In this study, a model of remineralization patterns was developed to explore the particulate organic matters (POM) decomposition process among marine mesopelagic zone (200 to 1000 m) using data from the South China Sea. The results suggest that three high C/N remineralization patterns are identified at 200 to 400 m, 600 to 700 m and 900 to 1000 m, and two low C/N remineralization patterns are found

The toxicity and bioavailability of Cu in seawater were estimated using its chemical speciation. In this study, the concentrations and conditional stability constants (K'CuL) of Cu complexes with Cu-binding organic ligands (L) in seawater were determined using the reverse titration–competitive ligand exchange–adsorptive cathodic stripping voltammetry method. The concentrations of strong and weak ligands

Amino acids (AAs) and amino sugars (ASs), compounds ubiquitous to living organisms, can provide information regarding degradation states and bacterial contributions to sedimentary organic matter (SOM). However, very few studies have utilized the combination of AAs and ASs as a proxy to assess the influence of bacterial degradation on SOM in the Yellow Sea (YS). In this study, surface sediments from

Competition for limited iron resources is a key driver of microbial community structure in many regions of the surface ocean. The bacterial siderophores ferrioxamine and amphibactin have been identified in marine surface waters, suggesting that they may represent an important bacterial strategy for obtaining iron from a scarcely populated pool. Using proteomics, siderophore isolation, and iron uptake

Concentrations of 4 volatile halocarbons (VHCs) in seawater and atmosphere of the Northern South China Sea (NSCS) were measured during summer 2015. Mean surface seawater concentrations of CH3I, CH3Br, CHBr3, and C2Cl4 were 2.0, 4.2, 15.7, and 12.5 pM, respectively; mean atmospheric concentrations were 0.4, 4.1, 8.0, and 7.2 ppt, respectively. The surface seawater concentrations of the 4 VHCs were significantly

Pore water and solid phase geochemical profiles of sediment cores collected along two transects on the western and eastern sides of the Mississippi River mouth in the northern Gulf of Mexico were incorporated into a reactive transport model to determine the role of manganese and iron in the remineralization of carbon. Reactive transport model calculations indicate that sedimentation rates control the

Due to the uptake of anthropogenic carbon dioxide (CO2) from the atmosphere, and the resulting ocean acidification, long term monitoring of the marine carbon cycle is of utmost importance and requires high precision and accuracy across many laboratories over several decades. Despite this, many uncertainties still remain in carbon system measurements and calculations. Calculations of the carbon system

The organic matter occluded in the silica of fossil diatom frustules is thought to be protected from diagenesis and used for paleoceanographic reconstructions. However, the location of the organic matter within the frustule has hitherto not been identified. Here, we combined high spatial resolution imaging by nanoSIMS and Raman micro-spectroscopy to identify where the organic material is retained in

Dissolved organic matter in sea ice is rich in extracellular polymeric substances (EPS) secreted by sea ice algae and bacteria. Carbohydrates are the most abundant component of EPS and they may contribute to the Fe-binding organic ligand pool, increasing the residence time of bioavailable Fe in the euphotic zone when sea ice melts. A new method for the determination of EPS in sea ice samples is presented

Molybdenum (Mo) and thallium (Tl) are known as conservative-type elements in open ocean settings, despite their involvement in bio-cycling processes. In coastal oceans like the southern North Sea, however, positive and negative anomalies of dissolved Mo and Tl concentrations occur during certain time periods of the year, which are characterized by intensive organic matter cycling. The main motivation

Estuaries are important sources of methane (CH4) to the atmosphere. However, the lack of adequate field studies for understanding the sources/sinks of CH4 in estuaries hampers global atmospheric budgeting. Therefore, more studies are needed to bridge this gap and improve our understanding of CH4 dynamics. This study investigated the impacts of tides on CH4 emissions along a salinity gradient of the

Most of the lead (Pb) in today's ocean is from human activities, although natural sources contribute small amounts of Pb that are usually masked by massive anthropogenic emissions. In the U.S. GEOTRACES East Pacific Section (GP16), anthropogenic Pb is observed throughout the water column, and as seen elsewhere in the Pacific, Pb concentrations are highest in the upper hundreds of meters of the ocean

The 231Pa/230Th ratio of seawater and in ocean sediments is a potentially powerful tool in tracing oceanic processes such as the ocean circulation and marine primary productivity. However, 231Pa/230Th reflects the combined signal of multiple controls associated with scavenging and oceanic transport, limiting its use as a paleo-proxy. Given that links between seawater and sedimentary 231Pa and 230Th

