土壤中镉、铅、锌及其相互作用对作物的影响

通过作物盆栽模拟试验(砂壤质褐土、pH值8.2)揭示：土壤中分别施入镉(CdCl2)、铅[Pb(CH3COO)2]或锌(ZnSO4)其影响表现为,植物各器官镉的含量超过对照植物的数倍至500倍。土壤镉浓度<5ppm和<10ppm分别造成某些蔬菜和水稻的污染。铅主要积累在植物根部,土壤铅污染对作物的影响较小。锌主要积累在植物叶片和根部,对水稻产生生长抑制的土壤锌浓度临界值不大于200ppm,此浓度对旱作无影响。土壤中同时施入镉和铅,植物对镉的吸收增加。而土壤中镉的增加却减少了植物体内铅的含量。土壤中由于镉、锌或铅、锌相互作用的结果,水稻对它们的吸收都有增加。在旱地土壤锌浓度的增高,降低了植物对镉、铅的吸收。镉、铅、锌同时施入土壤由于相互作用的结果,除锌之外,植物对镉、铅的吸收有明显下降。评价土壤重金属污染,不仅要看它们的含量及其存在形态,而且要分析它们之间的相互作用(促进或拮抗)特点。     

氟的危害及控制

环境中氟的危害是环境科学及卫生学界极为关注的问题。氟的过多吸收 ,对动植物及人体会产生危害[1 ,2 ] 。研究氟危害的表现特征及机理 ,目的是为了控制或减轻氟危害。综合评价氟的测定方法 ,在氟污染调查和环境质量评价中 ,有切实的实用价值。1　氟对植物及土壤微生物的毒害作用土壤氟污染对作物的危害是慢性积累的生理障碍过程。氟能抑制作物的新陈代谢、呼吸作用[3] 及光合作用[2 ] ,抑制新陈代谢过程中马来酸脱氢酶的活性[4] 。氟对作物的危害主要表现为干物质积累量少、产量降低、分蘖少、成穗率低、光合组织受损伤 ,出现叶尖坏死 ,叶…     

土壤Hg污染及修复技术研究

早在 2 0世纪 6 0年代初期 ,日本查明了“水俣病”[1] 是由甲基Ｈｇ污染造成的 ,引起世界范围内人们对Ｈｇ污染危害的重视 ,使其研究日益增多。Ｈｇ通过不同途径进入土壤环境 ,土壤中的Ｈｇ经过复杂的物理、化学反应 ,大部分以各种形态滞留在土壤中 ,同时Ｈｇ在作物可食部分积累并进入食物链循环 ,对人体健康构成威胁。我国被Ｈｇ污染的耕地面积有 3.2× 10 4 ｈａ ,每年产生污染环境的Ｈｇ达 1.9× 10 8ｋｇ[2 ] 。土壤一旦遭受Ｈｇ污染 ,对人类健康构成潜在的危害 ,因此土壤Ｈｇ污染的治理及生物修复技术研究应运而生。重金属污染治理的传…     

农作物体内铅,镉,铜的化学形态研究

本文报道了农作物体内重金属存在的化学形态。用逐步提取法分析了生长在污染土壤上的水稻、小麦的根与叶。结果表明,在两种作物中,根部的铅以活性较低的醋酸可提取态与盐酸可提取态占优势,而叶中的铅以盐酸可提取态占优势。不论根部或叶部,在各种形态镉中,以氯化钠可提取镉所占比例较高,作用较重要。作物体内的铜活性较强,根部以乙醇可提取态占优势,叶中以水提取态占优势。各种结合形态的重金属迁移能力、毒性效应有显著差异。作物体内重金属化学形态特征与其表观毒性效应有密切联系。     

