Suelos agrícolas como receptáculos para mitigar las emisiones

8/13/2019 Suelos agrcolas como receptculos para mitigar las emisiones

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Introduccin

El carbono orgnico ligado a minerales es

considerado como relativamente estable y controla alargo plazo el secuestro de MO.

Estructuras aromticas son las ms resistentes a la

biodegradacin.Cronosecuencia - Deriva mineralgicaCO almacenado.MO es sorbida selectivamente a minerales porfraccionamiento de tamao molecular y qumico.


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Experimentos de Calorimetra de escaneadodiferencial (DSC) dan cuenta de una disminucin

en la movilidad segmental de la MO con eltiempo.

Cambios mineralgicos afectan interaccin mineral-

orgnica por: Desarrollo de superficies reactivas; cambios en la

MO sorbida; fraccionamiento sortibo de la MO.

Investigacin de la naturaleza de las asociacionesminerales-orgnicas durante la meteorizacinprogresiva de basalto (0.3-4100 kyr/Plioceno-Holoceno) en el archipilago hawaiano.


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Objetivo

Examinar la formacin cronodependiente y lascaractersticas de las asociaciones minerales-orgnicas y las consecuencias de las propiedadesfsicas y qumicas de MOM.

HiptesisLas transformaciones cronodependientes de lossilicatos primarios que dominan en la lava basltica

juvenil en minerales secundarios mas maduros esacompaada por cambios distintivos en laspropiedades quimico-fsicas de la MOM.


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Materiales y mtodos


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1: Thaptic Udivitrand 2-4:Aquic Hydrudand 5: Aquic Hapludand 6: Plinthic Kandiudox MOAs se aislaron densiometricamente y se examinaron

segn: Cambios en composicin mineral, rea superficial y

porosidad mediante extraccin selectiva, espectroscopiafotoelectrnica de rayos X (XPS) adsorcin gaseosa ymicroscopa de transmisin electrnica (TEM) acopladacon espectroscopa de energa dispersiva.

Transformaciones qumicas de la MO en MOAs medianteXPS y anlisis de biomarcadores moleculares (fenoles delignina, carbohidratos no celulsicos).

Alteracin del estado fsico de la MO en MOAs por eltiempo se investig mediante calorimetra de escaneo

diferencial (DSC).


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Tabla 1Edad del suelo, origen, profundidad de muestreo y pH, adems de algunas propiedadesbsicas de las asociaciones mineral-orgnicas (MOAs) de horizontes A y B en cronosecuencia.

Site

age Island Depth

Soil

pH

(H2O)

Absolut

density

(MOA) MOCa MN

a C/N

MOC

NaOHb

XA

D-8c Fedith

d Feox

d

Feox/

Fedith Aloxd AlCu

e Siox

d

Clay mineral

compositionf

kyr cm g/cm3 mg/g mg/g % % mg/g mg/g mg/g mg/g mg/g

A horizons

Thurston 0.3 Hawaii 29 5.5 2.9 18.7 2.3 8 70 56 5 4.3 0.9 2.6 1.5 0.8 P, F, a

Laupahoehoe 20 Hawaii 010 4.1 2.4 177.5 9.9 18 47 66 153.6 84.2 0.5 3.3 0.9 0.3 F, A, m, q

Kohala 150 Hawaii 07 3.9 2.1 187.6 13.2 14 63 68 46.9 37.4 0.8 18.5 11.1 0.8 A, F, v, hiv, q

Pololu 400 Hawaii 010 3.9 1.8 290.4 19.4 15 66 81 43.7 40 0.9 7.6 6.1 0.1 A, F, v, hiv, k, q

Kolekole 1400 Molokai 08 4.2 2.3 131.1 9.7 13 60 65 40.1 15.4 0.4 4.2 1.9 0.1 K, Gi, F, he, q

Kokee 4100 Kauai 016 4.8 3.2 40.0 2.8 14 74 49 241.3 4.4 0 0.4 0.2 0.0 K, Gi, Go, he

B horizons

Thurston 0.3 1523 6.1 2.8 23.2 2.5 9 46 51 11.5 10.7 0.9 8.1 1.5 4.1 P, F, a

Laupahoehoe 20 4567 5.3 2.3 113.6 5.6 20 86 46 100.8 77.9 0.8 113.5 7.6 29.5 F, A, m, q

Kohala 150 4160 4 2.1 120.6 4.4 27 92 37 15.4 16.9 1.1 137.8 15.9 44.7 A, F, hiv, q

Pololu 400 4464 4.9 2.5 81.3 3.6 23 88 46 124.1 56.6 0.5 50.5 9.2 4.9 A, F, v, hiv, k, q

Kolekole 1400 3049 4.9 2.6 19.9 2.0 10 100 29 53.3 14.4 0.3 14 2.4 2.0K, Gi, F, he, q,m

Kokee 4100 50100 5.2 3.1 12.1 1.6 7 75 21 143.9 2.3 0 2.1 0.4 0.1 K, Gi, Go, he, m

a MOC and MN = mineral-associated organic C and N.

b Fraction of the mineral-associated OC extractable in 0.1M NaOH.

c Fraction of the NaOH-extractable OC that adsorbs to XAD-8 resin after acidification to pH 2.

d Fedith = dithionite-extractable Fe; Feox, Alox, Siox = oxalate-extractable Fe, Al, Si.

e AlCu = CuCl2-extractable Al.

f Data compiled from Chorover et al. (2004): upper case letters indicate major constituents, lower case letters indicate minor constituents; P, plagioclase; A, short-range-

ordered Al gels or

aluminosilicates (e.g., allophane); F, ferrihydrite; Q, quartz; V, vermiculite; HIV, hydroxyl-interlayered vermiculite; K, kaolin minerals (kaolinite and/or halloysite); Gi,gibbsite; He, hematite; Go,

goethite; M, magnetite.

