植物营养元素的土壤化学-土壤中的微量元素.ppt

第六章 土壤微量元素 Chapter 6 Micronutrients in Soil,高等植物必需的营养元素（16+1 或+2）,C,H,O,N,P,K,Ca,Mg,S, Cu,Zn,Mn,Fe,B,Mo,CI,Ni，Co,大量元素,微量元素,Other elements, such as silicon (Si), vanadium (V), and sodium (Na), appears to improve the growth of at least certain plant species. Animals, including humans, also requires most iodine (I), and fluorine (F), have been shown to be essential for animal growth but are apparently not required by plants.,Intensive plant production practices have increased crop yields, resulting in greater removal of micronutrients from soils. The trend toward high-analysis fertilizers has reduced the use of impure salts and organic manures, which formerly supplied significant amounts of micronutrients. Increased knowledge of plant nutrition and improved methods of analysis in the laboratory are helping in the diagnosis of micronutrient deficiencies that might formerly have gone unnoticed. Increasing evidence indicates that food grown on soils with low levels of trace elements may provide insufficient human dietary levels of certain elements, even though the crop plants show no signs of deficiency themselves.,为何微量元素营养问题越来越重要？,The extent of micronutrient-deficient soils are comparable to that of nitrogen-, phosphorus-, and potassium-deficient soils. Summary data (Table 1) from an extensive effort that examined 190 soil samples from 15 countries revealed that 49% of these soils were low in zinc and 31% low in boron (Sillanpaa, 1990).,Today, there are over 3.7 billion iron-deficient individuals and about 1 billion people that are or are at risk of developing iodine deficiency disorders. Additionally, there are over 200 million people that are vitamin A deficient (World Health Organization, 1999). Other micronutrient deficiencies (e.g., Zn, Se, vitamin C, vitamin D, and folic acid deficiencies) may be as wide spread as iron, iodine and vitamin A deficiencies, but there are no reliable data to confirm this although circumstantial evidence suggests that this may be so (Combs et al., 1996; World Health Organization, 1999).,Welch R M. The impact of mineral nutrients in food crops on global human health. Plant and Soil 247: 8390, 2002.,对人体健康的影响？,Figure 1. Global distribution of Fe, vitamin A and I deficiencies (map modified from Sanghvi, 1996).,Toxicity of some micronutrient in soils.,Expanding interests in the field of heavy metal research were associated with increasing world-production of metals and their common usage in the past century, and consequently, with their increasing emissions into the environment. This resulted in growing hazard to humans health posed by elevated metal