Huixiang Xie

Université du Québec à Rimouski UQAR | uqar · Institut des Sciences de la Mer de Rimouski (ISMER)

We report the first water‐column dissolved methane data set from the Estuary and Gulf of St. Lawrence (EGSL). Per surface‐water methane concentration and sea‐to‐air flux, the upper estuary behaved like a typical shallow macrotidal estuary, while the lower estuary and the gulf resembled outer shelf seas and ocean slopes, respectively. The EGSL emitt...

Photodissolution has the potential to efficiently remove microplastics from the surface ocean. Here, we examined the effects of temperature and incident sunlight composition on the photodissolution of submillimeter-sized microplastics of polypropylene (PP), polystyrene (PS), and thermoplastic polyurethane (TPU) in seawater. The photoproduction of d...

We report a high-spatial-resolution study on the distributions, characteristics, and environmental risks of microplastics in surface sediments of the southern East China Sea. Microplastics were omnipresent in the sediments (concentration range: 53.3–246.7; mean: 138.4 particles/kg dry-weight sediment) and enriched in nearshore areas close to urban...

Phytoplankton blooms can be an important source of autochthonous chromophoric dissolved organic matter (CDOM) in surface oceans. Here we report the first detection and optical characterization of CDOM produced during a Dictyocha fibula bloom occurring in the western central Bohai Sea in mid-summer 2019. The mean CDOM absorption coefficient at 330 n...

We investigated the bio- and photo-lability of dissolved organic matter (DOM) from the head, mixing zone, and mouth of the Pearl River estuary. At all three sites, bio- and photo-refractory dissolved organic carbon (DOC) and biorefractory chromophoric DOM (CDOM) dominated over the corresponding bio- and photo-labile constituents, while photolabile...

The MALINA oceanographic campaign was conducted during summer 2009 to investigate the carbon stocks and the processes controlling the carbon fluxes in the Mackenzie River estuary and the Beaufort Sea. During the campaign, an extensive suite of physical, chemical and biological variables were measured across seven shelf–basin transects (south–north)...

Near-shore environments are a significant source of atmospheric methane but the size of this source is poorly constrained, particularly for fjords and fjards. This study investigated the methane emission rates and the drivers controlling the dynamics of dissolved methane in the Saguenay Fjord, a deep, stratified, and well‑oxygenated subarctic fjord...

The MALINA oceanographic campaign was conducted during summer 2009 to investigate the carbon stocks and the processes controlling the carbon Fluxes in the Mackenzie River estuary and the Beaufort Sea. During the campaign, an extensive suite of physical, chemical and biological variables was measured across seven shelf–basin transects (south-north)...

Although methanogenesis is considered a strictly anaerobic process, oxygen‐replete surface open‐ocean waters are usually supersaturated with methane (CH4 ), a phenomenon termed the oceanic methane paradox. Here, we report that abiotic methane photoproduction from chromophoric dissolved organic matter (CDOM) significantly contributes to this paradox....

Increasing attention has recently been drawn to oxygen depletion and ocean acidification in coastal seas and their impacts on the marine ecosystem. Intensive organic matter degradation combined with weak water exchange is considered to be mainly responsible for bottom water oxygen depletion and acidification. Hypoxia and acidification in the bottom...

Carbonyl sulfide (OCS) and carbon disulfide (CS2) are volatile sulfur gases that are naturally formed in seawater and exchanged with the atmosphere. OCS is the most abundant sulfur gas in the atmosphere, and CS2 is its most important precursor. They have attracted increased interest due to their direct (OCS) or indirect (CS2 via oxidation to OCS) c...

Plain Language Summary The production, consumption, and transformation of dissolved organic matter (DOM) in the ocean play a key role in climate change, since the oceanic DOM stock in terms of carbon is similar to the amount of atmospheric CO2. The majority of oceanic DOM is contained in the deep ocean and resists bacterial degradation, which allow...

Carbonyl sulfide (OCS) and carbon disulfide (CS2) are volatile sulfur gases that are naturally formed in seawater and exchanged with the atmosphere. OCS is the most abundant sulfur gas in the atmosphere, and CS2 is its most important precursor. They have gained interest due to their direct (OCS) or indirect (CS2 via oxidation to OCS) contribution t...

Nanoplastics (<1 μm plastics debris) pollution, derived from degradation of larger plastic debris or direct release from cosmetic or cleaning products, becomes an emerging concern in the environment. In this study, we quantitatively investigated the degradation and mineralization of polystyrene (PS) nanoplastics under ultraviolet (UV) radiation at...

