Concentration Of Suspended Particles Research Articles

Seasonally variable interactions between dissolved organic matter and mineral particles in an agricultural river

Streams and rivers form an important link in the global carbon cycle by transporting and transforming large amounts of carbon imported from terrestrial ecosystems to the oceans. Since streams in agricultural areas often experience increased concentrations of suspended mineral particles from soil erosion, they are important sites where dissolved organic carbon (DOC) may be adsorbed to particles and retained in the sediment. As the extent of adsorption varies with the molecular composition of dissolved organic matter (DOM), which is seasonally variable, we expect also the fraction of organic material that adsorbs to mineral particles to fluctuate over time. We sampled the agriculturally impacted River Fyrisån (Sweden) monthly during 1 year, and measured DOC concentration and DOM composition based on several optical properties. At each sampling occasion, we estimated the potential for adsorption by exposing the samples to a reference clay. The potential for adsorption was greatest when riverine DOM had the most terrestrial character, as this fraction of the DOM pool was selectively adsorbed to clay surfaces. The extent of adsorption was negatively related to the concentration of base cations, most notably calcium. We suggest that the observed relationships between the potential for adsorption, DOM composition and base cations are linked by discharge. A bioavailability test at one sampling occasion suggested that DOM remaining after exposure to clay particles was more biodegradable. This implies that adsorption may alter the degradation potential of DOM remaining in solution, which could have far reaching effects on the fate of organic carbon.

Geochemical mobility of 137Cs in marine environments based on laboratory and field studies

Cesium-137, a unique geochemical tracer, behaves as a particle-reactive species in freshwater that is useful as a geochronometer, and soluble in seawater that is used as a water mass tracer, as evidenced by higher solid-solution partition coefficient, Kd, in freshwater and much lower Kd values in seawater. A suite of sediment cores were collected from the Southern Yellow Sea and coastal regions of Croatia in 2014 and analyzed for vertical profiles of excess 210Pb (210Pbex), 239+240Pu, and 137Cs. A set of laboratory experiments were also conducted to investigate the partitioning of 137Cs between a suite of solid material comprised of commonly occurring minerals in the environment and solution under different contact times, pH, and salinity. The partition coefficient showed that for illite Kd sharply increased during the first two hours and then slowly increased after 4 h. Overall, the salinity significantly affects the 137Cs behavior in aqueous environments. The Kd values of 137Cs were higher (6.5 × 103–1.1 × 104 mL g−1) when the salinity was below 0.5 psu but drastically decreased to 9.0 × 102 mL g−1 when salinity was 3.6 psu and then slowly decreased to 2.7 × 102 mL g−1 with the salinity of 27.5 psu. Combining with the previously published results, it is observed that higher suspended particle (SPM) concentration could enhance the Kd values of 137Cs when SPM was below 12 mg L−1. Our results show that post-depositional mobility of 137Cs in the marine environment, except for river-dominated coastal areas, result in the 137Cs chronology is not suitable to validate the 210Pbex-based chronology. The penetration depths of 137Cs were found to be much deeper than it was expected based on the 137Cs and 239+240Pu peak and 210Pb chronology. Chitin showed a higher affinity for 137Cs than clay particles (e.g., smectite and illite). The desorption experiment showed that the NH4+ could leach 5.6% of sorbed 137Cs, accounting for 79% of the total exchangeable fraction while 2.8% of the total 137Cs was bound to organic matter. These observations support the field observation degradation of organic matter in anoxic marine sediment could enhance the mobility of 137Cs.