concentrations in air, water, and food.,The most important sources of heavy metals in soils are those connected with anthropogenic activities, such as metal mining and smelting, production and usage of pesticides and wood preservatives, waste processing and disposal, etc.,Characteristics of micronutrient nutrition,需要量少，但不可替代 缺乏多呈一定的区域性 适宜浓度范围较窄,微量元素的生物地球化学循环 土壤中不同微量元素的含量、形态、转化及有效性 土壤微量元素与地方病 微量元素污染及治理,1.微量元素的生物地球化学循环,生物地球化学循环(Biogeochemical cycle),生态系统从大气、水体及土壤等环境中获得营养物质，通过绿色植物吸收，进入生态系统，被其它生物重复利用，最后再归还于环境的过程。,生物地球化学循环的过程研究主要是在生态系统水平和生物圈水平上进行的。,生产者 消费者 分解者 非生物环境（无机环境）,生物地球化学循环的类型,气体型循环 沉积型循环,气体型循环 沉积型循环,微量元素的生物地球化学循环,氯，溴，氟等循环。,铁，锰，铜，锌等循环,Humans have long influenced Zn inputs to soils. Two thousand years ago, approx. 10 000 tones Zn yr1 were emitted as a result of mining and smelting activities . Since 1850, emissions have increased 10-fold, peaking at 3.4 Mt Zn yr1 in the early 1980s, and then declining to 2.7 Mt Zn yr1 by the early 1990s. The ratio of Zn emissions arising from anthropogenic and natural inputs is estimated to be 20:1.,人类活动对微量元素循环的影响,Other anthropogenic inputs of Zn to soils： fossil fuel combustion, mine waste, phosphatic fertilizers (typically 501450 g Zn g1), limestone (10450 g Zn g1), manure (15250 g Zn g1), sewage sludge (91 49 000 g Zn g1), other agrochemicals particles from galvanized (Zn-plated) surfaces and rubber mulches.,土壤中微量元素的循环,2. Contents, forms and availability of micronutrients in soils,The initial trace element content of soils reflects the materials from which they form, but pedogenic processes and landscape age introduce much variation.,Iron, Zn, Mn, and Cu are somewhat more abundant in basalt; B and Mo are more concentrated in granite.,花岗岩 玄武岩 页岩 石灰石 砂岩 辉长岩 斜长石 辉石 橄榄石,Advances including the global positioning system (GPS), geographic information systems (GIS), inductively coupled plasma (ICP) spectrometry, geostatistics, and precision agriculture facilitate soil micronutrient mapping and provide quantitative support for decision and policy making to improve agricultural approaches to balanced micronutrient nutrition.,Mapping soil micronutrients,Field Crops Research, 60 (1999) 11-26,Example,Fig. 5. Map of kriged estimates of total soil zinc for the conterminous USA classed by deciles using data from USGS and USEPA soil studies (White et al., 1997). Crosses indicate sites of three high-zinc outliers excluded from the USGS data set.,Example,Fig. 3. Geographic distribution of low-, variable-, and adequate-selenium areas in the USA (after Kubota and Allaway, 1972).,Weathering of underlying parent materials, Natural processes (e.g., gases from volcanic eruption, rain/snow, marine