施用尿素对土壤中Cd、Pb形态分布及植物有效性的影响

采用室外盆栽试验,研究了在镉(25mg·kg-1)、铅(1000mg·kg-1)单一污染及其复合污染的土壤中,施用不同剂量尿素(0、100、200、400、800mg·kg-1)对小麦根际和非根际土壤镉、铅形态、小麦植物体镉、铅浓度的影响,为重金属污染土壤的防治提供依据。结果表明:增加尿素施用水平显著提高了小麦不同部位镉、铅浓度,尿素施用促进小麦对镉、铅的吸收与其对土壤中镉、铅形态分布的影响紧密相关,尿素施用引起土壤pH下降,提高土壤中交换态镉、铅含量,而交换态是最易被植物吸收利用的部分,这是尿素施用提高镉、铅植物有效性的主要原因;与单一污染相比,镉、铅复合污染抑制了小麦对铅的吸收,但促进了小麦对镉的吸收。     

湘潭莲子种植区土壤和莲子重金属污染的生态风险评价

为探讨湘潭莲子种植区土壤重金属的污染特征及潜在生态风险, 以6个主要的莲子种植区为研究对象, 分析了土壤和莲子籽粒中锰、铜、砷、镉、铅和铬的含量和污染特征, 并利用潜在生态危害指数法评价了土壤重金属的综合潜在生态风险。结果表明: 6种重金属中镉含量平均值高于风险筛选值, 低于风险管制值, 其它重金属含量的平均值低于或接近风险筛选值。各元素生态风险从大到小依次是镉、铅、砷、铜、铬、锰。6个位点的综合生态危害指数平均值为224.7, 属于中等污染风险水平。各位点对应的莲子也受到一定程度的重金属污染, 籽粒中镉和铅存在超标现象。通过以上分析说明, 莲子种植区土壤重金属整体呈现出中等生态风险状态。为了确保莲子的安全生产, 有必要加强莲子种植区的土壤检测和治理。     

铅、镉在蔬菜中的累积特性及对蔬菜生长的影响

采用不同浓度原位污染土盆栽试验,研究铅(Pb)、镉(Cd)在8种蔬菜中的累积规律及对蔬菜生长的影响,揭示蔬菜-土壤铅、镉含量相关关系,提出8种蔬菜的土壤铅、镉安全临界值。结果表明:油菜、甘蓝长势均好,生长未受抑制,其他几种蔬菜随铅、镉浓度的增加,生长受到不同程度抑制;铅、镉复合污染对8种蔬菜的生长抑制程度为芹菜莴苣胡萝卜豇豆辣椒番茄甘蓝、油菜,与蔬菜累积铅、镉能力一致;芹菜-土壤铅、镉含量呈显著线性相关(R2=0.923,0.956);土壤铅安全临界值为叶菜类(甘蓝、油菜)根茎类(莴苣、胡萝卜)豆类(豇豆)芹菜和辣椒,番茄土壤铅安全临界值待定;8种蔬菜土壤镉安全临界值相同。     

利用转基因植物消除铅镉的环境污染

NatureBiotechnology2003年21卷8期914～919页报道:铅是工业化国家最重要的污染性重金属之一。铅可蓄积于人体并影响众多的细胞、组织、器官和系统,包括中枢神经系统、血细胞和肾脏。美国环境保护局将铅称之为儿童健康的头号威胁者。镉污染也很普遍。已发现镉对人体有高度毒性,例如低浓度的镉可引起癌症。利用化学方法虽可清除环境中的铅和镉污染,但其经济代价极为高昂。最近已利用可吸收大量有毒金属的转基因植物来清除污染土壤中的金属。并已育成了可蓄积汞和镉的植物,但尚未发现可蓄积铅的。为了培育适合于消除铅污染的转基因植物,最近…     

