism of liquefaction for clayey soil.     

基于广义SMP准则及应力路径法的柱孔扩张分析

柱孔扩张理论广泛用于旁压试验机制分析、沉桩挤土效应等岩土工程问题中。基于经典的Vesic孔扩张理论,采用能够考虑中主应力效应的广义SMP屈服准则,并结合有限应变理论对均质土体中柱孔扩张问题进行分析,根据应力路径假设提出确定塑性区平均体应变的解析步骤。通过大量变参数计算给出具有不同刚度指标 、泊松比 和内摩擦角 的土中柱孔扩张极限状态下的塑性区平均体应变、孔扩张半径比和孔扩张系数。分析结果表明, 、 、 越大,塑性区平均体应变越小,塑性区半径比越大,孔扩张系数越大;随着 增加, 的变化对孔扩张系数的影响更显著。同时,将结果与基于Mohr-Coulomb准则的孔扩张解答进行比较,探讨不同土性参数时中主应力效应对孔扩张系数的影响。文中分析方法及给出的考虑中主应力效应的柱孔扩张系数表可为原位试验分析及桩侧摩阻力估算提供参考。     

Arsenic in groundwater affected by phosphate fertilizers at São Paulo, Brazil

. This paper studies metalloid mobility in soils produced by conventional farming methods. The mobility of arsenic in soils depends on several factors including redox potential, soil mineralogy, pH, and the presence of other anions that compete with As for soil retention sites, for example, phosphate. Phosphate enhances the mobility of As in soils by competing for adsorption sites. Arsenic may accumulate in soil through the application of fertilizers. Ingestion of inorganic arsenic contained in drinking water is known to cause cancer. Studies were carried out in an area of Jundiaí, São Paulo in Brazil with high arsenic levels in natural water from domestic wells. The mobility of arsenic in the soil of Jundiaí was studied in the period 1998–2001. The application of phosphate fertilizers on a wide scale is a common agricultural practice. Based on data from the field and laboratory experiments, the deterioration of soil and groundwater quality is a result mainly of fertilizer use due to excessive P application, overdosing of soil with phosphate, and undesirable additions of arsenic in P fertilizers.     

非饱和土的承载结构与岩土广义结构性

鉴于非饱和土的复杂性,经典的3相模型过于简单,不利于分析相间相互作用及正确定义土中应力。将非饱和土视为一种特殊结构,并细分为6相,定义了其承载结构--广义土结构,进而分析了饱和土与非饱和土的主要差异：承载结构和孔隙流体均不同。基于承载结构的共性,提出了一套定性描述土体结构特点的指标--广义结构性,其普遍适用于描述不同土的承载结构特点。结合实际现象,分析了各指标的合理性,指出湿陷的本质是广义土结构的弱化。此后,分析了两种代表性相间相互作用,揭示了中性应力的物理意义,并合理定义了吸应力,最终明确了土骨架总应力就是“有效应力”。     

Occurrence and source identification of organochlorine pesticides in the surrounding surface soils of the Ittehad Chemical Industries Kalashah Kaku,Pakistan

Surface soil and sediment samples were collected from the surroundings of the Ittehad Chemical Industries Kalashah Kaku industrial zone to assess residual level of 19 organochlorine pesticides (OCPs) and identify their sources. DDTs and HCHs were most prevalent OCPs and general pattern of contamination followed the order: ∑DDT > ∑HCH > dicofol > endrin > heptachlor > dieldrin > endosulfan II. Total measured concentrations of HCHs (6.38–121.71 ng/g) and DDTs (759.65–1811.98 ng/g) were greater in the soil samples collected from fodder/rice fields irrigated with the factory effluents and in the surrounding of waste disposal site. Ratios of β to γ-HCH highlighted an old mixed source of technical HCH and lindane in surface soils. Predominance of p,p′-DDT and p,p′-DDE among isomers and metabolites showed that large quantity of technical grade DDT is still present in the surrounding surface soils. Six soil samples were categorized as heavy polluted soils (class III category of DDT > 1,000 ng/g), two soil samples into less polluted soil between class I and II (50–500 ng/g) and 28 soil samples as non-polluted (<50 ng/g) according to environmental quality standards for surface soils. Six soil samples were categorized as less polluted between class I and II of HCHs (50–500 ng/g). Greater concentration of DDTs and HCHs above quality guideline poses potential exposure risk to biological organisms, safety of agricultural products and human health in the surrounding of the Ittehad Chemical Industries.     