aerosols, continental dust, forest fires Anthropogenic processes (industrial and automobile discharges, addition of fertilizers, lime, pesticides, manures, sewage sludges).,Available micronutrients in soil are derived from:,Forms of micronutrients dominant in the soil solution,B Zn Mn Fe Cu Mo CI Co Ni,H3BO3, H2BO3- Zn2+，Zn(OH)+ Mn2+ Fe2+, Fe(OH)2+, Fe(OH)2+, Fe3+ Cu2+, Cu(OH)+ MoO42-, HMoO4- CI- Co2+ Ni2+,Ni3+,It is bio-available metal species present in soil solution rather than high amounts of metals in solid phase that cause adverse biological effects on soil biota, control the uptake of metals by higher plants, and their input into the food chain.,Speciation of trace metals,Speciation (in the context of soils) refers to both the process and the quantification of the different defined species, forms and phases of a trace element. The speciation of trace metals in soils is related to their biogeochemical reactivity and to several physicochemical conditions of the soil.,Water-soluble As free cation As complexes with organic and inorganic ligands On exchange sites of clay minerals (can be extracted with a weak exchanger, such as NH4+) Specifically adsorbed (Some trace elements (e.g., Cu2+) are retained by clay minerals and/or Fe and Mn oxides in the presence of a large excess of Ca2+ or some other electrostatically bounded cation) Adsorbed or complexed by organic matters As insoluble precipitates, including occlusion by Fe and Mn oxides As the primary minerals,Forms of micronutrients in soil,Fractionation of micronutrients in soil,The sequential fractionation scheme: Based on the ability of certain solvents to remove specific bound forms of the metal.,Forms of Copper,Stevenson FJ, 1986. pp-342,土壤中一些金属离子可与土壤中存在的有机物，如腐殖质、蛋白质、有机酸等络合。,有机物中具有络合作用的基团?,羟基 OH 羧基 COOH 羰基 =CO 氨基 NH2 亚氨基=NH,稳定常数越大，金属离子与络合剂结合的能力越强，形成的络合物越稳定。,Nutrients in chelate forms,Nutrients in chelate forms,EDTA:乙二胺四乙酸 HEDTA:羟乙基乙二胺三乙酸 EDDHA:乙二胺二邻位苯酚乙酸,Table Stability constants (Log K) for selected chelating agents and nutrient cations,Brady NC, Well RR. 1996,Availability of micronutrients in soil,Uptake of micronutrients by plant is largely dependent on the availability of these elements in soils. The availability of micronutrients is not only related to the total contents of these elements in soil, but also to soil properties, such as soil pH, Eh, and texture, etc.,Highly leached, acid, sandy soils Organic soils Soils of very high pH Soils that have been very intensively cropped and heavily fertilized with macronutrient only,Micronutrients are most apt to limit crop growth in,黄土高原地区土壤多数微量元素含量分布具有明显的从西北向东南逐渐增加的趋势。(其中B、Mo由西北向东南含量增加的趋势不明显),黄土高原地区不同微量元素的含量水平：,锌、锰含量中等偏低 铜、硼中等 钼的含量很低,原因？