4. 海水中微量元素海水中微量元素2021/8/61 本章要点：本章要点： v海水中微量元素的含量、分布和存在形式海水中微量元素的含量、分布和存在形式v微量元素在海洋中的化学过程、生物过程、微量元素在海洋中的化学过程、生物过程、再循环模型再循环模型2021/8/62 海水中微量元素的含量和分布海水中微量元素的含量和分布 周期表中周期表中14种元素的浓度超过种元素的浓度超过1mg/L :O, H, Cl, Na, K, Mg, S, Ca, Br, C, Sr, B, Si, F 其中活性元素：其中活性元素：Si 2021/8/63 微量元素v通常把海水中含量小于通常把海水中含量小于通常把海水中含量小于通常把海水中含量小于1mg/L1mg/L的元素称为微量的元素称为微量的元素称为微量的元素称为微量元素仅占海水总量的元素仅占海水总量的元素仅占海水总量的元素仅占海水总量的0.10.1％左右v海水中除了海水中除了海水中除了海水中除了1414种元素（种元素（种元素（种元素（OO、、、、HH、、、、ClCl、、、、CaCa、、、、MgMg、、、、S S、、、、K K、、、、BrBr、、、、C C、、、、S S、、、、SrSr、、、、B B、、、、SiSi、、、、F)F)浓度大于浓度大于浓度大于浓度大于1mg/L1mg/L外，其余所有元素的浓度均低于此值，外，其余所有元素的浓度均低于此值，外，其余所有元素的浓度均低于此值，外，其余所有元素的浓度均低于此值，因此可以把这些元素称为因此可以把这些元素称为因此可以把这些元素称为因此可以把这些元素称为“ “微量元素微量元素微量元素微量元素” ”。
v微量元素在海水中涉及的平衡有微量元素在海水中涉及的平衡有微量元素在海水中涉及的平衡有微量元素在海水中涉及的平衡有络合络合络合络合( (螯合螯合螯合螯合) )、、、、氧化还原、氧化还原、氧化还原、氧化还原、生物吸收、生物吸收、生物吸收、生物吸收、颗粒物的吸附与解吸颗粒物的吸附与解吸颗粒物的吸附与解吸颗粒物的吸附与解吸等2021/8/64 Trace elements occur in minute quantities and are usually measured in parts per billion (ppb). -even in small quantities they can be important for either promoting or killing life.Trace ElementsTrace element Concentration [ppb]Lithium (Li)170Iodine (I)60Molybdenum (Mo)10Zinc (Zn)10Iron (Fe)10Aluminum (Al)10Copper (Cu)3Manganese (Mn)2Cobalt (Co)0.1Lead (Pb)0.03Mercury (Hg)0.03Gold (Au)0.0042021/8/65 微量元素的来源微量元素的来源v陆地径流陆地径流v海底火山活动海底火山活动v大气尘埃降落夹带的微量元素大气尘埃降落夹带的微量元素——大气大气输入输入v沥滤岩石沥滤岩石v人类活动人类活动2021/8/66 微量元素的特点微量元素的特点Ø非保守性（地球化学活性较大；生物活非保守性（地球化学活性较大；生物活性大；区域性变化大）性大；区域性变化大）Ø含量低含量低Ø微量元素循环及迁移转化复杂（水动力微量元素循环及迁移转化复杂（水动力迁移；化学过程；生物迁移）迁移；化学过程；生物迁移）Ø研究难度大（测定方法限制；采水器；研究难度大（测定方法限制；采水器；样品贮存；分析方法检出限）样品贮存；分析方法检出限）2021/8/67 Classification of Elements Type Concentration Major 0.05 to 550 mM Minor 0.05 to 50 M Trace 0.05 to 50 nM 2021/8/68 2021/8/69 2021/8/610 2021/8/611 2021/8/612 2021/8/613 2021/8/614 2021/8/615 2021/8/616 v微量元素的分布及其变化，受其来源及海微量元素的分布及其变化，受其来源及海洋环境中各种过程的影响。
洋环境中各种过程的影响v其中最主要过程：其中最主要过程：v生物过程生物过程v吸附过程吸附过程v海海—气交换过程气交换过程v热液过程热液过程v海水海水—沉积物界面交换过程等沉积物界面交换过程等2021/8/617 Broecker's Classification Unlimited: All Major except Ca, C and Si Biolimited: N, Si, and P (Fe) Intermediate: O, Ca, C, Sr, Ba, Ra, Se and most minor elements 2021/8/618 Goldberg's Classification of Metals do Cations Metals with rare gas configuration Na+, Mg2+, Ca2+, K+ d10 Cations Metals with 18 outer electrons Ag+, Zn2+, Ga3+, Ge4+ Transition Metals Metals between d0 and d10 Mn2+, Fe2+, Co2+, Ni2+, Cu2+ 2021/8/619 Electronic Configuration of Atom K L M N __ _______ _____________ ______ Period Z Element s s p s p d s p 1 1 H 1 2 He 2 2 3 Li 2 1 4 Be 2 2 5 B 2 2 1 