Dissolved organic carbon (DOC) concentration in the Pearl River estuary (PRE) of China was measured in May, August, and October 2015 and January 2016. Chromophoric and fluorescent dissolved organic matter (CDOM and FDOM) in the latter three seasons were characterized by absorption and fluorescence spectroscopy. CDOM and FDOM exhibited negligible se...

Chromophoric dissolved organic matter (CDOM) is highly enriched in bottom sea ice in the Arctic during ice algal blooms, giving rise to multifaceted ecological implications in both the sea ice and the underlying seawater. We conducted laboratory culture incubations to assess the potential role of ice algae in the accumulation of CDOM in Arctic sea...

Dissolved organic carbon concentration in the Pearl River estuary (PRE) of China was measured in May, August, and October 2015 and January 2016. Chromophoric and fluorescent dissolved organic matter (CDOM and FDOM) in the latter three seasons were characterized by absorption and fluorescence spectroscopy. Parallel factor analysis of the fluorescenc...

Groundwater is a potentially significant source of dissolved organic matter (DOM) to coastal oceans where it is subject to photochemical transformation and thus possibly influences major marine biogeochemical processes. Furthermore, groundwater DOM usually receives little prior light exposure, making it suitable for probing the photoreactivity of s...

The kinetics and temperature-, pH- and salinity-dependences of photobleaching of chromophoric dissolved organic matter (CDOM) in the Yangtze River estuary (YRE) were evaluated using laboratory solar-simulated irradiations and compared to those of Suwannee River humic substances (SRHS). Nearly all CDOM in water at the head of the estuary (headwater...

Exposure of dissolved organic matter (DOM) to irradiation leads to the losses of absorbance (photobleaching) and carbon (photomineralization), thereby impacting the optics and carbon cycle in aquatic environments. In this study, the apparent quantum yields (AQY) of DOM photodegradation in the Changjiang River Estuary and its adjacent sea was invest...

Rates and apparent quantum yields of photomineralization (AQYDOC) and photomethanification (AQYCH4) of chromophoric dissolved organic matter (CDOM) in Saguenay River surface water were determined at three widely differing dissolved oxygen concentrations ([O2]) (suboxic, air saturation, and oxygenated) using simulated-solar radiation. Photomineraliz...

Full-spectrum and visible broadband apparent quantum yields (AQYs) for carbon monoxide (CO) photoproduction from chromophoric dissolved organic matter (CDOM) and particulate organic matter (POM) were determined in the Delaware Estuary in two hydrologically contrasting seasons in 2012, an unusually low flow in August and a storm-driven high flow in...

Rates and apparent quantum yields of photomineralization (AQYDOC) and photomethanification (AQYCH4) of chromophoric dissolved organic matter (CDOM) in Saguenay River surface water were determined at three widely differing dissolved oxygen concentrations ([O2]) (suboxic, air-saturation, and oxygenated) using simulated-solar radiation. Photomineraliz...

Old Harry : première extraction... de données scientifiques.

La campagne océanographique de deux semaines qui s'est déroulée à bord du navire de recherche le Coriolis II (photo ci­-dessous) dans la région du prospect Old Harry au coeur du golfe du Saint­Laurent s'est terminée le 21 juin dernier. Malgré une météo qui n'a pas toujours été favorable, plusieurs jours de forte mer et quelques nausées, cette campa...

The absorption spectra of chromophoric dissolved organic matter (CDOM), along with general physical, chemical and biological variables, were determined in the Bohai Bay, China, in the springs of 2011 and 2012. The absorption coefficient of CDOM at 350 nm (a350) in surface water ranged from 1.00 to 1.83 m− 1 (mean: 1.35 m− 1) in May 2011 and from 0....

Apparent quantum yields of carbon monoxide (CO) photoproduction (AQYCO) for permafrost-derived soil dissolved organic matter (SDOM) from the Yukon River Basin and Alaska coast were determined to examine the dependences of AQYCO on temperature, ionic strength, pH, and SDOM concentration. SDOM from different locations and soil depths all exhibited si...

Photolysis of dimethylsulfide (DMS), a secondary photochemical process mediated by chromophoric dissolved organic matter (CDOM), has previously been demonstrated to be an important loss term of DMS in the surface layer of warm seas and the Southern Ocean. The role of photolysis in regulating the DMS dynamics in northern polar seas remains, however,...

The Arctic Ocean (AO) undergoes profound changes of its physical and biotic environments due to climate change. In some areas of the Beaufort Sea, the stronger haline stratification observed in summer alters the plankton ecosystem structure, functioning and productivity, promoting oligotrophy. A one-dimension (1-D) physical-biological coupled model...