Disinfection and particle removal by a nature-based Daphnia filtration system for wastewater treatment

Nature-based solutions (NBS) to treat wastewater are ecological treatments that work to mitigate the impact of conventional systems in wastewater treatment processes. In this study, the efficiency of an innovative wastewater tertiary treatment based on Daphnia filtration in removing suspended solids and E. coli is evaluated in combination with either vermifiltration or conventional secondary treatments. Daphnia filtration NBS was found to increase particle removal and E. coli inactivation over a wide range of water temperatures, solar radiation intensities, and hydraulic residence times. Moreover, two models to predict the quality of the treated wastewater, one that describes the removal of particles and another for E. coli inactivation, are developed and presented here. Both models depend on water temperature, the exposure to solar radiation and the hydraulic residence time in the reactor. The results using these models align with the experimental results in all cases. Hydraulic residence times above 24 h allowed suspended particle concentrations to be reduced by >75 % with water temperatures in the range of 10 °C to 27 °C and for E. coli to be inactivated by 1–3 log units in water temperature ranging from 8 °C to 27 °C. The developed models can also be used to provide information regarding the operating conditions (i.e. hydraulic residence times) required to obtain the desired regenerated water quality in accordance with reuse purposes and the regulations of different countries.

The composition of organic phosphorus in a river during the springtime irrigation period

Study regionThe study region was the Sakura River, a tributary of Lake Kasumigaura, Japan. Study focusWe asked whether particulate organic phosphorus (POP) contributed to the P cycle in rivers. Previous studies have focused on the interaction between PO43– and particulate inorganic P (PIP), but our study focused on whether POP could also be the source of PO43–. New hydrological insights for the regionAfter rain events during irrigation, concentrations of suspended particles and particulate P (PP) increased. POP accounted for 42.4 % of PP concentrations. The PIP and POP concentrations were both positively correlated with suspended particle concentrations. The PO43– concentrations were significantly higher during decomposition experiments when suspended particles were present in the water. Decomposition experiments revealed that the P composition changed and the proportion of organic P decreased as DNA-P disappeared from the PP. The fact that the DOP concentration was significantly lower in the treatment with suspended particles than without suspended particles suggested that DOP mineralization rates were increased by the presence of suspended particles. In addition to mineral-sorbed P, the POP derived from the irrigation of paddy fields may also be bioavailable.

A numerical approach for preventing the dispersion of infectious disease in a meeting room

Airborne transmission of respiratory aerosols carrying infectious viruses has generated many concerns about cross-contamination risks, particularly in indoor environments. ANSYS Fluent software has been used to investigate the dispersion of the viral particles generated during a coughing event and their transport dynamics inside a safe social-distance meeting room. Computational fluid dynamics based on coupled Eulerian–Lagrangian techniques are used to explore the characteristics of the airflow field in the domain. The main objective of this study is to investigate the effects of the window opening frequency, exhaust layouts, and the location of the air conditioner systems on the dispersion of the particles. The results show that reducing the output capacity by raising the concentration of suspended particles and increasing their traveled distance caused a growth in the individuals' exposure to contaminants. Moreover, decreasing the distance between the ventilation systems installed location and the ceiling can drop the fraction of the suspended particles by over 35%, and the number of individuals who are subjected to becoming infected by viral particles drops from 6 to 2. As well, the results demonstrated when the direction of input airflow and generated particles were the same, the fraction of suspended particles of 4.125%, whereas if the inputs were shifted to the opposite direction of particle injection, the fraction of particles in fluid increased by 5.000%.

PAH atmospheric log(KP) values in Great Lakes samples are related to black carbon levels near each site

Many semi-volatile organic pollutants are present in the atmosphere both in the vapor and particle phases. About 50 years ago, a partition coefficient (KP) was defined as the compound's concentration in the particle phase (Cpart, in ng/m3 or pg/m3) divided by its concentration in the vapor phase (Cvapor, also in ng/m3 or pg/m3) divided by the atmospheric concentration of total suspended particles (TSP, in μg/m3) or, more recently, by the concentration of particulate matter with aerodynamic diameters less than 2.5 μm (PM2.5, also in μg/m3). The original point of this term was to account for surface adsorption of pollutants to the particles, but over the years it has become apparent that absorption, particularly to black carbon (BC, also known as elemental carbon) in the particles, may also be important. This study investigates the importance of this particle term using about 3000 polycyclic aromatic hydrocarbon (PAH) concentrations measured from 1997 to 2018 (inclusive) in 24-h samples collected once every 12 days at five sites on the shores of the North American Great Lakes and using U.S. Environmental Protection Agency PM2.5 concentrations at the same sites. Analyses of variance of the annual mean log(KP) values show significant differences for all six compounds among the five sites, which we attribute to the composition of the particles at the five sites. For example, the particles from the urban sites are likely to have higher black carbon levels compared to those from the more rural and remote sites. With an additional term for black carbon in these samples, these new ratios are similar across sites for a given compound. These results suggest that a black carbon term is useful and potentially important.

