Studies on Heavy Metal Pollution in Soil-Plant System:A Review

Heavy metal pollution in soil-plant system is of major environmental concern on a world scale and in China in particular with the rapid development of industry. The heavy metal pollution status in soil-plant system in China, the research progress on the bioavailability of heavy metals (affecting factors, extraction methods, free-ion activity model, adsorption model, multivariate regression model, Q-I relationship, and compound pollution), and soil remediation are reviewed in the paper. Future research and monitoring is also discussed.

Distribution of Crystal Organic Fertilizer-N in Soil-plant System

The distribution of crystal organic fertilizer, urea and compound fertilizer-N in soil and plant system was researched with 15N-trace under tobacco pot experiment. The results showed that the leaf yield of tobacco used crystal organic fertilizer was 23.1% and 14.6% higher than that of urea and compound fertilizer treatments respectively. Compound fertilizer also resulted in higher yield of 8.5 % comparing with the urea treatment. Nitrogen content of the plant from the crystal organic fertilizer treatment was 138. 6% and 145.7% as high as that of the compound fertilizer and urea treatments respectively. The absorbed N from the organic fertilizer was 25.1% and 27.9% more than that from the compound fertilizer and urea respectively. However, the absorbed N from the soil with the organic fertilizer was 47.4% and 58.3% more than that with compound fertilizer and urea respectively. The N use efficiency of the organic fertilizer was 9.4% and 10.1% higher than that of the compound fertilizer and urea. It indicated that the crystal organic fertilizer not only had high N use efficiency, but also stimulated tobacco taking up more N from soil.

Effects of soil-plant system change on ecohydrology during revegetation for mobile dune stabilization, Chinese arid desert

Soil-plant systems play an important role in sand fixing and surface protection in the arid desert of China. This study examines the ecohydrological responses after a soil-plant system change for mobile dune stabilization by using a series of soil hydrological experiments and ecological investigation. The study results showed that decades of succession of soil-plant system has endangered the stability of the protection system. With the accumulated water and nutrient, a bio-logical system develops in a thinner and thinner surface soil. Redistribution of precipitation has changed completely in the ecosystem. In 3–15 mm of soil, a high capacity of crust water retention ultimately limits most rainfall from infiltrating below 10–20 cm deep. When that takes place, lower plants begin to compete for water with grasses and shrubs. A drought horizon forms in 20–500 cm depth with shrub transpiration. Artificial shrubs with deep roots obtain hardly rainfall supply and are gradually eliminated from the protection system. All changes in water environment affect the structure and func-tion and stabilization of whole protection systems. It is necessary to establish a relatively stable water environment by managing the soil-plant system for constructing a sustainable protective system in arid desert.

Comparison of Urea-Derived N_2O Emission from Soil and Soil-Plant System

A pot experiment with a sandy loam soil and spring wheat as test crop was conducted to compared the N2O emissio from soil system with plant cut off and from soil-plant syste with plant kept.The results showed that after urea fertilizer applied,the N2O emission from soil and soil-wheat system decreased exponentially with time,and its total amount was 0.34-0.63% and 0.33%-0.58% of applied urea-N respectively,no significant difference being found between these two systems.The N2O emission urea-N respectively,no significant difference being found between these two systems.The N2O emission had a very significant negative relationship (P=0.01) with the biomass of wheat plant.A combined application of urease inhibitor hydroquinone and nitrification inhibitor dicyandiamide could reduce the N2O emission by 50%-83% and 46-74%,respectively,from soil and soil-wheat system.The N2O was mainly produced and emitted from soil,and the soil biochemical regulation.i.e.applying related inhibitors into soil could effectively diminish the urea derived N2O emission.

