植物营养元素的土壤化学土壤中的微量元素

1、会计学1植物营养元素的土壤化学土壤中的微量植物营养元素的土壤化学土壤中的微量元素元素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 manures, which formerly supplied significa

2、nt 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 food grown on soils with low levels of trace

3、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-, phosphorus-, and potassium-deficient soils.

4、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 o

5、f 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 vitam

6、in 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

7、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 centu

8、ry, 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 m

9、etal 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

10、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

11、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. Twothousand years ago, approx. 10 000 tones Zn yr1 were emitted as a result of mining and smelting activities .

12、 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人类活动对微量元素循环的影响Other anthropogenic inputs

13、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 agrochemicalslparticles 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

14、环Plant uptakeM+n MChe(Soil solution)Removal in harvestBiomassResiduesInsoluble formOrganic chelatesM+nCO2Decay2. Contents, forms and availability of micronutrients in soilsThe initial trace element content of soils reflectsthe materials from which they form, but pedogenicprocesses and landscape age

15、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Advances including the global positioning system (GPS), geographic information systems (GIS), inductively coupled plasma (ICP)

16、 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 micronutrientsField Crops Research, 60 (1999) 11-26Example

17、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.ExampleFig. 3. Geographic distribution of low-, variable

18、-, and adequate-selenium areas in the USA (after Kubota and Allaway, 1972).uWeathering of underlying parent materials, uNatural processes (e.g., gases from volcanic eruption, rain/snow, marine aerosols, continental dust, forest firesuAnthropogenic processes (industrial and automobile discharges, add

19、ition of fertilizers, lime, pesticides, manures, sewage sludges).Available micronutrients in soil are derived from:Contents of different micronutrients in soils of China（mg/kg）MicronutrientBZnMnFeCuMoRange0-5003-79042-300010000-1000003-3000.1-6Mean64100710221.7Forms of micronutrients dominant in the

20、 soil solutionBZnMnFeCuMoCICoNiH3BO3, 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, contr

21、ol the uptake of metals by higher plants, and their input into the food chain.Speciation of trace metalsSpeciation (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 soil

22、s is related to their biogeochemical reactivity and to several physicochemical conditions of the soil.qWater-solubleAs free cationAs complexes with organic and inorganic ligandsqOn exchange sites of clay minerals (can be extracted with a weak exchanger, such as NH4+)qSpecifically adsorbed (Some trac

23、e 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)qAdsorbed or complexed by organic mattersqAs insoluble precipitates, including occlusion by Fe and Mn oxidesqAs the primary mineralsF

24、orms of micronutrients in soilFractionation of micronutrients in soilThe sequential fractionation scheme: Based on the ability of certain solvents to remove specific bound forms of the metal. Forms of Copper1. Soil solution2. Exchangeable3. Specifically adsorbed-4. Oxide occluded5. Biologically occl

25、uded6. Mineral latticeOn ClayOn O.M.On OxidesCaCl2Acetic acidK. pyrophosphateOxalate + UVHFStevenson 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 + chelateMeta

26、l ion-chelate稳定常数（K, stability constant）K =Metal ionchelateMetal ionchelate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 formsNutrients in chelate forms甘氨酸酒石酸EDTAEDTA: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 cationsChe

27、lating agentFe3+Fe2+Zn2+Cu2+Mn2+Ca2+Relative costEDTA25.014.2714.8718.7013.8111.04.4EDDHA33.914.316.823.94-7.243HEEDTA19.612.214.517.410.78.05.5Citrate8-Gluconate37.21.01.736.6-1.211.0Brady NC, Well RR. 1996Availability of micronutrients in soilUptake of micronutrients by plant i

28、s 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.qHighly leached, acid, sandy soilsqOrganic soilsqSoils of very

29、 high pHqSoils 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

30、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？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MnCK0.7760.561151.2Zn-2.568-Mn-191.3Cu5.240-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

31、元素肥料对土壤微量元素有效性的影响（mg/kg）1984-2003陕西陕西 长武长武(郝明德等郝明德等, 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)FormsExchangeable Zn typically ranges from 0.1 to 2 g Zn g1Concentrations of water-soluble Zn in the bulk soil solution are low, typically between 41010 and

32、 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).FormsExtractantWater solubleH2OExchangeableKNO3Organically boundNa4P2O7Carbonate/noncrystalline iron occludedEDTAManganese oxide occludedNH2

33、OHCrystalline iron oxide occludedNa2S2O4SulphidesHNO3ResidualHNO3 + H2O2% of total soil ZnSoil from Indiana,USA0.210.07.53.332.3%(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 so