各种改性剂对重金属迁移,积累影响的研究

采用盆栽实验．研究了在不同改性措施条件下,Ｃｄ、Ｐｈ、Ｃｕ、Ｚｎ、Ａｓ多元素复合污染物对水稻、大豆生长的影响及重金属在土壤－作物系统中迁移、积累的特性．结果表明,作物根系中的离子冲量越大,对作物危害越重．酸处理对作物生长影响较大,而腐殖酸和石灰处理有利于作物的生长．改性剂对重金属迁移能力影响大小依次为酸＞腐殖酸＞石灰．作物的不同部位对重金属吸收的顺序为根＞茎叶＞籽实．重金属在土壤－作物系统中的迁移能力为Ｃｄ＞Ｚｎ＞Ｃｕ＞Ａｓ＞Ｐｂ．     

植物响应Cd胁迫研究进展

镉(Cd)是一种毒性极强的重金属污染物,位于土壤无机污染物首位。Cd因具有强流动性和溶解性而容易被植物体吸收,不仅影响植物正常生理代谢并降低作物品质,还能通过食物链的传递和富集危害人体健康,因此植物对Cd胁迫的响应机制已成为研究的热点。本文综述了Cd胁迫对植物生理代谢和分子层次危害的同时,总结了植物在Cd胁迫下进化出的耐受性机制,以期为培育低积累作物和超积累Cd污染土壤修复植物提供理论依据。     

绿色食品生产中土壤作物系统铅的积累与迁移研究

研究了Pb在土壤-作物生态系统中的积累和迁移,并结合水稻绿色食品生产,进行了无机肥、有机肥和生物菌肥及其配比试验．结果表明,土壤全Pb含量随土层的加深而逐渐递减,收获后土壤全Pb含量在0～15和15～30cm分别为11．14和9．37mg·kg^-1．水稻根从土壤中吸收Pb,并向茎、叶和籽粒中迁移．在同一生长期,水稻植株不同部位全Pb累积态势为：根>茎叶>籽粒．在不同生长期,随水稻生长发育,全Pb含量缓慢增加,至收获时,606—14和辽粳294籽粒中全Pb含量分别为0．008和0．007mg·kg^-1,均低于绿色食品标准．方差分析表明,品种间产量差异显著;不同处理间产量差异不显著．试验结果表明。可以用有机肥或生物菌肥来代替无机肥进行水稻生产．     

我国北方3种典型土壤-作物体系中微生物量磷库特征

土壤微生物量磷(Microbial Biomass Phosphorus, MBP)是土壤磷组分中最为活跃的形态,在土壤磷素的形态转化与生物地球化学循环过程中起着关键作用,是植物可利用磷的重要来源。研究土壤MBP库容的大小对于充分认识微生物的固磷潜力和掌握土壤磷素循环与转化能力意义重大。以我国北方农田3种典型的土壤-作物体系为研究对象,基于定点采样,通过分析测定采集的362个表层(0—30 cm)土壤样品来量化不同土壤-作物体系MBP库容的大小。结果表明：黑土-春玉米、潮土-冬小麦/夏玉米、灰漠土-棉花体系表层土壤MBP平均含量分别为17.36、14.45、8.75 mg/kg,且不同土壤-作物体系间MBP含量存在显著差异;3种土壤-作物体系表层土壤(0—30 cm)MBP库容的大小分别为83.60、54.26、39.80 kg P/hm~2,其储存的磷在数量上相当于当季作物需磷量的1.10—2.73倍,表明土壤MBP库是农田生态系统中一个不容忽视的巨大有效养分磷储库。其库容的大小受土壤性质和气候因素的共同影响,土壤pH、有机碳、年均气温和年均降雨量是我国北方农田土壤MBP库容大小的主...     