Trace Elements in the Soil-Plant Systems of Copper Mine Areas-A Case Study From Murgul Copper Mine From the Black Sea Region of Turkey

This study presents a case study on the heavy metal analysis of soil and plant samples around the Murgul copper mine,one of the first and most important mining areas in Turkey.An attempt has been made to investigate the status of trace elements like Al^(3+),Fe^(2+),Cu^(2+),Zn^(2+),Pb^(2+),Ni^(2+),Co^(2+)and Cd^(2+)in soils and plants.The sampling localities were taken from 500 m,600 m,and 1000 m altitudes around the factory and at 1400 m in the forest zone.The aboveground parts and foliage ash of Silene compacta,Tussilago farfara,Smilax excelsa,Rhododendron ponticum,R.luteum,and herbal mix were analysed.The results of analysis have revealed the minimum and maximum concentrations measured in the plants as follows;aluminium(20-8985 mg kg^(-1)),cadmium(0.0-0.5 mg kg^(-1)),cobalt(0.0-5.5 mg kg^(-1)),copper(0.0-347.5 mg kg^(-1)),iron(25-9320 mg kg^(-1)),lead(2-51 mg kg^(-1)),nickel(1.5-16.5 mg kg^(-1)),and zinc(13.0-221.0 mg kg^(-1)).In the soil the concentrations of aluminium,cadmium,cobalt,copper,iron,lead,nickel,and zinc vary between 33-457,0.0-0.0,0.0-0.4,0.1-88.7,14-50,0.3-4.1,0.2-0.8,and 4.0-20.3 mg kg^(-1) respectively.These findings enlighten the fact that copper is generally toxic in the soils as well as plants.Silene compacta has been recorded as a high copper accumulator,behaving as a healthy plant on the polluted sites of the area alongside the Murgul creek(especially at 600 m).This study stresses the fact that it is imperative to assess and monitor the levels of heavy metals in the environment due to anthropogenic activities,including mining,for evaluation of human exposure and for sustainable environment.

Spatial variations of Pb in the vertical zone of the soil-plant system in the Changbai Mountain National Nature Reserve

The characteristics of vertical and horizontal variations of lead element(Pb) in soil plant system of vertical zone in Changbai Mountain National Nature Reserve(CNNR) were studied. The results showed that Pb concentrations in soils of vertical zone are all above 25 mg/kg, and the average Pb concentration of each soil zone negatively correlates its degree of variation, i.e. brown coniferous forest soil zone has the lowest average Pb concentration of four soil zones, and the highest horizontal variation; however, mountain soddy forest soil has the highest average Pb concentration, and the lowest horizontal variation; the average concentration of plant Pb of each plant zone is lower than the worldwide average level of Pb in plant(Clarke), respectively, and plant Pb content order is consistent with soil Pb content order, but their horizontal variations are different from those in soil zones, the variation of mountain tundra forest zone is highest, but Betula ermanii forest zone the lowest. Vertical variation of plant Pb is obviously higher than that in soils with variation coefficient of 89.76%; the enrichment capability of plant for Pb is depended on the plant types and the different organs of plant; parent material and parent rock, pH values, soil organic matter and soil particle fraction etc. are the main factors influencing variations of Pb content in soil plant system of vertical zone in CNNR.

Remediation of Arsenic Toxicity in the Soil-Plant System by Using Zinc Fertilizers

Availability of soil arsenic (As) and plant As at various levels of zinc (Zn) and As applications were examined. A pot-culture experiment with a leafy vegetable, Kalmi (Ipomoea aquatica), on an Inceptisols, was conducted where As was applied with irrigation water at the rates of 0 mg/L (As control), 0.5 mg/L, 1 mg/L and 2 mg/L and Zn was added to the soil as ZnCl2 solution at the rate of 0 mg/L (Zn control), 1 mg/L, 2 mg/L and 3 mg/L during pot preparation. The experiment was conducted in triplicates for 45 days till the plants were grown to maturity. At the end of the experiment the remedial effect of Zn on As toxicity was examined and as such, yield parameters, As and Zn accumulation in Kalmi plants, residual concentrations of As and Zn in soils and plants were measured. It appeared from the present study that there exists an antagonistic relationship between Zn and As i.e., Zn in soils was found to reduce As availability in soils as well as its accumulation in plants, particularly at an elevated application rate of 3 mg/L Zn. The findings could be used as a strategy to mitigate arsenic toxicity in As contaminated soils.

