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The focus of this study is organic matter changes and suspended particle and colloid behavior in riverine and marine water mixing zones. Laboratory experiments demonstrated that salinity, clay mineral type, and the nature of dissolved organic matter (DOM) have a strong influence on mineral suspension stabilities (clays, carbonates, and ferric hydro...
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Landfill leachate contains not only high concentrations of refractory organic matter and ammonia nitrogen, but also high concentrations of chloride ions (Cl−). The modification of reactive species of the peroxymonosulfate (PMS) oxidation system by Cl− and its priority sequence for the removal of NH4+-N and organic matter from landfill leachate rema...
Purpose
To compare Cd removal from different soils with three washing agents recovered from sewage sludge (dissolved organic matter (DOM), soluble humic-like substances (HLS), soluble humic substances (SHS)). Also, to investigate how washing with these agents changes soil organic-matter composition (OM).
Materials and methods
Sandy clay loam (S1)...
The dissolved organic matter (DOM) is one of the most sensitive indicators of changes in the soil environment, and it is the most mobile and active soil component that serves as an easily available source of nutrients and energy for microbes and other living organisms. In this paper, DOM structural characteristics and main properties were investiga...
To investigate the dissolution characteristics of low-temperature thermal pretreatment conditions and the process of sludge fermentation to produce acid, the influence of thermal pretreatment temperature on the dissolution of excess sludge organic composition and the mechanism of cell crushing of sludge thermal pretreatment were analyzed by an expe...
Long-term changes in dissolved organic matter (DOM) quality, especially in humic-rich raw waters, may lead to intensive adaptions in drinking-water processing. However, seasonal DOM quality changes in standing waters are poorly understood. To fill this gap, the DOM quality of a German drinking water reservoir was investigated on a monthly basis by...
Citations
... However, only a small part of the assimilated carbon reaches the bottom and is buried in sediments (~250 Mt), equivalent to~900-950 Mt CO 2 . At the same time, the bottom sediments of the world ocean are one of the main reservoirs of carbon storage in the biosphere on a geological time scale [176][177][178]. ...
Since the Industrial Revolution, human economic activity and the global development of society in general have been heavily dependent on the exploitation of natural resources. The use of fossil fuels, deforestation, the drainage of wetlands, the transformation of coastal marine ecosystems, unsustainable land use, and many other unbalanced processes of human activity have led to an increase both in the anthropogenic emissions of climate-active gases and in their concen-tration in the atmosphere. It is believed that over the past ~150 years these phenomena have contributed to an increase in the global average temperature in the near-surface layer of the at-mosphere by ~1 °C. Currently, the most pressing tasks facing states and scientific and civil societies are to reduce anthropogenic CO₂ emissions and to limit the global air temperature increase. In this regard, there is an urgent need to change existing production systems in order to reduce greenhouse gas emissions and to sequester them. In this review, we consider up-to-date scientific approaches and innovative technologies, which may help in developing roadmaps to reduce the emissions of climate-active gases, control rising temperatures, decarbonize economies, and promote the sustainable development of society in general.
... The technique for purifying highly colored natural waters by electrocoagulation is based on the metal anode dissolution under the electric current with further cotton complexation using humic and fulvic acids [11][12][13]. Iron hydroxide-based complexes formed as a result of the metal anode dissolution are coagulants that allow avoiding the use of additional chemical reagents for the organic acid colloidal suspension coagulation [14][15][16]. Interacting with dissolved substances, the electrochemically obtained coagulant, like chemical one, forms floccules gradually settling down in the settling tank, thereby clarifying water [17]. The water after clarification contains some molecules and macromolecules, viruses, and bacteria, not involved in the floccule formation due to the specifics of their surface charge, therefore, to comply with the SanPiN requirements, it requires fine purification and disinfection. ...
The practical application of the results of experimental studies of the aquatic environment of the Russian Federation Northern Territories has been considered for the case of the Republic of Sakha (Yakutia). Optimal water purification parameters were justified and chosen using electrocoagulation for the surface source of the Malaya Botuobiya River near the Tas-Yuryakh village. The optimal rate of water clarification and settling after electrochemical treatment is defined. The following dependencies have been obtained: water sample clarification on current density and treatment time; clarification time on power consumption; time dependence of coarse cotton settling kinetics. An accumulative-type unit with steady-state coagulation has been developed and tested for the practical application of experimental results, installed in the Tas-Yuryakh village pumping station. The following dependencies have been obtained in the research: the sludge quality on the electrolyzer current and water flow rate; the cotton settling time and quality on the electrolysis mode. The optimal water purification parameters allowed obtaining drinking quality water complying with the RF sanitary standards and regulations at the pumping station outlet.
