Characteristics Of Suspended Particulate Matter Research Articles

Assessment of organic contaminants at a paint manufacturing site: Implications for health risks and source identification

The daily variation of organic contaminants, both gaseous and associated with suspended particulate matter (PM), was investigated within the estate of the National Company of Paintings in Lakhdaria, Algeria, spanning the period 2014-2015. The research emphasizes the chemical characterization of suspended PM, analyzing a range of organic compounds, including n-alkanes, polycyclic aromatic hydrocarbons (PAHs), and highly polar organics (HPOC), such as phthalate esters and heterocyclic compounds. Vapors of PAHs and polychlorobiphenyls (PCBs) were also analyzed. Low molecular weight compounds were primarily associated with the gas phase (two-ring PAHs, approximately 95%; three-ring PAHs, around 70%), while high molecular weight congeners were mainly associated with the particle phase (six-ring PAHs, 55%). The concentrations of PCBs (ranging from 0.6 to 42 ng m–3) were higher than those reported in other cities in Algeria and Europe. The source reconciliation of organic contaminants through principal component analysis (PCA) demonstrated that the primary sources were petroleum combustion, industrial manufacturing, tobacco smoking, and vehicular traffic. The significance of tobacco smoke was further confirmed by the analysis of PAH diagnostic ratios. Differences in the rates of diagnostic ratios between gaseous and particulate PAHs were attributed to distinct contributions from sources such as industrial processes. Health risks for workers exposed to PAHs and PCBs in PM < 10 μm (PM10) were quantitatively assessed in terms of benzo[a]pyrene equivalent concentration and incremental lifetime cancer risk (ILCR). The ILCR presents novel findings showcasing heightened risks among workers exposed to specific PAHs within production areas, whereas those related to PCBs suggested a high potential of health risks for laboratory workers.

Confounding effects of seasonality and anthropogenic river regulation on suspended particulate matter-driven mercury transport to coastal seas

Riverine mercury (Hg) is mainly transported to coastal areas in suspended particulate matter (SPM)-bound form, posing a potential threat to human health. Water discharge and SPM characteristics in rivers vary naturally with seasonality and can also be arbitrarily disrupted by anthropogenic regulation events, but their effects on Hg transport remain unresolved. Aiming to understand the confounding effects of seasonality and anthropogenic river regulation on Hg and SPM transport, this study selected the highly sediment-laden Yellow River as a representative conduit. Significant variations in SPM concentrations (108 − 7097 mg/L) resulted in fluctuations in total mercury (THg, 3.79 − 111 ng/L) in river water corresponding to seasonality and anthropogenic water/sediment regulation. Principal component analysis and structural equation model revealed that SPM was the essential factor controlling THg and particulate Hg (PHg) in river water. While SPM exhibited equilibrium state in the dry season, a net resuspension during the anthropogenic regulation and net deposition in the wet season demonstrated the impact of SPM dynamics on Hg distribution and transport to coastal regions. Combining water discharge, SPM, and Hg concentrations, a modified model was developed to quantify Hg flux (2256 kg), over 98% of which was in particulate phase.

Characterization of suspended particulate matter using cascade impactor and X-ray fluorescence

Atmospheric pollution has become one of the biggest environmental and public health problems in large urban centers. The process of industrialization and urbanization of large cities together with population growth and motorized transport has caused an increase in the level of air pollution in these places. Thus, this work approaches the characterization of suspended particulates in the surroundings of the Duque de Caxias Refinery (REDUC) from the identification of the chemical elements present using the X-ray fluorescence technique - XRF. A PIXE 8-stage impactor was used to collect the particulate material (aerodynamic diameters of 16 – 0.12 µm). On the other hand, the experimental measurements of XRF were performed using a commercial system ARTAX 200 (Bruker) and under the following conditions: voltage of 45 kV, current of 500 µA, acquisition time of 300 s and no filter in the incident X-ray beam. The study allowed estimating the dimensions of the particulate materials, identifying the chemical elements present and pointing out possible sources, from samples collected in three residential points that are in the surroundings of REDUC in the region of Campos Elísios. The X-ray fluorescence technique proved to be efficient and it was possible to detect the following chemical elements: Silicon, Sulfur, Chlorine, Potassium, Calcium, Titanium, Manganese, Iron, Nickel and Zinc. Correlations were observed between some elements making it possible to identify possible sources of pollution.