A Comparative Study of Element Cycling in the Soil-Plant System: A Case Study of Shaly and Calcareous Soils, Southern Benue Trough, Nigeria

This study focused on the cycling of major and trace elements in the soil-plant system in parts of Southern Benue Trough, Nigeria. Surface soil samples and cassava crop samples were collected from cultivated farmlands underlined by shaly and calcareous soils and were analysed using standard techniques. The results show that shaly soils are relatively acidic (pH, 4.8 - 6.6) with high level of organic matter content (OM, 3.2% - 8.7%) compared to calcareous soils (pH, 5.6 - 7.2;OM 1.6% - 7.0%). The soils are enriched in elemental composition relative to the world average abundances in soil. The maximum levels of K, Al, and Zn were obtained from shaly soils. The computed accumulation factors are generally <1. Elemental levels decreased in the plant parts in the order tuber > leaf > stem. Significant correlation was obtained between elemental associations of calcareous surface soils compared to that of shaly soils. R-mode factor analysis revealed the controls of soil geochemistry to include lithology, anthropogenic and environmental factors. A stepwise linear regression analysis identified soil elemental component, pH and organic matter as some of the factors influencing soil-plant metal uptake.

Study on Transfer of Ni in Soil-Plant System Using^(63)Ni Tracer Method

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植物根系吸水模型研究进展

根系是植物获取水分的主要器官,它直接影响整个植株的输水量以及生命活动。在水资源短缺的状况下,了解根系生长过程中的需水特性并提高农业中水资源的利用率,一直是节水灌溉技术中研究创新的热点。因此,在研究过程中需要对植物根系的吸水量进行精确估算,建立根系吸水模型是定量化研究植物根系吸水特性的重要方法。概述根系吸水的原理及其主要影响因素,对不同研究方法下的根系吸水模型进行分类研究,并阐述其适用范围及优缺点,同时介绍了水盐共同胁迫下的根系吸水模型。最后对目前的根系吸水模型进行分析,提出了今后的研究方向。研究成果为构建水稻根系三维动态吸水模型提供了基础。

土壤-植物系统中硒的生物有效性及其影响因素研究进展

硒的生物有效性是决定硒在土壤-植物系统中转运、积累的关键因素,然而目前关于该方面研究进展还缺乏系统的总结和论述。本文结合赣南富硒脐橙调查研究结果,以硒在土壤-植物系统中的运移为切入点,系统总结和论述了硒在土壤-植物系统中的氧化-还原、吸收、转运过程,探讨了土壤理化性质、微生物、施肥、农艺管理和植物生长阶段等对硒生物有效性和迁移的影响,并提出未来硒的研究热点:土壤微生物活性与硒生物地球化学循环的耦合关系;植物生长、果实品质与硒代谢相关的分子机制;结合同位素示踪技术和薄膜扩散梯度(DGT)技术原位探究硒在生物地球化学中的归趋。本综述可为土壤硒生物有效性调控、植物体系中硒的有效积累和农艺生物强化富硒措施方面的研究提供理论参考。

微纳米塑料在土壤-植物系统中的迁移机制及毒性效应研究进展

微塑料是指粒径小于5 mm的塑料碎屑和颗粒,其中粒径小于100 nm为纳米塑料。微纳米塑料作为一种新型污染物,具有难以降解、容易发生积累和可长距离迁移等特点,进而对生态环境产生影响。但是,与其他环境中的微纳米塑料相比,人们对土壤环境中的微纳米塑料的认识与了解还比较少。所以,本文详细阐明了微纳米塑料在土壤环境中的生物和非生物迁移过程与机制,系统总结了微纳米塑料从土壤到植物的转运过程,并探讨了微纳米塑料对植物种子萌发和根系发育产生的直接毒性效应,通过改变土壤理化性质和吸附重金属、有机污染物进而成为污染物传输载体而对植物产生的间接毒性作用。最后,提出了土壤-植物系统中微纳米塑料污染目前还需要进一步研究和处理的问题。本文可为土壤-植物系统中微纳米塑料污染的生态风险评估提供科学参考。