,1) CK (对照,N 60 kg/ hm2 + P 26. 4 kg/ hm2) ; 2) Zn ( NP, 施Zn , ZnSO4 15 kg/ hm2) ; 3) Mn (NP, 施Mn ,MnSO4 22.5 kg/ hm2) 4) Cu (NP, 施Cu , CuSO4 15 kg/ hm2),长期施用微量元素肥料对土壤微量元素有效性的影响 （mg/kg）,1984-2003 陕西 长武 (郝明德等, 2006),基性火成岩发育的土壤含锌量高于酸性岩,矿质态锌 交换态锌 水溶性锌,含锌的矿物有：闪锌矿、红锌矿、菱锌矿等。 90%,2.1 Zinc(Zn),Exchangeable Zn typically ranges from 0.1 to 2 g Zn g1,Concentrations of water-soluble Zn in the bulk soil solution are low, typically between 41010 and 4106 M (Barber, 1995),Soil Zn fractions in the solid phase can be quantified using sequential extractions or isotopic dilution techniques (Young et al., 2006).,(Miller & McFee, 1983).,soil pH organic matter others (P in soil),一般认为，土壤有机质水平与有效锌含量间呈正相关。但有机质含量过高的土壤如泥炭土，锌的有效性会降低。,(3) Factors affecting Zn availability in soil,pH值大于6-6.5时，锌主要以Zn(OH)2形态存在，溶解度小。因此，土壤pH6.5, 土壤可能缺锌。 石灰性土壤上，锌可与碳酸盐反应，形成沉淀。,随土壤pH值的变化,土壤中锌的存在形态,表 不同碳酸钙含量塿土对锌的吸附强度,余存祖等，1984,锌的吸附可用Langmuir方程描述,式中：x表示吸附平衡时的吸附量 xm表示最大吸附量 Kl为Langmuir吸附常数 C平衡时溶液中吸附物的浓度,Langmuir吸附常数xm、Kl被用于评价土壤对锌的吸附特性,整理Langmuir方程得：,1/xm,1/Klxm,表 不同质地土壤对锌吸附的Langmuir方程参数,毕银丽等，1997,石灰性土壤多采用DTPA浸提，临界指标为 0.5mg/kg, 酸性土壤用 0.1 M 盐酸浸提，临界指标为 1.5mg/kg,(4)How to evaluate Zn availability in soil?,我国缺锌土壤的分布,主要分布在我国北方，与石灰性土壤的分布模式基本一致。包括黄潮土、棕壤、褐土、栗钙土、灰钙土、黄绵土和漠境土等。 南方长江冲积物和南方石灰岩母质发育的土壤亦易发生缺锌。,表 锌肥在土壤(塿土)中的残留(mg/kg),余存祖等，1986,土壤中含量较高 南方土壤高于北方土壤,2.2 Manganese(Mn),矿质态锰 易还原态锰 交换态锰 水溶性锰,与铁镁矿物共生，风化释放,易还原态锰为高价锰（通常为三价）；西北干旱及半干旱区土壤含量19-254 mg/kg,易还原态锰、交换态锰和水溶性锰总和称为活性锰,黄土高原区交换性锰含量, 3 mg/kg,Manganese（Mn）,锰在土壤中的转化示意图,Mn2+,Mn3+ Mn2O3.nH2O,Mn4+ MnO2.nH2O,MnO2,Soil pH Soil Eh,土壤pH值在4-9范围内，pH值每上升1个单位，土壤可给态锰会降低100倍。故缺锰多发生在pH值高的土壤上。,(3) Factors affecting Mn availability in soil,多采用DTPA浸提，临界指标为7 mg/kg,或 活性锰（1M 醋酸铵+0.2%的对苯二酚），100mg/kg,(4)How to evaluate Mn availability in soil?,Problem soils of Mn deficiency,Manganese deficiencies are most common in sands, organic soils, high-pH calcareous soils, and in soil growing fruits, small grains, and leafy vegetables.,Problem soils in China,在我国，缺锰土壤主要为北方石灰性土壤，如黄潮土、棕壤、褐土、栗钙土、灰钙土、黄绵土和漠境土等。 南方酸性土壤大量施用石灰后，交换态锰减少，有时会导致“诱发性缺锰”。,表 锰在土壤(塿土)中的残效,余存祖等，1986,(1)Content,基性火成岩发育的土壤含铜量高于酸性岩 含硫矿物中铜的含量高,矿质态铜 交换态铜 水溶性铜,(2)Forms,含铜的矿物有：孔雀石、黄铜矿、辉铜矿等,2.3 Copper (Cu),organic matter soil pH,一般认为，土壤有机质水平与有效铜含量间呈负相关。铜可被有机质牢牢吸附或络合。,相对于锌、锰来说，土壤pH对铜有效性的影响较小。,(3) Factors affecting Cu availability in soil,The general order of affinity for metal cations complexed by organic matter follows: Cu2+ Cd2+ Fe2+ Pb2+ Ni2+ Co2+ Mn2+ Zn2+,石灰性土壤多采用DTPA浸提，临界指标为 1.mg/kg, 酸性土壤用 0.1 M 盐酸浸提，临界指标为 1.9mg/kg,(4) How to evaluate Cu availability in soil?,Problem soils of Cu deficiency,Newly cultivated organic soils (reclamation disease) Sandy soils Calcareous soils with the high pH Competition of copper with other metals (Al, Zn, Fe),我国缺铜土壤的分布,从目前资料看，我国多数土壤有效铜含量较丰富或适中，但黄土区土壤有效铜含量较低。