Role Of Suspended Particles Research Articles

Layer-specific mechanisms of perfluoroalkyl acid (PFAA) transport and partition in estuarine environments: Unveiling the depth-dependent differences

Understanding of characteristics and transport of perfluoroalkyl acids (PFAAs) in heterogeneous estuarine environments is limited. Furthermore, the role of suspended particles (SPS) in different layers remains unclear. This study explores the multiphase distribution process and mechanism of PFAAs controlled by SPS across surface and bottom layers in five small estuaries. Peaks in PFAA concentrations are consistently observed at strongly stratified sites. Concentrations of the PFAAs in both surface and bottom SPS decreased as the degree of mixing increased from strongly stratified levels to well-mixed levels. The water-SPS partitioning of some short-chain PFAAs (PFBS, PFHxA, and PFHpA) is influenced by environmental factors (pH, depth, temperature, and salinity) due to electrostatic interactions, while the sorption of some long-chain PFAAs (PFOA, PFOS, and PFNA) is controlled by SPS and dissolved organic carbon (OC), driven by hydrophobic interactions. Additionally, SPS dominates OC transport in estuarine systems, except in sandy sediment environments. SPS plays a dominant role in PFAA partitioning in both surface and bottom water-SPS systems (p < 0.05), and salinity only significantly affects PFBS in bottom layer (p < 0.01). These findings are critical for understanding the drivers of PFAA partitioning and the roles of SPS in different layers, underscoring the necessity of considering particle-associated PFAA fractions in future coastal environmental management.

Microparticles in the air of industrial cities as a risk factor of bronchial asthma

Introduction. Suspended particles in ambient air of cities increase the risk of developing respiratory and cardiovascular diseases. At the same time, data on the role of suspended particles in the formation and complication of the course of bronchial asthma (BA) are extremely limited. The aim of study was to substantiate the design of a study to study the effect of fine suspended particles in atmospheric air on the development of the T2 endotype of BA. The design of a "case-control" study was developed and implemented, including patients with the T2-endotype of BA and persons in the control group. In order to verify the diagnosis of BA, General clinical methods of examination and specific allergological examination are used. In parallel, the quantitative characteristics and qualitative composition of suspended particles in atmospheric air are studied with the determination of the mass of suspended particles, dispersion, chemical and microbiological (muldi-tof mass spectrometry, PCR analysis) composition. Atmospheric air samples will be collected using a cascade impactor in the area where patients with bronchial asthma and control groups live. For each fraction, the following will be analyzed: suspended particle mass, dispersion, chemical and microbiological (muldi-tof mass spectrometry, PCR analysis) composition. Conclusions. The study will assess the risk of T2-endotype formation of bronchial asthma with various quantitative and qualitative characteristics of suspended microparticles in the atmospheric air.

Ti-6Al-4V Surfaces in SiC Powder Mixed Electrical Discharge Machining

The role of suspended particles on Ti-6Al-4V surface in Powder Mixed Electrical Discharge Machining (PMEDM) is studied using SiC powder mixing in water dielectric liquid. Surface modifications due to the additives in dielectric liquid are investigated by means of optical, scanning electron microscopy and energy dispersive spectroscopy. The attachment of added powders and surface topographies interrelated with powder suspension concentration, particle size and electrical parameters such as pulse on duration and current. The influence on discharge transitivity with respect to SiC additives is noticed with pock like features on the surface. The geometry and size of these features indicated a robust dependency with respect to operational parameters and indicated the role of secondary discharges during PMEDM. SiC particles severely transferred from di-electric liquid to machined surface at critical operational parameters and implied that the process could be also used as a surface alloying technique.