Assessment of inflammatory cytokines in exhaled breath condensate and exposure to mixtures of organic pollutants in brick workers.

Brick production causes a lot of pollution in the form of dust, fumes, and toxic substances. Therefore, brick workers are highly exposed to pollutants and present a high risk of developing respiratory diseases. The objective of this research was to determine the exposure to polycyclic aromatic hydrocarbons (PAHs) and toluene in urine and evaluate the effects on health using markers of oxidative stress in exhaled breath condensate (EBC) as well as the exposure to pollutants in suspended particles of the studied area. Exposure to PAHs and toluene was evaluated using hydroxylated markers (OH) of PAHs and hippuric acid in urine, respectively. Cytokines like TNF-α, INF-y, IL-2, IL-4, IL-6, IL-8, IL-10 y GMCSF in EBC were also evaluated. PM2.5 particles were measured during an 8-h work shift. The results in brick workers presented a total OH-PAHs concentration of 97.3µg/L and hippuric acid concentration of 0.2g/L. The environmental concentrations of suspended particles were found within a range of 41.67-3541.6μg/m3. The median of cytokines oscillated between 11.8pg/mL to 1041pg/mL. In conclusion, these results are similar to those of occupations in which there is high exposure to pollutants and populations with lung diseases. For that reason, the brick production sector requires prevention and control strategies against the pollutants emitted.

Numerical Imaging of the Seabed and Acoustic Flares with Topography and Velocity Variance

During seabed mapping, anomalous acoustic events in the seawater layer often degrade bathymetric quality. Acoustic-flare-like events that are induced by gas seepage occur accompanied by small seabed depressions known as pockmarks. In this study, we performed numerical imaging to verify whether acoustic flares are related to changes in the topography of the seabed. The input models assumed convex or concave upward structures which differ based on aperture size. The imaging study determined that acoustic flares appear because the sensing instrument measures the velocity changes in the water layer regardless of the seabed topography. Changes in the velocity of the seawater column can be caused by the concentration of suspended particles and the wave current above the seabed, but further quantification research is required.

In-Reservoir Physical Processes Modulate Aqueous and Biological Methylmercury Export from a Seasonally Anoxic Reservoir.

Anoxic conditions within reservoirs related to thermal stratification and oxygen depletion lead to methylmercury (MeHg) production, a key process governing the uptake of mercury in aquatic food webs. Once formed within a reservoir, the timing and magnitude of the biological uptake of MeHg and the relative importance of MeHg export in water versus biological compartments remain poorly understood. We examined the relations between the reservoir stratification state, anoxia, and the concentrations and export loads of MeHg in aqueous and biological compartments at the outflow locations of two reservoirs of the Hells Canyon Complex (Snake River, Idaho-Oregon). Results show that (1) MeHg concentrations in filter-passing water, zooplankton, suspended particles, and detritus increased in response to reservoir destratification; (2) zooplankton MeHg strongly correlated with MeHg in filter-passing water during destratification; (3) reservoir anoxia appeared to be a key control on MeHg export; and (4) biological MeHg, primarily in zooplankton, accounted for only 5% of total MeHg export from the reservoirs (the remainder being aqueous compartments). These results improve our understanding of the role of biological incorporation of MeHg and the subsequent downstream release from seasonally stratified reservoirs and demonstrate that in-reservoir physical processes strongly influence MeHg incorporation at the base of the aquatic food web.

Air pollutant removal by four sidewalk tree species in the largest city in Taiwan.

