Composition Of Suspended Particulate Matter Research Articles

Composition and sources of suspended particles in the Pacific Arctic region

During the 6th (2014) and 7th (2016) Chinese Arctic Expedition (CHINARE), samples of suspended particulate matter (SPM) were collected from both surface (depth: <1.0 m) and subsurface (depth: approximately between 10 and 150 m) waters over the northern shelf of the Bering Sea and in the western Arctic Ocean. To investigate the distribution and sources of organic matter in both the surface water and the vertical profile, the concentration and stable carbon isotopic composition of SPM, particulate organic carbon (POC), and particulate nitrogen (only in surface water samples) were determined, and some particle samples were selected for examination using scanning electron microscopy. Results showed apparent geographical partitioning and temporal variation in both the concentration and the composition of SPM. Higher SPM concentrations were observed in nearshore, shelf break, and sea ice edge areas; the distribution of POC concentration displayed a similar pattern, with higher values found from the northern part of the Bering Shelf to southern parts of the Chukchi Shelf. In surface water, SPM mainly comprised clay and detrital minerals with higher POC contents, lighter δ13C values, and higher POC/PN ratios, indicating organic matter predominantly derived from terrestrial sources in areas south of St. Lawrence Island and north of 73°N. The downward trend of heavier δ13C values, together with reduction in clay and detrital minerals, suggests that vertical transport of SPM is hindered by stratification, resulting in transport of terrestrial materials toward northern basin areas. In the Chukchi Slope and Canada Basin areas, extremely light δ13C values (as low as −33.41‰ PDB) were mainly observed at depths of 20–60 m, where the Polar Mixed Layer (PML) intersects with the Upper Halocline Layer (UHL). Under the condition of low sea ice extent in 2016, the POC-δ13C values were heavier in the PML than in the UHL in the Chukchi Slope and Canada Basin areas. These findings provide insights into the sources, transport, and fate of organic matter in the Pacific Arctic region, which have important implications for understanding the biogeochemical cycles and ecosystem dynamics in this remote and rapidly changing environment.

Adsorption and environmental behavior of mercury on suspended particulate matter from the Yellow River and Xiaoqing River estuaries

Estuaries control the amount of Hg transported from rivers to coastal seas. The adsorption of Hg(II) on suspended particulate matter (SPM) is the key process that affects the behavior of Hg in estuaries since most riverine Hg is deposited with SPM in estuaries. In this study, the concentrations of particulate Hg (PHg) were higher than those of dissolved Hg (DHg) at the Xiaoqing River Estuary (XRE) and the Yellow River Estuary (YRE), indicating that SPM plays a crucial role in controlling the fate of Hg in estuaries. A higher partition coefficient (logKd) of Hg was observed at the YRE compared to other estuaries, indicating that Hg(II) tends to be more adsorbed on SPM in this system. The adsorption kinetics of Hg(II) on SPM at both estuaries conformed to pseudosecond-order kinetics, while the adsorption isotherms at the XRE and YRE fitted well with the Langmuir model and Freundlich model, respectively, possibly due to the difference in SPM composition and properties. The logKd was significantly positively correlated with the adsorption capacity parameter kf at the YRE, indicating that the distribution of Hg(II) at the SPM-water interface is controlled by the adsorption of Hg(II) on SPM. The results of environmental parameter correlation analysis and adsorption-desorption experiments showed that SPM and organic matter are the key factors controlling Hg distribution and partitioning at the water-solid interface in estuaries.

Elemental Composition of Particulate Matter in the Euphotic and Benthic Boundary Layers of the Barents and Norwegian Seas

