Aeolian Particulate Matter as a Source of Bioavailable P to Sierra Nevada Soil
Abstract
Global environmental change models state that temperate ecosystems will serve as a carbon (C) sink as atmospheric carbon dioxide concentration continues to increase. However, any realized increased in C storage will also require increases in the availabilities of key nutrients, such as nitrogen (N) and phosphorus (P). Recent studies have suggested that aeolian particulate matter (PM) provides an important source of P, especially in areas with low bedrock nutrient concentration or slow weathering rates. We used multiple characterization approaches to provide mechanistic understanding of P biogeochemistry in soil and aeolian PM samples along an elevational gradient in the Sierra Nevada (low P-containing granitic parent material) - including using ICP-OES, 31P nuclear magnetic resonance spectroscopy (NMR), and X-ray absorption near edge structure (XANES) spectroscopy. Overall, aeolian PM P concentration at the high elevation site (66 µmol/g; 80-100% organic P [Po]) was dominated by extracted Po species including myo-inositol phosphate (i.e., phytate), DNA, and phospholipids as identified by NMR. The low elevation site (39 μmol/g; 30-60% Po) was comprised primarily of the Pi species Ca-phosphate solids and adsorbed Al-PO4 and Fe-PO4 based on XANES analysis. Soil P concentrations were less than the high elevation aeolian PM input at all sites in A, B, and C horizons. Specifically, the high elevation soil was 9 μmol/g (24% Po) and low elevation was 21 μmol/g (<10% Po) within the A horizons. Phytate was found in the soil at all sites; however, the fraction of DNA and phospholipids increased with elevation. Both high and low elevation soils were composed primarily of Ca-phosphates or sorbed Pi species. Our results establish that aeolian PM P concentration is up to 6 times greater than soil P and is composed of species with potentially high rates of P cycling. With expected increases in aeolian PM fluxes as the climate warms and land-use intensifies, aeolian PM may be a critical nutrient input allowing temperate ecosystems to continue to serve as a C sink.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B12B..03B
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0470 Nutrients and nutrient cycling;
- BIOGEOSCIENCES;
- 1622 Earth system modeling;
- GLOBAL CHANGE