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).

Characterization of suspended particulate matter in contrasting coastal marine environments with angle-resolved polarized light scattering measurements.

Optical proxies based on light scattering measurements have potential to improve the study and monitoring of aquatic environments. In this study, we evaluated several optical proxies for characterization of particle mass concentration, composition, and size distribution of suspended particulate matter from two contrasting coastal marine environments. We expanded upon our previous study of Southern California coastal waters, which generally contained high proportions of organic particles, by conducting angle-resolved polarized light scattering measurements in predominantly turbid and inorganic-particle dominated Arctic coastal waters near Prudhoe Bay, Alaska. We observed that the particulate backscattering coefficient bbp was the most effective proxy for the mass concentration of suspended particulate matter (SPM) when compared with particulate scattering and attenuation coefficients bp and cp. Improvements were seen with bbp as a proxy for the concentration of particulate organic carbon (POC), although only if particulate assemblages were previously classified in terms of particle composition. We found that the ratio of polarized-light scattering measurements at 110º and 18º was superior in performance as a proxy for the composition parameter POC/SPM in comparison to the particulate backscattering ratio bbp/bp. The maximum value of the degree of linear polarization DoLPp,max observed within the range of scattering angles 89°-106° was found to provide a reasonably good proxy for a particle size parameter (i.e., 90th percentile of particle volume distribution) which characterizes the proportions of small- and large-sized particles. These findings can inform the development of polarized light scattering sensors to enhance the capabilities of autonomous platforms.

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.

Degradation and Aging of Terrestrial Organic Carbon within Estuaries: Biogeochemical and Environmental Implications.

Estuaries are action zones for organic carbon (OC) degradation and aging. These processes influence the nature of terrestrial OC (OCterr) export and the magnitude of OCterr burial in marginal seas, with important environmental implications such as CO2 release and hypoxia. In this study, we determined the contents and carbon isotopic compositions (13C and 14C) of bulk OC and fatty acids (FAs) as well as the sedimentological characteristics of suspended particulate matter (SPM) samples collected from two sites over four seasons and of surface sediment samples from three sites in the Pearl River estuary (PRE) to evaluate processes controlling OCterr degradation and aging along an estuarine gradient. We found that the abundance-weighted average C24-32FA 14C ages increased by an average of ∼1170 years for SPM and by an average of ∼3440 years in PR/PRE sediments, along the ∼60 km PRE transect. These increases in the FA age coincided with an 86% decrease in the corresponding mineral surface area-normalized FA loading along the sediment transport pathway, implying that selective degradation of labile and younger OC resulted in apparent OC aging. These measurements reveal an important shift in the nature of OC, with implications for biogeochemical cycling within estuaries and for regional environmental changes.

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.

Spatiotemporal toxicity assessment of suspended particulate matter (SPM)–bound polycyclic aromatic hydrocarbons (PAHs) in Lake Chaohu, China: Application of a source-based quantitative method

The spatiotemporal associations between the emissions and environmental toxicities of polycyclic aromatic hydrocarbons (PAHs) in lake still remain an issue. Here, we focused on the suspended particulate matter (SPM)–bound PAHs in Lake Chaohu, China to quantitatively estimate their spatiotemporal toxicities from different sources. A source–based quantitative method, positive matrix factorization (PMF)–benzo[a]pyrene–based toxic equivalency (TEQBaP) model, was applied. Firstly, we investigated the spatiotemporal characteristics of SPM–bound PAHs. The concentrations of Σ21 PAHs ranged from 1646 to 19267 ng·g−1. Low–ring PAHs were found to have the highest fractions. T–distributed stochastic neighbor embedding (t–SNE)–partitioning around medoid (PAM) technic revealed significantly spatiotemporal variation characteristics of SPM–bound PAHs in Lake Chaohu. Season, location (west or east lake zone), and sample classification (estuary or lake) together governed the patterns. Then, their potential sources were apportioned. Our results found that diagnostic ratios did not work perfectly. However, 3 factors were separated by PMF model. Unburned petroleum (F1), biomass, coal and gasoline combustion (F2), and diesel, straw combustion (F3) were the main sources of PAHs, accounting for 36.16%, 48.96% and 14.88%, respectively. The patterns of the source profiles were season–dependent. Finally, the toxicity of SPM–bound PAHs from different sources were predicted by PMF–TEQBaP model, and the model predictions were satisfactorily acceptable. Overall, predicted Σ19 TEQBaP of SPM–bound PAHs in Lake Chaohu ranged from 20.8 to 947.9 ng·g−1. Benzo[e]pyrene (BeP), benzo[a]pyrene (BaP) and benzo[b]fluoranthene (BbF) were the main toxic species. Temporally, PAH toxicity posed significantly seasonal differences. F3 had primary contributions to Σ19 TEQBaP. Cutting the diesel consumption and using cleaner energy substitutes were suggested to reduce the PAH toxicity in Lake Chaohu. Overall, we expected this study could give new insights into the spatiotemporal associations between the sources and toxicities of SPM–bound PAHs in lake ecosystem.