Air pollutants pose risks to human health, especially in densely populated cities. We compared the interception of suspended particles and metal elements by four sidewalk tree species with different leaf surface wettability (based on contact angle), leaf area, and phenology in Taipei, Taiwan. Suspended particles were enriched 2.0-2.5 times in throughfall relative to rainfall due to wash-off of suspended particles deposited on leaf surfaces during rainless periods. The enrichment in throughfall was greater in tree species with larger leaf areas. Despite greater concentrations of suspended particles in rainfall during the low-leaf-area period, enrichment was greater in the high-leaf-area period, indicating that leaf area was a key factor affecting canopy interception of pollutants. Throughfall enrichment of suspended particles positively correlated with water quantity, indicating that air pollutants intercepted by tree canopies were not fully washed off by rainfall. Annually, ∼830g of suspended particles were intercepted and washed off from one tree canopy, with a crown area of 42 m2 . Scaling up, a rough estimate of 72.7 Mg of suspended particles were intercepted annually by the 90,000 sidewalk trees in Taipei City. Copper, chromium, and aluminum were enriched in throughfall compared with rainfall. However, lead was depleted in throughfall, indicating greater interception than wash-off. Based on our results, leaf area and length of foliated period are key characteristics affecting canopy interception of particulate matter and associated metal elements, whereas leaf surface wettability is of secondary importance.

Influence of suspended inorganic particles (kaolinite) on eggs and larvae of the pelagic shrimp Lucensosergia lucens

The pelagic shrimp Lucensosergia lucens is a commercially important species in Japan, predominantly harvested in Suruga Bay. It has been suggested that a marked decrease in the wild population over recent years is associated with an increased concentration of suspended particles. We tested the hypothesis that suspended inorganic particles (kaolinite) negatively affect the hatching ratio of fertilized eggs, and the survival, growth, and metamorphosis of nauplius and elaphocaris larvae. The relative hatching ratio of eggs decreased from 100 to 57.7% at 139 mg L−1 of kaolinite particles. Similarly, the relative survival ratio of nauplius larvae progressively decreased from 100% in filtered seawater to 73.6% after 72 h of exposure to 139 mg L−1 of kaolinite particles. Consequently, the survival ratio of elaphocaris larvae was greatly reduced at high particle concentrations. Exponential growth in the standard lengths of elaphocaris larvae occurred at particle concentrations < 6.9 mg L−1, but growth was inhibited at kaolinite concentrations > 20 mg L−1.

Fall of a large sphere in a suspension of small fluidized particles

The investigation of the fall of a sphere at finite Reynolds number in a concentrated suspension of small fluidized particles leads to unexpected results regarding the drag force exerted by a suspension on a moving object. These results, which seem to be associated with a slip velocity of the particles near the surface of the sphere, call into question the interpretation of the effective rheology of suspensions.

Hypoxemia as the mechanism of acute cationic polymer toxicity in rainbow trout and prevention of toxicity using an anionic neutralizing polymer.

Industrial operations such as surface mining, road building, and aggregate washing result in high concentrations of suspended particles (Total Suspended Solids; TSS) in surface waters which must be treated prior to discharge into fish-bearing waters. A common industrial practice is to add flocculants to improve the efficacy and speed of TSS sedimentation. A significant environmental issue even small amounts of uncomplexed cationic polymer coagulant/flocculant remaining in treated water is highly toxic to fish at very low concentrations (LC50 ∼ 0.3 mg L-1). Fingerling trout (Oncorhynchus mykiss) were exposed to (1) a cationic flocculant (Water Lynx 800 (WL800), (2) a Clearflow neutralizing polymer (CN369), and (3) a combination of WL800 and CN369 at various ratios with measured LC50 as an index of toxicity. Acute toxicity was entirely reversed by addition of the neutralizing polymer at WL800:CN369 ratios >1:1.5mg/L. Furthermore, we demonstrate that the proximal mechanism of acute cationic polymer toxicity is hypoxemia due to accumulation of polymer on the gill epithelia rather than gill damage. Exposure of 0.5mg/L WL800 reduced oxygen consumption by >50% reduction by 12h and this was accompanied by significantly increased blood, brain, and liver [lactate] and [glucose]. The development of an inexpensive amelioration technique preventing cationic polymer toxicity is a significant advancement in surface and industrial water treatment to prevent cationic polymer mediated fish kills.