Spectrally resolved efficiency (i.e. apparent quantum yield, AQY) of carbon monoxide (CO) photoproduction is a useful indicator of substrate photoreactivity and a crucial parameter for modeling CO photoproduction rates in the water column. Recent evidence has suggested that CO photoproduction from particles in marine waters is significant compared...

Photolysis of dimethylsulfide (DMS), a secondary photochemical process mediated by chromophoric dissolved organic matter (CDOM), has previously been demonstrated to be an important loss term of DMS in the surface layer of warm seas and the Southern Ocean. The role of photolysis in regulating the DMS dynamics in the Arctic Ocean, however, remains ob...

The Arctic Ocean (AO) undergoes profound changes of its physical and biotic envi-ronments due to climate change. The greater light exposure and stratification alter its plankton ecosystem structure, functioning and productivity promoting oligotrophy in some areas as the Beaufort Sea. A one-dimension (1-D) physical-biological coupled 5 model based o...

The Arctic Ocean (AO) undergoes profound changes of its physical and biotic environments due to climate change. The greater light exposure and stratification alter its plankton ecosystem structure, functioning and productivity promoting oligotrophy in some areas as the Beaufort Sea. A one-dimension (1-D) physical-biological coupled model based on t...

The rates of photoproduction, dark production, microbial consumption, and air–water exchange of dissolved carbon monoxide (CO) were independently assessed for the first time for a large sub-arctic estuarine water body, the Canadian St. Lawrence estuary system. Areal CO photoproduction in all four seasons increases from the Upper Estuary to the Lowe...

Spectrally resolved efficiency (i.e. apparent quantum yield, AQY) of carbon monoxide (CO) photoproduction is a useful indicator of substrate photoreactivity and a crucial parameter for modeling CO photoproduction rates in the water column. Recent evidence has suggested that CO photoproduction from particles in marine waters is significant compared...

Nitrous oxide (N2O) contributes ∼6% of the total radiative forcing from long-lived greenhouse gases. While tropospheric concentrations have increased by 20% since the beginning of the industrial revolution, sources and sinks of N2O are still poorly quantified. In the Arctic, N2O atmospheric concentrations vary seasonally, due mainly to vertical mix...

Photochemistry of dissolved organic matter (DOM) plays an important role in marine biogeochemical cycles, including the regeneration of inorganic nutrients. DOM photochemistry affects nitrogen cycling by converting bio-refractory dissolved organic nitrogen to labile inorganic nitrogen, mainly ammonium (NH4+). During the August 2009 Mackenzie Light...

No abstract available.

Photochemistry of dissolved organic matter (DOM) plays an important role in marine biogeochemical cycles, including the regeneration of inorganic nutrients. DOM photochemistry affects nitrogen cycling by converting bio-refractory dissolved organic nitrogen to labile inorganic nitrogen, mainly ammonium (NH₄⁺). During the August...

We monitored the spatiotemporal progression of dissolved organic carbon (DOC) and carbon monoxide (CO), along with general meteorological, hydrographic, and biological variables, in first-year sea ice in the western Canadian Arctic between mid-March and early July 2008. DOC and CO concentrations fluctuated irregularly in surface ice, but followed t...

Absorption spectra of chromophoric dissolved organic matter (CDOM) and particles were obtained in May 2007 in the St. Lawrence estuary (SLE, Canada), the northwestern Gulf of St. Lawrence (NWG), and the Saguenay Fjord (CDOM only), the main tributary of the SLE. CDOM absorption generally decreased down-stream and with depth and showed an inverse rel...

The effects of colored dissolved organic matter (CDOM) from freshwater runoff and seasonal cycle of temperature on the dynamic of phytoplankton and zooplankton biomass and production in the Gulf of St. Lawrence (GSL) are studied using a 3-D coupled physical-plankton ecosystem model. Three simulations are conducted: (1) the reference simulation base...

The temporal changes in dissolved inorganic (DIC) and organic carbon concentrations (DOC) were monitored from late autumn to spring 2006 in the Scholaert Channel, West Antarctic Peninsula. Surface DIC spanned a small range (2163.3 to 2194.5 mmol kg -1), increasing from late autumn to winter and then decreasing in spring. An excess of DOC (7.0–63.6...

Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 36 (2009): L23606, doi:10.1029/2009GL041158. Carbon monoxide (CO) photoproduction from particulate and chromophoric...

Microbial uptake of carbon monoxide (CO) in the Gulf of St. Lawrence and the estuary of the St. Lawrence River, Canada, typically followed first-order kinetics at ambient CO concentrations, [CO], but saturation kinetics occasionally occurred in spring. The first-order uptake rate constant, Kco, decreased from the upper estuary (8.48 d–1) to the low...

