Jianfang Chen

• PhD
• Principal Investigator at Second Institute of Oceanography MNR (SIOMNR)

Productive shelf seas are often considered hotspots for absorbing atmospheric CO2. However, the contribution of biological processes to carbon source or sink remains unclear in global large river‐dominated shelf seas. As a case study, we applied a three end‐members mixing model to quantify the contribution of biological processes (including the rel...

Ammonium concentrations in marine environments are typically found at the nanomolar level, and due to the transformation tendencies of ammonium species, there is a growing demand for a simple, convenient, and highly sensitive automated method for seawater ammonium quantification. Such a method should be suitable for in situ applications without the...

The Kuroshio, the North Pacific Ocean's most robust western boundary current, brings a rich infusion of nutrients (especially phosphate) and warm‐water species into the East China Sea (ECS), profoundly shaping its environmental conditions and ecological processes. However, the precise impact of Kuroshio intrusion on the composition and distribution...

The on-going global warming is causing rapid changes in the carbon cycle of the Arctic. Yet the response of the Arctic to these environmental changes are not fully understood. In this study, we investigate bulk organic parameters (TOC, TN, δ13Corg, δ15N, C/N) and terrestrial n-alkanes (TERR-alkanes) from 19 surface sediments and 5 210Pb-dated sedim...

The concentrations and distributions of particulate biogenic silica (PBSi) and its size-fractionated composition (>20 μm, 0.8–20 μm) of the Changjiang Estuary and its adjacent area were investigated during the summer of 2011. PBSi, primarily produced by diatoms in the surface waters of oceans, was examined for correlations with hydrographic conditi...

The Canada Basin is the largest basin in the Arctic Ocean. Its unique physical features have the highest concentration of nutrients being found in the subsurface layer, referred to as the subsurface nutrient maximum layer (SNM). Under climate change in the Arctic, the SNM is an essential material base for primary productivity. However, long-term tr...

Remote sensing observations reveal strong differences in winter cross-shore movements of the outer salinity fronts between the midfield and far-field regions outside China’s Changjiang River plume. However, the characteristics, mechanisms, and associated water exchanges of these outer fronts remain unclear. Based on 7-yr buoy salinity observations...

The Arctic Ocean has experienced significant sea ice loss over recent decades, shifting towards a thinner and more mobile seasonal ice regime. However, the impacts of these transformations on the upper ocean dynamics of the biologically productive Pacific Arctic continental shelves remain underexplored. Here, we quantified the summer upper mixed la...

Under the steadily intensifying human activities in coastal areas, it is crucial to distinguish the sources of organic matter (OM) in sediments for better understanding of the environmental change. In this study, 25 surface sediments collected along the harbor and creeks areas off Karachi coast were used for total organic carbon (TOC), total nitrog...

In this study, we reconstruct three-century of sea ice cover history in the Chukchi Sea from the downcore profile of total organic carbon (TOC) and biomarker proxies, namely the Ice Proxy with 25 carbon atoms (IP25), the di- and tri-unsaturated highly branched isoprenoid (HBI II and HBI III) and two phytosterols (brassicasterol and dinosterol) in t...

The degradation of coastal seawater quality off the Changjiang Estuary and adjacent waters is typically associated with monsoon wind, ocean currents and inputs of terrestrial pollutants. In addition to these factors, the passage of typhoons can be also important in driving short-term fluctuations in coastal water quality. Using a coupled Regional O...

Eutrophication caused by inputs of excess nitrogen (N) has become a serious environmental problem in Hangzhou Bay (China), but the sources of this nitrogen are not well understood. In this study, the August 2019 distributions of salinity, nutrients [nitrate (NO −3 ), nitrite, ammonium, and phosphate], and the stable isotopic composition of NO −3 (δ...

