A persistent increase in primary productivity east off Hainan Island (northwestern South China Sea) over the last decades as inferred from sediment records

Liu, Mingyang; Li, Chao; Zhang, Fang; Zhang, Run; Yang, Weifeng; Chen, Min; Zheng, Minfang; Qiu, Yusheng

A persistent increase in primary productivity east off Hainan Island (northwestern South China Sea) over the last decades as inferred from sediment records

2020

Sediment cores were analyzed from the continental shelf of the northwestern South China Sea aiming to understand the change history of primary productivity and provide insights into key changes of environmental conditions in this region over the past ~100 years. Multiple proxies including stable carbon isotopic composition (δ¹³C) of sedimentary organic matter, diatom abundance and biogenic silica burial flux were applied along with ²¹⁰Pb chronology. Notably, these independent evidences consistently point to a steady increase of primary production in this region only after ~1960s. We propose that increasing atmospheric deposition due to dramatically enhanced human activities especially from China supplies essential nitrogen nutrients to the N-poor region and probably acts a major reason for the observed enhancement of marine primary production. Our study provides insights into better understanding how human perturbation may have profoundly impacted biogeochemical cycling in marginal seas in the last decades.

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