氮负荷增强对闽江口短叶茳芏湿地植物-土壤系统氮累积与分配的影响

选择闽江河口短叶茳芏(Cyperus malaccensis)湿地为研究对象,基于野外氮负荷增强模拟实验,探讨了不同氮负荷水平下(NNT对照处理,0 g N m^(-2)a^(-1);LNT低氮处理,12.5 g N m^(-2)a^(-1);MNT中氮处理,25.0 g N m^(-2)a^(-1);HNT高氮处理,75.0 g N m^(-2)a^(-1))湿地植物-土壤系统的氮累积与分配特征。结果表明,不同氮负荷处理下湿地土壤(TN)、NH+4-N和NO-3-N含量均发生了明显改变。相较于NNT,LNT和MNT的TN、NH+4-N和NO-3-N含量均明显增加,增幅分别为9.44%、3.57%、11.99%(LNT)和6.71%、9.37%、46.50%(MNT)。与之不同,HNT的TN含量相比NNT增幅不大,而其NH+4-N、NO-3-N含量均显著降低,降幅分别为9.26%和40.77%。不同氮负荷处理下土壤氮含量的垂直分布特征亦发生了明显变化。除HNT外,LNT和MNT的TN、NH+4-N和NO-3-N含量均以表层土壤最高。不同氮负荷处理下的TN和NH+4-N含量分布主要受SOM的影响,而NO-3-N含量分布主要受植物吸收和垂直淋失的影响。氮负荷增强条件下植物不同器官的TN含量整体表现为叶>茎>根。不同氮负荷处理下植物-土壤系统的氮储量整体以LNT和MNT较高,而HNT最低。研究发现,短叶茳芏在中低氮负荷条件下可能将更多的氮优先分配给根系,进而以拓展地下空间和提高地下生物量的方式来适应环境;而在高氮负荷条件下,其可能通过增强“自疏效应”,并通过拓展地上空间的方式来适应环境。

西藏地区C·N·P生态化学计量学研究进展

生态化学计量学是从生态系统能量和元素平衡的角度,揭示元素在生物地球化学循环以及生态系统对环境变化的调控机制。总结近年来在我国西藏地区针对植物、凋落物、土壤和土壤微生物量C、N、P生态化学计量及其对环境变化的响应方面的研究成果,并对未来的研究方向进行展望。相关研究表明,植物-凋落物-土壤-土壤微生物系统C、N、P化学计量具有较强相关性,并受生物因子、非生物因子和人类活动的显著影响。植物生长主要受N元素的限制,C、P极度下降时N含量升高,植物通过自我调节能力表现出较强的竞争力和较高的内稳性;土壤养分表现出一定的“表聚性”效应;受海拔高度和温度的影响,微生物对凋落物的分解速率下降,可在一定程度上解释高海拔地区土壤肥力较贫瘠的原因。关于植物-凋落物-土壤-土壤微生物系统生态化学计量学的研究,今后可在多尺度、不同生态系统下进行长期的、多因子交互控制试验的研究。

碘在土壤-植物系统中的行为及其毒理学研究进展

碘作为一种亲生物元素,是甲状腺激素的重要组成部分,但人为核活动产生的放射性碘是潜在致癌物。碘在土壤中主要以有机碘、碘化物、碘酸盐的形式存在。土壤和植物也是碘进行全球化学循环的重要一环。碘元素的毒理学主要表现为,环境中的放射性碘对动植物的危害以及不同剂量和形态的碘对植物生长的影响。