The increasing influence of Atlantic inflows in the Arctic Ocean in recent decades has had a potential impact on regional biogeochemical cycles of major and trace elements. The warm and salty Atlantic water, entering the Eurasian Basin through the Norwegian Sea margin and the Barents Sea, affects particle transport, sink, phyto-, and zooplankton community structure and could have far-reaching consequences for the marine ecosystems. This study discusses the elemental composition of suspended particulate matter and fluffy-layer suspended matter derived from samples collected in the Barents Sea and northern Norwegian Sea in August 2017. The mosaic distribution of SPM elemental composition is mainly determined by two factors: (i) The essential spatial variability of biological processes (primary production, abundance, and phytoplankton composition) and (ii) differences in the input of terrigenous sedimentary matter to the sea area from drainage sources (weak river runoff, melting of archipelago glaciers, etc.). The distribution of lithogenic, bioessential, and redox-sensitive groups of elements in the particulate matter was studied at full-depth profiles. Marine cycling of strontium in the Barents Sea is shown to be significantly affected by increasing coccolithophorid bloom, which is associated with Atlantic water. Mn, Cu, Cd, and Ba significantly enrich the suspended particulate matter of the benthic nepheloid layer relative to the fluffy layer particulate matter within the benthic boundary layer.

Influence of the ITCZ and OMZ on the isotopic composition of suspended particulate matter in the western tropical North Atlantic

The tropical North Atlantic Ocean is a complex region where the intertropical convergence zone (ITCZ) and the oxygen minimum zone (OMZ) play important roles in the control of the physical and biogeochemical processes and affect the efficiency of the carbon pump. Changes in the composition of the particulate organic matter (POM) have been extensively studied in the eastern tropical North Atlantic and recent findings suggested less effective remineralization in the OMZ by comparison with well‑oxygenated waters. However, dynamics of the POM in the western tropical North Atlantic, including the effect of the hypoxic condition on the isotopic signature of the POM, has been poorly understood. This study uses data collected in October 2018 during the PIRATA XVIII cruise (38°W) to describe the biogeochemical variability and isotopic composition of suspended POM in the water column, with emphasis on the effect of the ITCZ and the OMZ on the POM. The ITCZ, located between 5°N and 10°N, was responsible for the low sea surface salinity and local upwelling, thus favoring the high biological productivity found in this band. Although a clear relation between δ13CPOC values and the ITCZ position was not found, low δ15NTPN values (∼2‰) and high silicate concentration observed on the surface between 4°N-6°N suggested that dust deposition and its associated enhancement of the diazotrophic activity may be important in the southernmost part of the ITCZ. Preferential remineralization of fractions rich in 13C (proteins, carbohydrates) and nitrogen compounds resulted in low δ13CPOC and high C:N values observed at depth. However, these alterations were attenuated in the OMZ, suggesting that reduced remineralization expected in waters with low oxygen concentrations may also affect the isotopic POM signature. Additionally, the minimum δ15NTPN value (∼1‰) observed in the core of the OMZ confirms that, although microbial activity may be important in this region, nitrogen-loss processes are not predominant in the western tropical Atlantic.

Adaptive optical algorithms with differentiation of water bodies based on varying composition of suspended particulate matter: A case study for estimating the particulate organic carbon concentration in the western Arctic seas

High complexity and variability in composition of water constituents pose major challenges for development of algorithms to estimate biogeochemical data products from optical observations over the continuum of diverse aquatic environments. To address these challenges, we examined an adaptive optical approach that accounts for variability in composition of suspended particulate matter. We use the ratio of particulate organic carbon to suspended particulate matter concentration, POC/SPM, for optically discriminating water bodies with varying proportions of organic and mineral particles. Through the analysis of field data from the western Arctic seas that exhibit a broad range of water composition and optical properties, we developed empirical algorithms to estimate SPM and POC/SPM either from the particulate inherent optical properties (IOPs) of seawater, i.e., the spectral particulate absorption ap(λ) or backscattering bbp(λ) coefficients, or directly from the spectral remote-sensing reflectance of the ocean, Rrs(λ). The capability to retrieve POC/SPM from optical measurements was used to formulate the particle composition-specific algorithms for estimating POC from particulate IOPs or Rrs(λ). The evaluation of algorithms with the development field dataset demonstrates that the algorithm formulations accounting for changes in POC/SPM provide significant improvements in POC estimates along the continuum of optically-complex Arctic waters compared with algorithms that do not account for variations in particulate composition, such as the current standard POC algorithm used for global satellite applications. The results of example application of the particle composition-specific algorithm and standard global algorithm to satellite observations are consistent with comparisons of these algorithms for our field dataset, which supports a conclusion that the standard algorithm tends to overestimate POC in Arctic waters that exhibit a broad range of particle composition. Although this study demonstrates the adaptive approach using data from the Arctic region, it has broader significance and is amenable to further enhancements by including other optically-derivable water constituent properties. Further validation analyses and efforts are needed towards a unified approach with improved representation of cause-and-effect relationships between water composition and optical properties to enable improved optically-based applications across a wide range of water bodies.

