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- Title
Effects of Phytoplankton on the Production and Emission of Estuarine Dimethyl Sulfide Under Different Nutrient Inputs From Changjiang River.
- Authors
Xu, Feng; Zhang, Hong‐Hai; Jia, Teng; Yan, Shi‐Bo; Wu, Jin‐Wei; Liu, Chun‐Ying; Yang, Gui‐Peng
- Abstract
Continuous input from the Changjiang River significantly reshuffled the ecosystems in the Changjiang Estuary and adjacent East China Sea, impacting the production, distribution, and emission of marine dimethyl sulfide (DMS). However, the effect of phytoplankton biomass and composition on DMS under different nutrient inputs remains poorly understood. Two comprehensive cruises to characterize their effects were conducted in spring and summer 2015. The areas with high concentrations of DMS, dimethylsulfoniopropionate (precursor of DMS), and dimethyl sulfoxide (photo‐oxidation product of DMS) were largely consistent with high phytoplankton abundances along the front of Changjiang Diluted Water in both seasons. Both the higher conversion ratio of dissolved dimethylsulfoniopropionate to DMS and the higher DMS biological production rate in summer contributed to the higher DMS levels. Once produced in seawater, more than half of the DMS was directly consumed by microbes, resulting in a turnover time of 1–2 days, which was shorter than that driven by ventilation. A ship‐based incubation experiment revealed that, with increasing N/Si and N/P ratios from the Changjiang River, phytoplankton biomass increased and the community shifted from diatom‐dominated to dinoflagellate‐dominated, which was conducive to DMS production. It was noteworthy that strong DMS photo‐degradation induced by high nitrate concentrations may have masked DMS production to some extent, while urea only had a promoting effect and therefore led to a maximum increase in DMS yield. Our findings indicated that the increase in phytoplankton biomass and succession of phytoplankton community induced by changes in nutrient inputs will promote DMS emissions from the Changjiang Estuary. Plain Language Summary: The Changjiang River is the third‐longest river in the world. It persistently discharges a large number of terrestrial materials into the Changjiang Estuary and adjacent seas and therefore results in a major reshuffling of marine ecosystems, inevitably affecting the production, distribution, and emission of marine dimethyl sulfide (DMS). DMS is the largest biogenic sulfur source for the atmosphere and plays a critical role in climate feedback. Therefore, a systematic investigation was conducted in relevant waters to study the effects of different nutrient inputs from the Changjiang River on the production and emission of estuarine DMS. Abundant nutrients imported from the Changjiang Diluted Water have promoted phytoplankton growth and subsequent DMS production. Besides, with the increasing ratios of N/Si and N/P in nutrients, the community succession shifting from diatoms (inefficient producer of DMS) to dinoflagellates (prolific producers of DMS) have further enhanced DMS production. It was noteworthy that strong DMS photo‐degradation induced by high nitrate concentration may mask DMS production to some extent, while urea only has a promoting effect and therefore led to a maximum increase in DMS yield. The resulting increases in DMS concentrations will promote DMS emissions and consequently play a non‐negligible role in regional climate regulation. Key Points: Frequent algal blooms led to drastic fluctuations in the concentrations and sea‐to‐air fluxes of dimethyl sulfideIncreasing trends of nutrient loads from the Changjiang River will enhance estuarine dimethyl sulfide productionIn seawater, urea caused larger increases in the concentrations of dimethyl sulfide than nitrate
- Subjects
DIMETHYL sulfide; BIOLOGICAL productivity; PHYTOPLANKTON; CLIMATE feedbacks; ALGAL blooms; DIMETHYL sulfoxide
- Publication
Journal of Geophysical Research. Oceans, 2022, Vol 127, Issue 4, p1
- ISSN
2169-9275
- Publication type
Article
- DOI
10.1029/2021JC017983