Monitoring of soil solution

Chapitre VI : Transfert vertical des traceurs dans le profil de sol

Figure VI-3: Excess ⁴⁴Ca in the litter-layer, the soil exchangeable and microbial biomass pools in the different soil (0-5 cm, 5-15 cm and 15-60 cm) during the two years after the tracing experiment expressed in percentage of applied tracers.

Error bars represent standard deviations.

Apport du multi-traçage isotopique (²H, ¹⁵N, ²⁶Mg et ⁴⁴Ca) à la connaissance des flux d’éléments minéraux dans les écosystèmes forestiers

Figure VI-4: •‘–‘’‹……‘’‘•‹–‹‘ȋɁ²ǡɁ²⁶‰ƒ†Ɂ⁴⁴Ca) of soil solution collected with zero-tension lysimeters at 0 cm and 10 cm depth plotted against cumulated matrix water flow since the application of tracers (mm) (van der Heijden et al., accepted Geoderma). Crosses represent individual replicates and circles represent the mean value at each sampling date. Correspondence between sampling dates and cumulated matrix water flow is given in Table VI-3.

164

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)

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ReplicatesMeanMean 2H

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ReplicatesMeanMean 2H 02000

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ReplicatesMeanMean 2H

Chapitre VI : Transfert vertical des traceurs dans le profil de sol

ͳ͸ͷ

0 500 1000 1500 2000 2500 3000

0 20 40 60 80 100 120 140 160 180 200

ɷ2H (‰) ɷ26Mg and ɷ44Ca (‰)

Cumulated matrix water flux (mm)

Replicate 15.1

26Mg 44Ca 2H

0 200 400 600 800 1000 1200

0 20 40 60 80 100 120 140 160 180

ɷ2H (‰) ɷ26Mg and ɷ44Ca (‰)

Cumulated matrix water flux (mm)

Replicate 15.2

44Ca 26Mg 2H

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

0 100 200 300 400 500 600 700 800 900 1000

ɷ2H (‰) ɷ26Mg and ɷ44Ca (‰)

Cumulated matrix water flux (mm)

Replicate 15.3

44Ca 26Mg 2H

0 500 1000 1500 2000 2500 3000 3500 4000 4500

0 200 400 600 800 1000 1200 1400

ɷ2H (‰) ɷ26Mg and ɷ44Ca (‰)

Cumulated matrix water flux (mm)

Replicate 15.4

44Ca 26Mg Series4 2H

3.3.2. Soil solutions collected with tension-cup lysimeters at 15 cm and 30 cm depth

Š‡ •‡’ƒ”ƒ–‹‘ ‘ˆ^ʹ͸‰ ƒ†^ͶͶƒ ‡Ž—–‹‘ ’‡ƒ• ˆ”‘ –Š‡^ʹ ‡Ž—–‹‘ ’‡ƒ ™ƒ• ‡š’”‡••‡†

™‹–Š–Š‡†‹ˆˆ‡”‡…‡ȋ‘–‡†ȟ‰Ǧ™ƒ–‡”ƒ†ȟƒǦ™ƒ–‡”Ȍ‘ˆ…——Žƒ–‡†ƒ–”‹š™ƒ–‡”ˆŽ‘™ȋȌ„‡–™‡‡

–Š‡‘……—””‡…‡‘ˆ–Š‡^ʹ͸‰‘”^ͶͶƒ‡Ž—–‹‘’‡ƒƒ†–Š‡^ʹ‡Ž—–‹‘’‡ƒǤ

Figure VI-5: Isotopic composition (Ɂ²H, Ɂ²⁶Mg and Ɂ⁴⁴Ca) of soil solution collected with tension-cup lysimeters at 15 cm depth plotted against cumulated matrix water flow since the application of tracers (mm) (van der Heijden et al., accepted Geoderma). The horizontal dotted line represents the analytical detection limit for excess ²⁶Mg and ⁴⁴Ca (10‰) (van der Heijden et al., accepted Plant and Soil). Correspondence between sampling dates and cumulated matrix water flow is given in Table VI-3.

