植物营养元素的土壤化学土壤中的微量元素

1、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

2、shown to be essential for animal growth but are apparently not required by plants. uIntensive plant production practices have increased crop yields, resulting in greater removal of micronutrients from soils. uThe trend toward high-analysis fertilizers has reduced the use of impure salts and organic

3、manures, which formerly supplied significant amounts of micronutrients. uIncreased 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. uIncreasing evidence indicates that f

4、ood 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？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-

5、, 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 ab

6、out 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) m

7、ay 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 huma

8、n 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

9、 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 thos

10、e 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，但不可替代需要量少，但不可替代 缺乏多呈一定的区域性缺乏多呈一定的区域性 适宜浓度范围较窄适宜浓度范围较窄 1.微量元素的生物地球化学循环 2.土壤中不同微量

11、元素的含量、形态、 转化及有效性 3.土壤微量元素与地方病 4.微量元素污染及治理 1. 1.微量元素的生物地球化学循环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，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。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。 生产者生产者 消费者消费者 分解者分解者 非生物环境（无机环境）非

12、生物环境（无机环境） 生物地球化学循环的类型生物地球化学循环的类型 植物植物 消费者消费者 落叶层落叶层 土壤土壤 土壤溶液土壤溶液 沉积型循环沉积型循环 消费者消费者 落叶层落叶层 微型分解者微型分解者 土壤溶液土壤溶液 植物植物 微生物微生物 大气大气 气体型循环气体型循环 气体型循环气体型循环 沉积型循环沉积型循环 气体型循环气体型循环 沉积型循环沉积型循环 微量元素的生物地球化学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 a

13、go, 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 nat

14、ural inputs is estimated to be 20:1. 人类活动对微量元素循环的影响人类活动对微量元素循环的影响 Other anthropogenic inputs of Zn to soils： lfossil fuel combustion, lmine waste, lphosphatic fertilizers (typically 501450 g Zn g1), llimestone (10450 g Zn g1), lmanure (15250 g Zn g1), lsewage sludge (91 49 000 g Zn g1), lother agroc

15、hemicals lparticles from galvanized (Zn-plated) surfaces and rubber mulches. 土壤中微量元素的循环土壤中微量元素的循环 Plant uptake M+n MChe (Soil solution) Removal in harvest Biomass Residues Insoluble form Organic chelates M+n CO2 Decay 2. Contents, forms and availability of micronutrients in soils The initial trace e

16、lement 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. 花岗岩花岗岩 玄武岩玄武岩 页岩页岩 石灰石石灰石 砂岩砂岩 辉长岩辉长岩 斜长石斜长石 辉石辉石 橄榄石橄榄石 Adva

17、nces 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 agricultu

18、ral 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 indic

19、ate 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). uWeathering of underlying parent materials, uNatural processes (e.g., gases from volcanic erupt

20、ion, rain/snow, marine aerosols, continental dust, forest fires uAnthropogenic processes (industrial and automobile discharges, addition of fertilizers, lime, pesticides, manures, sewage sludges). Available micronutrients in soil are derived from: Contents of different micronutrients in soils of Chi

21、na （mg/kg） Micronutrient B Zn Mn Fe Cu Mo Range 0-500 3-790 42-3000 10000- 100000 3-300 0.1-6 Mean 64 100 710 22 1.7 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+ Ni

22、2+,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

23、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. qWater-soluble As fr

24、ee cation As complexes with organic and inorganic ligands qOn exchange sites of clay minerals (can be extracted with a weak exchanger, such as NH4+) qSpecifically 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

25、+ or some other electrostatically bounded cation) qAdsorbed or complexed by organic matters qAs insoluble precipitates, including occlusion by Fe and Mn oxides qAs the primary minerals Forms of micronutrients in soil Fractionation of micronutrients in soil The sequential fractionation scheme: Based

26、on the ability of certain solvents to remove specific bound forms of the metal. Forms of Copper 1. Soil solution 2. Exchangeable 3. Specifically adsorbed- 4. Oxide occluded 5. Biologically occluded 6. Mineral lattice On Clay On O.M. On Oxides CaCl2 Acetic acid K. pyrophosphate Oxalate + UV HF Steven

27、son 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。络合。 有机物中具有络合作用的基团有机物中具有络合作用的基团? 羟基羟基 OH 羧基羧基 COOH 羰基羰基 =CO 氨基氨基 NH2 亚氨基亚氨基=NH 金属离子 + 络合物金属离子-络合物 Metal ion + chelateMetal ion-chelate 稳定常数（K, stability constant） K = Metal ionchelate Metal ionchelate 稳定常数越大，

28、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 甘氨酸 酒石酸 EDTA 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 Chelating agent Fe3+Fe2+Zn2+Cu2+Mn2+Ca2+ Relative cost EDTA25.014.2714.8718.