绿洲农田氮素积累与淋溶研究述评

作物对氮素的吸收利用及氮素在土壤中的积累和运移,制约着绿洲农田生产力并对农田环境造成影响,是绿洲农田生态系统可持续发展和绿洲稳定性研究的一个重要方面。针对农田氮素积累和淋溶这一绿洲资源消耗量增加、耕作方式粗放结果下的环境问题,对其特征及引发的环境效应进行了详细阐述,并从不同的角度综述了缓减绿洲氮素淋失及环境污染的对策。指出在未来还需加强绿洲地下水氮污染调查及农田氮素积累和淋溶现状的区域评价,并针对一些在绿洲大面积推广的农田管理技术开展其对农田氮素积累和淋溶影响的研究,并强调人文因素在绿洲农田氮素积累与淋溶调控中的重要性。     

Health Risks Assessment of Heavy Metal Pollution in the Soil-Crop System from an E-Waste Dismantling Area

Soil is an essential resource for agricultural production. In order to investigate the pollution situation of heavy metals in the soil-crop system in the e-waste dismantling area, the crop and soil samples (226 pairs, including leaf vegetables, solanaceous vegetables, root vegetables, and fruits) around the e-waste dismantling area in southeastern Zhejiang Province were collected. The concentrations of Cd, Cu, Pb, and Cr were determined. The average concentrations of Cd, Cu, Pb, and Cr in soils were 0.94, 107.79, 80.28, and 78.14 mg kg^-1, respectively, and their corresponding concentrations in crops were 0.024, 0.7, 0.041, and 0.06 mg kg^-1, respectively. The transfer capacity of leaf vegetables was significantly higher than that of non-leaf vegetables, and the accumulation of four heavy metals in crops tended to be Cd > Cu > Cr/Pb. The pollution index’s results revealed that the soil pollution degree under different land uses ranked as root vegetables soil > leaf vegetables soil > solanaceous vegetables soil > fruit soil. The carcinogenic and non-carcinogenic risks of heavy metal exposure were ranked as food intake > accidental ingestion > dermal contact > inhalation. The comprehensive non-carcinogenic risk was ranked as Cr > Cd > Pb/Cu. Our results could be used to provide useful information for further crop cultivation layout in the study area, which can guarantee the local residents’ health and food safety.

     

Heavy Metal Balances, Part I

The control of heavy metals in such a way that soil functioning and product quality are not impeded is a prerequisie to sustainable agricutture. The current status of heavy metal accumulation in agricultural soils differs widely by region, by metal, and by agricultural system; levels of concern have already been reached in several regions (for instance, in the Netherlands and Australia). An analysis of the input and output fluxes of cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) in agriculture and of their resulting accumulation in agricultural soils is necessary to define strategies that ensure sustainable management of these metals in agricultural systems. In this article, general aspects of heavy-metal balance studies are described for the agricultural sector within the broader context of substance flow analysis and industrial ecology. The approach chosen in this study is both precautionary and related to actual problem areas.     

Short-Rotation Coppice of Willow for Phytoremediation of a Metal-Contaminated Agricultural Area: A Sustainability Assessment

Large areas of land contaminated with cadmium (Cd), lead (Pb), and zinc (Zn) are currently in agricultural production in the Campine region in Belgium. Cadmium contents in food and fodder crops frequently exceed legal threshold values, resulting in crop confiscation. This imposes a burden on agriculture and regional policy and, therefore, encourages proper soil management. One way to increase agricultural income and improve soil quality is by growing alternative nonfood crops such as willows in short-rotation coppice (SRC) systems that remediate the soil. This paper compares SRC of willow with rapeseed and energy maize regarding four attributes: metal accumulation capacity, gross agricultural income per hectare, CO₂ emission avoidance potential, and agricultural acceptance. Based on multicriteria decision analysis, we conclude that, although SRC of willow has a high potential as an energy and remediating crop, it is unlikely to be implemented on the short term in Flanders unless the economic incentives for the farmers are improved.     