The international and interdisciplinary sea-ice drift expedition “The Multidisciplinary drifting Observatory for the Study of Arctic Climate” (MOSAiC) was conducted from October 2019 to September 2020. The aim of MOSAiC was to study the interconnected physical, chemical, and biological characteristics and processes from the atmosphere to the deep s...

This study investigated the distribution of sedimentary phosphorus (P) species along an area of a rapid current at the southern coast of Zhoushan Island. The objective of this study was to improve the understanding of P cycling in a zone of rapid water cycling. Results showed that the average percentage of each P form to total P (TP) was in the fol...

The frequency of riverine floods is predicted to increase in East Asia. However, the response of coastal hypoxia (<63 μmol L⁻¹) to floods has not been well understood. In the summer of 2020, characterized by one of the most significant Changjiang water fluxes in three decades, we conducted a cruise during the flood period on the East China Sea inne...

Seamounts are ecological oases nurturing abundant fisheries resources and epibenthic megafauna in the vast oligotrophic ocean. Despite their significance, the formation mechanisms underlying these seamount ecological oases remain uncertain. To shed light on this phenomenon, this study conducted interdisciplinary in situ observations focusing on a s...

A sediment core (YJK19-02) collected from the southern outlet of Hangzhou Bay near the Yongjiang River estuary in East China was analyzed for grain size, lignin, bulk elemental composition, stable carbon isotope, and rare earth elements (REEs) to determine the sources and diagenesis of sedimentary organic matter (OM) of the estuary and adjacent are...

Arctic and Caribbean phytoplankton distribution

A facile strategy to construct superhydrophobic coatings was carried out by one‐pot process using novel nano zero‐valent iron and hydrogen peroxide as trigger in ethanol and Tris buffer mixed system containing dopamine and 1H,1H,2H,2H‐perfluorodecanethiol (PFDT) for the first time. The polydopamine (PDA) modified by PFDT composite coating can be de...

As major sites of carbon burial and remineralization, continental margins are key components of the global carbon cycle. However, heterogeneous sources of organic matter (OM) and depositional environments lead to complex spatial patterns in sedimentary organic carbon (OC) content and composition. To better constrain the processes that control OM cy...

In the context of global warming and rapid environment change in the Arctic, the supply of organic matter (OM) has increased significantly and a large amount of OM are buried on the Arctic shelf. Studying the fate of OM in Arctic shelf sediments is crucial to understanding the global carbon sink. As a marginal sea of the Arctic Ocean, the Chukchi S...

Both human activities and climate change influence benthic macroinvertebrates in the Changjiang Estuary. We investigated long-term variations in benthic macroinvertebrates and related them to changes in depth, salinity, temperature, pH, and dissolved oxygen in bottom water off the Changjiang Estuary from 10 summer cruises during 2006–2021. The bi-m...

Land-ocean interactions greatly impact the evolution of coastal life on Earth. However, the ancient geological forces and genetic mechanisms that shaped evolutionary adaptations and allowed microorganisms to inhabit coastal brackish waters remain largely unexplored. Here, we infer the evolutionary trajectory of the ubiquitous heterotrophic archaea...

The drastic decline of Arctic sea ice due to global warming and polar amplification of environmental changes in the Arctic basin profoundly alter primary production with consequences for polar ecosystems and the carbon cycle. In this study, we use highly branched isoprenoids (HBIs), brassicasterol, dinosterol and terrestrial biomarkers (n-alkanes a...

Coastal estuaries are often heavily subject to riverine influences by the inputs of sediment from terrestrial sources. Hangzhou Bay (HZB) is threatened by the riverine derived trace metals from two large rivers of Qiantang River (QTR) and Yangtze River (YZR). However, previous studies mainly focused on the incidental transport from the largest rive...

Potassium isotopes are a novel tracer for continental weathering. Previous K isotope studies on chemical weathering generally targeted weathering profiles under a particular climate region, yet the effects of chemical weathering on K isotopes under different climatic backgrounds remain unclear. Moreover, little is known about the K isotope signatur...