34、ilpH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 Zn2+Zn(OH)+Zn(OH)2Zn(OH)3-pH值3-46-88表 不同碳酸钙含量塿土对锌的吸附强度余存祖等，余存祖等，1984土土 壤壤施锌量施锌量mg/kgDTPA提取的锌含量提取的锌含量(mg/kg)吸附强吸附强度度(%)第一次第一次第二次第二次第三次第三次合计合计中钙土壤中钙土壤(CaCO3 73g/kg,OM 11.5 g/kg)01.340.700.532.62102.701.921.2

35、05.8268.010021.408.005.1034.5068.2高钙土壤高钙土壤(CaCO3 160g/kg,OM 4.1 g/kg)082.87101.561.360.903.8790.51007.402.962.1612.5290.4锌的吸附可用Langmuir方程描述式中：式中：x表示吸附平衡时的吸附量表示吸附平衡时的吸附量 xm表示最大吸附量表示最大吸附量 Kl为为Langmuir吸附常数吸附常数 C平衡时溶液中吸附物的浓度平衡时溶液中吸附物的浓度1lmlK CxxK CLangmuir吸附常数吸附常数xm、Kl被用于评价土壤对锌的吸附特性被用于评价土壤对锌的

36、吸附特性整理Langmuir方程得：1lmlK CxxK C1mlmCCxxK xCC/x1/xm1/Klxm表 不同质地土壤对锌吸附的Langmuir方程参数土土 壤壤颗粒组成颗粒组成%最大吸最大吸附量附量（Xm）吸附常吸附常数数K土壤吸持土壤吸持性性Xm.K0.01 mm0.001mm坝富黏层坝富黏层64.7331.205.7510.2161.243坡红黏土坡红黏土60.6833.855.0670.1460.740坝轻壤层坝轻壤层28.6413.443.8400.0980.377坝轻壤层坝轻壤层26.4613.413.7830.0990.375毕银丽等，毕银丽等，1997u石灰性土壤多采用

37、DTPA浸提，临界指标为 0.5mg/kg,u酸性土壤用 0.1 M 盐酸浸提，临界指标为 1.5mg/kg 5.0很低低中高很高酸性土壤石灰性及中性土壤 4.0(4)How to evaluate Zn availability in soil? 我国缺锌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)施锌量施锌量1981.8.10不同时期土壤有效锌含量不同时期土壤有效锌含量锌在土壤锌在土壤中残留率中残留率（%）1981.

38、8.101982.9.131983.9.231984.9.2801.250.841.101.20-105.527.808.504.7035.010042.630.619.021.019.8余存祖等，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)q 矿质态锰q 易还原态锰q 交换态锰q 水溶性锰(1)Content(2)Forms与铁镁矿物共生，风化释放与铁镁矿物共生，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

39、活性锰黄土高原区交换性锰含量黄土高原区交换性锰含量, 3 mg/kgManganese（Mn） 锰在土壤中的转化示意图Mn2+Mn3+Mn2O3.nH2OMn4+MnO2.nH2OMnO2ReductionOxidation 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 soiln多采用DTPA浸提，临界指标为7 mg/kg,或n活性锰（1M 醋酸铵+0.2%的对苯二酚），100mg/kg 300很低低中丰富过量活性锰D

40、TPA浸提锰 15(4)How to evaluate Mn availability in soil? Problem soils of Mn deficiencyManganese 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

41、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)中的残效施锰量施锰量1981.5.23土壤有效锰含量（土壤有效锰含量（mg/kg）198119821985013.010.47.42026.016.210.820032.525.027.3余存祖等，余存祖等，1986(1)Contentq基性火成岩发育的土壤含铜量高于酸性岩q含硫矿物中铜的含量高n 矿质态铜n 交换态铜n 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

42、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 soilThe general order of affinity for metal cations complexed by organic matter follows: Cu2+ Cd2+ Fe2+ Pb2+ Ni2+ Co2+ Mn2+ Zn2+u石灰性土壤多采用DTPA浸提，临界指标为 1.mg/kg,u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 avai

43、lability in soil? Problem soils of Cu deficiencyNewly cultivated organic soils (reclamation disease)Sandy soilsCalcareous soils with the high pHCompetition of copper with other metals (Al, Zn, Fe)我国缺铜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

44、有所彭琳等研究，该区约有1/31/3土壤有效铜不足。特土壤有效铜不足。特别是质地较粗、肥力低的土壤。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。另外，沼泽土、泥炭土易发生缺铜问题。表 铜在土壤(黑垆土)中的残效施铜量（施铜量（mg/kg）1984.5土壤有效铜土壤有效铜（1985.7）小麦籽粒含铜小麦籽粒含铜00.863.711.133.852.375.7104.317.03011.597.5余存祖等，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