At 15 cm depthǡ‡ƒ…Š–‡•‹‘Ǧ…—’Ž›•‹‡–‡”•ȋȌ”‡’Ž‹…ƒ–‡•Š‘™‡†ƒ†‹ˆˆ‡”‡–•‡“—‡…‡

‘ˆ^ʹ͸‰ǡ^ͶͶƒƒ†^ʹ‡Ž—–‹‘’‡ƒ•ȋ ‹‰—”‡ǦͷȌǤReplicate 15.1Š‡^ʹ͸‰ƒ†^ͶͶƒ‡Ž—–‹‘’‡ƒ

™‡”‡ •‡’ƒ”ƒ–‡† ˆ”‘^ʹǣ ȟ‰Ǧ™ƒ–‡”αΪ͵Ͷ͹  ƒ† ȟƒǦ™ƒ–‡”αΪͳͷ͵ ǤReplicate 15.2Ǥ Š‡^ʹ͸‰

‡Ž—–‹‘ ’‡ƒ ™ƒ• ™‡ŽŽ •‡’ƒ”ƒ–‡† ˆ”‘ –Š‡^ʹ ’‡ƒ ȋȟ‰Ǧ™ƒ–‡”αΪ͵ͺ͵ ȌǤ Ɂ^ͶͶƒ ™ƒ• „‡Ž‘™ –Š‡

†‡–‡…–‹‘ –Š”‘—‰Š‘—– –Š‡ •–—†› ’‡”‹‘†ǤReplicate 15.3 ‹‰Š Ɂ^ʹ͸‰ ƒ† Ɂ^ͶͶƒ ™‡”‡ ‘„•‡”˜‡†

•‹—Ž–ƒ‡‘—•Ž›–‘–Š‹•ˆ‹”•–^ʹ’‡ƒǤ•‡…‘†^ʹ‡Ž—–‹‘’‡ƒ™ƒ•‘„•‡”˜‡†ƒ†ƒ•‡…‘†^ʹ͸‰

ƒ†^ͶͶƒ‡Ž—–‹‘’‡ƒƒŽ•‘‘……—””‡†„—–™ƒ••‡’ƒ”ƒ–‡†ˆ”‘–Š‡•‡…‘†^ʹ’‡ƒȋȟ‰Ǧ™ƒ–‡”αΪͳʹͲ

Apport du multi-traçage isotopique (²H, ¹⁵N, ²⁶Mg et ⁴⁴Ca) à la connaissance des flux d’éléments minéraux dans les écosystèmes forestiers

ƒ†ȟ^Ca-water=+120 mm). Replicate 15.4 A ²⁶Mg elution peak occurred simultaneously with the ²’‡ƒȋȟ^Mg-water=0 mm). The ⁴⁴Ca elution peak was well separated from ²ǣɁ⁴⁴Ca increased progressively during the study period and the maximum of the elution peak could not be distinguished.

Table VI-4: ²H, ²⁶Mg and ⁴⁴Ca transfer velocity in the soil profile (mm of tracer displacement per mm of cumulated matrix water flow) (van der Heijden et al., accepted Geoderma). Transfer velocities were computed using the maximum of elution peaks in soil solutions collected at 15 cm and 30 cm with tension-cup lysimeters.

At 30 cm depth, spatial variability was less pronounced for both ²⁶Mg and ⁴⁴Ca.

Replicates 30.1, 30.2 and 30.4 showed a similar sequence of ²⁶Mg, ⁴⁴Ca and ²H elution peaks (Figure VI-͸ȌǤ Ɂ²⁶Mg exceeded the detection limit after ~410 mm (January 2011), ~311 mm (December 2010) and ~430 mm (February 2011) in replicates 30.1, 30.2 and 30.4 respectively.

