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In response to the issue of small particle size and difficult removal of suspended particles in the mine water of Baorixile open-pit coal mine, this study probed into the optimal parameters of the coagulation and precipitation process through single-factor and orthogonal experiments, and explored the mechanism behind the coagulation of fine particles in mine water.The optimal process parameters for coagulation and precipitation include: 50 mg/L of polyaluminum chloride (PAC), 5.0 mg/L of non-ionic polyacrylamide (NPAM) under 1 minute of rapid stirring (300 r/min), 8 minutes of slow stirring (50 r/min), and 5 minutes of settling.Under these optimum process conditions, the concentration of suspended solids (SS) is 5.0 mg/L with a removal efficiency of 99.1 %.Compared to the sole addition of PAC, the removal efficiency of fine particles below 10 μm increased by 25.9 %.Additionally, theζpotential of the mine water decreased from -40.9 mV to -16.3 mV, indicating that the coagulation mechanism of fine particles is mainly attributed to the adsorption and charge neutralization of PAC and the bridging effect of PAM.

This study investigates the efficacy of a solar-powered single-stage distillation system for treating domestic wastewater, supplemented with complex conductivity analysis. Domestic wastewater samples were collected from a municipal manhole in El Jadida, Morocco, over a 24-h period. The single-stage distillation system, designed for domestic wastewater treatment, utilizes heat to vaporize the wastewater, followed by condensation to produce pure liquid water. The system demonstrated increased distilled water production with rising temperatures, with domestic wastewater outperforming seawater as a feed water source. Physical and chemical testing of the treated water revealed significant improvements in water quality, meeting, or exceeding Moroccan irrigation water standards. Reductions in parameters such as biological oxygen demand (BOD), chemical oxygen demand (COD), suspended matter, and heavy metals underscored the effectiveness of the distillation process. Complex conductivity analysis provided insights into the electrical properties of untreated wastewater and distilled water. Deconvolution of complex conductivity data using an equivalent electrical circuit model elucidated the electrochemical processes during treatment, highlighting the efficiency of the distillation process. The integration of solar energy addresses water scarcity while promoting environmental sustainability. Complex conductivity analysis enhances process understanding, offering avenues for monitoring and control in wastewater treatment. [ABSTRACT FROM AUTHOR]

The Secchi disc depth (Dsd) measurement is widely used to monitor eutrophication and the quality of the aquatic environment. This study aimed to investigate the relationship between Dsd and various factors, including the coefficient of attenuation of photosynthetically active radiation [Kd (PAR)], the depth of the euphotic zone (Deu), PAR at the Secchi disk depth (Esd) and the absorption coefficient of PAR (F) in the Neva Estuary, one of largest estuaries of the Baltic Sea. Environmental variables impacting these indices were identified using data collected from midsummer 2012 to 2020. The Dsd values in the estuary ranged from 0.3 to 4.0 m, with an average value of 1.8 m, while the Deu/Dsd ratio ranged from 1.5 to 6.0 with an average value of 2.8. These values were significantly lower than those observed in the open waters of the Baltic Sea. The highest Deu/Dsd ratio was observed in turbid waters characterized by high Kd(PAR) and low Dsd. Contrary to expectations, Dsd did not exhibit a significant relationship with the concentration of chlorophyll a, raising doubts about the utility of historical Dsd data for reconstructing phytoplankton development in the estuary. Principal component analysis did not identify the primary environmental variables strongly affecting the optical characteristics of water. However, recursive partitioning of the dataset using analysis of variance (CART approach) revealed that the concentration of suspended mineral matter (SMM) was the primary predictor of Deu/Dsd, Kd(PAR), and F. This SMM was associated with the frequent resuspension of bottom sediments during windy weather and construction activities in the estuary. Concentrations of suspended organic matter and the depth of the water area were found to be less significant as environmental variables. Furthermore, the CART approach demonstrated that different combinations of environmental variables in estuarine waters could result in similar optical indicator values. To reliably interpret the data and determine the optical characteristics of water in estuaries from Dsd, more complex models incorporating machine learning and neural connections are required. Additionally, reference determinations of Esd in various regions with specific sets of environmental variables would be valuable for comparative analyses and better understanding of estuarine systems. [ABSTRACT FROM AUTHOR]

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Suspended matter in seawater carries abundant nutrients and carbon, playing a significant role in carbon cycle and ecosystem in many oceanic settings such as atolls. The Zhongsha Great Atoll (hereafter ZGA), located in the deep South China Sea, sustains a both regionally and globally important ecosystem. Characteristic of the suspended matter in this area, however, remains poorly investigated. Using a data set encompassing temperature, salinity, depth, and suspended matter concentration (hereafter SMC) of seawater collected respectively in May 2019 (spring-summer monsoon transition period) and June 2020 (summer monsoon outbreak period) in the ZGA, the main components and spatial distribution of suspended matter together with their influencing factors were comprehensively analyzed. Our results show that the components of suspended matter vary widely in space and include more than 20 types of materials such as planktonic remains and biogenic siliceous debris. During the transit between spring and summer monsoons, the SMC in seawater was generally low, with an average value of approximately 3.26 mg L-1, which decreased from the surface to the middle layer and then increased to deep waters; Horizontally, the SMC in the west was generally higher than that in the east likely because the wind-driven current transport significant amounts of particles from the east to the west. During the 2020 summer monsoon outbreak, average SMC in this area was 6.27 mg L-1, higher than that during the 2019 spring-summer monsoon transit. Moreover, significantly higher SMC in the 1-100 m layer and lower SMC in the 150mlayer were observed in the west. Owing to the impact of mesoscale eddies, low SMC in the surface layer and high concentrations in the bottom layer can occur in parts of the ZGA, leading to the deepening of the west-high and eastlow distribution layers of SMC during the 2020 summer monsoon outbreak. Notably, we for the first time have observed an anomalously high SMC in the 1-100 m layer of the northwest area during the 2020 summer monsoon outbreak. This anomaly is higher than any previously reported values in the South China Sea and can be attributed to the multiple monsoon impacts. Sources of suspended matter, topography, currents, and wind field were identified as the main factors influencing the spatial distribution of SMC in this area. Our findings provide a basic context for understanding the sources and dynamics of suspended material in atolls. [ABSTRACT FROM AUTHOR]