BALANCE OF GLUTATHIONE-RELATED PROCESSES IN ALVEOLAR MACROPHAGES UNDER EXPOSURE TO SUSPENDED PARTICULATE MATTER OF ATMOSPHERIC AIR IN OF WISTAR RATS

Introduction. Air suspended particulate matter (SPM) directly influence on the human respiratory system. Dispersion is one of the characteristics of SPM determining their pathogenicity. Alveolar macrophages (AMs) produce reactive oxygen species in response to an exposure that may lead to oxidative stress. The aim of the study. To assess the contribution of the glutathione antioxidant system to the protection of AMs from oxidative stress induced by air SPMs in Vladivostok’s districts with various man-made loads. Material and methods. AMs were isolated from bronchoalveolar lavage of 17 Wistar rats. AMs were exposed by model suspensions (MS) for 2 days. MSs were identical air composition of Vladivostok’s districts with insignificant (MS № 1) and high (MS № 2) technogenic load. MS № 1 contained 22% of particles with a diameter of less than 10 µm. MS № 2 contained 70% of particles with a diameter smaller than 10 μm. The levels of malondialdehyde, glutathione and total antioxidant activity in cell culture and culture fluid were determined. Results. The gain in the proportion of fine and ultrafine particles in MS № 2 has been established to lead to an increase in lipid peroxidation in AMs and a compensatory elevation in the antioxidant activity. The elevation of oxidized glutathione concentration in cell culture indicates the intensification of hydroperoxide detoxification by AMs. The reduction of reduced glutathione exocytosis supports intracellular antioxidant processes. Conclusion. An increase in the fraction of fine and ultrafine particles in the air appears to shift AM redox balance towards oxidative stress, contributing to the formation and the progression of pathological disorders.

Biogeochemical characteristics of suspended particulate matter in deep chlorophyll maximum layers in the southern East China Sea

Abstract. Continental shelves and marginal seas are key sites of particulate organic matter (POM) production, remineralization and sequestration, playing an important role in the global carbon cycle. Elemental and stable isotopic compositions of organic carbon and nitrogen are thus frequently used to characterize and distinguish POM and its sources in suspended particles and surface sediments in the marginal seas. Here we investigated suspended particulate matter (SPM) collected around deep chlorophyll maximum (DCM) layers in the southern East China Sea for particulate organic carbon and nitrogen (POC and PN) contents and their isotopic compositions (δ13CPOC and δ15NPN) to understand provenance and dynamics of POM. Hydrographic parameters (temperature, salinity and turbidity) indicated that the study area was weakly influenced by freshwater derived from the Yangtze River during summer 2013. Elemental and isotopic results showed a large variation in δ13CPOC (−25.8 to −18.2 ‰) and δ15NPN (3.8 to 8.0 ‰), but a narrow molar C ∕ N ratio (4.1–6.3) and low POC ∕ Chl a ratio (< 200 g g−1) in POM, and indicated that the POM in DCM layers was newly produced by phytoplankton. In addition to temperature effects, the range and distribution of δ13CPOC were controlled by variations in primary productivity and phytoplankton species composition; the former explained ∼ 70 % of the variability in δ13CPOC. However, the variation in δ15NPN was controlled by the nutrient status and δ15NNO3- in seawater, as indicated by similar spatial distribution between δ15NPN and the current pattern and water masses in the East China Sea; although interpretations of δ15NPN data should be verified with the nutrient data in future studies. Furthermore, the POM investigated was weakly influenced by the terrestrial OM supplied by the Yangtze River during summer 2013 due to the reduced sediment supply by the Yangtze River and north-eastward transport of riverine particles to the northern East China Sea. We demonstrated that the composition of POM around DCM layers in the southern East China Sea is highly dynamic and largely driven by phytoplankton abundance. Nonetheless, additional radiocarbon and biomarker data are needed to re-evaluate whether or not the POM around the DCM water depths is influenced by terrestrial OM in the river-dominated East China Sea.