Ɂ²⁶Mg increased progressively during the study period for all three replicates. A ²⁶Mg peak occurred 480 and 600 mm (March to October 2011) in all three replicates. However, this event

‘Ž›”‡’”‡•‡–‡†–Š‡ƒš‹—‘ˆ–Š‡‡Ž—–‹‘’‡ƒˆ‘””‡’Ž‹…ƒ–‡͵ͲǤͳǤɁ⁴⁴Ca remained under the detection limit until October 2011 (~600 mm). Beyond that date, Ž‘™ Ɂ⁴⁴Ca was observed in replicate 30.2 (~35‰). And no data was available for replicate 30.1 and 30.4. Replicate 30.3 The ²⁶Mg elution peak occurred simultaneously to the ² ’‡ƒǤ Ɂ²⁶Mg was maximum at the beginning of the study period and decreased contin—‘—•Ž› –Š‡”‡ƒˆ–‡”Ǥ Ɂ⁴⁴Ca exceeded the detection limit in October 2010 (~175mm) and increased progressively throughout the study

’‡”‹‘†ǤɁ²⁶‰ƒ†Ɂ⁴⁴Ca in replicate 30.3 were much higher than the other replicates.

At 60cm depth and throughout the monitor‹‰ ’‡”‹‘†ǡ Ɂ²⁶‰ ƒ† Ɂ⁴⁴Ca in all replicates were below the detection limit (data not shown).

2H, ²⁶Mg and ⁴⁴Ca tracer flow velocities (millimeter of tracer displacement per millimeter of percolated water) were computed using the cumulated matrix water flow at the maximum of the elution peak (Table VI-4). Because, for many replicates at both 15cm and 30cm depth, no

‡Ž—–‹‘’‡ƒ…‘—Ž†„‡‹†‡–‹ˆ‹‡†ȋ‡‹–Š‡”Ɂ⁴⁴Ca values were below detection limit or the highest Ɂ⁴⁴Ca values were at the end of the study period), maximum velocities were computed.

166

Rep 1 Rep 2 Rep 3 Rep 4

15 cm ²H 2.3 1.6 1.6 2.3

26Mg 0.4 0.3 0.7 2.3

44Ca 0.7 <0.2 0.7 <0.2

30 cm ²H 3.2 1.7 13.6 3.2

26Mg 0.5 0.4 1.4 0.4

44Ca <0.4 <0.4 <0.4 <0.4

Flow velocity (mm.mm-1)

Chapitre VI : Transfert vertical des traceurs dans le profil de sol

ͳ͸͹

0 500 1000 1500 2000 2500

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ɷ2H (‰) ɷ26Mg and ɷ44Ca (‰)

Cumulated matrix water flux (mm)

Replicate 30.1

44Ca 26Mg 2H

0 100 200 300 400 500 600 700

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ɷ2H (‰) ɷ26Mg and ɷ44Ca (‰)

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Replicate 30.2

44Ca 26Mg 2H

0 500 1000 1500 2000 2500 3000 3500

0 50 100 150 200 250 300

ɷ2H (‰) ɷ26Mg and ɷ44Ca (‰)

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Replicate 30.3

44Ca 26Mg 2H

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0 10 20 30 40 50 60 70

ɷ2H (‰) ɷ26Mg and ɷ44Ca (‰)

Cumulated matrix water flux (mm)

Replicate 30.4

44Ca 26Mg 2H

Figure VI-6 : Isotopic composition (Ɂ²H, Ɂ²⁶Mg and Ɂ⁴⁴Ca) of soil solution collected with tension-cup lysimeters at 30 cm depth plotted against cumulated matrix water flow since the application o of tracers (van der Heijden et al., accepted Geoderma). The horizontal dotted line represents the analytical detection limit for excess ²⁶Mg and ⁴⁴Ca (10‰) (van der Heijden et al., accepted Plant and Soil). Correspondence between sampling dates and cumulated matrix water flow is given in Table VI-3.