... Suspended sediment particles may flocculate as the result of strong attractive physicochemical forces due to salinity in water and form colloids (Chandra et al. 2010;Pokrovsky et al. 2014) which may sediment at the bottom of the water body and favor reduction in turbidity. Flocculation is higher in saline environments than in freshwater ones, but the relations among the processes, flocculation speed and salinity have been widely discussed and opinions differ (Chandra et al. 2010;Lasareva et al. 2019;Mhashhash et al. 2018). Another hypothesis of low turbidity is the dilution of effluents of the São Lourenço Stream from the salt water inlet. ...
Coastal zones have great environmental and economic importance, since anthropogenic activities are very intense, and consequently, their water quality can be affected. Spatial and temporal variations in physicochemical parameters [temperature, pH, electrical conductivity (EC), salinity, dissolved oxygen (DO) and turbidity] in the surface water from the São Lourenço Watershed, a coastal zone in southern Brazil, were investigated. The influence of Patos Lagoon on the watershed in dry periods was confirmed by the increase in salinity and EC of up to 6.43 and 10,810.00 µS cm−1, respectively. In addition, the DO content with low values at the mouth in some samplings, below the Brazilian legislation, calls attention for the water quality. The principal component analysis showed considerable differences in the lower course by comparison with the upper course and the middle course due to climatic and anthropogenic factors. Results from the monitoring enabled to understand fluvial dynamics involving the system of a watershed that contributes to disposal in coastal lagoons through seasonal and climatic factors. Besides, from a managerial point of view, the obtained results support effective decision-making for the preservation of coastal ecosystems.
... The supplementation of organic matter lessens the soil's tendency to become compacted and increases the capacity of the soil to retain water, both of which lead to increased crop growth and development (Prasad et al., 2017). The decay of organic substances results in the flocculation of soil particles, which improves soil structure and water conduction, increased porosity, and a reduction in compaction (Lasareva et al., 2019). There is no viable alternative to the usage of chemical fertilizers because organic manures are unable to satisfy the crop's nutritional demand over a vast area due to infinite requirements, a slower release of nutrients, and a high level of labor requirement (Wu and Ma, 2015). ...
The properties of the soil, both physical and chemical, have a considerable impact on the development and production of the crops. The soil texture, an unchanging soil physical property that affects the soil, has a secondary effect on crop growth. The goal of this study is to determine how different textures and organic amendments affect the root development of maize, which in turn affects the plant's ability to grow. In 2019 a pot experiment was conducted at Arid Zone Research Center in DI Khan, Pakistan, using two native soil types, clay loam and sandy loam. Farm manure was added as an amendment to the trial at rates of 0 (T0), 5 (T1), 10 (T2), and 15 (T3) Mg ha-1. Half the recommended NPK dose of 150:90:60 kg ha-1 was added to each treatment pot. The plant parameters including shoot length (89.6 cm), fresh weight (176.42 g), and dry weight (16.89 g), as well as root length (39.1 cm), fresh weight (37.11 g), dry weight (11.01 g) and 100-grain weight (22.23 g). The organic amendment added at a rate of 10 Mg ha-1 (T2) under sandy loam texture produced noticeably higher values. It was concluded that every plant parameter increased as the quantity of organic matter increased in the soil, however as the quantity of added organic matter reached 10 Mg ha-1, a significant drop was noticed. Additionally, it was discovered that crops performed well in sandy loam than in clay loam soil
... The Kara Sea receives 1300-1400 km 3 of fresh water annually, which accounts for 41% of the total freshwater runoff to the Arctic Ocean [1]. Coastal marine systems in the Arctic typically contain high concentrations of inorganic and organic particles, which enter the water column via the melting of land and sea ice [2]. Studies conducted in different Arctic regions have demonstrated that all components of the plankton community play a significant role in the functioning in cold waters, particularly in the southwestern Kara Sea [3,4]. ...
Knowledge of the features of the structure and productivity of the Arctic communities of marine planktonic algae is necessary to identify possible changes in the pelagic ecosystem functioning under the changing climate condition of the Kara Sea. This study shows that the species diversity, abundance of phytoplankton, and production activity of algae are at a maximum at the beginning of summer during a seasonal ice melting period. The studies were carried out in the southwestern Kara Sea and in the estuarine zone of the Ob and Yenisei rivers from 29 June to 15 July 2018. The concentrations of nutrients and dissolved organic carbon were determined. The optical properties of chromophoric dissolved organic matter, species composition, abundance and biomass of all size groups of phototrophic and heterotrophic phytoplankton, and parameters of primary production and potential photosynthetic capacity were considered. Statistical data analysis showed that the leading factors influencing changes in the abundance of phytoplankton and its productivity are the content of silicates and salinity. At the same time, the production potential of algae is realized as short-lived and small phytoplankton assemblages differed in number taxa and diversity, with an equally rapid decrease in photosynthetic activity. Such changes affect the Marine Zone to a greater extent and the Estuarine Zone to a lesser extent.