Spatiotemporal changes in the concentration and composition of suspended particulate matter in front of Hansbreen, a tidewater glacier in Svalbard

Summary Tidewater glaciers supply large amounts of suspended particulate matter (SPM) and freshwater to fjords and affect oceanographic, sedimentological and biological processes. Our understanding of these processes, is usually limited to the short summer season. Here, we present the results of a one-year-long monitoring of the spatial variability in SPM characteristics in a context of oceanographic and meteorological conditions of a glacial bay next to Hansbreen, a tidewater glacier in Hornsund (southern Spitsbergen). The observed range of SPM concentrations was similar to ranges measured in other sub-polar glaciated fjords, especially in Svalbard. The major source of SPM is the meltwater discharge from the glacier. The maximum water column-averaged SPM concentrations did not correlate with peaks in freshwater discharge and were observed at the beginning of the autumn season, when the fjord water transitioned from stratified to fully mixed. The observed spatiotemporal variations in the total SPM, particulate organic matter (POM) and particulate inorganic matter (PIM) are likely controlled by a combination of factors including freshwater supply, water stratification and circulation, bathymetry, the presence of sea ice, biological productivity and sediment resuspension. During the ablation season, the SPM maximum concentrations were located within the upper water layer, whereas during the winter and spring, the greatest amounts of SPM were concentrated in deeper part. Thus, typical remote sensing-based studies that focus on SPM distributions may not reflect the real SPM levels. POM and PIM concentrations were correlated with each other, during most of the time suggesting that they may have a common source.

Characteristics of suspended particulate matter in a typical slow-moving river of northern China: Insight into its structure and motion behavior

To investigate the characteristics of suspended particulate matter (SPM) in rivers of northern China, SPM was collected from 20 sampling sites within the severely polluted slow-moving Ziya River Mainstream (ZRM) and from 20 sampling sites within the less-polluted fast-moving Luanhe River (LR) between October and November of 2016. Physical and chemical attributes of river water from the ZRM and LR were measured; the microstructure, specific surface area and particle size of the SPM were also determined. The SPM had thicker organic coated layers on inorganic particles within the ZRM, compared with the LR, indicating strong interaction of the SPM with the water column. Along the ZRM length, these organic coated layers evolved, first plugging particle pores and then increasing in volume, causing the specific surface area to decrease at first and then increase. The presence of organic coated layers on inorganic particles greatly changed their particle size, density and inducing changes in their motion behavior. Such changes in SPM microstructure were most apparent in the slow-moving polluted ZRM. Given that SPM can adsorb contaminants, such as phosphorus and heavy metals, onto its surfaces and transport them downstream, these changes could have a profound impact on both sediment transport and river ecosystem function. Our results suggest we need to reevaluate our previous river management measures for slow-moving polluted rivers.

Influence of environmental factors on absorption characteristics of suspended particulate matter and CDOM in Liaohe River watershed, northeast China.

Absorption characteristics of optically active substances, including non-algal particles, phytoplankton, and chromophoric dissolved organic matter (CDOM), were measured in conjunction with environmental factors in five rivers within the Liaohe River watershed. Spectral absorption of non-algal particles [a NAP(λ)] was similar to that of total particles for most samples, suggesting that the absorption of the total particles [a p(λ)] was dominated by a NAP(λ). The CDOM absorption spectra [a CDOM(λ)] of West Liaohe and Taizihe rivers were easily distinguished from those of Hunhe, Liaohe, and East Liaohe rivers. Redundancy analysis indicated that absorption by optically active substances and anthropogenic nutrient disturbances probably resulted in the diversity of water quality parameters. The environmental variables including dissolved organic carbon, total alkalinity (TAlk), and total nitrogen (TN) had a significant correlation with CDOM absorption at 440nm [a CDOM(440)]. There was almost no correlation between a p(λ) and chlorophyll a, TN, total phosphorus, and TAlk. Moreover, total copper ion concentration and mercury ion concentration had a strong correlation with a p(440), a p(675), a NAP(440), and a NAP(675). The concentration of total aluminum ions exhibited a positive correlation with a p(675) and a NAP(675) (p<0.05), and a significant correlation was observed between total arsenic concentration and a CDOM(440). Furthermore, the interaction between metal ions and optically active substances provided an insight into particulates and CDOM properties linked to water quality characteristics for rivers in semiarid areas.