Distribution and sources of REEs in suspended particulate matter of cryospheric water in northeast Tibetan plateau

Rare earth elements (REE) are widely used as tracers for surface processes due to their zonal differences in composition and special geochemical indicators. In this study, we collected 30 glacial meltwater samples from a large area of the northeastern Tibetan Plateau region and analyzed the REE composition of suspended particulate matter (SPM, d > 0.45 μm) to explore the spatial distribution, origins and the influencing factors of REE in SPM. Results suggested that chondrite-normalized REE distribution patterns were characterized by steep LREE and relatively flat HREE, which is different from that of PAAS-normalized. The high (La/Sm)N ratio and low (Gd/Yb)N ratio indicated that the degree of LREE fractionation was higher than that of HREE. We found an obvious correlation between REE concentration and SPM concentration, indicating that REE concentration in glacial runoff was significantly affected by SPM contents. It was found that Ce/Ce* decreased first and then increased with the decrease of altitude in the glacial river basins, which may contribute to weathering, oxidation, and physicochemical property of the water environment in the study areas. At the glacier forefield, the degree of weathering is intense, resulting in the highest Ce/Ce* value in the altitude between 3200 and 4800 m. However, this was not obvious in non-glacial regions. Compared REE geochemical parameters (e.g., LREE/HREE, Eu/Eu*, LaN/SmN) of SPM in the glacier basin with those of Asian potential dust sources and long-range transport (LRT) dust deposited on the studied glaciers, we found that the SPM in the glacial river basins is affected by lithology of parent materials, the LRT dust from the surrounding deserts, the release of ice/snow dust, and the detrital material from local rock weathering. This study provides a new perspective on the composition, distribution and variation in the altitude of REE in the glacial river basin of the northeast TP, and thus is of significance to improve the understanding of the source and migration process of REE in SPM of glacial river basins.

Generation of reproducible model freshwater particulate matter analogues to study the interaction with particulate contaminants

Aquatic fate models and risk assessment require experimental information on the potential of contaminants to interact with riverine suspended particulate matter (SPM). While for dissolved contaminants partition or sorption coefficients are used, the underlying assumption of chemical equilibrium is invalid for particulate contaminants, such as engineered nanomaterials, incidental nanoparticles, micro- or nanoplastics. Their interactions with SPM are governed by physicochemical forces between contaminant-particle and SPM surfaces. The availability of a standard SPM material is thus highly relevant for the development of reproducible test systems to evaluate the fate of particulate contaminants in aquatic systems. Finding suitable SPM analogues, however, is challenging considering the complex composition of natural SPM, which features floc-like structures comprising minerals and organic components from the molecular to the microorganism level. Complex composition comes with a heterogeneity in physicochemical surface properties, that cannot be neglected. We developed a procedure to generate SPM analogue flocs from components selected to represent the most abundant and crucial constituents of natural riverine SPM, and the process-relevant SPM surface characteristics regarding interactions with particulate contaminants. Four components, i.e., illite, hematite, quartz and tryptophan, combined at environmentally realistic mass-ratios, were associated to complex flocs. Flocculation was reproducible regarding floc size and fractal dimension, and multiple tests on floc resilience towards physical impacts (agitation, sedimentation-storage-resuspension, dilution) and hydrochemical changes (pH, electrolytes, dissolved organic matter concentration) confirmed their robustness. These reproducible, ready-to-use SPM analogue flocs will strongly support future research on emerging particulate contaminants.