29、7013.8111.04.4 EDDHA33.914.316.823.94-7.243 HEEDTA19.612.214.517.410.78.05.5 Citrate11.24.84.865.93.74.68- Gluconate37.21.01.736.6-1.211.0 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 so

30、ils. 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. qHighly leached, acid, sandy soils qOrganic soils qSoils of very high pH qSoils that have been very intensively cropped and

31、 heavily fertilized with macronutrient only Micronutrients are most apt to limit crop growth in 黄土高原地区黄土高原地区土壤多数微量元素含量分布具有明显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。的从西北向东南逐渐增加的趋势。(其中其中B、Mo由西由西 北向东南含量增加的趋势不明显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：黄土高原地区不同微量元素的含量水平： u锌、锰含量中等偏低锌、锰含量中等偏低 u铜、硼中等铜、硼中等 u钼的含量很低钼的含量很低 原因

32、？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) 处理处理有效有效Cu有效有效Zn有效有效Mn CK0.7760.561151.2 Zn-2.568- Mn-191.3 Cu5.240- 长期施用微量元素肥料对土壤微量元素有效性的影响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

33、明德等, 2006) 基性火成岩发育的土壤含锌量高于酸性岩 q 矿质态锌 q 交换态锌 q 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) (1)Content (2)Forms 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 fracti

34、ons in the solid phase can be quantified using sequential extractions or isotopic dilution techniques (Young et al., 2006). FormsExtractant Water solubleH2O ExchangeableKNO3 Organically boundNa4P2O7 Carbonate/noncrystalline iron occluded EDTA Manganese oxide occludedNH2OH Crystalline iron oxide occl

35、uded Na2S2O4 SulphidesHNO3 ResidualHNO3 + H2O2 % of total soil Zn Soil from Indiana,USA 0.2 10.0 32.5 7.9 7.2 7.5 3.3 32.3% (Miller uSeafoods including fishHg; uUnwashed, hairy, leafy vegetablesPb (especially in urban areas); uDrinking waterAs. 生物治理方法生物治理方法 工程治理方法 农业治理方法 化学治理方法 土壤重金属污 染治理方法 养分/元素的吸收

36、及在植物内的运输 Soil Root Shoot Grain or fruit Uptake transportation utilization Re-transportation Hyperaccumulation Thlaspi caerulescens (Brassicaceae)（遏兰菜） hyperaccumulator of Zn, Cd, (Pb) and Ni on Zn wastes in Belgium. Some hyperaccumulators Picture from Alan Baker 浙江大学 杨肖娥教授 In principle, phytoremedia

37、tion includes: pPhytoextraction: heavily contaminated soils; pPhytostabilisation: moderately contaminated soils pPhytofiltration: lightly contaminated agricultural soils pPhytodegradation: organic contaminants- rhizosphere remediation; pPhytovolitilisation: some metals, Hg, Se etc. References 1)土壤植物

38、营养学原理和施肥，鲁如坤等，化学工业出版社，北土壤植物营养学原理和施肥，鲁如坤等，化学工业出版社，北 京，京，1998 2)刘铮刘铮. 微量元素的农业化学微量元素的农业化学. 农业出版社，农业出版社，1991 3)余存祖余存祖. 中国旱地的微量元素管理中国旱地的微量元素管理. 李生秀编李生秀编. 中国旱地农业，农业中国旱地农业，农业 出版社，出版社，2004. pp:433-482 4)Mortvedt JJ, Cox FR, Shuman LM, Welch RM. Micronutrients in Agriculture, 2nd edn, SSSA, Madison, WI , 1991 5)Stevenson FJ. Cycles of Soil: Carbon, Nitrogen, Phosphorus, Sulfur, Micronutrients. John Wiley & Son