半干旱风沙草原区盐湖植物防护体系土壤理化性状特征

为探究植物防护措施对半干旱风沙草原区土壤的改良效应,以查干淖尔盐湖植物防护体系为研究对象,采用野外调查结合室内试验的方法,测定不同区域土壤理化性质,分析0—30 cm深度土壤含盐量、土壤酸碱度、土壤粒径组成、土壤有机质和氮磷钾含量的变化。结果表明,查干淖尔盐湖植物防护体系营造建设20年后,在防护带阻挡风蚀物质和植物改善土壤的协同作用下,原有高盐强碱土壤环境出现了显著变化。与干涸湖心相比,植物防护体系内各样地pH均有不同程度的降低,碱蓬防护带内土壤含盐量降低75.34%;碱蓬防护带内土壤粘粒和粉粒含量增幅明显,较干涸湖心分别增加51.60%和22.14%,粗砂含量较干涸湖心降低72.06%;碱蓬防护带内土壤速效钾、速效磷、有机质含量较高,分别是干涸湖心的86%、39%、55%;过渡带白刺灌丛速效氮含量较高,为干涸湖心的28%。总体上各养分含量与粘粒和粉粒呈显著相关(P<0.05)。历经20年的营建,碱蓬防护带内土壤速效钾、速效磷、有机质含量较建设初期明显增长,表明植物防护体系对土壤具有明显的改良作用。研究成果为盐湖植物防护体系防护效应评价提供数据支撑,并为半干旱风沙草原区干涸盐湖风蚀控制和区域植被恢复重建提供科学依据。

玉米种植制度对红壤钾素形态及其有效性的影响

【目的】探讨玉米种植制度对红壤土壤钾形态及其有效性的影响,为该区域合理安排种植制度和玉米地土壤钾素管理提供依据。【方法】于春播前采集红壤区撂荒(CK)、玉米连作(CY)、豌豆-玉米轮作(RWY)和西葫芦-玉米轮作(RXY)4个种植制度下耕层(0~20 cm)和亚耕层(20~40 cm)土壤,测定其土壤理化性质和各形态钾含量,并分析其相关性。【结果】4个玉米种植制度下土壤各形态钾分布规律不同,耕层土壤水溶性钾、非特殊吸附钾、特殊吸附钾和非交换性钾含量均高于亚耕层,矿物钾含量未表现出典型规律,种植制度对耕层土壤钾素含量影响更大。耕层和亚耕层土壤的水溶性钾、特殊吸附钾和非特殊吸附钾均与速效钾含量呈极显著正相关,特殊吸附钾是该区有效钾的最大供应源。与玉米轮作相比,玉米连作导致土壤酸化程度增加,尽管其速效钾含量显著高于其他土壤(P<0.05),但长期采用玉米连作不利于维持土壤钾素平衡。轮作可降低土壤酸化程度,防止速效钾过度累积,其中西葫芦-玉米轮作可使土壤供钾能力处于较高水平并保持稳定。【结论】玉米种植制度对红壤耕层钾形态及其有效性影响较大,其中西葫芦-玉米轮作是该区钾素可持续利用的玉米最佳种植制度。

Diversity of endophytes across the soil-plant continuum for Atriplex spp. in arid environments