Assessment of the influence of the composition of atmospheric microparticles on redox homeostasis of alveolar macrophages

Introduction. The components and dimensions of suspended particulate matter (SPM) depend on territory, the sources of generation. The aim is to assess the relationship between the quality and dispersed composition of atmospheric SPMs with oxidative and antioxidant processes in alveolar macrophages. Materials and methods. The impact of actual multi component pollution of the surface layer of atmospheric air on alveolar macrophages (AMs) of Wistar rats was modelled. Correlations between the characteristics of AMs and pollution were assessed using the Spearman correlation coefficient. Results. The predominant contribution of the quality characteristics of SPM has been founded. The effect of the dispersed composition increases with an increase of the finely dispersed particles fraction. Metal particles have caused oxidative damage to lipids, with the formation of stable lipid products. The antioxidant system (AOS) has been characterized by the activation of compensatory response. Mineral components have caused irreversible oxidative damage to lipid and protein compounds, activating the thioredoxin formation. Soot particles have showed the most pathogenic effect, leading to oxidative damage to lipids, proteins, and nucleic acids. The AOS stress was accompanied by an increase in the formation of oxidized glutathione and thioredoxin, which performs restoration of proteins and DNA. Limitations. Our study characterizes the response of the AMs of a particular territory. Conclusion. The established tendencies characterize the impact of composition of SPMs of the urban atmospheric on AMs. The study made it possible to identify the most sensitive criteria for the response of AMs upon contact with atmospheric SPMs (thioredoxin, protein carbonyl, 8-hydroxy-2’-deoxyguanosine).

Seasonal occurrence of multiple classes of antibiotics in East China rivers and their association with suspended particulate matter

Understanding the occurrence and fate of antibiotics from different categories is vital to predict their environmental exposure and risks. This study presents the spatiotemporal occurrence of 45 multi-class antibiotics and their associations with suspended particulate matter (SPM) in Xiaoqing River (XRB) and Yellow River (YRB) via 10-month monitoring in East China. Thirty-five and 31 antibiotics were detected in XRB and YRB, respectively. Among them, fluoroquinolones (FQs) had the highest total mean concentration (up to 24.8 μg/L in XRB and 15.4 μg/L in YRB), followed by sulfonamides (SAs) (14.0 μg/L and 15.4 μg/L) and macrolides (MLs) (1.1 μg/L and 1.6 μg/L). Significant spatial-temporal variations were found in both rivers where higher concentrations of antibiotics were observed in urban and densely populated areas during winter and spring. Hydrological factors such as river flow and water volume, instream attenuation and antibiotic usage may cause the observed variabilities in the seasonal patterns of antibiotic pollution. Using linear regression analysis, for the first time, this study confirmed that the total concentrations of MLs (p < 0.05), FQs (p < 0.001) and SAs (p < 0.001) were strongly correlated with the turbidity/total suspended solids in the studied rivers (except MLs in YRB). It is thus suggested that partitioning processes onto SPM might affect the distribution of detected antibiotics in rivers, which are largely dependent on SPM composition and characteristics. The risk quotient (RQ) determined for up to 87 % of individual compound was below 0.1 in both rivers; however, the high joint toxicity reflected by the mixed RQs of detected antibiotics may rise risk alarm for aquatic species. Further aspects regarding active mechanisms of SPM-antibiotic interactions and ecological risks of coexistence of multiple antibiotics need to be investigated.

Suspended Matter and Hydrocarbons Fluxes in the Kara and Laptev Seas

The distribution of suspended particulate matter (SPM) by filtration and the magnitude of its fluxs using sediment traps in the Kara and Laptev Seas (cruise 72 of the R/V Akademik Mstislav Keldysh, August–September 2018) was studied. The composition of the SPM was determined by the material composition using an electron microscope, the organic component (Corg and hydrocarbons) and the inorganic component (amorphous silica and calcium carbonate). It was found that the SPM content in surface waters varied from 0.2 to 5.9 mg/L (on average 0.90 mg/L) with a maximum in the Blagopolychia Bay and aliphatic hydrocarbons from 10 to 49 µg/L (average 22 µg/L) with a maximum in the area of the removals of the river Ob. The SPM flux decreased from the surface to the near-bottom horizon only into the Blagopolychia Bay (from 13,127 to 11,900 mg/m2/day), but in most samples the flux increased in the near-bottom horizon with a maximum of 6920 mg/m2/day in the Ob’s discharge water area and correlated with the maximum of the Corg flux 695 mg/m2/day. In the composition of SPM, as well as in organic compounds, including hydrocarbons, allochthonous basically prevailed over autochthonous.

