土壤硒及其与植物硒营养的关系

综述了土壤中Se的形态分布、有效性及其与植物关系研究方面的进展。论述了不同形态的Se在土壤中分布情况、对植物的有效性与土壤pH值、化学及矿物学组成、吸附表面、氧化还原状态等物理化学性质的关系;Se在植物中的富集、转化及其对植物的抗氧化、促进生长、提高产量和质量等各种生物学效应;并在此基础上对Se的应用前景做了展望。     

土壤—小麦食物链硒转移模式及其应用

利用~(75)Se为示踪剂,研究了土壤-小麦系统中Se的迁移和分布规律。土壤Se植物可利用系数SA=0.3—1.9,土壤不同,SA值也不同。土壤固液两相中Se的分配系数Kd=141—395,说明土壤对Se有强烈的吸附作用,Kd大小顺序为:暗棕色森林土>黑土>草甸棕壤。小麦对土壤Se的浓集系数CF=0.09—0.14,小麦不是浓集Se的作物;Se在小麦各器官间CF值>1,表明其在小麦体内运转比较容易。作者提出了一个食物链Se转移模式,评价了土壤有效Se水平,指出草甸棕壤有效Se充足,黑土和暗棕色森林土则不足。估算了病区每人每天摄Se量为26.6μg,远低于我国成人安全摄Se量建议值40—240μg/人·日的下限值。     

土壤植物营养与农产品品质及人畜健康关系

综述了土壤中Ca,Mg,S,Zn,Fe等中微量营养元素及Se,I等有益元素的丰缺情况,概述了矿质营养元素和有机物质对农产品品质的影响与人畜健康的关系,展望了今后应预以加强的研究方向,为进一步开展土壤植物营养与产品品质的研究提供参考。     

烟草根际土壤硒、硫形态相互作用与烟草对硒、硫吸收的研究

通过烟草根际营养试验研究发现,烟草根际土壤Se总量及可溶态Se、交换态Se及有机Se均表现出明显的亏缺.而根际土中S总量及吸附性S、有机S则表现明显的富集.施S对根际土Se亏缺程度的影响与施Se处理有关,而施Se对根际土S富集程度的影响随施S的水平而有一定差异.未施Se处理时,施S降低了烟草根际土中相应几种Se形态的亏缺率,施Se处理时施S的影响则相反.不施S时,加入Se可以增加根际土全S量的富集程度;施S时,加入Se则减少根际全S量的富集程度.前期烟草的Se含量主要受根际土壤可溶态Se的影响,而Se积累量除受土壤可溶态Se的影响外,还受到根际土壤交换态Se、有机Se及酸溶态Se的影响.前期烟草地上部分中S含量主要受根际土壤可溶性S及有机S影响.     

海南稻田土壤硒与重金属的含量、分布及其安全性

采集了海南省18个市(县)代表性的稻田土壤耕作层(0—20cm)样品280个,研究了硒(Se)和5种有毒重金属元素(Hg、Cd、Cr、Pb和As)的含量、分布及其相关关系,并对Se和重金属的安全性进行评价,可为合理区划清洁且富Se稻田提供理论依据。结果表明:海南稻田土壤中Hg、Cd、Cr、Pb和As平均含量均低于国家土壤环境质量一级标准值和全国土壤背景值,以绿色食品产地环境技术条件限量标准为标准,用单项污染指数法和内梅罗综合污染指数法评价海南稻田土壤重金属的污染状况,结果都是清洁的。但以海南省土壤背景值做参比值,Hakanson潜在生态危害指数达到211.54,属于强生态危害,从潜在生态危害系数来看,Hg(102.61)和Cd(98.89)达到强生态危害,分别比海南省土壤背景值增加1.56和2.3倍,今后应注意控制Hg和Cd污染源。稻田土壤Se含量从痕量到1.532mg/kg之间,平均值为0.211mg/kg,占47.5%的稻田土壤Se含量处于中等及以上水平(>0.175mg/kg)。Se含量高的稻田土壤主要集中在东北部的海口及其周边的澄迈、定安、文昌和琼海,还有东南部的万宁和保亭。由于重金属平均含量还比较低,可暂时忽略重金属污染,故可在上述Se含量高的稻田土壤上种植富Se水稻。稻田土壤Se含量与Hg、Cd和As含量呈极显著或显著正相关,因此今后应加强研究稻田土壤Se与Hg、Cd和As的有效性及其相互作用,以便生产出绿色的富Se优质大米。     

