Factors affecting distribution patterns of organic carbon in sediments at regional and national scales in China

Qingqing Cao,Rattan Lal,Yiran Zhang,Xiuli Ge,Renqing Wang,Hui Wang,Jian Liu

doi:10.1038/s41598-017-06035-z

Abstract

Wetlands are an important carbon reservoir pool in terrestrial ecosystems. Light fraction organic carbon (LFOC), heavy fraction organic carbon (HFOC), and dissolved organic carbon (DOC) were fractionated in sediment samples from the four wetlands (ZR: Zhaoniu River; ZRCW: Zhaoniu River Constructed Wetland; XR: Xinxue River; XRCW: Xinxue River Constructed Wetland). Organic carbon (OC) from rivers and coasts of China were retrieved and statistically analyzed. At regional scale, HFOC stably dominates the deposition of OC (95.4%), whereas DOC and LFOC in ZR is significantly higher than in ZRCW. Concentration of DOC is significantly higher in XRCW (30.37 mg/l) than that in XR (13.59 mg/l). DOC and HFOC notably distinguish between two sampling campaigns, and the deposition of carbon fractions are limited by low nitrogen input. At the national scale, OC attains the maximum of 2.29% at precipitation of 800 mm. OC has no significant difference among the three climate zones but significantly higher in river sediments than in coasts. Coastal OC increases from Bohai Sea (0.52%) to South Sea (0.70%) with a decrease in latitude. This study summarizes the factors affecting organic carbon storage in regional and national scale, and have constructive implications for carbon assessment, modelling, and management.

Highlights

Increasing in atmospheric concentration of carbon dioxide (CO2) and methane (CH4) since mid-20th century[1] causes the global warming[2]
Neither Total organic carbon (TOC) nor heavy fraction organic carbon (HFOC) exhibited any significant differences among two study zones (Fig. 1), two wetland types or the four wetlands in Shandong Province of China (Fig. 1; Table 1)
Cluster analysis of Light fraction organic carbon (LFOC) showed that XR and XRCW had similar LFOC clustering

Summary

Introduction

Increasing in atmospheric concentration of carbon dioxide (CO2) and methane (CH4) since mid-20th century[1] causes the global warming[2]. The principal objectives of this study were to: 1) Assessing the distribution difference of three C fractions in two wetland types, two sampling campaigns, and among the sampling stations, 2) Evaluating the distribution of OC at the national scale, and, 3) Determining the relevant factors (precipitation, nitrogen content, microbes, etc.) affecting the distribution and storage of OC in wetland ecosystems. These objectives are realized by testing the hypothesis that sampling season and wetland types can significantly affect the storage of C fractions at regional scale, and OC is affected by precipitations and climatic zones at large scale

Objectives

Methods

Results

Conclusion