Dimethylsulfide (DMS) emissions from the ocean contribute approximately 28.1 Tg S yr −1 to the atmosphere, representing 90% of oceanic biogenic sulfur emissions and more than 50% of global biogenic sulfur emissions (Arnold et al., 2013;Lana et al., 2011). DMS is the predominant biogenic sulfur compound, and is produced through the secondary metabolism of dimethylsulfoniopropionate (DMSP) by algal cells (Stefels et al., 2007). DMS has received more interest since the CLAW hypothesis proposed that DMS emissions from the seawater and their effect on climate change are part of a feedback loop (Charlson et al., 1987). When emitted to the atmosphere, DMS is rapidly oxidized to form a variety of sulfur-containing compounds (Zhang et al., 2017). These compounds lead to the formation of aerosol particles that act as cloud condensation nuclei (CCN) in the marine boundary layer (Charlson et al., 1987;Uher et al., 2017), which can impact the global climate (Jian et al., 2017). DMSP, the primary precursor of DMS, is an essential part of the biogeochemical cycle of DMS (Keller et al., 1989). Algal cells release DMSP naturally in small amounts, but its release can be accelerated when the algal cells undergo senescence, grazing, or viral attack (Andreae Abstract The spatial distributions of dimethylsulfide (DMS), dimethylsulfoniopropionate (DMSP), and dimethylsulfoxide (DMSO) were investigated in the Yangtze River Estuary from 9 to 23 March, 2018. The average concentrations of DMS, dissolved DMSP (DMSPd), particulate DMSP (DMSPp), dissolved DMSO (DMSOd) and particulate DMSO (DMSOp) were 3.

Dimethylsulfide (DMS) is the dominant volatile biogenic sulfur compound and plays a crucial part in the global sulfur cycle and budget (Stefels et al., 2007;Jian et al., 2017). The CLAW hypothesis (Charlson et al., 1987) proposes that emissions of DMS and climate change form a negative feedback loop. Indeed, DMS oxidation products can lead to the formation of aerosol particles (Charlson et al., 1987;Quinn & Bates 2011). These DMS-derived aerosols may have a strong influence over cloud albedo, which implicates them in changes in global radiative forcing (Rap et al., 2013), and have a large potential to counteract the warming of Earth's climate system (Xu et al., 2016). Dimethylsulfoniopropionate (DMSP) is mainly synthesized by phytoplankton and plays a fundamental role in the biogeochemical cycling of the climate-trace gas DMS, for which it is the primary precursor (Keller et al., 1989). Dimethylsulfoxide (DMSO), a photooxidation and bacterial consumption product of DMS (Hatton, 2002;Toole et al., 2004;Jian et al., 2017), can also be synthesized by phytoplankton (Spiese et al., 2009). Because of its relationship with DMS, DMSO can be considered equally important to the global biogeochemical sulfur cycle (Zindler-Schlundt et al., 2015). The concentrations of biogenic sulfur compounds (BSCs) are directly related to phytoplankton species, and dinoflagellates and haptophytes are major DMSP and DMSO producers (Keller et al., 1989;Hatton & Wilson, 2007;Stefels et al., 2007;Gypens et al., 2014). Although diatoms are not major producers of BSCs, their high abundances and diversity can give them an important role in BSCs production (Keller et al., 1989). Furthermore, BSC concentrations are also affected by the pH, chemical factors, nutrient

This study investigates observed and modeled contributions of global sea surface temperature (SST) to China winter climate trends in 1960-2014, including increased precipitation, warming through about 1997, and cooling since then. Observations and Atmospheric Model Intercomparison Project (AMIP) simulations with prescribed historical SST and sea ice show that tropical Indian Ocean (TIO) warming and increasing rainfall causes diabatic heating that generates a tropospheric wave train with anticyclonic 500-hPa height anomaly centers in the TIO or equatorial western Pacific (TIWP) and northeastern Eurasia (EA) and a cyclonic anomaly over China, referred to as the TIWP-EA wave train. The cyclonic anomaly causes Indochina moisture convergence and southwesterly moist flow that enhances South China precipitation, while the northern anticyclone enhances cold surges, sometimes causing severe ice storms. AMIP simulations show a 1960-1997 China cooling trend by simulating increasing instead of decreasing Arctic 500-hPa heights that move the northern anticyclone into Siberia, but enlarge the cyclonic anomaly so it still simulates realistic China precipitation trend patterns. A separate idealized TIO SST warming simulation simulates the TIWP-EA feature more realistically with correct precipitation patterns and supports the TIWP-EA teleconnection as the primary mechanism for long-term increasing precipitation in South China since 1960. Coupled Model Intercomparison Project (CMIP) experiments simulate a reduced TIO SST warming trend and weak precipitation trends, so the TIWP-EA feature is absent and strong drying is simulated in South China for 1960-1997. These simulations highlight the need for accurately modeled SST to correctly attribute regional climate trends.

Dimethylsulfoniopropionate (DMSP) is widespread in the oceans, and its biological metabolite, dimethyl sulfide (DMS), plays an important role in the atmosphere. The Antarctic region has become a hotspot in DMS studies due to the high spatial and temporal variability in DMS(P) concentration, but the level of bacterial DMS production remains unclear. In this study, a bacterium isolated from Antarctic floating ice, Rhodococcus sp. NJ‐530, was found to metabolize DMSP into DMS, and the rate of DMS production was measured as 3.96 pmol·mg protein−1·h−1. Rhodococcus sp. NJ‐530 had a DddD‐Rh enzyme containing two CaiB domains, which belonged to the CoA‐transferase III superfamily. However, the DddD‐Rh had a molecular weight of 73.21 kDa, which was very different from previously characterized DddD enzymes in sequence and evolution. In vitro assays showed that DddD‐Rh was functional in the presence of acetyl‐CoA. This was the first functional DddD from Gram‐positive Actinobacteria. Moreover, a quantitative real‐time polymerase chain reaction revealed that high temperature facilitated the expression of dddD‐Rh, and changes of salinity had little effect on it. This study adds new evidence to the bacterial DMS production in the Southern Ocean and provides a basis for investigating the metabolic mechanism of DMSP in extreme environments.

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