45、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)FormqAs anionic form（MoO42-, HMoO4-）qIts behavior in soil resembles phosphate or sulfateSoil pHTotal Mo content in soilMo 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

46、。(3) Factors affecting Mo availability in soilpH每增加一个单位，钼酸根离子的浓度增大100倍！H2MoO4HMoO4- + H2OMoO42- + H2O+H+H+OH-+OH-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 deficiencyMolybdenum deficiencies will be most common in acidic sandy soils, where leaching l

47、osses, strong molybdate adsorption, and few molybdenum minerals exist.我国缺钼钼土壤的分布 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耕地土壤钼供应不耕地土壤钼供应不足足(余存祖，余存祖，2004)Mo toxicitySoils which are high in Mo and give rise to herbage containing high levels

48、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%q 矿质态q 有机结合态 q 交换态q 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+

49、+ 3OH-1 Fe(OH)3 Fe3+ Fe(OH)2+ Fe(OH)2+Fe(OH)3OH-1OH-1OH-1Simple cation(Soluble)Hydroxy metal cations(Soluble)Hydroxide(Insoluble)Soil pH and Fe availabilitySoil Eh淹水后三价铁可以还原为二价铁Fe(OH)3 + e-1 + 3H+ Fe2+ + 3H2OSoil 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（l

50、ime 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,缺乏临界适量石灰性土壤 4.5(4) How to evaluate Fe availability in soil? Soi

51、ls deficient in FeIron 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)Content2.6 Boron(B)花岗岩及其他酸性火成岩、片麻岩、红砂岩等成土母质

52、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。q Mineral-Bq Organic-Bq Adsorbed-Bq 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 colloidOOBOH Soil pH Clay types Organic contents(3) Facto

53、rs 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/kg0.5 mg/kg作为临界指标作为临界指标 2.50很低低适量丰富过量

54、中毒Problem soils of B deficiencyuStrongly weathered coarse textured soil with low base exchange developing under humid conditions.uSandy 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、浙江西部和南部和于广东、福建、江西南部、浙江西部和南部和

55、四川等地。土壤全硼和水溶性硼含量均较低。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，包主要是黄土和黄河冲积物发育的各种土壤，包括括塿塿土、黄绵土和黄潮土等。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 micronutrientsTransformation of micronutrien

56、ts in soil 我国土壤缺乏微量元素的面积种类ZnBMoMnCuFe亿亩7.294.926.683.040.980.71占耕地%51.534.546.5土壤临界值（mg/kg）550.25 ppm)，会引起牲畜中，会引起牲畜中毒，患毒，患“碱质病碱质病(alkali disease)”和和“盲跚病盲跚病”。世界上约有世界上约有110多个国家的多个国家的10亿人口患有此病。我亿人口患有此病。我国患病人口分布在国患病人口分布在20多个省市区，人口约多个省市区，人口约4.25亿亿。（2 2）地方性缺碘病）地方性缺碘病( (甲状腺肿大病甲状腺肿大病) )地方

57、性甲状腺肿是世界上流行最广泛的一种地方病俗称地方性甲状腺肿是世界上流行最广泛的一种地方病俗称“大粗脖大粗脖”，以甲状，以甲状腺肿大为主要特征。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我国贵州的都匀市、黔西县属高度缺碘地区, ,发病率相当高。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。个大循环。土壤土壤植物植物人体人体水水大气大气动物动物岩石岩石图图 碘的生物地化循环碘的生物地化循环碘的生物地化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。碘非常活泼，

58、迁移性强。土壤中的碘易随水迁移。碘分布特性碘分布特性： “山区少于平原，平原少于沿海，沿海少于海洋山区少于平原，平原少于沿海，沿海少于海洋”我国自然土壤碘含量平均我国自然土壤碘含量平均4.22 ppm，在世界土壤正常范围，在世界土壤正常范围(1-5 ppm)。但黄土高原。但黄土高原土壤全碘含量低。土壤全碘含量低。褐土褐土 1.59 ppm灰钙土灰钙土 2.74 ppm供应含碘食盐，即食盐中加供应含碘食盐，即食盐中加KIO3。预防措施：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。主要表现为毒疾病。主要表现为氟斑牙氟斑牙和和氟骨症氟骨症

59、。(3)(3)地方性氟中毒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。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伊朗村病是缺少微量元素锌锌而引起的地方性侏儒症而引起的地方性侏儒症, , 因因1958 1958 年在伊朗锡拉兹地区年在伊朗锡拉兹地区发现，故得名。发现，故得名。“伊朗村病伊朗村病”口服用口服用ZnSOZnSO4 4 和和V VB B 做成的复合锌片进行预防和治疗效果良好。我国卫生部门批准做成的

60、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。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 popula