Estimating Mass Flux From Size‐Fractionated Filtered Particles: Insights Into Controls on Sinking Velocities and Mass Fluxes in Recent U.S. GEOTRACES Cruises

AbstractWe compile full ocean‐depth size‐fractionated (1–51 and &gt;51 μm) particle concentration and composition of suspended particulate matter from three recent U.S. GEOTRACES cruises, and exploit detailed information of particle characteristics measured to give insights into controls on sinking velocity and mass flux. Our model integrates the concept of fractal scaling into Stokes' Law by incorporating one of two porosity‐size power law relationships that result in fractal dimensions of 1.4 and 2.1. The medians of pump‐derived total (&gt;1 μm) mass flux in the upper 100 m of gyre stations are 285.1, 609.2, and 99.3 mg/m2/d in the North Atlantic, Eastern Tropical South Pacific, and Western Arctic Ocean cruises, respectively. In this data set, variations in particle concentration were generally more important than sinking velocity in controlling variations in mass flux. We examine different terms in a Stokes' Law model to explore how variations in particle and water column characteristics from these three cruises affect mass flux. The decomposition of different aspects of the Stokes' relationship sheds light on the lowest total mass flux of the three cruises in the Western Arctic, which could be explained by the Arctic having the lowest particle concentrations as well as the lowest sinking velocities due to having the smallest particle sizes and the most viscous water. This work shows the importance of both particle characteristics and size distribution for mass fluxes, and similar methods can be applied to existing and future size‐fractionated filtered particulate measurements to improve our understanding of the biological pump elsewhere.

Comparison of 3R4F cigarette smoke and IQOS heated tobacco product aerosol emissions

In this study, the smoke from a 3R4F research cigarette and the aerosol generated by the Heated Tobacco Product IQOS, also referred to as the Tobacco Heating System (THS) 2.2 in the literature, were compared. The objective was to characterize the gas and suspended particulate matter compositions in the mainstream smoke from a combusted 3R4F cigarette and in the aerosol generated by IQOS during use. The results indicated that the determined aerosol emissions from IQOS were notably lower than in the cigarette smoke under a Health Canada Intense puffing regimen. As an interesting detail in this study, the maximum nicotine concentrations within a puff were practically the same in both the 3R4F smoke and the IQOS aerosol, but the average concentration was lower for the IQOS aerosol. For both products, water constituted a significant proportion of the particulate matter, although it was substantially higher in the IQOS aerosol. Furthermore, combustion-related solid particles observed in the 3R4F smoke contained elements such as carbon, oxygen, potassium, calcium, and silicon. In contrast, IQOS aerosol particulate matter was composed of semi-volatile organic constituents with some minor traces of oxygen and silicon. The particulate matter found in the IQOS aerosol was volatile, which was especially noticeable when exposed to the electron beam of the scanning electron microscope (SEM) and Transmission Electron Microscope (TEM).

Validation of measurements of pine pollen grain concentrations in Baltic Sea waters

Each spring, pine pollen coats considerable expanses of Baltic Sea surface waters. Measurements have shown that there are areas where its concentrations in this surface layer are so high that they are the dominant constituent of the suspended particulate matter (SPM) (Pawlik and Ficek, 2016). It then determines to a large extent the optical properties of the water surface, inter alia by modifying the sea colour. To date, however, the concentration of this constituent in the marine environment has rarely been studied, and its presence is not accounted for in the satellite algorithms used to define the composition and properties of sea water. This may well be the source of substantial errors in the remote sensing of the optical properties of the water and the measurement of concentrations of the optically important constituents it contains (chlorophyll a, TSM, CDOM). Measuring the concentration of pollen suspensions in Baltic Sea water, which often contains prodigious amounts of other SPM, is a daunting experimental challenge. Firstly, we characterized the pollen from pine trees growing near the southern shores of the Baltic Sea (northern Poland) using a microscope and two instruments routinely used in oceanography for measuring SPM size distributions: the LISST-100X and the Coulter counter. The measurements and analyses showed that a correct interpretation of the LISST-100X and Coulter measurements, is sufficient to count the number of pollen grains in distilled water alone. Furthermore, our laboratory analysis of the particle size distribution spectra enabled the fraction due only to pine pollen grains to be separated from the overall SPM. We then tested our method of analysing the SPM composition, which showed that the LISST-100x instrument is both a useful and an effective means for the in situ detection of the pine pollen that one sees in spring in Baltic waters.