The content of 237Np, 239,240Pu, and 241Am in seawater, suspended matter, and bottom sediment cores of the Ussuri and Amur Bays, sampled in July 2021 and August 2022, was analyzed. The activity concentrations of 237Np, 239,240Pu, and 241Am in the water of Peter the Great Bay were determined for the first time and were found to be equal to (19–105) × 10–3, 2.0–5.3, and 24.1–33.5 mBq/m3, respectively. The activity concentrations as well as the 239Pu/240Pu isotope ratio (⁓0.18) in the bottom sediments definitely indicate that global fallout is the main source of plutonium in the investigated territory. The sedimentation rates were determined for the Amur Bay (in the Razdolnaya River estuary), 0.9 mm/year, and for the Ussuri Bay, 4.1 mm/year. Actinide transfer coefficients were determined for Peter the Great Bay in the system dissolved forms (including colloids)–suspended matter–bottom sediment. [ABSTRACT FROM AUTHOR]

The chlorophyll monitoring assesses the abundance of algea blooms in the water. The rate of chlorophyll activity and suspended matter on the coast of Oran (western Algeria) was monitored from physico-chemical analyses of 300 water samples taken during the four-year summer season: 2018, 2019, 2020 and 2021. Remote sensing data available on the Google Earth Engine platform with Sentinel- 3 images generated during the same sampling period were also used. The mapping of the variation of the parameters of chlorophyll activity and suspended matter shows the persistence of a gradient parallel to the coast and this takes a center-north direction with the strongest trends. While the eastern zone shows a weakness of activity. This decrease extends, showing a greater transition zone. These results show the appearance of summer algal fluorescences from south to north, which may indicate an expansion of eutrophication in correlation with environmental changes and anthropogenic activities, This allows to highlight the general trends of the sea throughout the year, while exhausting large quantities of oxygen in the water, which increases the pollution of the coastline of Oran. [ABSTRACT FROM AUTHOR]

The Secchi disc depth (Dsd) measurement is widely used to monitor eutrophication and the quality of the aquatic environment. This study aimed to investigate the relationship between Dsd and various factors, including the coefficient of attenuation of photosynthetically active radiation [Kd (PAR)], the depth of the euphotic zone (Deu), PAR at the Secchi disk depth (Esd) and the absorption coefficient of PAR (F) in the Neva Estuary, one of largest estuaries of the Baltic Sea. Environmental variables impacting these indices were identified using data collected from midsummer 2012 to 2020. The Dsd values in the estuary ranged from 0.3 to 4.0 m, with an average value of 1.8 m, while the Deu/Dsd ratio ranged from 1.5 to 6.0 with an average value of 2.8. These values were significantly lower than those observed in the open waters of the Baltic Sea. The highest Deu/Dsd ratio was observed in turbid waters characterized by high Kd(PAR) and low Dsd. Contrary to expectations, Dsd did not exhibit a significant relationship with the concentration of chlorophyll a, raising doubts about the utility of historical Dsd data for reconstructing phytoplankton development in the estuary. Principal component analysis did not identify the primary environmental variables strongly affecting the optical characteristics of water. However, recursive partitioning of the dataset using analysis of variance (CART approach) revealed that the concentration of suspended mineral matter (SMM) was the primary predictor of Deu/Dsd, Kd(PAR), and F. This SMM was associated with the frequent resuspension of bottom sediments during windy weather and construction activities in the estuary. Concentrations of suspended organic matter and the depth of the water area were found to be less significant as environmental variables. Furthermore, the CART approach demonstrated that different combinations of environmental variables in estuarine waters could result in similar optical indicator values. To reliably interpret the data and determine the optical characteristics of water in estuaries from Dsd, more complex models incorporating machine learning and neural connections are required. Additionally, reference determinations of Esd in various regions with specific sets of environmental variables would be valuable for comparative analyses and better understanding of estuarine systems.

Purpose. The purpose of the work is to present and discuss the results of determining the mass concentration of suspended matter and its organic and mineral fractions by measuring the light volume scattering functions in the South Ocean in the 20ºE meridian region from 37º to 55ºS. Methods and Results. The measurement data on the light volume scattering function were obtained in the 10th cruise of the R/V “Akademik Vernadsky” in January–February, 1975 at the oceanographic section along the 20ºE meridian from 37º to 55ºS at the stations located 1º apart. The suspended matter composition was calculated based on the results of these measurements. The distribution of mass concentration of the suspended matter (total, organic and mineral) at the section was obtained. The maximum increase in the organic suspension concentration at the section was observed in the area of water rise at 53ºS: Corg = 0.830 mg/l (Ctotal = 1.062 mg/l), that indicates the highest water productivity in this region. Based on the empirical relationship with the organic suspension concentration, the chlorophyll concentration at the section was calculated. The relation between the total mass concentration of suspended matter and the scattering coefficient in surface waters in the form Ctotal = 1.496 s520 – 0.0676 (R = 0.95) was established. The features of the organic suspension vertical distribution in the areas of water rise and lowering, and with no signs of water vertical movement were considered. Conclusions. Measurements of the light volume scattering functions in the South Ocean in the region of 20ºE and 37º–55ºS permitted to obtain the data on mass concentration of the total suspended matter, as well as its organic and mineral fractions. The maximum concentration of organic suspension is located in the vicinity of the average long-term position of the Polar Front, where the mass development of phytoplankton is observed regularly. The features of vertical structure of the suspension organic fraction are directly related to the water vertical dynamics. There is a close relationship between the mass concentration of total suspended matter and the scattering coefficient in the surface waters.