Diatoms and biogenic silica (biogenic Si) in sediments are commonly analyzed as paleoceanographic environmental indicators. However, the correspondence between these sedimentary components and their counterparts in the water column above can vary over time and space. This study, undertaken in the northern South China Sea, compares diatoms and bioge...

Biological carbon pump (BCP) inefficiency was first observed in the South China Sea (SCS) throughout the 1997–1999 El Niño Southern Oscillation (ENSO) event, but the BCP usually recovers its efficiency when the climate conditions change from El Niño to La Niña conditions in the Pacific Ocean. Enhanced stratification and Kuroshio intrusion led to we...

An international and interdisciplinary sea ice drift expedition, the ‘The Multidisciplinary drifting Observatory for the Study of Arctic Climate‘ (MOSAiC), was conducted from October 2019 to September 2020. The aim of MOSAiC was to study the interconnected physical, chemical and biological characteristics and processes from the atmosphere to the de...

The subsurface layer of the Canada Basin contains large reservoirs of dissolved inorganic nitrogen and carbon (DIN and DIC, respectively). Under rapid change of Arctic climate system, these reservoirs may not only serve as potential material bases for primary production, but also for carbon source and sink. However, the long‐term trends in reservoi...

Marine environments wherein long-term microbial oxygen consumption exceeds oxygen replenishment can be associated with oxygen minimum zones (OMZ). The Bay of Bengal OMZ (BOB-OMZ) is one of the most intense OMZs globally. To assess the contribution of bacterial oxygen consumption to oxygen loss in BOB-OMZ, we measured bacterial production (BP), temp...

Time-series samples intercepted via three synchronized moored sediment traps, deployed at 1000 m, 2150 m, and 3200 m in the northern South China Sea (NSCS) during June 2009–May 2010, were analyzed to quantify the bioactive trace metal fluxes in sinking particles and investigate their different source contributions. Iron (Fe) primarily originated fr...

Hypoxia has long been a symptom of deteriorating ecosystem that threatens the health of estuarine and coastal waters. Episodic hypoxia events and intraseasonal variation of coastal hypoxia have been amply investigated. However, interannual variability of coastal hypoxia has only been assessed in few regions. Bottom hypoxia forms seasonally off the...

Ammonia-oxidizing archaea (AOA) are ubiquitously found in diverse habitats and play pivotal roles in the nitrogen and carbon cycle, especially in estuarine and coastal environments. Despite the fact that the diversity and distribution of AOA are thought to be tightly linked to habitats, little is known about the relationship that underpins their ge...

Accurately assessing the capacity of the modern ocean to photosynthetically fix and sequester atmospheric CO2, termed the biological carbon pump (BCP), is a key component in studies on the marine carbon cycle and the global climate system. Particulate organic carbon (POC) flux into the ocean interior is an important indicator of the BCP strength, a...

Accurately assessing the capacity of the modern ocean to photosynthetically fix and sequester atmospheric CO 2 , termed the biological carbon pump (BCP), is a key component in studies on the marine carbon cycle and the global climate system. Particulate organic carbon (POC) flux into the ocean interior is an important indicator of the BCP strength,...

The drastic decline of Arctic sea ice due to global warming and polar amplification of environmental changes in the Arctic basin profoundly alter primary production with consequences for polar ecosystems and the carbon cycle. In this study, we use highly branched isoprenoids (HBIs), brassicasterol, dinosterol and terrestrial biomarkers (n-alkanes a...

Decreasing sea ice extent caused by climate change is affecting the carbon cycle of the Arctic Ocean. In this study, surface sediments across the western Arctic Ocean are investigated to characterize sources of sedimentary organic carbon (OC). Bulk organic parameters (total organic carbon, total nitrogen, δ13Corg, and δ15N) and molecular organic bi...