6 C 2 2 2 7 N 2 2 3 8 O 2 2 4 9 F 2 2 5 10 Ne 2 2 6 2021/8/620 K L M N __ _______ _____________ ______ Period Z Element s s p s p d s p 3 11 Na 2 2 6 1 12 Mg 2 2 6 2 13 Al 2 2 6 2 1 14 Si 2 2 6 2 2 15 P 2 2 6 2 3 16 S 2 2 6 2 4 17 Cl 2 2 6 2 5 18 Ar 2 2 6 2 6 4 19 K 2 2 6 2 6 1 20 Ca 2 2 6 2 6 2 21 Sc 2 2 6 2 6 1 2 22 Ti 2 2 6 2 6 2 2 23 V 2 2 6 2 6 3 2 24 Cr 2 2 6 2 6 5 1 25 Mn 2 2 6 2 6 5 2 26 Fe 2 2 6 2 6 6 2 27 Co 2 2 6 2 6 7 2 28 Ni 2 2 6 2 6 8 2 29 Cu 2 2 6 2 6 10 1 30 Zn 2 2 6 2 6 10 2 31 Ga 2 2 6 2 6 10 2 1 32 Ge 2 2 6 2 6 10 2 2 2021/8/621 d0 CationsvForms Few Complexes with Ligandsv只能氟离子或含氧酸离子形成络合物只能氟离子或含氧酸离子形成络合物vComplexes or Ion Pairs that are Formed are Electrostatic in Nature (Strength Z/r where Z is the Charge and r is the Radius) M + L ML KML = [ML]/[M][L] Ion Log KMF Log KMOH Radius Be2+ 4.29 10.28 0.31 Å Mg2+ 1.82 2.3 0.65 Ca2+ 1.04 1.4 0.99 Sr2+ - 0.9 1.13 Ba2+ 0.45 0.8 1.35 2021/8/622 d10 Cations（阳离子）（阳离子）v单单价价d10金金属属阳阳离离子子与与d0金金属属完完全全不不同同，，和和卤卤素素能能形形成强络和物成强络和物v随着原子量或配位体体积的增加，稳定性增加。
随着原子量或配位体体积的增加，稳定性增加 M + L ML KML = [ML]/[M][L] Log KML Complex F- Cl- Br- I- AgL 0.3 3.0 4.3 8.1 CuL - 2.7 3.2 5.7 •由于海水中氯的浓度最高，因此氯的络合物在海水中是主由于海水中氯的浓度最高，因此氯的络合物在海水中是主要的OH-跟氯有竞争跟氯有竞争•logKMCl-logKMOH必须大于必须大于-5.4,氯化物才占优势氯化物才占优势 2021/8/623 Hg2+ + Cl- HgCl+ Hg2+ + 2Cl- HgCl2 Hg2+ + 3Cl- HgCl3- 随氯离子浓度的增加，可形成下列系列络合物随氯离子浓度的增加，可形成下列系列络合物:2021/8/624 Transition Metals (d0 to d10)vForms Strong Complexes with Organic Ligands vIrving - Williams Order: Mn2+ < Fe2+ < Co2+ < Ni2+ < Cu2+ > Zn2+ Log KMX ______________________________________________ Ion EDTA Ethylenediamine Nitrilotriacetic acid Mn2+ 14 2.7 7.4 Fe2+ 14 4.3 8.3 Co2+ 16 5.9 10.5 Ni2+ 18 7.9 11.4 Cu2+ 19 10.5 12.8 Zn2+ 16 6.0 10.5 2021/8/625 2021/8/626 Residence Times of ElementsInput of Elements Into the Oceans 1. The fallout of substances from the atmosphere 2. Influx of river water 3. Interior of earth 海洋中某一种元素浓度较低的原因：海洋中某一种元素浓度较低的原因：1、反应活跃，快速转移到沉积物中、反应活跃，快速转移到沉积物中 (Al3+)2、源头浓度低、源头浓度低 (Cs+)2021/8/627 = Concentration in Ocean/Amount Supplied dA/dt = R - S = 0 Steady State Condition S = k [A] = 1/k = [A]/R = [A]/S R = River Input to Oceans (also Atm. and Interior) S = Sedimentation Rates 2021/8/628 Residence Times of Some Elements in Seawater (My) Element River Input Sedimentation Na 210 260 Mg 22 45 Ca 1 8 K 10 11 Sr 10 19 Si 0.935 0.01 Li 12 19 Rb 6.1 0.27 Ba 0.05 0.084 Al 0.0031 0.0001 Mo 2.15 0.5 Cu 0.043 0.05 Ni 0.015 0.018 Ag 0.25 2.1 Pb 0.00056 0.002 2021/8/629 Comparison of Ratio of Saturated Concentration to