Organic carbon sequestration in sediments of subtropical Florida lakes.

Dafeng Hui,Mark Brenner,Matthew N Waters,William F Kenney,Benjamin C Webster

doi:10.1371/journal.pone.0226273

Dafeng Hui, Mark Brenner + Show 3 more

Open Access

https://doi.org/10.1371/journal.pone.0226273

Copy DOI

Journal: PloS one	Publication Date: Dec 13, 2019
Citations: 9	License type: CC BY 4.0

Affiliation: University of Florida, Auburn University

Abstract

Recent studies have shown that sediments of temperate and tropical lakes are sinks for organic carbon (OC), but little is known about OC burial in subtropical lakes. There are questions regarding the ability of subtropical lakes to store OC, given their relatively warmwater temperatures, lack of ice cover, frequent water-column mixing, and labile carbon forms. We used 210Pb-dated sediment cores from 11 shallow Florida (USA) lakes to estimate OC burial, i.e. net OC storage, over the last ~100 years. Shallow Florida water bodies average ~30% OC content in their sediments and displayed rates of net OC accumulation (63–177 g C m-2 a-1) that are similar to natural temperate lakes, but lower than temperate agricultural impoundments. We considered the influence of lake morphometry on OC storage in our study lakes, but did not observe an inverse relationship between lake size and OC burial rate, as has been seen in some temperate lake districts. We did, however, find an inverse relation between mean water depth and OC sequestration. Despite recent cultural eutrophication and the associated shift from macrophyte to phytoplankton dominance in the Florida study lakes, overall OC burial rate increased relative to historic (pre-1950 AD) values. Lakes cover >9000 km2 of the Florida landscape, suggesting that OC burial in sediments amounts to as much as 1.6 Mt a-1. The high rate of OC burial in Florida lake sediments indicates that subtropical lakes are important for carbon sequestration and should be included in models of global carbon cycling.

Highlights

As evidence for recent anthropogenic climate change has grown, there has been increasing interest in carbon cycling in the biosphere
Inland waters were once viewed as shortterm organic carbon (OC) storage areas or simple conduits for transport of terrestrial carbon to the coasts, their perceived role in carbon cycling has expanded, and they are viewed as complex aquatic ecosystems that receive, transport, process and store both allochthonous and autochthonous carbon [1]
OC burial rate did not decrease with increasing lake size (Fig 2), unlike the relationship reported for temperate water bodies [5, 6]

Summary

Introduction

As evidence for recent anthropogenic climate change has grown, there has been increasing interest in carbon cycling in the biosphere. Inland waters were once viewed as shortterm organic carbon (OC) storage areas or simple conduits for transport of terrestrial carbon to the coasts, their perceived role in carbon cycling has expanded, and they are viewed as complex aquatic ecosystems that receive, transport, process and store both allochthonous and autochthonous carbon [1]. Organic carbon sequestration in sediments of subtropical Florida lakes sediments [2]. Lake sediments that accumulate organic matter are effective long-term sinks for carbon [3], and annual OC burial in lakes and reservoirs worldwide exceeds OC sequestration in ocean sediments [4]. OC burial in lakes increases in response to human-induced eutrophication [5]. OC burial may be orders of magnitude greater than burial in natural inland waters [6]

Methods

Results

Discussion

Conclusion