据水保所彭琳等研究，该区约有1/3土壤有效铜不足。特别是质地较粗、肥力低的土壤。 另外，沼泽土、泥炭土易发生缺铜问题。,表 铜在土壤(黑垆土)中的残效,余存祖等，1986,(1)Content,是土壤含量最低的微量元素之一； 含量与成土母质关系密切。,2.4 钼(Molybdenum, Mo),花岗岩母质发育的土壤含钼量高 黄土母质发育的土壤含钼量低,黄土和黄土状母质发育的土壤全钼含量为 0.21-1.45 mg/kg,平均为0.62 mg/kg，远远低于全国平均水平（1.7 mg/kg）,(2)Form,As anionic form（MoO42-, HMoO4-） Its behavior in soil resembles phosphate or sulfate,Soil pH Total Mo content in soil,Mo availability in soil increases with soil pH,土壤pH 3-6：钼的吸附量最大； 土壤pH 6: 钼的吸附量减弱； 土壤pH 8: 土壤胶体几乎不再吸附钼酸盐。,(3) Factors affecting Mo availability in soil,pH每增加一个单位，钼酸根离子的浓度增大100倍！,多采用草酸-草酸铵浸提，临界指标为 0.15 mg/kg,(4) How to evaluate Mo availability in soil?,Problem soils of Mo deficiency,Molybdenum deficiencies will be most common in acidic sandy soils, where leaching losses, strong molybdate adsorption, and few molybdenum minerals exist.,我国缺钼土壤的分布,北方缺钼，主要是由于成土母质含钼量极低； 南方土壤全钼含量并不低，但由于钼的有效性低，故土壤有效钼含量不足。,华北及黄土高原地区是我著名的低钼区，估计约有2/3耕地土壤钼供应不足(余存祖，2004),Mo toxicity,Soils which are high in Mo and give rise to herbage containing high levels of Mo causing molybdenosis in cattle and sheep.,(1)Content,是岩石和土壤中含量最高的四个元素（O, Si, AI, Fe）之一。 土壤Fe2O3含量可达3.8%,矿质态 有机结合态 交换态 水溶性,(2)Forms,含铁的矿物有：磁铁矿、赤铁矿、针铁矿等,2.5 Iron (Fe),Soil pH Soil Eh organic matter Soil moisture others,(3)Factors affecting Fe availability in soil,土壤pH每增加一个单位，溶液中活性铁减少约1000倍。 Fe2+ + 3OH-1 Fe(OH)3,Soil pH and Fe availability,Soil Eh,淹水后三价铁可以还原为二价铁 Fe(OH)3 + e-1 + 3H+ Fe2+ + 3H2O,Soil organic matter,有机质可以增加土壤中铁的有效性（why？） （有机酸的络合、酸化作用以及还原性物质）,Soil moisture,石灰性土壤通气不良易发生缺铁失绿症 （lime induced chlorosis）(原因？),HCO3- affects the uptake and translocation of Fe CaCO3 + H2O + CO2 Ca2+ + HCO3-,How to solve the problem?,Improve soil structure Soil water management Application of organic manures,石灰性土壤多采用DTPA浸提，临界指标为 2.5mg/kg,(4) How to evaluate Fe availability in soil?,Soils deficient in Fe,Iron deficiencies are most common in calcareous soils, in arid soils cropped to high-iron-demand plants. High levels of bicarbonate and phosphates also lower iron availability of plant.,我国缺铁土壤的分布,主要分布在我国北方，与石灰性土壤的分布模式基本一致。 南方土壤上常常会发生铁中毒现象。,(1)Content,2.6 Boron(B),花岗岩及其他酸性火成岩、片麻岩、红砂岩等成土母质发育的土壤，全硼及水溶性硼含量往往偏低。,沉积物发育的土壤火成岩发育的土壤 干旱地区湿润地区,我国主要土壤硼含量的一般规律：有由北向南、由西向东逐渐降低的趋势。西部内陆地区土壤含硼较高，东南部红壤含硼低。,Mineral-B Organic-B Adsorbed-B B-in solution,(2) Forms of B in soil,矿质态硼存在于矿物晶格内，经过风化后才可释放。土壤中含硼的矿物以电气石为主，含B 3%左右,有机态硼包括含硼的有机化合物和被有机物吸附的硼,Soil pH Clay types Organic contents,(3) Factors affecting B availability in soil,土壤pH值在4.7-6.7范围内，水溶性硼随pH值上升而增加，但当pH值7,水溶性硼随pH值上升而降低(原因？) （专性吸附增强，与钙、镁等形成沉淀）,Illite Kaolinite (伊利石高岭石),有机质对硼有效性的影响，看法不一,(4) How to evaluate B availability in soil?,我国多采用沸水浸提、姜黄素比色法测定土壤有效性硼的含量。