Measured Values and Residence Times Metal Insoluble Ra Years Compound Sat Conc./Meas. Pb2+ PbCO3 10,000 - 20,000 2,000 Ni2+ Ni(OH)2 10,000 - 225,000 18,000 Co2+ CoCO3 50,000 - 400,000 18,000 Cu2+ CuCO3 133 - 266 50,000 Ba2+ BaSO4 3.7 84,000 Zn2+ ZnCO3 120 - 250 180,000 Cd2+ CdOHCl 40,000 - 10,000,000 500,000 Ca2+ CaCO3 0.25 - 1.2 8,000,000 Sr2+ SrCO3 2.75 190,000,000 Mg2+ MgCO3 27 450,000,000 a) Measure of degree of Undersaturation. R = saturation conc./measured conc. 2021/8/630 Water samples must be collected in inert containers and isolated as they are recovered so as to prevent contamination.vThe Niskin bottle has valves at each end which are automatically closed when a weight, called a messenger, is sent down the cable and causes the bottle to flip over and seal itself.vSample depth can be determined from cable inclination and length or with a pulsating sound source.2021/8/631 2021/8/632 2021/8/633 2021/8/634 Distribution of Elements in the Oceans1.Conservative Profiles 2. Nutrient Type Profiles 3.Surface Enrichment and Depletion at Depth 4.Mid-Depth Minima 5.Mid-Depth Maxima6.Mid-Depth Maxima or Minima in the sub-oxic layer 7.Anoxic Waters 2021/8/635 1. Conservative Profiles Constant Ratio of Concentration to Cl or S (Major Ions, Rb+, Li+, Cs+, WO42-, MoO42-) v在海水中比较稳定，反应活性低在海水中比较稳定，反应活性低v垂直分布断面从表层到底层均匀垂直分布断面从表层到底层均匀v与海水中常量元素一样可视为保守型元素，保守型与海水中常量元素一样可视为保守型元素，保守型元素在海水中逗留时间较长，浓度较大。
元素在海水中逗留时间较长，浓度较大2021/8/636 vElements have essentially constant concentrations with depth.vElements behave like major ions, having long residence times and being well-mixed.vNot major components of seawater owing to very low crustal(外壳的) abundances.vElements form simple anions or cations with low Z/r, e.g., Cs+, Br-, or complex oxyanions, e.g., WO42-, MoO42-.vLittle involvement in biological cycles.2021/8/637 EXAMPLES OF CONSERVATIVE BEHAVIOR2021/8/638 2. Nutrient Type Profiles ØRemoved by Phytoplankton(浮游植物；浮游植物；浮游植物浮游植物(群落群落)) in Surface Waters and Regenerated in Deep Waters (Follow Nutrients) Soft Parts－－ Cd （１（１km）） Hard Parts－－SiO2, Ba, Zn, Ge, Be Combination－－Ni, Se 2021/8/639 vProduction of biological material removes nutrient elements from surface seawater.vOn the death of organisms, this biological material sinks through the water column, decomposing and releasing the nutrients.vInvolvement in biological cycling involves chemical transformations.vElements showing nutrient behavior tend to have long residence times.2021/8/640 EXAMPLES OF NUTRIENT BEHAVIOR2021/8/641 2021/8/642 3. Surface Enrichment and Depletion (损耗损耗)at Depth v Input from Atmosphere(dust), Rivers, Land (Pb, Mn, Ra, Cr, Sn, Co )v主要由大气输入海洋表层，接着在水体中被清除。