The authors, as part of the realization of scientific projects, methodically substantiated, created and implemented systems for monitoring sediment flows in river and sea basins based on a complex of field equipment for sampling suspended matter from the aquatic environment. In particular, sedimentation traps (cylinders for accumulating particles settling in the water layer) were used to observe the distribution of suspended matter. Experimental studies on the improvement and simultaneous simplification of structures and elements of field equipment for studies of suspended matter in rivers and seas water areas allowed proposing a new design of sedimentation cylinders. The publication considers the possibilities and advantages of using sedimentation traps with a removable sampler, which is simultaneously used as a container for transporting the sample for further laboratory research. It is suggested to use a standard glass jar with a capacity of 0.5 l, the versatility and low cost of which are prerequisites for successful use. The main advantage of this option is the maximally approximate parameters of the jar for use as a liner in a plastic sedimentation cup made of standard Ostendorf polypropylene sewer pipes with a diameter of 90 mm with a socket connection system. Light, compact and inexpensive variants of sedimentation cylinders are proposed, which meet the requirements of complex studies of the sedimentary substrate in the conditions of various water areas with a significant range of depths. Field tests of experimental structures have previously proven their efficiency and ease of use. Ease of assembly and disassembly, small weight, and low manufacturing and operating costs will allow the trap to be widely used for further research. In the future, this will be followed by a study of the qualitative composition of the marine suspension, quantitative characteristics of its temporal and spatial distribution, questions of the formation of the organic component of suspended matter to assess the seasonality of development and planar distribution of producers in the photic zone, their species composition and quantitative characteristics. The possibility of using a glass sampler also allows sampling for the determination of a wide range of pollutants (heavy metals, pesticides, oil products and organic substances, microplastics) in the suspension.

Abstract—Sedimentation transport of 137Cs can lead to the significant accumulation of this radionuclide at depths that could not be reached through the vertical water exchange alone; therefore, a comparative assessment of its contents for different types of suspended matter (SM) and regions of the Black Sea is of particular interest. For this purpose, we have collected samples of SM and seawater at deep-water and coastal stations for the subsequent determination of the 137Cs activity in the surface water layer. To calculate the fraction of lithogenic matter, the potassium content in the SM was additionally determined. The range of 137Cs content on SM at different stations differed by more than an order of magnitude: from 7 to 111 Bq/kg for specific activity, and from 0.03 to 0.69% for its content on SM, in % of the total content in the surface water layer. Stations located farther away from the coast were characterized by the lowest percentage of 137Cs in SM, while its content at the coastal stations was more variable. The comparison of the lithogenic and biogenic contribution to SM and data on 137Cs for different stations suggests that the content of this radionuclide on SM is primarily determined by the dynamic variations of the lithogenic matter. Based on the 137Cs migration on SM, the Black Sea is divided into at least two types of regions. One regions are water areas far removed from sources of lithogenic matter where SM is formed mainly due to the hydrobiont activity. The 137Cs content in SM due to the predominance of biogenic matter and an insignificant concentration of lithogenic matter in this case accounts for hundredths of a percent of its total content in the surface water layer. Other regions are coastal and shelf water basins, which, on the one hand, are subjected to the significant coastal and river lithogenic runoff, and on the other, they are characterized by the elevated trophicity and biological productivity. In these water areas, 137Cs content on SM owing to the variability of biotic and abiotic factors is more variable and can fluctuate from values typical for the open sea to an order of magnitude higher. [ABSTRACT FROM AUTHOR]

The coefficient of attenuation of photosynthetically active radiation (Kd(PAR)) and the depth of the euphotic zone (Deu) are widely used to study biogeochemical processes and eutrophication in marine ecosystems. However, determination of Kd(PAR) and Deu in estuaries is hampered by the simultaneous influence of many environmental factors. In this study, we analyzed the relationship between water turbidity (Turb), Kd(PAR), Deu, and environmental variables in the Neva Estuary, the largest estuary in the Baltic Sea. The summer values of Kd(PAR) and Deu were significantly higher than in the open waters of the Baltic Sea and varied in the range of 0.5–9.1 m−1 and 0.5–8.5 m, respectively. Mixed-effects regression analysis showed that the concentration of suspended mineral matter primarily determined the Turb. This variable fluctuated widely due to frequent wind-induced resuspension of bottom sediments and the periodic construction of port infrastructure in the shallow upper reaches of the estuary. Deu was determined by the depth of the water area, concentration of chlorophyll a, and concentrations of suspended mineral and organic matter. The average efficiency of using PAR energy for gross primary production (PP) was about 2%. However, PP did not depend on the amount of radiation incident on the water surface, but was mostly determined by underwater light and nutrient conditions. The study showed that more research on the impact of environmental variables on underwater light conditions in different regions is needed to predict the impact of climate change and anthropogenic factors on phytoplankton productivity in coastal areas. [ABSTRACT FROM AUTHOR]

Chlorophyll a concentration and suspended matter concentration, as typical water quality parameters related to spectral characteristics, are essential for characterizing the degree of eutrophication in water bodies. They have become crucial indicators for water quality assessment of inland water bodies. The support vector regression model (SVR) is suitable for small samples, has excellent generalization ability, and has high prediction accuracy. Still, it has the problem of difficult selection of model parameters and quickly falling into local extremes. To solve this problem, a hybrid Differential Evolution-Grey Wolf Optimizer (DE-GWO) algorithm is introduced into the parameter selection process of the support vector regression model, and an improved SVR algorithm (DE-GWO-SVR) is proposed for the remote sensing inversion of chlorophyll a concentration and suspended sediment concentration in water bodies. In this paper, the spectral reflectance of the water surface and the chlorophyll a and broken matter concentration values were obtained by field measurements in the Tangdao Bay waters of Qingdao, Shandong Province. The inverse model between the concentration values of the two water quality parameters and the corresponding sensitive factors was established by first determining the sensitive factors based on the response of the spectral reflectance to the two water quality parameters and introducing the DE-GWO optimization algorithm into the parameter selection process of the SVR model. Finally, the accuracy of the model was verified using Sentinel II satellite remote sensing spectral data, and then the inverse accuracy of the two water quality parameters was obtained. The mean relative error (MRE) of the chlorophyll a prediction model built by the DE-GWO algorithm optimizing the SVR is 25.1%, and the mean relative error (MRE) of the suspended matter prediction model is 32.5%. The inversion results were all better than the other models (linear regression, SVR, and GWO-SVR model). When the best model, built from the measured water surface spectral data, was applied to the Sentinel II satellite data, the improved SVR model outperformed the other models in terms of mean relative error. The experimental results confirm that the DE-GWO-SVR algorithm is an effective method for remote sensing inversion of chlorophyll a and suspended matter concentrations in water bodies, which can provide a reference for remote sensing inversion of chlorophyll a and suspended matter concentrations in Chinese offshore waters and subsequent scientific management of waters. [ABSTRACT FROM AUTHOR]