一般以0.5 mg/kg作为临界指标,Problem soils of B deficiency,Strongly weathered coarse textured soil with low base exchange developing under humid conditions. Sandy soils (very low in B and prone to leaching),Soils potentially deficient of B in China,包括红壤、砖红壤、赤红壤和紫色土等。分布于广东、福建、江西南部、浙江西部和南部和四川等地。土壤全硼和水溶性硼含量均较低。,南方缺硼红壤区,北方缺硼土壤,主要是黄土和黄河冲积物发育的各种土壤，包括塿土、黄绵土和黄潮土等。,新建及河西走廊地区气候干旱，蒸发量大于降水量，盐分在土壤表层累积，是我国的高硼区。,而东北、华北及黄土高原地区有大面积的缺硼土壤。估计缺硼及可能缺硼的土壤占耕地面积的70%左右(余存祖等，2004)。,Effects of soil pH on availability of micronutrients,Transformation of micronutrients in soil,3. 土壤微量元素与地方病,地方病亦称生物地球化学性疾病: 系指在自然环境中由于一些元素分配失衡而直接或间接的引起生物体内微量元素平衡严重失调时产生的特殊性疾病。,克山病 大骨节病 地方性缺碘病(甲状腺肿大病) 地方性氟中毒,在我国较常见的地方病有:,克山病是以心肌坏死为症状的地方病，因1935 年首见于我国黑龙江克山县而得名。 大骨节病以关节疼痛、增粗、关节畸形、软骨坏死为特征，最终瘫痪和残疾的疾病。,(1)克山病及大骨节病,克山病和大骨节病流行于我国黑龙江、吉林、辽宁、内蒙古、河北、山东、山西、河南、陕西、甘肃、四川西藏及青海(只有大骨节病)和云南(只有克山病)等14个省区。,克山病及大骨节病病带的地球化学环境以低硒为其特点，故又称为我国的低硒地球化学带。,该地带土壤硒含量平均为0.10mg/kg，而东南及西北非病带土壤硒含量分别为0.30和0.20mg/kg.,大骨节病的发生集中在陕西渭北高原及甘肃的陇东一带，其中以陕西的麟游、永寿最高。 克山病以陕北南部的黄龙山-崂山-陕甘交界的子午岭和关山一带病情最为严重。,黄土高原地处我国低硒带的中心，是我国克山病及大骨节病的重发区, 其中:,图 黄土高原地方病分布图（田均良等，1994）,硒在地壳中的含量为0.09mg/kg,土壤中硒的含量与形态,一些地区富硒土壤中硒的含量为在1-1200 mg/kg,黄土母质系低硒母质。这一地区土壤硒含量在38-324 g/kg，平均108g/kg。,表 黄土高原病区及非病区硒含量的比较(g/kg),田均良等，1994,提出的黄土高原病区与非病区土壤全硒含量缺乏的阈值为110 g/kg，水溶性硒的阈值为2.4 g/kg,微域的变化,李继云等，1979-1983,表 永寿县发病程度不同的相邻两个村土壤等硒含量(g/kg)比较,预防措施：,口服亚硒酸钠 增加粮食中的硒 增加饮水中的硒,硒中毒,土壤和饲草中的硒含量过高(5 ppm)，会引起牲畜中毒，患“碱质病(alkali disease)”和“盲跚病”。,世界上约有110多个国家的10亿人口患有此病。我国患病人口分布在20多个省市区，人口约4.25亿。,（2）地方性缺碘病(甲状腺肿大病),地方性甲状腺肿是世界上流行最广泛的一种地方病俗称“大粗脖”，以甲状腺肿大为主要特征。,我国贵州的都匀市、黔西县属高度缺碘地区,发病率相当高。,碘由陆地进入海洋，由海洋逸出进入大气，再通过降水进入陆地，形成了一个大循环。,碘的生物地化循环,碘非常活泼，迁移性强。土壤中的碘易随水迁移。,碘分布特性： “山区少于平原，平原少于沿海，沿海少于海洋”,我国自然土壤碘含量平均4.22 ppm，在世界土壤正常范围(1-5 ppm)。但黄土高原土壤全碘含量低。,褐土 1.59 ppm 灰钙土 2.74 ppm,供应含碘食盐，即食盐中加KIO3。,预防措施：,是长期摄入高氟水、粮食等而引起的一种慢性氟中毒疾病。主要表现为氟斑牙和氟骨症。,(3)地方性氟中毒,过量的氟在体内与钙结合成氟化钙，使人体内钙磷代谢平衡受到破坏，血钙因而降低，导致溶骨细胞活性增强，促进溶骨作用和骨的吸收。,伊朗村病是缺少微量元素锌而引起的地方性侏儒症, 因1958 年在伊朗锡拉兹地区发现，故得名。,“伊朗村病”,口服用ZnSO4 和VB 做成的复合锌片进行预防和治疗效果良好。我国卫生部门批准,在食品加工中添加硫酸锌、葡萄糖酸锌、乳酸锌，还有氨基酸锌，这些均是有效的锌制剂。,Welch R M. The impact of mineral nutrients in food crops on global human health. Plant and Soil 247: 8390, 2002.,Furthermore, micronutrient-rich fruit and vegetable production has not kept pace with population growth in many nations (Welch & Graham, 1999). Finally, the decrease in food crop diversity brought about during the green revolutions drive to improve cereal production and expand cereal crop acreage most likely is also a contributing factor (Graham et al., 2001).,Welch R M. The impact of mineral nutrients in food crops on global human health. Plant and Soil 247: 8390, 2002.