Resultados y discusin


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MOC y MN estrechamente relacionados a la

deriva mineralgica. Media de 74 % OC y 88% Nt en MOAs.

MOC-MN (r2= 0.92).

% MOC en B-MOAs liberado >A-MOAs. OC en A-MOAs s. aromticas/ B-MOAs menos

hifrofbicos.


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rea de superficie especfica y mesoporosidad

a SSA corrected for OM content (see Section 2.5).bMicropore volume (


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Fig. 3. Plot of the volumetric ratio of sorbed OM (VOM) versus mineralmatter (Vmineral) in mineralorganic associations from A (A-MOA)and B horizons (B-MOA) of the long substrate age gradient.


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F Representative transmissionelectron micrographs andX-ray electron dispersivespectra of mineralorganicassociations from Ahorizons of the long

substrate age gradient.Primary mineral particles atthe 0.3-kyr site are partlycovered with phases ofpoor crystallinity (A) whilesuch poorly crystallinephases dominate the 20-kyr (B), 150-kyr (C) and400-kyr site (D). Note, thepresence of film-likestructures at the 400-kyrsite (black arrow). At the1400-kyr (E) and 4100-kyr

(F) site, aggregates arecomposed to a much largerextent by secondarycrystalline aluminosilicatesand Fe (hydr)oxides, thelatter particularly coveringlarger mineral particles at

the 4100-kyr site.


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Fig. 5. Examples of high-resolution XPS C1s spectra of mineralorganic associations from A horizons of the0.3-kyr, 150-kyr, and 4100-kyr site of the long substrate age gradient. Numbers of deconvoluted sub-peaksrefer to (1) unsubstituted aromatic carbon (ArA-C-C/Ar-C-H), (2) aliphatic carbon (C-C/C-H), (3) a-carbon (C-

C(O)O), (4) ether or alcohol carbon (C-O), (5) ketonic or aldehyde carbon (C=O), (6) amide carbon (C(O)N),(7) carboxylic carbon (C(O)O), and (8) p-p*-shake-up satellite from the aromatic structure.


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Fig. 6. (AC) Regression plots of XPS-based carbon types with oxalate-extractable Fe, Al, and Siconcentrations in mineralorganic associations from A (A-MOA) and B horizons (B-MOA). Note thatthe oxalate-extractable metal concentrations refer to bulk MOA samples whereas XPS data reveal theaverage composition of OM at particle surfaces.


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Fig. 7. Change of the inorganic surface composition (Al, Si, Ti and Fe) and of C and N

concentrations in mineral

organic associations from A horizons upon Ar+ sputtering. The datafor C and N represent the percentage loss of C and N concentrations after 30 min of etching.


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Fig. 10. (AF) Time-dependent change of lignin-derived phenol concentrations (K8) in organic layers and mineralorganicassociations from A (A-MOA) and B horizons (B-MOA) (A); acid-to-aldehyde ratio of vanillyl (B) and syringyl units (C). Thegrey bands in B and C connote the acid-to-aldehyde ratios in collected plant source materials. Non-cellulosic carbohydrateconcentrations (D); the GM/AX ratio (E) and RF/AX ratio (F). The GM/AX ratio refers to the mass quotient of (galactose +mannose)/(arabinose + xylose) and that of the RF/AX ratio to (rhamnose + fucose)/(arabinose + xylose).


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Fig. 11. (AD) Time-dependent change ofphenol concentrations (A = A horizon; B =B horizon) and non-cellulosiccarbohydrate concentrations (C = Ahorizon; D = B horizon) normalized tomineral-associated OC (MOC).Abbreviations: K8, lignin phenols; BA,benzoic acid; 2H BA, 2-hydroxybenzoicacid; 3H BA, 3-hydroxybenzoic acid; 4HBA, 4-hydroxybenzoic acid; 3,5 diH BA,3,5-dihydroxybenzoic acid; Xyl, xylose;Ara, arabinose; Rib, ribose; Rha,rhamnose; Fuc, fucose; Man, mannose;

Gal, galactose; Glu, glucose; GluA,glucuronic acid; GalA, galacturonic acid.


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Fig. 12. (AC) Plot of the syringyl-to-vanillyl ratio versus the cinnamyl-to-vanillyl ratio of sourcevegetation leaves, organic layers, and mineralorganic associations (A), MOC-normalizedconcentration of lignin phenols (K8) versus the ratio of benzenecarboxylic acids (BA) to ligninphenols (B), and the time-dependent change of the lignin-to-carbohydrate ratio in organic layersand mineralorganic associations (C).


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Fig. 14. Time-dependent change of the DSC step transition temperature (T*) of organic matter inmineralorganic associations from A (AMOA) and B horizons (B-MOA). Marked samples did notshow transitions in every replicate (*) or showed a weak, but reversing transition only (**).


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Conclusiones

Transformaciones minerales a travs de lacronosecuencia causan un almacenamientodiferencial de la MO en MOAs.

En horizontes superficiales ricos en MO, la pp enadicion a las reacciones de adsorcion estaninvolucradas en la formacion de MOAs.

No existe completo recubriminto de lassuperficies minerales


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Conclusiones

Evidencia del secuestro de C por suelos bienmanejados.

Estrategias clave son incrementar el tiempo del

suelo vegetado, reducir o eliminar la labranza,estimular la produccin primaria e incrementarsu retorno al suelo, aumentar el uso devegetacin perene.

Mayor capacidad de buscar incrementar elsecuestro de C por pases industrializados ytemperados y mayor informacin al respecto.

Suelos agrícolas como receptáculos para mitigar las emisiones

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