Determination of 137Cs, 40K and 210Po in water, bottom sediments and suspended matter of river systems of the Can Gio Biosphere Reserve, Vietnam was carried out. The average activity concentration of 137Cs in waters of Ca Gau and Long Tau was 0.89 ± 0.14 and 1.08 ± 0.15 Bq m−3 and was comparable to the levels of this radioisotope in waters of the East Sea. The activity concentration of 137Cs in bottom sediments was 2.23 ± 0.81 and 3.63 ± 1.24 Bq kg−1. The activity concentration of 137Cs in water and bottom sediments could be characterized as low. So, the water areas of the Ca Gau and Long Tau rivers could be attributed to areas with insignificant pollution by technogenic radionuclides. The 210Ро activity concentration in bottom sediments of the Ca Gau and Long Tau rivers ranged from 9.2 ± 1.2 to 25.5 ± 2.1 Bq kg−1, which is typical for river bottom sediments. Such values indicate the absence of anthropogenic enhancement of the entry of this radionuclide into the Can Gio river systems. The 40K activity concentration varied within 467 ± 42–651 ± 39 Bq kg−1 and represented typical values of potassium content in the bottom sediments of coastal water bodies, subject to a significant influence of the lithogenic component of suspended matter.

Human activities and climate change are currently dominant processes that affect hydrological processes, resulting in alterations in water and sediment flows. Evaluation of the settling velocity of suspended solids is a critical parameter in modelling sediment transport. In this study, we investigated seasonal changes in suspended solids' settling velocity and trapping capacity in the presence and absence of water turbulence on a dam reservoir. Using key parameters such as flow rate, mean settling velocity ( V ¯ ), critical velocity ( v c ), suspended solids concentration, ratio V ¯ / v c , and shape parameter 'r', the trapping capacity on the dam reservoir on the Lobo River in a tropical region was estimated. The results show that, considering the settling velocity of suspended solids, following the Gamma distribution law remains an innovative solution proposed to evaluate the trapping capacity in water reservoirs. The results show that the mean suspended solids settling velocity V ¯ is well above the median rate V50%. For a parameter V ¯ / v c ≥ 4, there is an increase in the trapping capacity of the water retention. As established, a large proportion of the sediment is trapped. Furthermore, for a parameter V ¯ / v c ≤ 4, a decrease in the trapping capacity of the Lobo River water reservoir is observed. [ABSTRACT FROM AUTHOR]

The article presents the results of geochemical studies of Lake Onego. The chemical composition of the water was investigated, the uneven distribution of elements (Fe, Mn, Al, Cu, Zn, and Cr) and the forms of their migration along the lake water area were revealed. It is shown that the suspended form of metals prevails in bays exposed to an anthropogenic load. The study of the chemical composition of sediment from sedimentation traps showed its difference from the composition of suspended matter and bottom sediments. The mineralogical composition of suspended matter and sediment from sedimentation traps has been studied. Their comparison with the bottom sediments of the lake is carried out. The close composition of the terrigenous component of sedimentary matter in different areas of Lake Onego has been revealed. The features of detrital matter are studied. [ABSTRACT FROM AUTHOR]

The construction of new port facilities and the creation of new lands is a natural consequence of the rapid growth in the population of ocean coastlines. Despite the fact that such human activity is becoming more and more widespread, its impact on various components of aquatic ecosystems, including phytoplankton, is still poorly understood. The aim of the study was to assess the effect of the large-scale construction of new port facilities on biomass and taxonomic composition of phytoplankton in the Neva Estuary (northeastern Baltic Sea). Studies have shown that digging and displacing large amounts of bottom sediments during these works led to a significant increase in suspended mineral matter and a decrease in water transparency in the estuary. This significantly reduced the species richness and biomass of phytoplankton. However, the analysis of beta diversity did not show significant changes in the phytoplankton community during the periods of port construction and the periods when no works were carried out. The changes mainly concerned rare species, while the occurrence and biomass of dominant and subdominant species changed to a lesser extent. Due to various adaptations, the phytoplankton species common in the estuary are apparently able to survive under prolonged shading and successfully compete with species that are unable to withstand the lack of light for a long time. To correctly take into account the effects of the construction of new port facilities on phytoplankton and, if possible, minimize it, additional studies of the ecology of certain phytoplankton species, their relationships, and physiological responses to various environmental factors are required. [ABSTRACT FROM AUTHOR]

Lake water surface albedo (LWSA) is a critical parameter for describing energy flux balance at the air–water interface. It is used to measure the capacity of lake water surface reflectance in the shortwave radiation band, which controls the energy partitioning between atmosphere and lake. LWSA and its driving factors, including solar radiation angle, water quality and meteorology, in lakes of Northeast China was analyzed in this research. Solar altitude angle emerged as the most important controlling factor of LWSA. The results showed a strong reduction in LWSA values with increase in solar altitude angle. The study also documented a strong effect of suspended matter on the radiative properties of lakes surface, leading to increased LWSA with increased in suspended matter concentration, especially at high solar altitude angles (R2: 0.76). While no significant association (R2: 0.11) was found between LWSA and chlorophyll-a concentration, LWSA was positively correlated with wind speed (R2 of 0.62 and 0.50 at high and low solar altitude angles, respectively), likely a consequence of wind-driven sediment resuspension in lake waters. Although chromophoric dissolved organic matter (CDOM) and organic particulate matter can affect energy partitioning and spectral distribution of incident solar radiation in lake waters, there was insufficient evidence of measurable effects on LWSA. Variations in LWSA recorded in this study were primarily dependent on similar solar altitude angles and backscattering properties of inorganic particulate matter suspended in the water column. Higher surface albedo was found in the turbid lakes.