... Among the various factors determining the transport mechanisms of river substances, the role of dissolved organic matter (DOM) should be particularly noted [13][14][15]. Depending on the nature (recalcitrant or labile) and its concentration, DOM can act either as a flocculant that causes aggregation of mineral particles, or a stabilizer that adsorbs on the surface of particles, increases their aggregative stability and helps them move through the mixing zone [16][17][18][19][20]. Currently, there is an increasing interest in extracellular polymeric substances (EPS) released by marine biota that can act as flocculants, as well as in the study of the bio-flocculation process itself. ...
... In our study, we have proposed COC/PM and COC/CM criteria (where COC is colloid organic carbon, PM is particulate matter and CM is colloid matter) the values of which increase sharply in the flocculation zone. In combination with microbiological data, these indicators allow us to identify flocculation zones [17]. ...
... Using the method described above (isolation of the colloids by electrolytic coagulation) colloidal fraction of natural waters were obtained in RSTZ of Arctic rivers (Northern Dvina, Lena and Ob) [17]. Colloids have been shown to be a key form of transport of riverine matter to the sea, two orders of magnitude higher than particulate matter. ...
The River-Sea Transition Zone has a significant impact on marine ecosystems, especially at present, due to increased anthropogenic pressure on rivers. The colloidal form of river runoff has not been practically studied, unlike the dissolved and suspended one, but this form is particularly important for the transport of river substances. The mechanisms of substance transfer were studied using model systems (colloidal clay, Fe(OH) 3 sol), particle aggregation was estimated by changes in optical density, turbidity and particle size. The influence of the nature of dissolved organic matter (DOM) and salinity on colloid transport was studied. It was found that humic substances (HS) (recalcitrant DOM) stabilize mineral colloids with increasing salinity, while their interaction with chitosan (labile DOM) promotes flocculation and further precipitation in the mixing zone. In natural conditions, labile DOM can be released during viral lysis of bacteria or salt stress of biota. It was shown that clay particles modified with HS are flocculated more effectively than pure clays. HS can facilitate the transport of Fe(OH) 3 into the outer part of the mixing zone even in the presence of flocculants. The flocculation mechanism and modern views on this process are considered.
... This behavior may dominate by the interaction between salinity, pH, and the accumulation of colloid matter (Cantwell and Burgess, 2001). Salt may induce organic matter to aggregate with each other for flocculation (Lasareva et al., 2019), but not completely flocculate the large sized colloidal matter (Herzog et al., 2019). The colloidal material can be stable under high pH and high salinity such as humic acid (Liu and Gao, 2019;Furukawa et al., 2014). ...
Colloids of natural river water is a key intermediate carrier of lead (Pb). It is important to monitor the transport–transformation behavior of Pb in the colloidal phase of seaward water because this behavior is related to the levels of pollution input and environmental risks posed to the sea, especially in coastal delta areas. In this study, the fractionation behavior and distribution of toxic Pb from the truly dissolved phase and the different colloidal phases in seven seaward rivers in the Yellow River Delta were investigated. The concentrations of total dissolved Pb, truly dissolved Pb, and colloidal Pb were 0.99–40.09 μg L–1, 0.40–8.10 μg L–1, and 0.60–35.88 μg L–1, respectively. In freshwater rivers, the main component of total dissolved Pb (about > 50%) is truly dissolved Pb but the main component of total dissolved Pb in the seawater environment is colloidal Pb (> 80%). A dramatic increase in salinity causes the deposition (about ≈94%) of all forms of Pb to sediment from estuarine water in winter. However, this sedimentation behavior of colloidal Pb gradually decreases (in the Shenxiangou River) when the river salinity approaches seawater salinity (S = ≈29). In the industrial port (Xiaoqinghe River) and mariculture (Yongfenghe River) estuarine areas, which have extensive seawater, the deposition behavior of colloidal Pb (<15%) is less affected by the change in salinity. This suggests that human activity contributes to the spread of Pb in the offshore environment. The concentration of 100 kDa–0.22 μm Pb has a postive correlation with total colloidal Pb. Its variation is minimally affected by salinity compared with other colloidal components. In addition, the correlation between the molecular weight and aromaticity of chromophoric dissolved organic matter (CDOM) and colloidal Pb suggests that macromolecules in seawater will be important transport carriers of Pb. In all, truly dissolved Pb is the main transport form of dissolved Pb in river freshwater; however, in brackish water in estuaries, colloidal matter gradually becomes the main transport carrier. Surging salinity immobilizes truly dissolved Pb in the estuarine region, but colloidal matter inhibits this deposition. Colloidal phase is the important conversion for land–sea transport of Pb by seaward rivers.