New insights into nitrogen removal potential in urban river by revealing the importance of microbial community succession on suspended particulate matter

The importance of suspended particulate matter (SPM) in nitrogen removal from aquatic environments has been acknowledged in recent years by recognizing the role of attached microbes. However, the succession of attached microbes on suspended particles and their role in nitrogen removal under specific surface microenvironment are still unknown. In this study, the causation among characteristics of SPM, composition and diversity of particle-attached microbial communities, and abundances of nitrogen-related genes in urban rivers was firstly quantitatively established by combing spectroscopy, 16 S rRNA amplicon sequencing, absolute gene quantification and supervised integrated machine learning. SPM in urban rivers, coated with organic layers, was mainly composed of silt and clay (87.59–96.87%) with D50 (medium particle size) of 8.636–30.130 μm. In terms of material composition of SPM, primary mineral was quartz and the four most abundant elements were O, Si, C, Al. The principal functional groups on SPM were hydroxyl and amide. Furthermore, samples with low, medium and high levels of ammoxidation potential were classified into three groups, among which significant differences of microbial communities were found. Samples were also separated into three groups with low, medium and high levels of denitrification potential and significant differences occurred among groups. The particle size, content of functional groups and concentration of SPM were identified as the most significant factors related with microbial communities, playing an important role in succession of particle-attached microbes. In addition, the path model revealed the significantly positive effect of organic matter and particle size on the microbial communities and potential nitrogen removal. The content of hydroxyl and temperature were identified as the most effective predicting factors for ammoxidation potential and denitrification potential respectively by Random Forests Regression models, which had good predictive performances for potential of ammoxidation (R2 = 0.71) and denitrification (R2 = 0.61). These results provide a basis for quickly assessing the ability of nitrogen removal in urban rivers.

Iron isotope of suspended particulate matter in Zhujiang River, Southwest China: Characteristics, sources, and environmental implications

Understanding the environmental iron cycle influenced by natural and anthropogenic processes is significant to obtain the key information on earth-surface evolution. Iron isotope compositions and elemental compositions of the suspended particulate matter (SPM) in Zhujiang River were investigated to provide key insights for the earth-surface iron cycle. The δ56Fe values of SPM display the range from −0.05‰ to 0.34‰ (averaged 0.19‰) while the iron contents range from 0.73 wt% to 7.63 wt% (averaged 4.15 wt%). The Chemical Index of Alteration (CIA) shows that the main weathering type of SPM is intermediate weathering (mean CIA value: 79.12). While the main chemical weathering types are similar, the δ56Fe values vary dramatically, indicating that chemical weathering is not the governing factor of δ56Fe values of SPM. Furthermore, evidence from the enrichment factors (EF, 0.78 to 1.29) of iron and Zinc isotopes reveals that the iron input from anthropogenic activities is quite limited. The significant correlation between (Fe/Ca)SPM and (Na/Ca)SPM, (Mg/Ca)SPM, (Al/Ca)SPM and (K/Ca)SPM (0.73 < r < 0.99, p < 0.01, n = 22) and the A–CN–K diagram could confirm that clay minerals (especially smectite and illite) are important components of SPM. Meanwhile, the higher enrichment rates of La, Pr and Nd with the increasing iron contents denote heavy minerals (mainly Fe oxides/oxy-hydroxides) are also important compositions of SPM. Based on the isotopic mass balance, it shows that the iron flux of SPM to the oceans during the wet season would reduce the δ56Fe values of the bulk ocean by 0.3%. The present study reports the iron isotope and elemental compositions of Zhujiang SPM and identifies its influencing factors (weathering, anthropogenic inputs, and minerals effect), and also provides a quantitative reference for the intriguing question on the distinct δ56Fe values of oceans, which is beneficial for understanding iron cycle in earth-surface system.