Spatial and temporal variations of particulate organic matter from Moselle River and tributaries: A multimolecular investigation

The spatial and temporal composition of organic matter (OM) was investigated in the Moselle watershed (Lorraine, France). The spatial composition was studied using different stations along the river and four tributaries. In addition, one anchor station was used in order to better understand the temporal OM composition during different hydrologic regimes and seasons. The first part of the organic characterization consisted of the extraction of the lipid. OM with an automatic extractor. The extracts were analyzed for their lipid fatty acids (Lip-FAs), polycyclic aromatic hydrocarbons (PAHs) and sterols using gas chromatography-mass spectrometry (GC–MS). The insoluble fraction was also analyzed with thermochemolysis-GC–MS (TMH-GC–MS) using tetramethylammonium hydroxide (TMAH) and lignin phenols, permethylated deoxy aldonic acids and refractory FAs (Ref-FAs) were analyzed. The results showed that one station (Florange station) on the small Fensch stream tributary displayed variation in the composition of the molecular OM, with higher microbial markers (C16:1, C18:1w7, C18:1w9, coprostanol) inputted to the highly industrialized and urbanized areas in this small sub-catchment. The other stations showed rather similar organic composition (Lip-FAs, Ref-FAs, sterols, lignin compounds, PAHs) due to the size of the catchment (10,000km2) or the integrative state of the suspended particulate matter (SPM). The regime flow involved a decrease in SPM OM content as well as a decrease in the palmitoleic acid/palmitic acid (C16:1/C16:0) ratio and an increase in the (stigmastanol+sitostanol+stigmasterol+sitosterol)/(cholesterol+cholestenol) (C29/C27(ST)) ratio, revealing the presence of more allochthonous OM. The increase in regime flow was also correlated with a growing contribution of more degraded OM to the SPM that could be related to the leaching of subsurface soils from the watershed or to the remobilization of surface sediments. Seasonal variations were also observed, with a stronger contribution of autochthonous production during low flow level in summer. The work shows the importance of OM characterization of SPM in order to better assess the spatial and temporal OM variation in the water column.

Grain Size Distribution Characteristics of Suspended Particulate Matter as Influenced by the Apparent Pollution in the Inorganic Type Urban Landscape Water: Taking the Canal of Suzhou Section as Example

Grain size distribution characteristics of suspended particulate matter(SPM) provides important information for water environment apparent quality. The size distribution characteristics and influencing factors of suspended particulate matter under different apparent pollution levels in the inorganic type urban landscape water were discussed taking the canal which is flowing through Suzhou as the research object. The apparent pollution mechanism of inorganic type urban landscape water was explained from the aspect of the size of the suspended particles. The results showed that: SPM had mainly a uni-modal distribution in the inorganic type water, and the median particle diameter range was 13-25.2 μm. The component Ⅱ was perdominant, and the particle size range was 3.8-16 μm(with an average volume fraction of 29.4%-59.6%). Sensitive components of the apparent polluted water were component Ⅱ and component Ⅳ (particle size range 32-64 μm). The relation of the sensation pollution index(SPI) and component Ⅱ was segmented, and the node was 45NTU. When the turbidity was less than 45NTU, SPI value and volume fraction of component Ⅱ had a significant positive correlation, and volume fraction of component Ⅳ had a significant negative correlation with SPI value; when the turbidity was equal to or greater than 45NTU, the correlation was the opposite. The influencing factors of particle size distribution of Suzhou canal mainly included organisms and hydrodynamic conditions. The biological factors mainly led to increase of the algae and the hydrodynamic condition caused resuspension and increased the large particles.