The study shows a possibility of practical application of remote sensing data for digital marking and estimation of the areas of regions with a high content of suspended matter in coastal sea waters. The relations between seasonal and domestic winds and cases of high suspended matter content are shown based on data of high- and medium-resolution optical satellite sensors in 2017–2019 for a region at southwestern coast of Crimea. The contribution of continental runoff depends on the season; it is lower than the wind contribution. The approach suggested can be useful for prompt mapping of the dynamics of suspended matter based on observations from several satellites. [ABSTRACT FROM AUTHOR]

At the Blankaart Water Production Center, a reservoir containing 3 million m 3 of raw surface water acts as a first biologic treatment step before further processing to drinking water. Over the past decade, severe algal blooms have occurred in the reservoir, hampering the water production. Therefore, strategies (e.g., the injection of algaecide) have been looked at to prevent these from happening or try to control them. In this context, the HYperspectral Pointable System for Terrestrial and Aquatic Radiometry (HYPSTAR), installed since early 2021, helps in monitoring the effectiveness of these strategies. Indeed, the HYPSTAR provides, at a very high temporal resolution, bio-optical parameters related to the water quality, i.e., Chlorophyll-a ( C h l a ) concentrations and suspended particulate matter ( S P M ). The present paper shows how the raw in situ hyperspectral data (a total of 8116 spectra recorded between 2021-02-03 and 2022-08-03, of which 2988 spectra passed the quality check) are processed to find the water-leaving reflectance and how S P M and C h l a are derived from it. Based on a limited number of validation data, we also discuss the potential of retrieving phycocyanin (an accessory pigment unique to freshwater cyanobacteria). The results show the benefits of the high temporal resolution of the HYPSTAR to provide near real-time water quality indicators. The study confirms that, in conjunction with a few water sampling data used for validation, the HYPSTAR can be used as a quick and cost-effective method to detect and monitor phytoplankton blooms. [ABSTRACT FROM AUTHOR]

Purpose: Large rivers play an important role in the global carbon cycle through the transportation of particulate organic carbon (POC) from the continent to the ocean. Human disturbance such as water–sediment regulation (WSR) significantly changes the downstream fluxes of sediment and POC. However, the sources and variations of POC affected by WSR in the lower Yellow River remain poorly understood. Methods: The surface water samples were collected in the lower Yellow River, and the concentration and the median grain size (MGS) of suspended particulate matter (SPM) and the particulate organic carbon (POC) were measured. In addition, the C/N ratios and stable carbon isotopic composition (δ13Corg) of the POC in the surface waters of the lower Yellow River before and after the WSR of the Xiaolangdi reservoir were also analyzed to explore the spatio-temporal changes of POC transport. Results: Both SPM and POC concentrations were significantly higher before WSR than after WSR and showed different deposit and scour features along the lower Yellow River, mainly due to the different water discharge and particulate contents. Correlation analysis shows that POC% and MGS were the main factors that influence the variation of POC before WSR, while SPM was the main factor after WSR. The C/N ratio in the surface water of the lower Yellow River before WSR was significantly higher than that after WSR, while δ13Corg showed the opposite trend. Application of a two-end-member mixing model of δ13Corg suggests that, on average, about 56.4% and 82.0% of the POC is derived from terrestrial soil and that approximately 43.6% and 18% of the POC is derived from C3 plant detritus before and after WSR, respectively. Conclusion: Our research indicates that SPM and POC transport in the lower Yellow River was significantly affected by the WSR of the Xiaolangdi Reservoir. Therefore, the effect of WSR on the transport and environmental implication of POC should be considered in the management of the Xiaolangdi Reservoir in the future. [ABSTRACT FROM AUTHOR]

Chlorophyll a concentration and suspended matter concentration, as typical water quality parameters related to spectral characteristics, are essential for characterizing the degree of eutrophication in water bodies. They have become crucial indicators for water quality assessment of inland water bodies. The support vector regression model (SVR) is suitable for small samples, has excellent generalization ability, and has high prediction accuracy. Still, it has the problem of difficult selection of model parameters and quickly falling into local extremes. To solve this problem, a hybrid Differential Evolution-Grey Wolf Optimizer (DE-GWO) algorithm is introduced into the parameter selection process of the support vector regression model, and an improved SVR algorithm (DE-GWO-SVR) is proposed for the remote sensing inversion of chlorophyll a concentration and suspended sediment concentration in water bodies. In this paper, the spectral reflectance of the water surface and the chlorophyll a and broken matter concentration values were obtained by field measurements in the Tangdao Bay waters of Qingdao, Shandong Province. The inverse model between the concentration values of the two water quality parameters and the corresponding sensitive factors was established by first determining the sensitive factors based on the response of the spectral reflectance to the two water quality parameters and introducing the DE-GWO optimization algorithm into the parameter selection process of the SVR model. Finally, the accuracy of the model was verified using Sentinel II satellite remote sensing spectral data, and then the inverse accuracy of the two water quality parameters was obtained. The mean relative error (MRE) of the chlorophyll a prediction model built by the DE-GWO algorithm optimizing the SVR is 25.1%, and the mean relative error (MRE) of the suspended matter prediction model is 32.5%. The inversion results were all better than the other models (linear regression, SVR, and GWO-SVR model). When the best model, built from the measured water surface spectral data, was applied to the Sentinel II satellite data, the improved SVR model outperformed the other models in terms of mean relative error. The experimental results confirm that the DE-GWO-SVR algorithm is an effective method for remote sensing inversion of chlorophyll a and suspended matter concentrations in water bodies, which can provide a reference for remote sensing inversion of chlorophyll a and suspended matter concentrations in Chinese offshore waters and subsequent scientific management of waters.