Energy dispersive X‐ray fluorescence methodology and analysis of suspended particulate matter in seawater for trace element compositions and an intercomparison with high‐resolution inductively coupled plasma‐mass spectrometry

AbstractA modification of energy dispersive X‐ray fluorescence (ED‐XRF) for analysis of trace element concentrations in suspended particulate matter (SPM) in seawater and intercomparison with high‐resolution inductively coupled plasma‐mass spectrometry (HR ICP‐MS) is presented. Approximately 250 SPM samples were collected on polycarbonate track‐etched filters in the Indian Ocean during the U.S. CLIVAR/CO2 Repeat Hydrography meridional section I09N cruise in 2007. Samples were first analyzed by ED‐XRF, a nondestructive technique, for Al, P, Ti, Mn, Fe, Ni, Cu, and Zn and subsequently digested and quantified by HR ICP‐MS, creating two blind, basin‐scale data sets used for a paired statistical comparison. Our results found (1) ED‐XRF analysis using thin‐film principles can quantify the elemental composition of SPM at nanomolar concentrations found in the open ocean; (2) there was excellent agreement between ED‐XRF and HR ICP‐MS analyses for Al, Fe, and Mn and good agreement for P and Ti; (3) analytical differences were the largest for Cu, Ni, and Zn; (4) HR ICP‐MS methods have lower detection limits for most elements when compared to the ED‐XRF; (5) ED‐XRF analysis has a closer agreement to reported values for the NIST SRM 2783 standard and lower relative standard deviations when compared to the HR ICP‐MS. We recommend continued refinement of nondestructive ED‐XRF methods as this would allow for the easy exchange of filtered samples between lab groups for intercalibration and intercomparison of basin‐scale hydrographic cruises and archival for future analysis.

Dominance of Autochthonous Phytoplankton-Derived Particulate Organic Matter in a Low-Turbidity Temperate Estuarine Embayment, Gwangyang Bay, Korea

In estuaries, the sources of organic matter, its composition, and its functional role in the coastal ecosystem food web are all influenced by dominant estuarine processes. We investigated seasonal variations in the quantity and composition of dissolved inorganic nutrients, suspended particulate matter (SPM), and phytoplankton across a low-turbidity estuarine–coastal continuum in Gwangyang Bay, South Korea. The narrow estuarine channel has a sharp salinity gradient (from 0 to around 30) and low SPM concentrations (<20 mg L−1). The channel carries river discharge, with a large quantity of nutrients (NO3 and SiO2), into the bay. The especially low SPM concentrations in the estuary (range: 2.0–29.1 mg L−1), and generous nutrient source, create an exceptionally low-turbidity condition in the water column and high primary productivity with no conspicuous spatial or seasonal trends. Gradually increasing 13C values, low POC:Chla (<200), and low molar C:N (4–8) in the SPM, together with higher Chla concentrations at low SPM locations along the longitudinal transect, suggest that local production of phytoplankton has a strong influence on the distributional patterns of particulate organic matter. Short water-residence times, within the bay system, impede the accumulation of diverse-origin organic matter. The community composition of phytoplankton, distinguished by their size group, also plays a role in characterizing SPM quantity and composition. The results indicate that autochthonous pelagic production governs biogeochemical features in the low-turbidity estuarine embayment, contrasting with a prevalence of allochthonous organic matter, and its active processing, in highly turbid and/or longer residence-time systems.