Lead (Pb) is a primary tracer of natural and anthropogenic processes in the marine environment, with atmospheric deposition being one of its main sources to open ocean surface waters. However, the impact of short-term (daily) dust storms on the oceanic water column is poorly constrained due to the typically low sampling temporal resolution in deep open ocean settings. The Gulf of Aqaba (GoA), northern

We assessed the qualitative composition of fluorescent dissolved organic matter (FDOM) in Arctic Ocean surface water and in sea ice north of the Svalbard Archipelago (in the Sophia Basin, the Yermak Plateau and the north Spitsbergen shelf) in May and June 2015, during the “TRANSSIZ” expedition (Transitions in the Arctic Seasonal Sea Ice Zone). Samples collected in open lead waters (OW), under-ice waters

The concentrations of bioactive trace metals (Fe, Cu, Mn, Zn, Co, Ni, Cd, and Pb), Fe-and Cu-binding organic ligands, and electroactive Fe-binding humic substances were measured in surface waters across the West Florida Shelf in the eastern Gulf of Mexico in June 2015 and in February-March 2018. Seasonal differences in dust deposition were associated with increased concentrations of Fe, Mn and Pb in

Significant calcium enrichment relative to seawater was observed in bulk and size-segregated aerosols in the marine atmospheric boundary layer over the Arctic Ocean in summer. The calcium enrichment factor generally increased with decreasing particle size (aerodynamic diameter) in the fine mode (particle size <1.8 μm), especially within the particle size ranges of 1.8 μm to 0.56 μm and 0.18 μm to 0

The Southern Ocean is the most important carbon sink in the world because of its relatively cold seawater temperature and unique overturning circulation which provides a conduit for atmospheric CO2 to enter into the deep ocean. However, it remains less clear how physical-biogeochemical processes control the carbon source/sink status because of the sparse spatiotemporal coverage of observations in the

Many different atmospheric trace gases have been directly and indirectly linked to biological sources and sinks. Here we assess how atmospheric mixing ratios of a range of halocarbons (CH3Br, CH2Br2, CHBr3, CH3Cl, CHCl3, and CH3I) and COS are causally connected to naturally occurring marine eukaryotic phytoplankton in coastal Southern California. We use a self-organizing map to characterize the abiotic

Diatom frustules record the variations of seawater Ge/Si, a ratio related to continental weathering, early diagenesis, and biological productivity. To investigate the geochemistry of germanium and the possibility of using opal Ge/Si as a proxy of changes in Ge and Si budgets in high latitude Antarctic marginal sea, nine surface sediment samples and one sediment core were collected from Prydz Bay during

Estimates of coral reef calcification and organic productivity provide valuable insight to community functionality and the response of an ecosystem to stress events. High-latitude coral reefs are expected to experience rapid changes in calcification rates and become refugia for tropical species following climate change and increasing bleaching events. Here, we estimate ecosystem-scale calcification

The Bay of Bengal is a semi-enclosed ocean basin situated in the eastern part of the North Indian Ocean. Though the physical dynamical features of the Bay of Bengal have been studied and measured in detail, the carbonate chemistry of this basin has been less explored, and very few reliable data-sets exist. This paucity of data has emerged as a major challenge in modeling and understanding the carbonate

The effects of Ocean Acidification (OA) and the resulting decrease of CaCO3 saturation state (Ω) on marine organisms and biogeochemistry are observed through regionally dispersed monitoring programs. The standard of data collected by these programs is assessed based on the computed propagated uncertainties of [CO32−], with data quality regulated by thresholds defined by the Global Ocean Acidification

Tropical estuarine deltas generally present poorly buffered waters in their freshwaters. Carbonate chemistry predicts that mixture of such warm freshwater with seawater will create rapid consumption of the freshwater carbon dioxide (CO2) by the carbonate buffering capacity of the seawater. In this study, we used the Paraiba do Sul River as a laboratory to investigate how thermodynamics compare with

We have developed a density-based method for determining porewater salinity that can be performed shipboard on small volume samples with greater efficiency and precision than the currently available shore-based chloride titration technique. This approach is based on a recently developed water column method that determines salinity at the precision of a conductivity measurement through density measurements

The partial pressure of CO2 (pCO2) and concentration of dissolved CH4 and N2O were studied during July 2017 in three estuaries of the southern Iberian Atlantic basin: the Guadalquivir, Tinto - Odiel and Guadiana. Two different sampling methods were adopted for each estuary: a longitudinal sampling along the course of the river, and a tidal cycle sampling of 24 h in the mouth of the estuary. In general