Effects of Migration and Diffusion of Suspended Sediments on the Seabed Environment during Exploitation of Deep-Sea Polymetallic Nodules

With the increase in demand for metal resources, research on deep-sea polymetallic nodule mining has been reinvigorated, but the problem of its environmental impact cannot be ignored. No matter what method is used for mining, it will disturb the surface sediments of the seabed, thereby increasing the concentration of suspended solid particles and metal ions in the water body, changing the properties of the near-bottom water body and sediments, and affecting biological activity and the living environment. Focusing on the ecological and environmental impacts of deep-sea polymetallic nodule mining, taking as our main subject of focus the dynamic changes in sediments, we investigated the environmental impacts of nodule mining and their relationships with each other. On this basis, certain understandings are summarized relating to the ecological and environmental impacts of deep-sea polymetallic nodule mining, based on changes in the engineering geological properties of sediment, and solutions for current research problems are proposed.

Spatialized Analysis of Air Pollution Complaints in Beijing Using the BERT+CRF Model

(1) Background: To better carry out air pollution control and to assist in accurate investigations of air pollution, in this study, we fully explore the spatial distribution characteristics of air pollution complaint results and provide guidance for air pollution control by combining regional air monitoring data. (2) Methods: By selecting the air pollution complaint information in Beijing from 2019 to 2020, in this study, we extract the names and addresses of complaint points, as well as the complaint times and types by adopting the BERT (bidirectional encoder representations from transformers) + CRF (conditional random field) model deep learning method. Moreover, through further filtering and processing of the complaint points’ address information, we achieve address matching and spatial positioning of the complaint points, and realize the regional spatial representation of air pollution complaints in Beijing in the form of a heat map. (3) Results: The experimental results are compared and analyzed with the ranking data of total suspended particulate (TSP) concentration of townships (streets) in Beijing during the same period, indicating that the key areas of air pollution complaints have a high correlation with the key polluted township (street) areas. The distribution of complaints and the types of complaints in each township (street) differ according to the population density in each township (street), the level of education, and economic activity. (4) Conclusions: The results of this study show that the public, as the intuitive perceiver of air pollution, is sensitive to the air pollution situation at a smaller spatial scale; furthermore, complaints can provide guidance and reference for the direction of air pollution control and law enforcement investigations when coupled with geographical features and economic status.

Quality of rainwater drained by a green roof in the metropolitan region of Recife, Brazil

The objective of this study was to evaluate the potential non-potable uses that can be given to the water flowing from a green roof through the characterization of its quality using the parameters and reference values contained in the Brazilian Standard ABNT NBR 15527:2007. The research was carried out in the Garage Building of the Charles Darwin Business, for a period of five months. Fifteen samples were collected from three collection points (rainwater, irrigation, and drainage from the green roof) and evaluated. For the qualitative characterization of the waters, the physicochemical parameters hydrogen potential (pH), turbidity (TBD), apparent color (AC), free residual chlorine (FRC) and electrical conductivity (EC), in addition to the microbiological parameters total coliforms, Escherichia coli and number of heterotrophic bacteria (HB), were determined. Data were subjected to descriptive and multivariate statistical analysis. The results obtained show that the green roof contributed to the reduction of rainwater pH. The green roof drainage water had higher levels of AC and TBD due to the concentrations of suspended particles, which acted as a source of EC. The FRC values complied with the legislation in all treatments. Likewise, the microbiological parameters partially complied with the standards established by the legislation. Cluster analysis formed two distinct groups, G1 comprising HB and TBD, and G2 containing the variables pH, AC, EC, and FRC. Although the quality of the drainage water does not meet all the standards required by law, this water has the potential for reuse for non-potable purposes.