This study sought to clarify whether suspended particles containing high Cu concentrations are present in the sea-surface microlayer (S-SML). For this reason, suspended particles (10–2000 μm) in the S-SML were collected periodically from a ship mooring pond during 2018–2020, and the acid-soluble Cu concentration in the suspended particles was measured as particulate Cu (P-Cu). The highest concentration of P-Cu in the S-SML of the pond was 75 μg L−1 with a 90th percentile value of 2.5 μg L−1. This is below P-Cu values reported for the S-SML in North American ports, but 140 times higher than this found in bulk seawater in the Atlantic Ocean. The highest P-Cu concentration in the S-SML of non-organism (abiotic) origin was 17 μg L−1, and the abiotic P-Cu to P-Cu ratio varied from 0.2 to 100%, likely depending on the quality and quantity of biogenic material in the S-SML samples. It is assumed that the S-SML particles examined here contain high Cu concentrations originating from ship antifouling paints. [ABSTRACT FROM AUTHOR]

A significant increase in the human population on marine coast and steady growth of maritime water transport causes the construction of port infrastructure and the creation of new lands, which affects the ecosystems of coastal waters. Despite the widespread occurrence of such large-scale engineering projects in coastal areas, their impact on various components of aquatic ecosystems, including phytoplankton, is still poorly understood. The aim of the study was to assess the effect of the construction of ports and the alluvium of new lands in the Neva Estuary in 2000s on the productivity of phytoplankton. Digging and dredging of bottom sediments results in one order of magnitude elevation of suspended particulate matter (SM), which mostly consisted of sand and clayed deposits and in significant decrease water transparency, as compared to the average long-term values. Concentrations of total phosphorus in the estuarine waters during the works significantly positively correlated with the concentrations of SM. However, the multiple increase in nutrients was less important for phytoplankton development than expected. Analysis of variance and stepwise multiple regression analyses showed that the main predictor of the primary production of plankton in the periods of construction was water transparency. Gross primary production decreased significantly. In contrast to short-term effects caused by wind-induced events, which often stimulated phytoplankton development, long-term construction works of new port facilities negatively influenced phytoplankton productivity. Apart from pristine conditions when the phosphorus concentration was the main factor limiting the primary production in the estuary, the main limiting factor during long-term engineering projects became water transparency. Taking into account plans for further development of ports in coastal areas around the world, the influence of the large-scale engineering projects on the conditions for the development of phytoplankton may provide a new aspect of long-term regulation of algal blooms and ecosystem functioning in the coastal and estuarine zones.

The Sambia Peninsula (Kaliningrad region) is historically well known for its amber mining. The 2019 year was the last year of direct overburden disposal into the Baltic Sea as a part of technological amber mining process. The extremely high-suspended particulate matter concentrations during that disposal were recorded immediately after the discharge of significant volumes of pulp and reached 200 mg/L. The impact of pulp discharge had sequentially suppressed plankton communities development due to the high content of suspended solids and afterwards stimulated plankton development due to the glauconite infusion. Cladocera were the most sensitive group to the effects of suspended matter. According to the preliminary forecast, when the pulp discharge stops, the restoration of plankton communities may take from 1 to 2 seasons to 1 year for different groups. This is due to the timing of the removal of fine suspended particulate matter from sediments and the possibility of secondary entry during resuspension. • Amber open-pit mining causes suspended particulate matter concentration rise in discharge area to extreme level >100 mg/L. • Extreme suspended matter concentrations affect benthos communities negatively in a broader way than plankton communities. • Long-term effect on benthos is more severe, while plankton may benefit from glauconite from overburden discharge. [ABSTRACT FROM AUTHOR]

Human activities and climate change are currently dominant processes that affect hydrological processes, resulting in alterations in water and sediment flows. Evaluation of the settling velocity of suspended solids is a critical parameter in modelling sediment transport. In this study, we investigated seasonal changes in suspended solids’ settling velocity and trapping capacity in the presence and absence of water turbulence on a dam reservoir. Using key parameters such as flow rate, mean settling velocity (V¯), critical velocity (vc), suspended solids concentration, ratio V¯/vc, and shape parameter ‘r’, the trapping capacity on the dam reservoir on the Lobo River in a tropical region was estimated. The results show that, considering the settling velocity of suspended solids, following the Gamma distribution law remains an innovative solution proposed to evaluate the trapping capacity in water reservoirs. The results show that the mean suspended solids settling velocity V¯ is well above the median rate V50%. For a parameter V¯/vc ≥ 4, there is an increase in the trapping capacity of the water retention. As established, a large proportion of the sediment is trapped. Furthermore, for a parameter V¯/vc ≤ 4, a decrease in the trapping capacity of the Lobo River water reservoir is observed.

The attachment-detachment of heavy metal ions and suspended matter (SM), such as copper ions (Cu2+), graphene oxide (GO) and silica powders, onto a quartz sand porous medium (SiO 2 particles) in water was investigated. The experimental results showed that the attachment-detachment process can be described by a nonlinear model. The detachment curves appeared as a group of parallel scanning curves. The attachment/detachment curves ranged from linear to nonlinear for copper ions, GO and silica powders (ranging from ions to particles). Finally, a unified static attachment-detachment model was established. The attachment mechanism mainly involved the interfacial electrostatic attraction between SM and the solid matrix, the formation and directional adjustment of metal bonds, and the complementary molecular structure characteristics of the different materials. The irregular motions of Cu2+, GO and silica powder were significantly enhanced by increasing the temperature. [Display omitted] • Differences in the attachment mechanisms of ionic/nanoscale/microscale substances onto sand are revealed. • A unified nonlinear static attachment-detachment model in water is established. • The model is explained by metallographic microscopy and functional group characterization of SM. • Increasing the temperature promotes irregular motion of Cu2+, GO and silica powders. [ABSTRACT FROM AUTHOR]