主要由大气输入海洋表层，接着在水体中被清除例如例如 Pbv主要由河流输入海洋表层或由大陆架沉积物中释放，主要由河流输入海洋表层或由大陆架沉积物中释放，通过水平混合进入海水表层，导致表层产生最大值通过水平混合进入海水表层，导致表层产生最大值如如Mn, Ra等v在海洋表层中，因生物的还原作用与整个水体的氧在海洋表层中，因生物的还原作用与整个水体的氧化化-还原平衡相结合，使某些元素的氧化态或颗粒还原平衡相结合，使某些元素的氧化态或颗粒态在表层中富集如态在表层中富集如Cr（（III））,As（（III）和）和I（（-1价）价）等2021/8/643 vElements that are highly particle-reactive, characterized by high Z/r.vThey have a minimum concentration at an intermediate depth and a maximum concentration at the surface.vInitial decreasing concentration with depth is a result of adsorption and cation exchange on particle surfaces.vThese elements have short residence times; the river inputs are largely removed by estuarine processes.vThe atmosphere provides the main input of these elements to the open ocean (e.g., input of Pb from gasoline emissions can be traced in corals).vThe element concentration may increase again after a certain depth if particles become unstable with depth, e.g., reduction of Fe-Mn oxyhydroxides or decomposition of organic matter.2021/8/644 2021/8/645 4. Mid-Depth Minima vSurface Input and Regeneration at Bottom (Cu, Al) v因因Gibbs原理和有机配体的络合作用，以及颗粒物原理和有机配体的络合作用，以及颗粒物的交换吸附和的交换吸附和“浮选浮选”原理等综合结果，导致在海洋原理等综合结果，导致在海洋微表层中元素富集。
几乎所有的有机物、营养盐和微表层中元素富集几乎所有的有机物、营养盐和金属等无机物都可为例金属等无机物都可为例v表层因大气或河流输入而具有浓度较大值，中层真表层因大气或河流输入而具有浓度较大值，中层真光层因生物作用而减少，如营养盐光层因生物作用而减少，如营养盐v深层或海底因物质再循环或悬浮物再溶解，再生作深层或海底因物质再循环或悬浮物再溶解，再生作用与清除作用的综合结果如用与清除作用的综合结果如Al, Cu等2021/8/646 5. Mid-Depth Maximav冬季保留所致，例如溶解氧等；冬季保留所致，例如溶解氧等；v洋中脊水热流的注入引起，如洋中脊水热流的注入引起，如Mn和和３３He等2021/8/647 6. Mid-Depth Maxima or Minima in the sub-oxic layer v在东热带太平洋和北印度洋发现有典型的亚氧化层在东热带太平洋和北印度洋发现有典型的亚氧化层的分布，在水柱或在邻近斜坡沉积物中，由于还原的分布，在水柱或在邻近斜坡沉积物中，由于还原作用而会出现微／痕量元素的最大值和／或最小值作用而会出现微／痕量元素的最大值和／或最小值v如果元素的还原形式相对于其氧化形式是可溶解的，如果元素的还原形式相对于其氧化形式是可溶解的，将出现最大值。
如锰和铁将出现最大值如锰和铁v当元素的还原形式比其氧化形式更难溶时或易于与当元素的还原形式比其氧化形式更难溶时或易于与固体结合时，将出现最小值，如固体结合时，将出现最小值，如Cr（（III））2021/8/648 7. Anoxic Waters v在水循环受限制的区域，由于氧化一还原电对在水循环受限制的区域，由于氧化一还原电对SO42-－－H2S的产生而变为缺氧状态并产生还原条件，例的产生而变为缺氧状态并产生还原条件，例如如Cariaco海沟和海沟和Saanich海湾此时又分成两种情海湾此时又分成两种情况况:v当某元素的还原形式比其在氧化条件下存在的形式当某元素的还原形式比其在氧化条件下存在的形式更易溶时，曲线出现最大值，例如更易溶时，曲线出现最大值，例如Mn2+和和Fe2+v当某元素还原形式相对而言比较难溶或易于与固体当某元素还原形式相对而言比较难溶或易于与固体相结合时，就出现最小值，例如相结合时，就出现最小值，例如Cr（（III）2021/8/649 Vertical profilesBiolimiting trace metals will be depleted in surface waters If a trace element is associated with org. matter, there will be a mid water column maximaIf a trace element is associated with CaCO3 shell material there will be aa deep water maxima (CCD)If a trace element is associated with opaline(蛋白石蛋白石(似似)的，发乳光的。