外来植物入侵对土壤生物多样性和生态系统过程的影响

随着科学家对生态系统地下部分的重视,评价外来植物入侵对土壤生态系统的影响成为当前入侵生态学领域的研究热点之一。本文综述了外来植物入侵对土壤微生物、土壤动物以及土壤碳、氮循环动态影响的研究,并探讨了其影响机制。已有的研究表明,植物入侵对土壤生物多样性及相关生态系统过程的影响均存在不一致的格局,影响机制也是复杂多样的。外来植物与土著植物凋落物的质与量、根系特征、物候等多种生理生态特性的差异可能是形成格局多样性和影响机制复杂性的最主要原因。今后,加强多尺度和多生态系统的比较研究、机制性研究、生物多样性和生态系统过程的整合性研究及土壤生态系统对植物入侵的反馈研究是评价外来植物入侵对土壤生态系统影响的发展趋势。     

土壤微食物网生物和土壤微生物对小星穗薹草生长和土壤养分的影响差异

土壤微食物网生物是影响土壤养分循环的重要驱动因素,其对植物生长和土壤养分的影响大于广受关注的土壤微生物。通过土壤生物添加实验,对比分析了在土壤微食物网生物添加、土壤微生物添加和灭菌土壤三种处理条件下,湿生草本植物小星穗薹草的生物量、形态和生理性状以及土壤养分含量等指标,以探究土壤微食物网生物和土壤微生物对植物生长和土壤养分的差异性影响。结果表明,土壤微食物网生物对植物的促进作用显著大于土壤微生物的作用。土壤微食物网生物未改变植物的根系性状,而土壤微生物使植物的根系形态发生明显改变。不同土壤生物添加处理的土壤有效养分含量也存在显著差异。该研究证明了土壤微食物网生物更有利于植物生长。研究结果为深入认识土壤微食物网生物对植物生长和土壤养分周转的重要性、推动植物与土壤生物相互作用过程和影响机制研究提供了新视角和可靠数据。     

西鄂尔多斯地区土壤与四合木微量元素含量特征分析

从西鄂尔多斯地区生境适宜性特征的角度,研究四合木(Tetraena mongolia)的生态适应性,探讨迁地保护不易成活的原因,对不同生境条件下四合木分布区土壤和植株微量元素含量的测定结果表明,四合木分布区土壤中Cu、Fe、Mn、Zn、B、Mo、Se、Co、CI9种微量元素中,除B的含量明显高于国内土壤平均含量水平和荒漠区土壤平均含量水平;其它元素都低于国内土壤的平均含量;迁地实验区土壤中除Cu的有效量略低于荒漠区土壤和四合木分布区土壤的含量外,Fe、Mn、Zn、B、Mo的有效量均略高于荒漠区土壤和四合木分布区土壤,四合木植株中Fe、Cu、Zn、B、Se、Co的含量远高于各种类型草原植物,而Mo含量高于植物体含量均值,但低于荒漠草原植物,仅为荒漠草原植物的50％,四合木分布区土壤与四合木成株、幼苗9种微量元素相关性不显著,而且植物体中9种元素含量远远大于土壤中的有效量,从四合木植株中各元素含量与各类型草原植物(包括荒漠草原植物)和土壤中含量比较表明,四合木在生长过程中对各种元素呈富集特征,可见土壤微量元素的含量不是四合木迁地种植的制约因子。     

植物、土壤及土壤管理对土壤微生物群落结构的影响

土壤微生物是土壤生态系统的重要组成部分,对土壤微生物群落结构多样性的研究是近年来土壤生态学研究的热点。本文综述了有关植物、土壤类型以及土壤管理措施对土壤微生物群落结构影响的最新研究结果,指出植物的作用因植物群落结构多样性、植物种类、同种植物不同的基因型,甚至同一植物不同根的区域而异;而土壤的作用与土壤质地和有机质含量等因素有关;植物和土壤类型在对土壤微生物群落结构影响上的作用存在互作关系。不同的土壤管理措施对土壤微生物群落结构影响较大,长期连作、大量的外援化学物质的应用降低了土壤微生物的多样性;而施用有机肥、免耕可以增加土壤微生物群落结构多样性,有利于维持土壤生态系统的功能。     