Spatial variability of ammonium concentrations along repeat transects were examined on the Chukchi shelf during 2012-2018. Two distinct near-bottom high ammonium pools (>1 μmol/kg) near 67.5°N and 72.5°N of the transects were identified in all years. The accumulation of ammonium in the regions is driven primarily by a combination of biogeochemical...

Huge amount of trace metals emitted through manmade activities are carried by the Changjiang River into the East China Sea. Most of them deposit in the Changjiang River Estuary and threaten the regional aquatic environment. In this study, major and trace elements of 34 archive surface sediments and two cores are examined. Sequential extraction proc...

Recent evidence has shown active N2 fixation in coastal eutrophic waters, yet the rate and controlling factors remain poorly understood, particularly in large estuaries. The Changjiang Estuary (CE) and adjacent shelf are characterized by fresh, nitrogen-replete Changjiang Diluted Water (CDW) and saline, nitrogen-depletion intruded Kuroshio water (T...

Estuaries are crucial components of the global ocean carbon cycle due to their high productivity. However, our understanding of the carbon source-sink dynamics at the air-sea interface of estuaries is incomplete, largely due to the rapidly changing environmental conditions. To address this, we conducted a study in early autumn 2016 using high-resol...

The western boundary currents are characterized by abundant diazotrophs including Trichodesmium, which may fuel N2 fixation when they intrude into marginal seas. The Kuroshio, a western boundary current in the North Pacific, flows into the East China Sea (ECS) and southern Yellow Sea (SYS), which transports abundant Trichodesmium and diatom‐diazotr...

Nitrate is the main form of dissolved inorganic nitrogen, playing an important role in both marine biogeochemical research and water environment management. In this work, the most commonly used coppered cadmium column was modified and a novel on-line Cu/Cd column with a spiral structure coupled with a de-bubbling device and syringe-type filter was...

It remains unclear how the suspended non-fed bivalve mariculture will alter the coastal transfer and cleaning process of trace elements, the non-degradable contaminants, which have been reported to accumulate in sediment from bivalve mariculture areas. Herein, we set up a field in situ comparative test in the suspended oyster (Crassostrea plicatula...

Flood events significantly increase water discharges and terrigenous material inputs to coastal waters. Riverine nutrients in the Changjiang Estuary are transported by the dispersion of Changjiang Diluted Water (CDW) plumes and detached low-salinity water patches. However, the effects of flooding on nutrient offshore transports have not been well e...

Wind mixing is important in regulating dissolved oxygen (DO) variability; however, the transect response of DO dynamics to wind disturbance has seldom been documented with field data. In the summer of 2017, repeat transect observations off the Changjiang Estuary were conducted throughout a fresh wind (the maximum wind speed was 9.8 m s–1) event to...

Here, we report the results of high-resolution nitrate measurements using an optical nitrate profiler (in situ ultraviolet spectrophotometer, ISUS) along transect across a high-turbidity shelf (East China Sea) and a low-turbidity shelf (Chukchi Sea). The ISUS-measured nitrate concentrations closely reproduced the results measured by conventional bo...

Decreasing sea ice extent in summer caused by climate change is affecting the carbon cycle of the Arctic Ocean. In this study, surface sediments across the western Arctic Ocean are investigated to characterize sources of sedimentary organic carbon (OC). Bulk organic parameters (total organic carbon, total nitrogen, δ13Corg and δ15N) combined with m...

This study investigates the relationship between macrobenthic functional group composition and hypoxia in the Changjiang River estuary and its adjacent sea areas. A total of 82 stations were divided into three areas, named non-hypoxic area, hypoxic area and the Changjiang River, respectively. A total of 256 macrobenthic species were collected, whic...

The summer hypoxia off the Changjiang Estuary is one of the largest coastal hypoxic systems in the world and has displayed spatial heterogeneity in recent years. Based on observation data in the summer of 2014, hypoxia was identified both in the bottom and mid-layers. Except for the typical bottom hypoxia in the submarine canyon, the subsurface oxy...