的，发乳光的) shell material, its conc.will be correlated to Si2021/8/650 2021/8/651 2021/8/652 2021/8/653 2021/8/654 2021/8/655 2021/8/656 2021/8/657 2021/8/658 2021/8/659 2021/8/660 海洋中微量元素的浓度海洋中微量元素的浓度Metals in Atlantic and Pacific Deep Waters (nM) Metal Atlantic Pacific P/A Cd 0.29 0.94 3.2 Zn 1.5 8.2 5.5 Ni 5.7 10.4 1.8 Cu 1.7 2.7 1.6 Mn 0.6 - - 2021/8/661 为什么太平洋深层水中微量元素浓度为什么太平洋深层水中微量元素浓度比大西洋高？比大西洋高？2021/8/662 Pb和和Al与其它元素不同，与其它元素不同，为什么？为什么？2021/8/663 2021/8/664 2021/8/665 Metals on Shelf versus Open Sea Surface Waters Metal Shelf Open Mn 21 nM 2.4 nM Ni 5.9 nM 2.3 nM Cu 4.0 nM 1.2 nM Zn 2.4 nM 0.06 nM Cd 200 pM 2 pM 陆架区高于大洋，表明为陆源输入陆架区高于大洋，表明为陆源输入2021/8/666 Metals in Central Gryes Metal Atlantic Pacific Mn 2.4 nM 1.0 nM Cu 1.2 nM 0.5 nM Ni 2.1 nM 2.4 nM Zn 0.06 nM 0.06 nM Cd 2 pM 2 pM 高浓度表明是大气输入高浓度表明是大气输入2021/8/667 2021/8/668 2021/8/669 2021/8/670 2021/8/671 2021/8/672 2021/8/673 2021/8/674 2021/8/675 Illustration in a global biogeochemical model:regulation of macro-nutrient pathways by aeolian iron source (Dutkiewicz et al., 2005) Modeled Surface Chl (mg m-3)2021/8/676 Aeolian Iron Source (mmol Fe m-2 yr-1)Luo et al (2003)Sensitivity studies with uniform “high” and “low” aeolian iron flux...2021/8/677 difference in primary producitivity(high – low) aeolian iron supply (g C m-2 y-1)Sensitivity of primary production to aeolian iron source More dust, higher productivityMore dust, lower productivity2021/8/678 Pacific basin reflects regulation of intergyre exchange2021/8/679 地球化学平衡地球化学平衡vPresent Concentration (mol cm-2 of surface) of Major Components of Seawater Compared with the Amount Added by Rivers over Last 100 Million Years Na Mg Ca K Cl SO4 CO3 NO3 Present 129 15 2.8 2.7 150 8 0.3 0.01 Added by Rivers 196 122 268 42 157 84 342 11 Excess Added 67 107 265 39 7 76 342 11 2021/8/680 2021/8/681 Ocean to Atmosphere G. Suspended Load from New Rocks B. Atmosphere to Streams H. Suspended Load from Old Rocks C. Total Suspended Load of Streams I. Flux from New Rocks to Old Rocks D. Total Sediment Flux J. Dissolved Load from New Rocks E. Dissolved Load of Streams K. Dissolved Load from Old Rocks F. Total Flux Dissolved from Rocks NEW ROCKS BIOSPHERE 4800 x 1020 g of 0.01 x 1020 gC Living elements (150 x 106 y) 0.04 x 1020 gC Dead OLD ROCKS ATMOSPHERE OCEAN 8450 x 1020 g of 0.065 x 1020 g C 500 x 1020 g of elements (663 x 106 y) as CO2 elements 2021/8/682 。