Remote passive optical measurements of the state of waters in water basins studied from ships, airborne platforms, or satellites are most informative because they cover a large territory and are performed at a high frequency. At the same time, for correct estimation of the remotely obtained data some in situ measurements of the state of waters in water samples, taken at a limited number of points, should be performed. Studies carried out in the coastal regions of the Middle Caspian Sea were used as an example to identify the conditions when such point-like measurements are suitable for calibrating the remote hydro-optical measurements by the Ecological Monitoring of Marine Waters (EMMA) complex onboard a cruising vessel. The limitations identified were explained through analysis of the structure of coastal waters; this structure was measured through vertical sensing of water at stations and by operating a flow-through system for determining the temperature and salinity of surface waters. An algorithm is proposed for selecting water samples suitable for calibration of remote measurement by correlating them with Secchi disk depth, and the efficiency of this method is demonstrated. We showed what hydrophysical conditions should be taken into consideration for the preliminary selection of water sampling sites for calibrating remote measurements. [ABSTRACT FROM AUTHOR]

A model linking suspended solids to liquid flows was used in this study to estimate the particulate matter fluxes in the Mazafran wadi. We determined suspended solid fluxes and, for the first time in an Algerian wadi, organic and inorganic carbon fluxes. Based on the results of our study, the amount of suspended solids transported by the Mazafran wadi reaches 0.08 million tons per year, while the calculated flow of suspended solids is equal to 42t/km2/year. This value is quite low compared to those previously recorded in other Algerian wadis. This phenomenon is probably linked to the low rainfall during the study period but also to the type of rocks upstream of the wadi that are mainly crystalline (eruptive and metamorphic). The particulate organic carbon flux is 415 t/year upstream, while the particulate inorganic carbon flux is 1629 t/year. In the downstream portion, the POC values are almost twice the upstream values (736 t/year). The PIC values are approximately the same upstream and downstream. [ABSTRACT FROM AUTHOR]

The problem of estimating the distribution of suspended matter during dredging works is relevant due to the large volume of annual major and operational dredging activities in the ports of Ukraine constituting more than 4.5 million m3 of soil. The execution of dredging works is associated with the inflow of suspended matter into the marine environment having a negative impact on the marine ecosystem. The magnitude of the inflicted damage depends on the characteristics of a zone of increased turbidity and a reliable assessment of such characteristics makes it possible to determine the actual damage to be indemnified according to the current environmental legislation. The numerical modelling of the suspended matter distribution is the easiest way that may be used for evaluation of the characteristics of the zone of increased turbidity. The possibility of obtaining solutions on more general grounds in comparison with analytical methods, much less time and cash to be spent than for field experiments and modern computer software allowed widespread implementation of research methods of such modelling. The article is devoted to the study of the numerical model of suspended matter distribution during dredging works. It considers explicit, implicit and mixed finite-difference schemes for solving a stationary differential equation of turbulent suspended matter diffusion in the flat problem formulation. Several series of calculations have been performed for various model parameters based on which the obtained solutions have been analyzed, the assessment of the difference between the calculation results under different schemes has been done and the optimum parameters of the calculation grid have been proposed. The research presents some recommendations for numerical modelling of the suspended matter distribution in the water flow including: use of an explicit scheme; the number of jets in the excavated area should not exceed 3; the number of steps to the control opening – not less than 75; when using an implicit or mixed scheme it is necessary to introduce an adjustment in an unstable zone based on the total amount of matter accumulated into the opening until the final result is achieved.

The construction of new port facilities and the creation of new lands is a natural consequence of the rapid growth in the population of ocean coastlines. Despite the fact that such human activity is becoming more and more widespread, its impact on various components of aquatic ecosystems, including phytoplankton, is still poorly understood. The aim of the study was to assess the effect of the large-scale construction of new port facilities on biomass and taxonomic composition of phytoplankton in the Neva Estuary (northeastern Baltic Sea). Studies have shown that digging and displacing large amounts of bottom sediments during these works led to a significant increase in suspended mineral matter and a decrease in water transparency in the estuary. This significantly reduced the species richness and biomass of phytoplankton. However, the analysis of beta diversity did not show significant changes in the phytoplankton community during the periods of port construction and the periods when no works were carried out. The changes mainly concerned rare species, while the occurrence and biomass of dominant and subdominant species changed to a lesser extent. Due to various adaptations, the phytoplankton species common in the estuary are apparently able to survive under prolonged shading and successfully compete with species that are unable to withstand the lack of light for a long time. To correctly take into account the effects of the construction of new port facilities on phytoplankton and, if possible, minimize it, additional studies of the ecology of certain phytoplankton species, their relationships, and physiological responses to various environmental factors are required.

At the Blankaart Water Production Center, a reservoir containing 3 million m3 of raw surface water acts as a first biologic treatment step before further processing to drinking water. Over the past decade, severe algal blooms have occurred in the reservoir, hampering the water production. Therefore, strategies (e.g., the injection of algaecide) have been looked at to prevent these from happening or try to control them. In this context, the HYperspectral Pointable System for Terrestrial and Aquatic Radiometry (HYPSTAR), installed since early 2021, helps in monitoring the effectiveness of these strategies. Indeed, the HYPSTAR provides, at a very high temporal resolution, bio-optical parameters related to the water quality, i.e., Chlorophyll-a (Chla) concentrations and suspended particulate matter (SPM). The present paper shows how the raw in situ hyperspectral data (a total of 8116 spectra recorded between 2021-02-03 and 2022-08-03, of which 2988 spectra passed the quality check) are processed to find the water-leaving reflectance and how SPM and Chla are derived from it. Based on a limited number of validation data, we also discuss the potential of retrieving phycocyanin (an accessory pigment unique to freshwater cyanobacteria). The results show the benefits of the high temporal resolution of the HYPSTAR to provide near real-time water quality indicators. The study confirms that, in conjunction with a few water sampling data used for validation, the HYPSTAR can be used as a quick and cost-effective method to detect and monitor phytoplankton blooms.