The dissolved organic matter (DOM) in the ocean is a large carbon pool that plays an important role in the global carbon cycle. Investigation of the characteristics and behaviors of DOM in some areas facilitates a better understanding of biochemical processes in the water column. In February 2020, water samples were collected to characterize the di...

Plain Language Summary The trend of sea surface temperature (SST) is used as a climate change indicator over global areas. The recent temperature trend in the Kuroshio can be separated into three stages, namely, the cooling period (1982–1998), the warming period (1999–2014) and the rapid warming period (2014‐present). However, the SST trend in the...

To explore the ecological risks of trace metals in sediments and their relationship with benthic organisms, 12 trace metals were analyzed and the macrobenthos were identified in the sediments collected from the south coast of Zhejiang province which belongs to the East China Sea. Spatially, the concentrations of most trace metals were high in the e...

Dissolved oxygen (DO) is essential for the survival of most aquatic organisms. Hypoxia, defined as a DO concentration of less than 2 mg L–1, is a significant issue for ecosystems in estuaries and coastal waters and is one of the top themes of the United Nations Decade of Ocean Science for Sustainable Development (2021–2030). An area off the Yangtze...

Time-series samples intercepted via three synchronized moored sediment traps, deployed at 1000 m, 2150 m, and 3200 m in the northern South China Sea (NSCS) during were analyzed to quantify the bioactive trace metal fluxes in sinking particles and investigate their different source contributions. Iron (Fe) primarily originated from lithogenic source...

Water quality in Hangzhou Bay is inferior (grade 5) because of discharged from Yangtze River and Qiantang River, and from factories around the bay. This study analyzed relationships between the environment and macrobenthic communities at 44 stations throughout Hangzhou Bay, based on samples collected in 2006, from 2016–2018, and in 2021. Long-term...

The Arctic Ocean has experienced rapid warming and sea ice loss in recent decades, becoming the first open-ocean basin to experience widespread aragonite undersaturation [saturation state of aragonite (W arag) < 1]. However, its trend toward long-term ocean acidification and the underlying mechanisms remain undocumented. Here, we report rapid acidi...

The rise of microbial species is associated with multiple genetic changes and niche reconstruction. While recombination, lateral gene transfer and point mutations can contribute to microbial speciation, acquisition of niche-specific genes was found to play an important role in initiating ecological specialization followed by genome-wide mutations....

In this study, the sedimentary archaeal community composition and abundance were detailed revealed and quantified based on 16S rRNA genes off the Changjiang River Estuary. We found that the community composition was distinct between hypoxia and non-hypoxia regions, while Thaumarchaeota and Bathyarchaeota dominated in non-hypoxia and hypoxia samples...

Lateral particle transport in shelf/slope settings of marginal sea systems may potentially supply allochthonous particulate organic carbon (POC) to the ocean interior. The magnitude and prevalence of such processes has implications for our understanding of the functioning and efficiency of modern biological carbon pump processes, as well as for int...

Plain Language Summary The availability of nutrients in the sunlit layer is the main factor limiting microalgae growth, which is the primary producer of marine ecosystems. Particularly in the tropical oceans, strong stratification due to warm and less salty surface water inhibits nutrient replenishment from the deep layer, leading to weak seasonali...

The dissolved silicate concentrations in the supernatant of sediment trap sampling bottles retrieved from deep water (1000-3000 m) at four stations in the South China Sea (SCS) were measured to calculate the underestimated flux of biogenic silica (bSi) in sinking particles due to bSi dissolution. High dissolved silicate concentrations in the supern...

The dissolved silicate concentrations in the supernatant of sediment trap sampling bottles retrieved from deep water (1000-3000 m) at four stations in the South China Sea (SCS) were measured to calculate the underestimated flux of biogenic silica (bSi) in sinking particles due to bSi dissolution. High dissolved silicate concentrations in the supern...