湘西北河谷特殊生境植物多样性和区系成分及其与土壤环境因子的相关性

对湘西北猛洞河和德夯河谷9类小生境(凹槽、干旱石壁、滴水岩壁、石土坡、瀑布、微土台、溪沟、岩溶洞穴和河水浸没带)的土壤环境因子(包括含水量、pH值和矿质元素含量)和植物物种组成及区系成分进行了调查,并采用RDA排序法分析了该区域植物区系成分与土壤环境因子的相关性.结果表明:该区域生境异质性较高,各类小生境土壤的含水量、pH值和矿质元素含量均有差异;其中,瀑布生境中土壤含水量最高(达51.9％),干旱石壁土壤含水量最低(仅13.0％);绝大多数生境土壤偏碱性,仅石土坡土壤偏酸性(pH 6.4);9类小生境土壤中Al、Ba、Cd、Co、Cu、K、Mg、Mn、Se和Zn含量差异明显,其中Al含量均最高.各生境中分布的植物种类数量有明显差异,其中,石土坡生境中植物种类最多(共735种)、岩溶洞穴生境中植物种类最少(仅6种);有724种植物的分布辐射范围为1个小生境,分布辐射范围达7个小生境的植物仅1种.各类小生境中植物科、属的分布型数量变化规律基本一致,即以热带分布型为主,但温带分布型属的数量略有增加.RDA排序结果显示:土壤环境因子的12个变量分别可解释科、属区系成分变异信息量的75.9％和88.9％,其中矿质元素含量及pH值与科、属区系成分呈不同程度的正相关或负相关;总体上看,土壤Cd、Se、Zn和Ba含量及pH值是影响该区域植物区系组成的主要土壤因子.研究结果显示:湘西北河谷特殊生境中植物物种分布生境较为专一,植被抗干扰能力较差,不利于物种多样性的长期维持;生境异质性在一定程度上影响植物区系成分的变化,但在科、属层次上影响程度有差异.     

Effects of different water management on absorption and accumulation of selenium in rice

Rice is the staple food for more than half of the world's population, but selenium (Se) is low in many rice growing countries. Water management model affects rice soil pH and Eh, and then affects the bioavailability of Se in soil. A pot experiment was conducted to investigate the effects of water management on soil Se species, dynamics and selenium uptake by rice plants. Sodium selenite was added to the soil so that the soil selenium content reached 0.5 mg kg^?1 to study the effects of 3 different water management modes on soil selenium uptake by rice plants. These three modes are flood irrigation (F), aerobic irrigation (A) and alternate flood and aerobic irrigation (AFA). The results showed that flooded irrigation treatment increased the soil soluble selenium concentration, and the selenium in soil solution mainly existed in the form of selenite and selenomethionine selenium oxide. The content of selenium in grain was 2.44 and 1.84 times that of flooded irrigation treatment under A and AFA respectively. The content of selenium in straw was 1.32 and 1.58 times that of flooded treatment under A and AFA respectively. After rice grain enzyme hydrolysis, HPLC-ICP-MS analysis showed that Selenomethionine was the main selenium speciation in rice grains. This study showed that aerobic flooded treatment is one of the most effective ways to increase selenium content in rice field.     

Selenium status of Omsk oblast

For 32 districts of Omsk oblast, the levels of selenium accumulation were determined across trophic levels: soil, plants, animals, and human. An inverse correlation was found between serum selenium concentration and parameters of total mortality, as well as the incidence of lung, ovarian, and rectal cancer. Significant differences were shown in the coefficient of plant selenium accumulation depending on the soil type. We discuss the most promising approaches to optimizing the selenium status of the population.     