Effects of riverine suspended particulate matter on the post-dredging increase in internal phosphorus loading across the sediment-water interface

Dredging is frequently used in the river mouths of eutrophic lakes to reduce internal phosphorus (P) loading from the sediment. However, the accumulation of P-adsorbed suspended particulate matter (SPM) from the inflowing rivers negatively affects the post-dredging sediment-water interface and ultimately increases internal P loading. Here, a 360-d experiment was carried out to investigate the influence of riverine SPM on the efficacy of dredging in reducing internal P loading. SPM was added to dredged and undredged sediments collected from the confluence area of Lake Chaohu. Several parameters related to internal P loading, including oxygen profile, soluble reactive P, and ferrous iron across the sediment-water interface, organic matter, alkaline phosphatase activity, and P fractions, were measured throughout the experimental period. The results showed that the P content (especially mobile P) in the sediment increased to the pre-dredging level with the accumulation of SPM in the dredged sediment. In addition, the P flux across the sediment-water interface increased with the accumulation of SPM. Several characteristics of SPM, including high organic matter content, mobile P, high activity of alkaline phosphatase, and high biological activity, were considered correlated with the post-dredging increase in internal P loading. Overall, this study showed that the heavily contaminated riverine SPM regulates the long-term efficacy of dredging as a nutrient management option in the confluence area. Management is needed to avoid or reduce this phenomenon during dredging projects of this nature.

Characterisation of suspended particulate matter in the Rhone River: insights into analogue selection

Environmental contextThe fate and behaviour of pollutants such as pesticides, metals and nanoparticles in natural waters will influence their effects on the environment and human health. Owing to the complexity of natural waters and suspended particulate matter (SPM) that can interact with pollutants, as well as low pollutant concentrations, determination of pollutant fate and transport is non-trivial. Herein, we report a characterisation of the Rhone River chemistry to provide insight into selecting SPM analogues for experimental and modelling approaches. AbstractSelection of realistic suspended particulate matter (SPM) analogues remains vital for realising representative experimental and modelling approaches in predicting the environmental fate of pollutants. Here, we present the characterisation of dissolved-ion and SPM compositions for nine sampling sites over the length of the Rhone River. Dissolved-ion concentrations remained stable, but SPM concentrations varied among sampling sites. Size fractionation and mineralogical characterisation of the SPM revealed that the same minerals (e.g. quartz, calcite, muscovite) constituted every size class from 0.5 to &gt;50µm, as is usually found with allochthonous and large-scale systems. To gain insight into SPM analogue selection, aggregation kinetics of silica, calcite, muscovite, feldspars and clays were monitored in the native filtrate and related to the respective zeta potentials (ζ). An SPM mixture of calcite (49%), muscovite (14%), feldspar (23%) and chlorite (14%) proved the best match for the Rhone SPM, demonstrating that mineral surface chemistry, structure and size are all important in selecting a realistic SPM analogue for a riverine system.

Characterization of suspended particulate matter in the Moselle River (Lorraine, France): evolution along the course of the river and in different hydrologic regimes

Purpose Suspended particulate matter (SPM) plays an important role in the transport and fate of contaminants in the environment. To better understand the relationships between contaminants and SPM, SPM properties, and their variations with flow regime, river size, land use, and season should be considered.

Effects of riverine suspended particulate matter on post-dredging metal re-contamination across the sediment-water interface.

Environmental dredging is often used in river mouth areas to remove heavy metals. However, following dredging, high levels of metal-adsorbed suspended particulate matter (SPM) originating from polluted inflowing rivers might adversely affect the sediment-water interface (SWI). Here, we conducted a 360-day-long experiment investigating whether the riverine SPM adversely affects dredging outcome in a bay area of Lake Chaohu, China. We found that the heavy metal concentrations in the post-dredging surface sediment increased to pre-dredging levels for all metals studied (As, Cd, Cr, Cu, Ni, Pb, and Zn) after the addition of SPM. In addition, the increased concentrations were mostly detected in the relatively bioavailable non-residual fractions. Of the metals studied, the rate of increase was the greatest for Zn and Cd (482.98% and 261.07%, respectively), mostly in the weak acid extractable fraction. These results were probably due to certain characteristics of SPM (fine grain size, and high concentrations of organic matter and heavy metals) and the good oxic conditions of the SWI. Furthermore, As was the only metal for which we observed an increasing trend of diffusive flux across the SWI. However, the flux was still significantly lower than that measured before dredging. In conclusion, the quantity and character of riverine metal-adsorbed SPM affect metal re-contamination across the post-dredging SWI, and this information should be incorporated into the management schemes of dredging projects dedicated to reducing metal contamination in similar areas.