Trace metal dynamics in an industrialized Brazilian river: A combined application of Zn isotopes, geochemical partitioning, and multivariate statistics

The Paraiba do Sul (PSR) and Guandu Rivers (GR) water diversion system (120 km long) is located in the main industrial pole of Brazil and supplies drinking water for 9.4 million people in the metropolitan region of Rio de Janeiro. This study aims to discern the trace metals dynamics in this complex aquatic system. We used a combined approach of geochemical tools such as geochemical partitioning, Zn isotopes signatures, and multivariate statistics. Zinc and Pb concentrations in Suspended Particulate Matter (SPM) and sediments were considerably higher in some sites. The sediment partition of As, Cr, and Cu revealed the residual fraction (F4) as the main fraction for these elements, indicating low mobility. Zinc and Pb were mostly associated with the exchangeable/carbonate (F1) and the reducible (F2) fractions, respectively, implying a higher susceptibility of these elements to being released from sediments. Zinc isotopic compositions of sediments and SPM fell in a binary mixing source process between lithogenic (δ66/64ZnJMC ≈ + 0.30‰) and anthropogenic (δ66/64ZnJMC ≈ + 0.15‰) end members. The lighter δ66/64ZnJMC values accompanied by high Zn concentrations in exchangeable/carbonate fraction (ZnF1) enable the tracking of Zn anthropogenic sources in the studied rivers. Overall, the results indicated that Hg, Pb, and Zn had a dominant anthropogenic origin linked to the industrial activities, while As, Cr, and Cu were mainly associated with lithogenic sources. This work demonstrates how integrating geochemical tools is valuable for assessing geochemical processes and mixing source effects in anthropized river watersheds.

In situ Measurements of the Characteristics of Suspended Particles in the Barents Sea by the LISST-Deep Laser Diffractometer

The key indicators of marine sediment genesis are the particle size distribution (PSD) and volume concentration of suspended particulate matter (SPM). However, their study is not widespread in ship oceanology research. This paper reviews experience in using the LISST-Deep laser particle size analyzer for the study of marine SPM in situ. We present the first data on the volume concentration and PSD of SPM in the Barents Sea obtained during the 75th cruise of the RV Akademik Mstislav Keldysh in June 2019. We carried out an assessment of the adequacy of information display on the polydisperse system composition of the Barents Sea water body, which contains particles of a wide particle size spectrum of differing genesis and shape. This paper gives a regression and correlation analysis of LISST-Deep data with a Wet Labs turbidity meter and Multisizer 3 Coulter Counter, as well as the SPM mass concentration measured by the membrane filtration technique. All of them demonstrated reliable correlations between characteristics of SPM of the Barents Sea. Their correlation and determination coefficients varied from 0.6 to 0.8. The laser diffractometer produces more detailed vertical distributions of marine SPM parameters than does a turbidity meter, especially for euphotic zones. We found a significant correlation of LISST-Deep data with the concentration of dissolved oxygen, which increases for coarse–silty and sandy fractions (47.7–92.6 and 92.6–250 µm, respectively). Also, there is a correlation with SPM composition between parameters as organic carbon concentration and phytoplankton pigments. These correlations give some indirect indications of SPM composition from laser diffractometer measurements.

Seasonal Variations in the Grain Size Distribution and Mineral Composition of Suspended Particulate Matter of the Northern Dvina River

The paper presents the first results of a study of seasonal variations in the grain size distribution and mineral compositions of suspended particulate matter (SPM) of the Northern Dvina River. The SPM samples were collected every month during 2016–2017 at the outlet of the Kuznetchiha arm to Dvina Bay of the White Sea. The grain size fractions were separated by Petelin’s water-mechanical method with retention of fractions for subsequent analyses using an electron microscope, energy-dispersion microanalyzer, and X-ray difractometer. The results demonstrated that the pelitic and subcolloidal fractions predominated in the grain size distribution of river SPM, with subordinate coarser fractions. Seasonal variations in the SPM concentration and the total amount of detrital and clay minerals are influenced by river water discharge and achieved a maximum in high water periods (spring flood and partly at the end of summer–autumn heavy rains). The subcolloidal fraction in the March sample stands out in the fine fraction distribution. Its share in this sample was the highest among these fractions throughout the year. The reason is probably related to the highest content of fine dispersed detrital minerals in the fraction. The question of why this is encountered only in March remains open.