Calcium Biogeochemical Cycle in a Typical Karst Forest: Evidence from Calcium Isotope Compositions
In order to better constrain calcium cycling in natural soil and in soil used for agriculture, we present the δ<sup>44/40</sup>Ca values measured in rainwater, groundwater, plants, soil, and bedrock samples from a representative karst forest in SW China. The δ<sup>44/40</sup>...
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MDPI AG
2021-05-01
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| Series: | Forests |
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| Online Access: | https://www.mdpi.com/1999-4907/12/6/666 |
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| author | Guilin Han Anton Eisenhauer Jie Zeng Man Liu |
| author_facet | Guilin Han Anton Eisenhauer Jie Zeng Man Liu |
| author_sort | Guilin Han |
| collection | DOAJ |
| description | In order to better constrain calcium cycling in natural soil and in soil used for agriculture, we present the δ<sup>44/40</sup>Ca values measured in rainwater, groundwater, plants, soil, and bedrock samples from a representative karst forest in SW China. The δ<sup>44/40</sup>Ca values are found to differ by ≈3.0‰ in the karst forest ecosystem. The Ca isotope compositions and Ca contents of groundwater, rainwater, and bedrock suggest that the Ca of groundwater primarily originates from rainwater and bedrock. The δ<sup>44/40</sup>Ca values of plants are lower than that of soils, indicating the preferential uptake of light Ca isotopes by plants. The distribution of δ<sup>44/40</sup>Ca values in the soil profiles (increasing with soil depth) suggests that the recycling of crop-litter abundant with lighter Ca isotope has potential effects on soil Ca isotope composition. The soil Mg/Ca content ratio probably reflects the preferential plant uptake of Ca over Mg and the difference in soil maturity. Light Ca isotopes are more abundant in mature soils than nutrient-depleted soils. The relative abundance in the light Ca isotope (<sup>40</sup>Ca) is in the following order: farmland > burnt grassland > forests > grassland > shrubland. Our results further indicate that biological fractionation in a soil–plant system is a vital factor for Ca–geochemical transformations in soil surface systems. |
| first_indexed | 2024-03-10T11:04:51Z |
| format | Article |
| id | doaj.art-da27095193104bdeb88a1c63705a54b2 |
| institution | Directory Open Access Journal |
| issn | 1999-4907 |
| language | English |
| last_indexed | 2024-03-10T11:04:51Z |
| publishDate | 2021-05-01 |
| publisher | MDPI AG |
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| series | Forests |
| spelling | doaj.art-da27095193104bdeb88a1c63705a54b22023-11-21T21:14:09ZengMDPI AGForests1999-49072021-05-0112666610.3390/f12060666Calcium Biogeochemical Cycle in a Typical Karst Forest: Evidence from Calcium Isotope CompositionsGuilin Han0Anton Eisenhauer1Jie Zeng2Man Liu3Institute of Earth Sciences, China University of Geosciences (Beijing), Beijing 100083, ChinaGEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel, Wischhofstr. 1-3, 24148 Kiel, GermanyInstitute of Earth Sciences, China University of Geosciences (Beijing), Beijing 100083, ChinaInstitute of Earth Sciences, China University of Geosciences (Beijing), Beijing 100083, ChinaIn order to better constrain calcium cycling in natural soil and in soil used for agriculture, we present the δ<sup>44/40</sup>Ca values measured in rainwater, groundwater, plants, soil, and bedrock samples from a representative karst forest in SW China. The δ<sup>44/40</sup>Ca values are found to differ by ≈3.0‰ in the karst forest ecosystem. The Ca isotope compositions and Ca contents of groundwater, rainwater, and bedrock suggest that the Ca of groundwater primarily originates from rainwater and bedrock. The δ<sup>44/40</sup>Ca values of plants are lower than that of soils, indicating the preferential uptake of light Ca isotopes by plants. The distribution of δ<sup>44/40</sup>Ca values in the soil profiles (increasing with soil depth) suggests that the recycling of crop-litter abundant with lighter Ca isotope has potential effects on soil Ca isotope composition. The soil Mg/Ca content ratio probably reflects the preferential plant uptake of Ca over Mg and the difference in soil maturity. Light Ca isotopes are more abundant in mature soils than nutrient-depleted soils. The relative abundance in the light Ca isotope (<sup>40</sup>Ca) is in the following order: farmland > burnt grassland > forests > grassland > shrubland. Our results further indicate that biological fractionation in a soil–plant system is a vital factor for Ca–geochemical transformations in soil surface systems.https://www.mdpi.com/1999-4907/12/6/666calcium cyclecalcium stable isotopeforest ecosystemkarstSouthwest China |
| spellingShingle | Guilin Han Anton Eisenhauer Jie Zeng Man Liu Calcium Biogeochemical Cycle in a Typical Karst Forest: Evidence from Calcium Isotope Compositions Forests calcium cycle calcium stable isotope forest ecosystem karst Southwest China |
| title | Calcium Biogeochemical Cycle in a Typical Karst Forest: Evidence from Calcium Isotope Compositions |
| title_full | Calcium Biogeochemical Cycle in a Typical Karst Forest: Evidence from Calcium Isotope Compositions |
| title_fullStr | Calcium Biogeochemical Cycle in a Typical Karst Forest: Evidence from Calcium Isotope Compositions |
| title_full_unstemmed | Calcium Biogeochemical Cycle in a Typical Karst Forest: Evidence from Calcium Isotope Compositions |
| title_short | Calcium Biogeochemical Cycle in a Typical Karst Forest: Evidence from Calcium Isotope Compositions |
| title_sort | calcium biogeochemical cycle in a typical karst forest evidence from calcium isotope compositions |
| topic | calcium cycle calcium stable isotope forest ecosystem karst Southwest China |
| url | https://www.mdpi.com/1999-4907/12/6/666 |
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