环境与植物中硒形态研究进展

本文综述了近年来在环境及植物中的硒形态研究方面的进展。在土壤和水中各种不同形态硒的分布情况与ｐＨ值及其它特性之间的关系;植物中各种有机硒化合物的含量,可能的结构和硫素之间的关系,植物对硒的吸收转化过程等等     

正交试验分析不同作物的产量、含硒量与土壤酸碱度、硒酸盐、亚硒酸盐含量的相关性

采用正交试验研究了碎米荠、韭菜、大豆、马铃薯的产量、含硒量与土壤酸碱度、硒酸盐、亚硒酸盐含量的关系。结果表明:影响作物含硒量最大的因素是作物品种,不同作物间差异极显著。在土壤中施用硒酸钠和亚硒酸钠均能够提高作物含硒量,用量均以1.0 mg/kg为宜;硒酸钠会使作物产量降低,用量过高使作物硒吸收总量下降;土壤pH值增加有利于植物对硒的吸收,但综合考虑作物产量、含硒量和硒摄入总量,土壤适合的pH值应在6.7～7.9之间。     

Recent Developments to Mitigate Selenium Deficiency in Agricultural Eco-Systems

Under changing climate, trace elements like selenium (Se) have emerged as vital constituent of agro-ecosystems enabling crop plants to off-set the adverse effects of suboptimal growth conditions. The available form of selenium is important for boosting its bioavailability to crop plants having varied agro-botanical traits and root architectural systems. As compared to selenite, the selenate has a weaker soil bonding, higher absorption in the soil solution which results in a comparatively absorption by plant roots. Various factors including dry climate, high pH, optimal ambient air temperature, less accumulation of water, and low concentration of organic matter in the soil tend to boost the selenate ratio in the soil. The use of selenium pelleted seeds has emerged as an interesting and viable alternative to alleviate selenium deficiency in agricultural eco-systems. Similarly, the co-inoculation of a mixture of Selenobacteria and Arbuscular mycorrhizal fungi represents an evolving promising strategy for the bio-fortification of wheat plants to produce selenium-rich flour to supplement human dietary needs. Furthermore, in-depth research is required to assure the effectiveness of biological fertilization procedures in field conditions as well as to explore and increase our understanding pertaining to the underlying main mechanisms and channels of selenium absorption in plants. The focus of this review is to synthesize the recent developments on Se dynamics in soil-plant systems and emerging promising strategies to optimize its levels for crop plants. Recent developments regarding the use of micro-organisms as a biotechnological mean to enhance plant nutrition and crop quality have been objectively elaborated. The study becomes even more pertinent for arid and semi-arid agro-ecosystems owing to the potential role of selenium in providing stress tolerance to crop plants. Moreover, this review synthesizes and summarizes the recent developments on climate change and bioavailability, and the protective role of selenium in crop plants.

     

环境与植物中硒形态研究进展

本文综述了近年来在环境及植物中的硒形态研究方面的进展。在土壤和水中各种不同形态硒的分布情况与pH值及其它特性之间的关系;植物中各种有机硒化合物的含量,可能的结构和硫素之间的关系,植物对硒的吸收转化过程等等。     

Effect of selenium fertilization on the accumulation of cadmium and lead in rice plants

Background and Aims

The accumulation of cadmium and lead in rice (Oryza sativa L.) grains is a potential threat to human health. In this study, the effect of selenium fertilization on the uptake and translocation of cadmium and lead in rice plants was investigated.

Methods

Rice plants were cultivated using cadmium and lead contaminated soils with selenium addition at three concentrations (0, 0.5 and 1 mg kg^?1). At maturity, plants were harvested, and element concentrations in rice tissues were analyzed by using ICP-MS.

Results

Selenium application significantly increased selenium accumulation in rice grain, and markedly decreased cadmium and lead concentrations in rice tissues. In brown rice grains, selenium application reduced cadmium concentrations by 44.4 %, but had no significant effect on lead accumulation. Selenium application significantly decreased metal mobility in soils, at 0.5 mg kg^?1 treatment, the translocation factor of cadmium and lead from soil to iron plaque decreased by 71 and 33 % respectively.

Conclusions

The mechanism of selenium mitigating of heavy metal accumulation in rice could be decreasing metal bioavailability in soil. Selenium fertilization could be an effective and feasible method to enrich selenium and reduce cadmium levels in brown rice.     