͵ǤͶǤ

^ʹ͸

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ƒ–”ƒ…‡”ˆŽ—š‡•‹–Š‡•‘‹Ž’”‘ˆ‹Ž‡

——Žƒ–‡†^ʹ͸‰ƒ†^ͶͶƒˆŽ—š‡•‘˜‡”–Š‡–™‘›‡ƒ”•ƒˆ–‡”–Š‡–”ƒ…‹‰‡š’‡”‹‡–ˆ”‘–Š‡

Ž‹––‡”ǦŽƒ›‡”ƒ†‹–Š‡•‘‹Ž’”‘ˆ‹Ž‡™‡”‡…‘’ƒ”‡†–‘^ʹ͸‰ƒ†^ͶͶƒ’‘‘Ž•‹–Š‡•‘‹Ž’”‘ˆ‹Ž‡‹

ƒ”…ŠʹͲͳʹȋ ‹‰—”‡Ǧ͹ȌǤ‘–Š^ʹ͸‰ƒ†^ͶͶƒ–”ƒ…‡”•™‡”‡ƒ‹Ž›”‡–ƒ‹‡†‹–Š‡•—’‡”ˆ‹…‹ƒŽ•‘‹Ž

Žƒ›‡”•ȋͲǦͳͷ…Ȍȋ̱ͷͺΨƒ†̱Ͷ͸Ǥ͹Ψ”‡•’‡…–‹˜‡Ž›Ȍƒ†‹–Š‡Ž‹––‡”ǦŽƒ›‡”ȋ̱ͺΨƒ†̱͵͵ΨȌǤŠ‡

’”‡ˆ‡”‡–‹ƒŽˆŽ‘™…‘’‘‡–‘ˆ–Š‡^ʹ͸‰Ž‡ƒ…Š‹‰ˆŽ—šƒ–ͳͲ…”‡’”‡•‡–‡†̱ͳͳΨ‘ˆ–Š‡ƒ’’Ž‹‡†

ʹ͸‰ ™Š‡^ʹ͸‰ ‹ –Š‡ •‘‹Ž „‡Ž‘™ ͳͲ… †‡’–Š ”‡’”‡•‡–‡† ̱ͳͷΨ ȋͷǤͶΨΪ͸Ǥ͵ΨΪ͵ǤͺΨȌǤ Š‡

ƒ–”‹šˆŽ‘™…‘’‘‡–•‘ˆ–Š‡^ʹ͸‰Ž‡ƒ…Š‹‰ˆŽ—šƒ–ͳͷƒ†͵Ͳ…™‡”‡ƒŽ•‘Ž‘™‡”–Šƒ^ʹ͸‰‹

–Š‡•‘‹Ž„‡Ž‘™„‘–Š†‡’–Š•Ǥ–ͳͲ…†‡’–Šǡ–Š‡’”‡ˆ‡”‡–‹ƒŽˆŽ‘™…‘’‘‡–‘ˆ–Š‡^ͶͶƒŽ‡ƒ…Š‹‰

ˆŽ—š”‡’”‡•‡–‡†̱ͺΨ‘ˆƒ’’Ž‹‡†^ͶͶƒ™Š‹…Š™ƒ•Š‹‰Š‡”–Šƒ^ͶͶƒ‹–Š‡•‘‹Ž„‡Ž‘™ͳͲ…†‡’–Š

ȋ̱ͳǤͶΨȌǤŠ‡ƒ–”‹šˆŽ‘™…‘’‘‡–•‘ˆ–Š‡^ͶͶƒŽ‡ƒ…Š‹‰ˆŽ—šƒ–ͳͷƒ†͵Ͳ…†‡’–Š™‡”‡˜‡”›

Ž‘™ȋδͳΨȌƒ†‘ƒ–”‹šˆŽ‘™Ž‡ƒ…Š‹‰‘ˆ^ʹ͸‰ƒ†^ͶͶƒ™ƒ•‡˜‹†‡…‡†ƒ–͸Ͳ…Ǥ

Apport du multi-traçage isotopique (²H, ¹⁵N, ²⁶Mg et ⁴⁴Ca) à la connaissance des flux d’éléments minéraux dans les écosystèmes forestiers

4. Discussion

No documento Apport du multi-traçage isotopique (26Mg, 44Ca et 2H) à la connaissance des flux d’éléments minéraux dans les (páginas 164-169)