Juncus maritimus is the dominant halophyte in the marshes of the Nalón estuary, a Spanish area contaminated by mercury (Hg) as a consequence of mining activities. With the purpose of clarifying the Hg bioaccumualtion of this halophyte in this contaminated Hg salt marsh, sediments and Juncus maritimus samples were collected from seven locations. Hg uptake and allocation in the plant parts were evaluated

The Gulf of Cádiz, located in the Southern Iberian Atlantic Basin, connects the North Atlantic Ocean and the Mediterranean Sea and receives freshwater input from three main estuaries: Guadalquivir, Guadiana, and Tinto-Odiel. These estuaries differ in their hydrology, basin characteristic, and land use. One of them, Tinto-Odiel, is one of the most polluted estuaries in the world. However, little is

The Fram Strait is the only deep connection between the Arctic and Atlantic Oceans. The main water and mercury (Hg) fluxes between these oceans occur via the Fram Strait and Barents Sea Opening. Several Hg mass balance studies indicated a net Hg export from the Arctic to the Atlantic Ocean. However, in the absence of Hg measurements in the Fram Strait and Barents Sea Opening, these estimates were based

Isoprene is the most abundant biogenic volatile organic compound (BVOC) on the planet, with annual emissions accounting for up to half of all BVOC emissions. Isoprene has been measured extensively in terrestrial habitats where it is highly abundant; however, there is limited knowledge on marine systems where it is found at lower concentrations. Here, we report for the first time isoprene fluxes from

A recent study using Fe-limited phytoplankton strains, showed that iron (Fe) uptake rates normalized by cellular surface area were best related to dissolved iron (dFe) concentrations as the inorganic Fe (Fe’) supply rates were not sufficient to satisfy the Fe biological demand. Short-term (24 h) shipboard incubations with the in-situ phytoplankton community were used to measure Fe uptake rates that

The internal P cycling in coastal sediments during early diagenesis is of great importance to aquatic ecosystems, but its relationship with sulfate reduction is still unclear and lacks visualized evidence. In this study, diffusive gradients in thin films (Zr-oxide DGT and AgI DGT) techniques at a two-dimensional (2D) submillimeter resolution were utilized to synchronously characterize the in situ labile

The karstic Krka River is characterized by having lower dissolved organic carbon (DOC) concentrations (~30 μM) than coastal seawater (~60 μM). This peculiarity, together with the pristine nature of this area, makes the Krka River estuary a natural laboratory where it is possible to discriminate among the different dissolved organic matter (DOM) sources (riverine, marine and produced in-situ) and to

The concentrations of dissolved and particulate manganese (Mndiss and Mnpart) were studied in the Wadden Sea and adjacent estuaries to gain insights into spatial and regional differences, but also to assess the source function of the tidal basins for the open North Sea compared to river discharge. Ten transects across tidal basins of the southern and northern Wadden Sea as well as the estuaries of

We present here results of an 18-month survey (July 2007–March 2009) of a suite of selected trace metals (TM: Co, Ni, Cu, Pb) in a 2350 m-deep offshore water column in the Ligurian Sea (Northwestern Mediterranean Sea). This low-nutrient low-chlorophyll region is characterised by a long stratification period (May–November) during which surface waters are depleted of macronutrients. Trace metals exhibit

Formation of dense shelf water (DSW) in coastal polynyas (open water or thin sea-ice cover) in the sea-ice zone around Antarctica supplies Antarctic Bottom Water (AABW) through overflow down the continental slope. In coastal polynyas, atmospheric carbon dioxide (CO2) is absorbed by the ocean in the early spring because of active primary production, and DSW formation is an important process for transporting

We examined the spatial variations in radiocesium (134Cs and 137Cs) and radium (226Ra and 228Ra) concentrations (activities) in and around the western Bering Sea in August 2018. 134Cs concentrations in the surface seawater samples were 1.1–2.0 mBq/L, decay-corrected to the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident date. The northward slope current-dominated water of the Bering Sea exhibited

The branched glycerol dialkyl glycerol tetraethers (brGDGTs) can be produced in situ under methanotrophic/hypoxic conditions in lakes. However, the effect of dynamic methanotrophic activities in the widely-distributed seafloor methane seeps on brGDGTs distributions in global continent margins remains enigmatic. In this study, we firstly report the occurrence of in situ produced brGDGTs in cold seep