Citrate sorption and biodegradation in acid soils with implications for aluminum rhizotoxicity

Citrate and other organic acids play an important role in the rhizosphere and pedogenic processes. Although secreting citrate from roots in response to Al and heavy metal stress has been recognized as a central mechanism for plants to avoid toxicity, the efficiency of root citrate on metal detoxification is still contradictory in acid soil with abundant oxide minerals that serve as a potential sorption site for citrate. The objective of this study was to investigate sorption and biodegradation of citrate in subtropical acid soils with different mineralogical properties. A batch experiment was conducted to assess the possible fates (adsorption and biodegradation) of citrate in the three acid soils (Cecil, Creedmoor and Norfolk) under microbial-active and inactive conditions. Citrate adsorption isotherms for all soils were adequately described by the Freundlich equation with the R² value being over 0.90. The Cecil soil had the highest affinity for citrate adsorption among the soils with 99% adsorption observed throughout the citrate concentration range, which was due primarily to the abundant Al and Fe oxides. Citrate sorption to the mineral phase significantly reduced its biodegradation by 56%, 65% and 99% for the Creedmoor, Norfolk and Cecil soils, respectively. The results suggest the efficiency of rhizosphere processes for Al detoxification by root-secreted citrate would be significantly reduced in acid soil with abundant Al and Fe oxides.     

非饱和土的本构模型研究

引用平均土骨架应力的概念,研究推导出非饱和土的刚度参数随吸力变化而变化的关系式,进而推导得到用平均土骨架应力表述的非饱和土LC屈服面函数以及硬化规律。从土力学原理推导,得到土样由于在净应力和吸力作用下产生体积变形引起土样饱和度变化的关系式。由平均土骨架应力推广,得到三轴应力状态的椭圆屈服函数,这一非饱和土本构模型的优点在于考虑了应力作用后土样饱和度的变化,通过对已有试验数据的初步验证,表明提出的非饱和土本构模型的合理性和适用性。     

Evaluation of ecological risk and source of heavy metals in vegetable-growing soils in Fujian province,China

Heavy metal pollution in vegetable-growing soils is of increasing concern due to the potential health risk via food chain. The present study aimed at assessing the potential ecological risk (RI) of heavy metals (HMs) in the vegetable-growing soils collected from Fujian Province, China, and identifying the potential sources with multivariable methods including correlation matrix and principal component analysis (PCA). The concentrations of HMs including Pb, Cd, Hg, Cr, As, Cu, Zn, and Ni in 160 soils collected from 25 sites of vegetable-growing land in Fujian Province, China, are measured with inductively coupled plasma mass spectrometry and hydrogen generation-atomic fluorescence spectrometer, respectively. Results show that most of the soil samples have been seriously contaminated with HMs, especially the metals of Hg, Cd, and Pb, compared with both of the background values of soils in Fujian Province and the limitation of total HMs in soil environmental quality for edible agricultural products set in China (HJ 332-2006). The indexes of RI indicate that only 8% of the 25 sites are environmentally safe, whereas according to the present study 28% of the sampling sites are heavily contaminated with HMs with 628–1,076 of the RI values. Based on PCA analysis, Zn, Cd, and Pb associated with PC1 are found to derive from anthropogenic sources, especially the local industrial activities, such as porcelain plants in Dehua, zinc metallurgical plants in Nan’an, and sewage irrigation from industrial estate in Taijiang. The concentrations of As, Ni, and Cu loaded in PC2 are found to be mainly controlled by natural factors (i.e., the lithogenic process of natural parent soils). Hg in PC3 is also found to originate from the anthropogenic sources, such as local coal combustion in Longhai and industrial activities in Cangshan. However, Cr in PC3 is mainly derived from the lithogenic sources.