Long-term arrays of satellite optical measurements of Landsat-5,7,8 and Sentinel-2 were used to describe the characteristics of submesoscale eddy (SE) dynamics in different parts of the Crimean coast: their geometric and kinematic characteristics, the main sites and mechanisms of formation, and impact on the redistribution of suspended matter. The dynamic characteristics of SE were computed on the base of the 4D variational assimilation method from the pair of consecutive Landsat-8/Sentinel-2 images. The orbital velocity of submesoscale cyclonic eddies (SCE) with a diameter of 1 km reaches 0.15 m/s, indicating the cyclostrophic balance with a high Rossby number (RO) exceeding 2. Submesoscale cyclones were detected much more frequently than the usually larger submesoscale anticyclones. High-resolution satellite imagery gives a possibility to observe complex submesoscale dynamic processes, such as the generation of chains of SCE, large cyclones behind the capes consisting of densely packed arrays of SCEs, topographic submesoscale anticyclones with a number of attached SCEs, mushroom-like current structures, and frontal SE. Despite the diversity of the processes considered, several basic mechanisms of formation of submesoscale eddies can be identified on the basis of satellite data: (1) Separation of the boundary current, often wind-driven, behind the capes; (2) barotropic instability due to the horizontal shear on the coastal periphery of mesoscale anticyclones or alongshore currents; (3) formation of the mushroom-like structure due to the interaction of offshore currents with deep waters near the capes or due to offshore winds; and (4) frontal instabilities on the coastal upwelling. The results of the analysis were used to create a scheme of the spatial variability of submesoscale processes near the Crimean coast and compare it to the results of the high-resolution modeling. The model was able to describe the main areas of SE formation, which was located near the major capes. It provides additional data about SE generation near the rocky capes of the South Crimea, where satellite data was limited by the absence of optical tracers. [ABSTRACT FROM AUTHOR]

In this work, for the first time, a physicochemical assessment of the parameters of snow cover based on their chemical composition for the territory of the Ile River delta is given. The physicochemical properties of the snow cover from the moment of its occurrence under the influence of air temperature, humidity, own weight, wind, solar radiation, as well as technogenic impact are constantly changing. Hydrometeorological conditions and orographic features of the location play a significant role, contributing to the accumulation of pollutants in the snow cover. Chemical analyzes were performed for the following parameters: pH, organic substances by permanganate oxidizability, suspended matter and mineralization. According to the preliminary results of the assessment of the physicochemical parameters of the snow cover, some pollution was found in the central zone, which are characterized by the maximum content of solid particles and the mineralization of the snow cover. The acidity (pH) of the snow cover ranged from 6.1 to 8.0, and the average for the territory was 6.9 (neutral). The content of suspended solids in the snow varied from 12 to 80 mg/dm³, and organic matter from 1.60 to 11.52 mg/dm³.The values of the mineralization of the snow cover were in the range of 135-731 mg/dm³.High values of the considered parameters were typical for point 25, i.e. the central part of the territory of the Ile river delta. The high values are due to air pollution, characterized by the maximum content of solid particles and the mineralization of the snow cover, which gives an idea of the level of pollutants accumulated during the cold period. [ABSTRACT FROM AUTHOR]

In this paper, the theoretical preconditions in favor of the use of thin-layer settling tanks for industrial wastewater treatment are substantiated by the corresponding laboratory studies. The data from the results of studies of wastewater treatment of the textile, knitwear and silk industries conducted on laboratory thin-layer settling tanks according to the basic schemes of wastewater supply and precipitating sediment are given. As stated by these data, according to the generally accepted criteria for the effectiveness of suspended solids retention for wastewater of the above-mentioned industries, it is more preferable to use thin-layer sedimentation in a cross-sectional scheme.

Periphyton is an ecological essential in freshwater lakes and rivers. Its abundance and biomass are very dynamic in various habitats and subject to various factors, for example, nutrient and light. Following flooding events, the transitional area adjacent to a river inlet and the shallow lake generates diverse habitats for periphyton with gradients in current velocity, suspended matters, nutrients, and light, which would strongly shape the growth and community of periphyton. In this study, three sampling sites were established around a river inlet in Erhai Lake, China, and a field survey was conducted in the sites from April to August (flooding seasons) in 2019 to investigate the abundance and biomass of periphyton and explore influential factors. The results showed that three study areas have different gradients of current velocity depending on the distance to the river inlet, thereby regulating the concentrations of nutrients and suspended matters, which strongly affected the periphyton community; to be specific, the biomass of periphyton was inhibited by the concentration of suspended matters and high concentrations of silicate mainly reduced the diversity of periphyton. Our results imply that the study on the driving factors of periphyton could help to understand its community assembly mechanism and biomass and species composition of periphyton can provide some reference for trophic state of the lake.

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BACKGROUND Although abandoned mines are no longer exploited, waste mines, old smelting sites and buried tailings can still pollute downstream areas through rainwater leaching and surface runoff. The study on the distribution and relationship of heavy metals in sediments and suspended particulate matter (SPM) along rivers in abandoned mines has important significance. OBJECTIVES To preliminarily investigate heavy metals in river sediments and SPM in Wanshan Mercury Mines, and provide basic information for monitoring and remediation of contaminated cultivated land. METHODS The contents of Cr, Ni, Cu, Cd, Pb, As, Hg, Zn and Co in sediments and SPM samples were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Atomic Fluorescence Spectrometry (AFS) with wet digestion pretreatment. The pollution status and spatial distribution characteristics were identified in order to obtain information of pollutant migration and diffusion downstream. RESULTS The total mercury content (Hg) in sediments ranged from 0.10 to 16.0μg/g (dry weight), averaging 5.79μg/g, which was ten times higher than the Hg limit of the Class Ⅱ soil environmental quality standard of China. The average contents of Ni, Cu and Co were not higher than the standard. The variation coefficients of Hg and Cd were large, indicating the heterogeneously spatial distribution of Hg and Cd. Mercury in sediments reached a high potential ecological risk level. CONCLUSIONS The Hg in sediments and SPM in the study area are related to the hydrodynamic conditions, and the maximum values occurred at the sites with broad river channel and low flow rate. As the mining and smelting of Wanshan Mercury Mine has been stopped for a long time, the weathering and leaching of the abandoned mining area under natural conditions will cause Hg and Cd pollution in the lower reaches of the river.