We present dissolved neodymium and hafnium concentrations and isotope compositions of surface and deep-water masses from the Bay of Biscay. Neodymium isotope signatures in surface waters of the Bay of Biscay are mostly dominated by local weathering inputs from the surrounding continental margin. Subsurface Eastern North Atlantic Central Water (ENACW) shows a distinct Nd isotope signature (εNd ≅ −12)

Samples for organic copper (Cu)-binding ligand characterization were collected along the 2013 U.S. GEOTRACES Pacific (GP16) cruise transect from Peru to Tahiti. Full depth profiles of Cu speciation were collected across a dynamic range in oceanographic conditions including a highly productive coastal region, an oxygen deficient zone, a high nutrient low chlorophyll (HNLC) region, an oligotrophic region

A wide selection of pollutants in several estuarine environments exposed to different types and grades of pollution were evaluated. The obtained data from the combination of both, a complete set of pollutants and a range of areas with different degrees of exposure to pollution, was used to analyze the pollutants presence, levels and sources, and finally to determine benchmark values of organic and

Estuaries are essential drivers of primary productivity in coastal waters through the export of dissolved and suspended material. This study aims at quantifying this fertilization process at the two main estuaries in South Portugal, where typical low river discharge conditions occur in winter due to strong flow regulation by upstream dams and seldom-local rain events. Data were collected across the

Experimental studies characterizing the reactivity of siliceous materials, such as biogenic silica from the field or laboratory cultures, typically require organic matter removal prior to experimental analysis. Consequently, it is highly desired to develop and optimize a cleaning protocol that imposes minimal alterations to the reactivity of the siliceous substrate and can be robustly employed among

Submarine groundwater discharge (SGD) is an important component of the marine 87Sr/86Sr budget, which is currently in an imbalance with a missing source. In this contribution, dissolved Sr concentrations and 87Sr/86Sr of the Chilika lagoon (India), the largest brackish-water lagoon in Asia, have been investigated for three different seasons (pre-monsoon (May 2017), monsoon (Aug., 2017) and post-monsoon

Understanding the natural dynamics of estuaries and their response to changes in the human-related or climatic drivers is fundamental to guarantee their environmental quality. This study aims to contribute to a better understanding of the water quality dynamics in an urban estuary, the Tagus estuary (Portugal), across different temporal scales. This estuary supports diverse uses and activities and

The diversity of nitrogen-based dissimilatory metabolisms in anoxic waters continues to increase with additional studies to the marine oxygen deficient zones (ODZs). Although the microbial oxidation of nitrite (NO2–) has been known for over a century, studies of the pathways and microbes involved have generally proceeded under the assumption that nitrite oxidation to nitrate requires dioxygen (O2)

There is a paucity of data on Fe-binding ligands in the Arctic Ocean. Here we investigate the distribution and chemical properties of natural Fe-binding ligands in Fram Strait and over the northeast Greenland shelf, shedding light on their potential sources and transport. Our results indicate that the main sources of organic ligands to surface waters of Fram Strait included primary productivity and

Aerosol samples (n = 14), collected over the eastern North Pacific (ENP, 27–52°N and 150–172°W), were studied for dicarboxylic acids (hereafter diacids, C2-C10), ω-oxoacids, pyruvic acid, and α-dicarbonyls as well as water-soluble organic carbon (WSOC) and total nitrogen (WSTN). We found diacids as the most abundant compound class followed by ω-oxoacids and α-dicarbonyls. Molecular distributions of

Sulfur cycling is ubiquitous in marine sedimentary environments and is influenced by microbial and abiotic processes that alter both the abundance and isotopic composition of sulfur species that can ultimately be captured as sedimentary minerals. Microbial metabolisms that generate sulfur isotopic (δ34S) signatures in hydrogen sulfide have a spatial distribution that varies on the micron scale, yet

The hadal trenches (>6000 m) are considered to be ultimate sinks of organic carbon (OC) from biosphere. However, highly spatial heterogeneity of geographic background and organic matter in different zones make significant influences on the OC cycling, and further the carbon burial. In this study, three sediment cores were drilled across the northern Yap Trench axis (9.8–9.9°N, 138.3–138.7°E). The elemental

The impact of aquaculture chemotherapeutants (antibiotics, and anti-lice parasiticides) on non-target organisms is dependent on their dissipation and degradation in marine sediments. Abiotic and biotic weathering may change their composition and toxicity, and influence their fate. In this study, biodegradation of a few aquaculture chemotherapeutants was investigated over a 96 days period at 4 °C in