Role of suspended particles for extracellular enzyme activity and biotic control of pelagic bacterial populations in the large lowland river Elbe

Large rivers are often highly loaded with suspended particles, but the microbial metabolism related to these particles has rarely been studied. Hence, we investigated activities of the extracellular enzymes leucine aminopeptidase (LAP), phosphatase, β-D-glucosidase and exo-1,4-β-glucanase as well as microbial communities associated with suspended particles from the 8 th order River Elbe, and their potential controls. Three fractions were investigated separately - rapidly sinking particles (largest particles), intermediately sinking particles (medium- sized particles), and bulk water including slowly sinking particles (smallest particles). Overall, bulk water had the highest abundances of bacteria, heterotrophic fl agellates and ciliates. Extracellular enzyme activities per dry mass were also highest in bulk water, as 83-95 % of total bacteria occurred in this fraction. Medium-sized and large particles had lower enzyme activity per dry mass because of their smaller relative surface area and lower propor- tions of particulate organic carbon (POC) and particulate nitrogen (PN). Bulk water, the medium-sized and the largest particle fractions contributed 40-85 %, 5-20 % and 10-40 % to total enzyme activity per volume of river water, respectively. Leucine aminopeptidase exhibited its highest relative activity in bulk water, which also had the highest chlorophyll-a content. Cell-specifi c enzyme activities were generally correlated with the availability of particulate organic matter (POM) per bacterial cell and were therefore highest on medium and large-sized particles. These results indicate that the abundance and activity of attached bacteria were bottom-up controlled by the size and biochemical composition of the particles. However, bacterivorous fl agellates and ciliates were abundant on the larger particles. Thus, number and feeding types of particle-attached protozoans suggest that top-down control may have occurred during an algal bloom. Our results show that free-living bacteria dominated the overall microbial metabolism of the water column in the River Elbe. However, bacteria attached to medium-sized and large particles were the most active ones, and contributed 15-58 % to total extracellular enzyme activity in the water column, depending on enzyme and season.

Influences of Suspended Particles on the Runoff of Pesticides from an Agricultural Field at Askim, SE-Norway

Field and laboratory experiments were conducted to study the loss of particles from agricultural fields, and the role of suspended particles in carrying pesticides in surface runoff and drainage water. Propiconazole, a widely used fungicide was applied to experimental fields located at Askim, SE-Norway. Samples from surface runoff and drainage water were collected and analyzed for sediment mass, pesticides, particulate and dissolved organic carbon through a whole year. The surface soil and the runoff material were characterized by its particle size distribution, organic carbon content in size fractions and its ability to bind propiconazole. The results show that (1) particle runoff mostly occurred during the rainfall event shortly after harrowing in autumn. The highest particle concentration observed in the surface runoff water was 4600 mg l(-1), and in the drainage water 1130 mg l(-1); (2) the erosion of surface soil is size selective. The runoff sediment contained finer particle/aggregates rich in organic matter compared to its original surface soil; (3) the distribution coefficient (Kd) of propiconazole was significantly higher in the runoff sediment than in the parent soil. According to our calculation, particle-bound propiconazole can represent up to 23% of the total amount of propiconazole in a water sample with a sediment concentration of 7600 mg l(-1), which will significantly influence the transport behavior of the pesticide.

95/05401 The role of suspended particles in the discharge of 210Pb and 7Be within the Kuji River watershed, Japan

95/05401 The role of suspended particles in the discharge of 210Pb and 7Be within the Kuji River watershed, Japan

The role of suspended particles in the discharge of 210Pb and 7Be within the Kuji River watershed, Japan

Fluvial discharge of atmospherically-derived 210Pb and 7Be was studied in the Kuji River watershed in Japan. The daily load of 210Pb and 7Be, associated with suspended particles, greatly increased during high-flow conditions. However, the activity concentrations of 210Pb and 7Be in the suspended particles were found to be rather independent of the flow rate. Due to this feature, the daily load of the activities associated with the suspended particles was mainly controlled by that of the suspended particles. Compared with the other reported values, the estimated mean residence time of atmospherically-derived 210Pb in the present study was rather short (about 800 years), possibly reflecting the high availability of the suspended particles eroded from the top soil in the watershed. The annual load of 210Pb and 7Be was predominantly of particulate form (approx 90%). These results suggest that the fluvial discharge of atmospherically-derived, highly adsorptive (k d ≳ 10 4 mg l −1) radionuclides in a river watershed is primarily due to the discharge of suspended particles, which strongly depends on the flow rate of river water and also on the location of the watershed.

Subsurface Migration of Radioactive Waste Materials by Particulate Transport

The role of suspended particles as carriers of dissolved nuclides from high-level radioactive waste repositories has been investigated. Depending on the concentrations of suspended particles and th...