Speciation, Distribution, and Bioavailability of Soil Selenium in the Tibetan Plateau Kashin–Beck Disease Area—A Case Study in Songpan County, Sichuan Province, China

To clarify the relationship between the soil selenium distribution and its bioavailability with the distribution of Kashin–Beck disease (KBD) endemic areas on the eastern edge of the Tibetan Plateau, samples of natural soil (0–20 cm), cultivated topsoil, and main crops of the region (highland barley) were collected at different altitudes according to topographical and geomorphological features in both KBD and non-KBD areas of Songpan County. These samples were used for determination and analysis of total selenium content in soil and highland barley and available selenium that can be absorbed and utilized by plants. The results showed that the average total selenium content of natural and cultivated topsoil in KBD areas was lower than that in non-KBD areas (natural soil, P?=?0.061; cultivated soil, P?=?0.002), which is in agreement with the geographical distributions of selenium in other KBD-affected areas. However, the total soil selenium content exhibits certain micro-spatial distribution features, namely, the total selenium content in some endemic areas was significantly higher than that of non-KBD areas. This result was contrary to the general distribution that total selenium content in a KBD-affected area is lower than that in a non-KBD area. We further studied the extraction rate and content of soil selenium in six different fractions. The results indicated that the content and extraction rate of available selenium in KBD-affected areas were significantly lower than those in non-KBD areas. There is a distinct positive correlation between plant-available selenium and highland barley selenium (r?=?0.875, P?=?0.001) and a distinct negative correlation with altitude (r?=??0.801, P?=?0.010). Therefore, in KBD endemic areas, the selenium content in crops decreases as the available selenium content in soil decreases and is closely related to the geographical environment features (such as altitude and precipitation). These results suggest that the soil available selenium and ecological features are important factors that restrict the dietary selenium flux for residents in KBD endemic areas of the Tibetan Plateau, providing a theoretical and experimental basis for implementing agricultural measures to regulate the ecological cycle of the selenium flux in the KBD endemic area.     

生态环境中微量元素硒与克山病

一、前言 生态环境中的生物地球化学过程,决定于自然因素和人为因素的综合作用。生态环境中的化学元素,主要来源于自然界的基岩,以后通过地下水、土壤、植物、动物,最后多以食物形式进入人体。所以生态环境中的生物地球化学过程,是受各个元素之间相互关连、相互制约的复杂反应所控制。人类也必然受到这种生态环境中的生物地球化学过程的深刻影响。为了研究我国多年来没有解决的克山病(地方性心肌病)病因及其防治,把岩石—土壤—生物—人体视为统一的生态系统,并研究人体必需的微量元素在此系统中的迁移变化规律及与人体的关系,来说明环境中微量元素与克山病之间的关系,具有十分重要的意义。     

Selenium speciation profiles in selenite-enriched soybean (Glycine Max) by HPLC-ICPMS and ESI-ITMS

Soybean (Glycine Max) plants were grown in soil supplemented with sodium selenite. A comprehensive selenium profile, including total selenium concentration, distribution of high molecular weight selenium and characterization of low molecular weight selenium compounds, is reported for each plant compartment: bean, pod, leaf and root of the Se-enriched soybean plants. Two chromatographic techniques, coupled with inductively coupled plasma mass spectrometry (ICPMS) for specific selenium detection, were employed in this work to analyze extract solutions from the plant compartments. Size-exclusion chromatography revealed that the bean compartment, well-known for its strong ability to make proteins, produced high amounts (82% of total Se) of high molecular weight selenospecies, which may offer additional nutritional value and suggest high potential for studying proteins containing selenium in plants. The pod, leaf and root compartments primarily accumulate low molecular weight selenium species. For each compartment, low molecular weight selenium species (lower than 5 kDa) were characterized by ion-pairing reversed phase HPLC-ICPMS and confirmed by electrospray ionization ion trap mass spectrometry (ESI-ITMS). Selenomethionine and selenocystine are the predominant low molecular weight selenium compounds found in the bean, while inorganic selenium was the major species detected in other plant compartments.