... Organic matter reaches the bottom of the reservoir (especially at great depths) as biochemically transformed and is depleted in biogenic elements [62,70,179]. Along with this, during the sedimentation and early diagenesis, the processes of the sorption/desorption of chemical elements take place actively on the surface of organomineral particles formed after the death of a phytoplankton cell [8,11,12,180]. Taken together, these processes significantly change the chemical composition of the initial phytogenic OM formed in the photic layer of aquatic ecosystems. ...
In freshwater and marine ecosystems, the phytoplankton community is based on microalgae and cyanobacteria, which include phylogenetically very diverse groups of oxygenic photoautotrophs. In the process of evolution, they developed a wide range of bio(geo)chemical adaptations that allow them to effectively use solar radiation, CO2 , and nutrients, as well as major and trace elements, to form O2 and organic compounds with a high chemical bond energy. The inclusion of chemical elements in the key processes of energy and plastic metabolism in the cell is determined by redox conditions and the abundance and metabolic availability of elements in the paleoenvironment. Geochemical evolution , which proceeded simultaneously with the evolution of biosystems, contributed to an increase in the number of metals and trace elements acting as cofactors of enzymes involved in metabolism and maintaining homeostasis in the first photoautotrophs. The diversity of metal-containing enzymes and the adaptive ability to replace one element with another without losing the functional properties of enzymes ensured the high ecological plasticity of species and allowed microalgae and cyanobacteria to successfully colonize a wide variety of habitats. In this review, we consider the main aspects of the modern concepts of the biogeochemical evolution of aquatic ecosystems and the role of some metals in the main bioenergetic processes in photosynthetic prokaryotes and eukaryotes. We present generalized data on the efficiency of the assimilation of key nutrients by phytoplankton and their importance in the cycle of carbon, silicon, nitrogen, phosphorus, sulfur, and iron. This article presents modern views on the evolutionary prerequisites for the formation of elemental signatures in different systematic groups of microalgae, as well as the possibility of using the stoichiometric ratio in the study of biological and geochemical processes in aquatic ecosystems.
... Another interesting application of Ch is its use in models that allow the study of processes occurring in nature. For instance, the variety of factors affecting the processes in the river-sea mixing zone required the study of the transfer process in laboratory conditions, where Ch is chosen as a model of fresh dissolved organic matter (flocculant) released in situ in the river-sea area [216]. When studying the formation of the soil structure, chitosan can be used as a model of the in situ forming organic matter capable of binding mineral particles modified by humic substances [217]. ...
Increasing attention is now being paid to applying green chemistry compounds, i.e., compounds that cause minimum environmental damage. Biopolymers have a leading place in this issue, and chitosan and its derivatives are leading among them. The unique structure of chitosan allows it to exhibit a set of properties such as biodegradability, antimicrobial activity, non-toxicity, biocompatibility, and others, due to which it has found wide application in various fields. Modifications of its structure by alkylation, esterification, graft copolymerization, acylation, and other types of modification and new technologies have greatly expanded the possible applications of chitosan and its derivatives. The important aspect is also that the technologies used for modification can be attributed to green chemistry, and the modification products are eco-friendly. This article provides an overview of recent trends in preparing chitosan derivatives and their use in light of environmentally friendly technologies.
... When the stationary phase of growth was reached, 15 mL of each sample was taken and combined to obtain a sample of 45 mL volume for each single algae strain. The combined samples were then filtered through Whatman 47-mm GF/F fiberglass filters with an effective pore diameter of 0.5-0.7 μm (preliminarily heat-treated at 450 °C) under a 200-400-mbar vacuum using a standard method [91]. ...
Dissolved organic matter (DOM) is an important component of aquatic environments; it plays a key role in the biogeochemical cycles of many chemical elements. Using excitation-emission matrix fluorescence spectroscopy, we examined the fluorescent fraction of DOM (FDOM) produced at the stationary phase of growth of five strains of microalgae sampled and isolated from the Ob and Yenisei gulfs. Based on the morphological and molecular descriptions, the strains were identified as diatoms (Asterionella formosa, Fragilaria cf. crotonensis, and Stephanodiscus hantzschii), green microalgae (Desmodesmus armatus), and yellow-green microalgae (Tribonema cf. minus). Three fluorescent components were validated in parallel factor analysis (PARAFAC): one of them was characterized by protein-like fluorescence (similar to peak T), two others, by humic-like fluorescence (peaks A and C). The portion of fluorescence intensity of humic compounds (peak A) to the total fluorescence intensity was the lowest (27 ± 5%) and showed little variation between species. Protein-like fluorescence was most intense (45 ± 16%), but along with humic-like fluorescence with emission maximum at 470 nm (28 ± 14%), varied considerably for different algae strains. The direct optical investigation of FDOM produced during the cultivation of the studied algae strains confirms the possibility of autochthonous production of humic-like FDOM in the Arctic shelf regions.