Endophytes are hypothesized to be transferred across the soil-plant continuum, suggesting both the transfers of endophytes from environment to plant and from plant to soil. To verify this hypothesis and to assess the role of locality, we evaluated the similarity of microbial communities commonly found both in soils and endophytic communities in three arid regions, i.e. the Jornada LTER （Long Term Ecological Research） site in New Mexico, USA, and the research station of Jordan University of Science and Technology （JUST） and Khanasd research station in Badia region of Jordan. Rhizosphere and non-rhizosphere soils, leaves and seeds of Atriplex spp. were sampled. Diversity and distribution of bacteria and fungi across the soil-plant continuums were assessed by tag-encoded FLX amplicon pyrosequencing and sequence alignment. Of the total bacterial OTUs （operational taxonomic units）, 0.17% in Khanasri research station, 0.16% in research station of JUST, and 0.42% in Jornada LTER site were commonly found across all the plant and soil compartments. The same was true for fungi in two regions, i.e. 1.56% in research station of JUST and 0.86% in Jornada LTER site. However, in Khanasri research station, 12.08% of total fungi OTUs were found in at least one soil compartment and one plant compartment. Putative Arthrobacter, Sporosarcina, Cladosporium and members of Proteobacteria and Actinobacteria were found across all the soil-plant continuums. Ascomycota, mainly including Didymellaceae, Pleosporaceae and Davidiellaceae were present across all the soil-plant continuums. Microbial communities in two regions of Jordan were similar to each other, but both of them were different from the Jornada LTER site of USA. SIMPER （similarity percentage） analysis of bacterial and fungal taxa for both soil and endophyte communities revealed that dissimilarities of two bacterial genera （Arthrobacter and Sporosarcina） and two fungal genera （Cladosporium and Alternaria） are very high, so they play key roles in the soil-plant continuums. A weighed Pearson correlation analysis for the specific bacterial OTUs in the soil-plant continuums only showed high similarity between the two regions of Jordan. However, fungal groups showed higher similarities among all regions. This research supports the hypothesis of continuity of certain bacterial and fungal communities across the soil-plant continuums, and also explores the influences of plant species and geographic specificity on diversity and distribution of bacteria and fungi.

Effects of the expressway on the soil-plant systems in the Longitudinal Range-Gorge Region

作为一个例子在纵的范围峡区域( LRGR )拿 Da-Bao 高速公路，沿着道路的三种土壤植物系统上的高速公路的效果被索引的七种类型分析，它是土壤营养素，土壤的重金属，土壤潮湿和土壤的 pH ，种植物和植物差异的滋养的、重金属。通过比较典型采样点和他们的通过对比区别的点，第一，单个索引上的高速公路的效果被分析并且讨论；第二，在高速公路之中的相互作用和各种索引与关联词分析被讨论；最后，三个系统上的效果的范围和紧张与灰色的相关分析被分析。所有结果显示出那 1 ) 在由高速公路的效果的范围以内，所有索引的表示的形式对高速公路的干扰不同。2 ) 高速公路能引起 HMS 和 HMP 的累积，特别在农田系统；并且带土壤的一点碱性化，特别在灌木系统。3 ) 高速公路是森林和灌木里的 HMS， SM， HMP 和 PD 的最重要的影响因素在农田系统的系统，而是仅仅 HMS 和 HMP。到与道路的不足道的关联的索引，高速公路通过系统的效果链间接地工作。与三种土壤植物系统作比较，效果主要在森林和农田系统里从高速公路专注于 10 m 的区域，并且在灌木系统上的 30 m 的区域上。

农田土壤—植物系统中钒的迁移富集规律

钒(V)是维持生物体正常生命活动的必需微量元素之一,也是联合国环境规划署列入环境优先污染物的有害元素之一。研究V在土壤—植物系统中的迁移富集规律,对于深入了解其生态地球化学行为、保障农产品安全与人体健康具有重要现实意义。本文以山东临沂某地普通农田为例,对土壤、植物进行系统的采样,分析测试土壤与植物中的V与伴生元素的含量。采用描述性统计、相关性分析、聚类分析等统计方法与单因子污染指数法、潜在生态风险指数法、生物富集系数法等分析方法对研究区内V进行来源分析、污染评价以及V在土壤—植物系统的迁移转换规律的研究。结果表明:V在研究区内分布较为集中,其含量随着Fe、Ti含量的升高而升高,随SiO_(2)、Na_(2)O、Sr、CaO含量升高而下降。研究区内V主要来源于母岩风化,高含量部分与磁铁矿相关。根据单因子指数法与潜在生态风险指数法评价结果,V在研究区土壤内较为清洁,但区内伴生的Cd污染需引起注意。V在植物中主要富集在根部,植物对V的吸收能力总体上与土壤中Cu、Pb、Zn、Ni、Co、Cd、Cr的含量呈负相关,以Cr最为显著;与土壤中As的含量呈正相关。该研究丰富了V的生态地球化学理论,也为区域农业生产、环境质量评估和生态污染防治提供了科学依据。