Calculation theory and experiment verification of sedimentation potential of the complex particle system

In this paper, the equations for calculating the sedimentation potential of complex particle systems composed of solid-liquid mixtures are established, and the multifactorial coupling effects are also taken into consideration, especially different types and shapes of particles in the system, suspended particle concentration, ion concentration, solid-fluid interaction, as well as the coupling effect of the electric field induced by the sedimentation current, etc. In this context, the theoretical calculation results are proved to be consistent with the test results. The equations established in the paper are of substantial value in exploring the principles of particle behavior control in the fields of the chemical industry, metallurgy, pharmacy, air pollution, water environment treatment, etc. Moreover, this paper further discovers the sedimentation potential characteristics of the "time-switch" function of the uniform particle system, and based on this finding, the logical calculation unit is constructed, which can be expected to have a wide range of potential applications in the fields of hydrology, atmosphere, water quality, and other intelligent monitoring.

Convolutional Neural Network for Measurement of Suspended Solids and Turbidity

The great potential of the convolutional neural networks (CNNs) provides novel and alternative ways to monitor important parameters with high accuracy. In this study, we developed a soft sensor model for dynamic processes based on a CNN for the measurement of suspended solids and turbidity from a single image of the liquid sample to be measured by using a commercial smartphone camera (Android or IOS system) and light-emitting diode (LED) illumination. For this, an image dataset of liquid samples illuminated with white, red, green, and blue LED light was taken and used to train a CNN and fit a multiple linear regression (MLR) by using different color lighting, we evaluated which color gives more accurate information about the concentration of suspended particles in the sample. We implemented a pre-trained AlexNet model, and an MLR to estimate total suspended solids (TSS), and turbidity values in liquid samples based on suspended particles. The proposed technique obtained high goodness of fit (R2 = 0.99). The best performance was achieved using white light, with an accuracy of 98.24% and 97.20% for TSS and turbidity, respectively, with an operational range of 0–800 mgL−1, and 0–306 NTU. This system was designed for aquaculture environments and tested with both commercial fish feed and paprika. This motivates further research with different aquatic environments such as river water, domestic and industrial wastewater, and potable water, among others.

Comment prélever les sédiments en suspension dans les cours d’eau ?

Measurement of suspended sediment is an important issue for river management. Suspended particles can be mineral or organic and of natural or artificial origin. They have different sizes that are often described by a median diameter. To quantify the concentrations of suspended particles or their composition, samples are taken at one or more points of the cross section. These samples can be either instantaneous or averaged over time, at a single point, or integrated over depth. The choice of sampling technique should be adapted to the size of the river, the purpose of the study and the available samplers. This article presents some characteristics of the samplers currently used in the Rhône watershed and raises the question of the harmonisation of practices for suspended solids sampling in rivers. This harmonisation is necessary in order to be able to compare and discuss the calculated suspended sediment fluxes in order to understand and manage them.

Разработка методов выбора средств защиты от пыли органов дыхания для горнорабочих

Currently, the mining industry of the Republic of Uzbekistan is dominated by an open method for solid minerals extraction. In the open pit mining, dust is the main adverse production factor. Its concentration in the environment depends on the development technology, the type and humidity of the mineral and host rocks, the mining equipment used, anti-dust measures, etc. Increase in the volume of mineral extraction due to the intensification of production processes and the introduction of high-performance equipment leads to an increase in the level of dust generation at the workplaces. In this regard, the fight against dust as a harmful professional factor remains an urgent task. In a dusty atmosphere, especially with a high concentration of hazardous suspended particles, various means of individual respiratory protection are used. This allows a significant reduction in the inhaled fraction. Conducted research proved that the real coefficients of respiratory protection in the modern personal protective equipment in the production conditions do not correspond to the declared ones. The main reason is the penetration of the unfiltered air into the area under mask through the gaps between the protective mask and the face of the worker. The necessity of developing a methodology for the selection of respirators that will provide reliable protection of the respiratory organs of the workers was identified. The dust load attributable to the respiratory organs of a miner is determined considering the use of BPS and ASDA respirators.