The photochemical mineralization of dissolved organic carbon (DOC) to dissolved inorganic carbon (DIC) is a key process in carbon cycling. Using a Suntest CPS solar simulator, Suwannee River humic acid (SRHA) was photooxidated to examine the effects of O2 levels, the wavelength of incident light, and the concentration of Fe on the photoproduction o...

We investigated the distribution, photoproduction, microbial uptake, and air-sea exchange of carbon monoxide (CO), a key photoproduct of chromophoric dissolved organic matter ( CDOM), in open waters of the southeastern Beaufort Sea in autumn 2003 and spring 2004. Diurnal cycles of surface water CO concentration ([CO]) occurred in autumn but not in...

We investigated the thermal (dark) production of carbon monoxide (CO) from dissolved organic matter (DOM) in the water column of the St. Lawrence estuarine system in spring 2007. The production rate, Q co , decreased seaward horizontally and downward vertically. Q co exhibited a positive, linear correlation with the abundance of chromophoric dissol...

We investigated the distribution, photoproduction, microbial uptake, and air-sea exchange of carbon monoxide (CO), a key photoproduct of chromophoric dissolved organic matter (CDOM), in open waters of the southeastern Beaufort Sea in autumn 2003 and spring 2004. Diurnal cycles of surface water CO concentration ([CO]) occurred in autumn but not in s...

Sorption is a natural process that takes place in sediments or soils and changes the mobility and availability of hydrophobic organic compounds, such as toxaphene pesticide in the environment. The sorption of the 2-exo,3-endo,5-exo,8,9,10,10-heptachlorobornane (B7-1450), used as a model compound of the toxaphene heptachlorobornane congeners found i...

Rapid bio-oxidation of carbon monoxide (CO), a photoproduct of dissolved organic matter, results in diel cycles reflecting photochemical-biogeochemical-physical interactions. These cycles were characterized by time-series studies of hydrography, meteorology, insolation, optics, and CO concentration ([CO]). Diel patterns of near-surface [CO] general...

We present the first reported net loss-rate constants of molecular hydrogen, H2, in seawater. Net loss rates and depth profiles of hydrogen were measured in coastal seawater at two mid-latitude sites in eastern Canada: the St. Lawrence Estuary and Halifax Harbour, between November 2005 and July 2006. Net loss-rate constants ranged between 0.29 d− 1...

This study examined the effects of water temperature and the origin (terrestrial vs marine) and light history of chromophoric dissolved organic matter (CDOM) on the apparent quantum yields of carbon monoxide (CO) photoproduction for water samples collected along a salinity gradient (salinity range: 0-33) in the St. Lawrence estuarine system (Canada...

Molecular weight (MW) is a key control on the physical, chemical, and biological characteristics of dissolved organic mater (DOM). This study investigated the effect of photooxidation on the average MW of DOM by exposing DOM of diverse origins to simulated solar radiation at varying levels of dissolved oxygen and under different incident light wave...

Photomineralization of terrigenous dissolved organic matter (tDOM) in the Arctic Ocean is limited by persistent sea ice cover that reduces the amount of ultraviolet (UV) radiation reaching the underlying water column. UV-dependent processes are likely to accelerate as a result of shrinking sea ice extent and decreasing ice thickness caused by clima...

Dissolved organic matter (DOM) in natural waters can bind various organic pollutants, and the affinity of this binding is strongly influenced by the chemical characteristics of the DOM and water pH. This study examined the effects of photochemically induced alteration of the DOM's chemical properties and water pH on the binding of benzo(a)pyrene (B...

1] Photomineralization of terrigenous dissolved organic matter (tDOM) in the Arctic Ocean is limited by persistent sea ice cover that reduces the amount of ultraviolet (UV) radiation reaching the underlying water column. UV-dependent processes are likely to accelerate as a result of shrinking sea ice extent and decreasing ice thickness caused by cl...

Photochemical oxidation of the CDOM and the resulting production of CO 2 is now known to be a significant process in the cycling of carbon in the ocean-atmosphere system. One environment where that process may take a major role in the context of climate change is the Arctic ocean because of: 1) the increasing amount of terrestrial CDOM released by...

The concentration of carbon monoxide ([CO]) in firstyear ice in Franklin Bay, southeastern Beaufort Sea, was ∼40 times higher than in the underlying seawater and ∼15 times higher than in the adjacent open water. The [CO] in the sea ice decreased with increasing depth and increased rapidly at the bottom where there was an abundance of ice microalgae...

Microbial consumption is the dominant sink of oceanic carbon monoxide (CO), one of the major carbon-containing photoproducts of chromophoric dissolved organic matter in marine waters. This study presents first-order microbial CO consumption rate constants (k(CO)) determined using whole-water dark incubations in summer and fall in diverse marine eco...