设施土壤生态环境特点与调控

论述了设施土壤生态环境的特性主要是土壤养分富集 ,土壤板结 ;土壤酸化、次生盐渍化和连作障碍严重 ;土壤产生有害气体 ;土壤微生物区系变化很大。这些特点主要是盲目大量施肥 ,土壤长期连续利用 ,土壤环境密闭 ,单一化栽培 ,用肥种类不合理及某些化学物质积累造成的。利用生物、农业耕作、地上环境和工程措施调控相结合 ,是调控设施土壤生态环境的有效方法 ,土壤生物学的应用将是改善设施土壤生态环境新的研究方向。     

Physiological traits for crop yield improvement in low N and P environments

Nitrogen and phosphorus are recognized as essential elements in crop production, but the full extent of the requirement for these elements in the physiological processes leading to crop growth seems not to be always fully appreciated. Virtually all the biochemical compounds in plants that support development and growth contain N and/or P. Deficiencies in either element lead to a lost ability for plant growth such that there is a quantitative relationship between crop yield and accumulation by plants of each of these elements. Few options appear to exist to greatly diminish the requirement for either element in crop growth and the formation of seed yield. Consequently, crop yields cannot be increased without increased acquisition of N and P by plants. If the soil environment does not offer these elements, then crop yield will necessarily be restricted. While little opportunity exists to increase N recovery under low nutrient environments, several options can be investigated for increasing P accumulation by the crop. Ultimately, however, the rigid limitation on yields of inadequate N means that without external supplies of N for the cropping system, biological fixation of N must be enhanced to increase N input. In particular, it appears that considerable research needs to be focused on whole-plant processes in legumes that lead to enhanced symbiotic N fixation. A critical aspect of increased legume production will be improved management of P to allow legumes to achieve high N fixation rates and yields.     

Fertilizer Impacts on Cadmium Availability in Agricultural Soils and Crops

Ingestion in food is a major pathway of cadmium (Cd) exposure for humans. It is therefore desirable to ensure that Cd concentrations in crops that enter the human food chain do not increase to levels that may lead to health risks. Phosphorus fertilizers contain Cd as a contaminant at levels varying from trace amounts to as much as 300 mg Cd kg^–1 of dry product and therefore can be a major source of Cd input to agricultural systems. Fertilization can influence Cd accumulation in crops by direct Cd addition and by indirect effects on soil pH, ionic strength, Zn concentration, rhizosphere chemistry, microbial activity, and plant growth. Cadmium will accumulate in the soils from fertilizer applications if the amount of Cd added in fertilizer is greater than the amount of Cd removal, whether in harvested crop removal or other loss pathways such as leaching, erosion, or bioturbation. Assessment of the impact of fertilizer management practices on the risk of Cd toxicity to the soil ecosystem and the risk of movement of Cd into the human diet must consider both the direct influence of Cd addition as a fertilizer contaminant and the indirect effects of fertilizer application on Cd phytoavailability. Cadmium accumulation in soils and crops can be minimized by adoption of management practices that improve fertilizer-use efficiency while minimizing Cd input.     

The role of organic amendments to soil for crop protection: Induction of suppression of soilborne pathogens

Application of external organic inputs to soils can be considered as one of the most ancient strategies in agriculture, and it has been commonly used since the very beginning of human-based agricultural practices. During all this time, application of several organic matters to agricultural soils has demonstrated their benefit to plants and soils. Organic amendments have proved to be useful in recovering soil properties, improving soil quality and, in some cases, can be directly involved in providing beneficial effects to plants. All these obtained effects finally lead to an increase in crop protection and sustainability. One most expected effect caused by the application of organic amendments, is the suppression of a wide range of soilborne pathogens (mainly bacterial and fungal pathogens) due to the induction of physicochemical and biological changes in soils. In order to get insight into the nature of the induced soil suppression of soilborne plant pathogens, the analysis of the physical, chemical and the microbial changes, pointed to the key role of beneficial activities produced by soil microorganisms finally adapted to the environmental changes produced by the influence of organic amendments. As shown in the case studies reported here, participation of soil microbes specifically selected after organic amendment is crucial in the control of fungal soilborne diseases. Moreover, the development of “omics” approaches allowed these recent studies to go one step further, revealing the main actors involved in the induced soil suppressiveness and their activities. Thus “omics” techniques will help to understand the soil and its microbiome as a whole system, and to assign the important roles of its biological components.