Publications by authors named "Chengxue Ma"

9 Publications

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Machine learning in natural and engineered water systems.

Water Res 2021 Sep 14;205:117666. Epub 2021 Sep 14.

Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, College of Environmental and Ecology, Chongqing University, Chongqing 400044, China.

Water resources of desired quality and quantity are the foundation for human survival and sustainable development. To better protect the water environment and conserve water resources, efficient water management, purification, and transportation are of critical importance. In recent years, machine learning (ML) has exhibited its practicability, reliability, and high efficiency in numerous applications; furthermore, it has solved conventional and emerging problems in both natural and engineered water systems. For example, ML can predict various water quality indicators in situ and real-time by considering the complex interactions among water-related variables. ML approaches can also solve emerging pollution problems with proven rules or universal mechanisms summarized from the related research. Moreover, by applying image recognition technology to analyze the relationships between image information and physicochemical properties of the research object, ML can effectively identify and characterize specific contaminants. In view of the bright prospects of ML, this review comprehensively summarizes the development of ML applications in natural and engineered water systems. First, the concept and modeling steps of ML are briefly introduced, including data preparation, algorithm selection and model evaluation. In addition, comprehensive applications of ML in recent studies, including predicting water quality, mapping groundwater contaminants, classifying water resources, tracing contaminant sources, and evaluating pollutant toxicity in natural water systems, as well as modeling treatment techniques, assisting characterization analysis, purifying and distributing drinking water, and collecting and treating sewage water in engineered water systems, are summarized. Finally, the advantages and disadvantages of commonly used algorithms are analyzed according to their structures and mechanisms, and recommendations on the selection of ML algorithms for different studies, as well as prospects on the application and development of ML in water science are proposed. This review provides references for solving a wider range of water-related problems and brings further insights into the intelligent development of water science.
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http://dx.doi.org/10.1016/j.watres.2021.117666DOI Listing
September 2021

Cotransport of thallium(I) with polystyrene plastic particles in water-saturated porous media.

J Hazard Mater 2021 Aug 14;422:126910. Epub 2021 Aug 14.

Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400044, China. Electronic address:

Exploring the transport behaviors of thallium (Tl) in porous media is crucial for predicting Tl pollution in natural soils and groundwater. In recent years, the misuse of plastics has led to plastic becoming an emerging pollutant in soil. In this work, the effects of plastic particles on Tl(I) transport in water-saturated sand columns were investigated under different ionic strengths (ISs), pH values, and plastic particle sizes. The two-site nonequilibrium model was selected to fit the breakthrough curves (BTCs) of Tl(I). The results demonstrated that nanoplastics (NPs) accelerated Tl(I) transport at pH 7, which might be attributed to the competitive adsorption of NPs and Tl(I) on sand surfaces. However, at pH 5, the deposited NPs might provide more adsorption sites for Tl(I), and thus enhance its retention in the columns. In addition, the "straining" process could intercept microplastics (MPs) with Tl(I) that was attached under unfavorable attachment conditions, which would result in the inhibited mobility of Tl(I). On the other hand, the migration of plastics was restrained to some extent when Tl(I) was present. Overall, the findings from this work provided a new perspective for understanding the transport of Tl(I) and plastics in subsurface environments.
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http://dx.doi.org/10.1016/j.jhazmat.2021.126910DOI Listing
August 2021

Release of deposited MnO nanoparticles from aqueous surfaces.

J Environ Sci (China) 2020 Apr 31;90:234-243. Epub 2019 Dec 31.

Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400044, China. Electronic address:

Changes in solution chemistry and transport conditions can lead to the release of deposited MnO nanoparticles from a solid interface, allowing them to re-enter the aqueous environment. Understanding the release behavior of MnO nanoparticles from naturally occurring surfaces is critical for better prediction of the transport potential and environmental fate of MnO nanoparticles. In this study, the release of MnO nanoparticles was investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D), and different environmental surface types, solution pH values and representative macromolecular organics were considered. MnO nanoparticles were first deposited on crystal sensors at elevated NaNO concentrations before being rinsed with double-deionized water to induce their remobilization. The results reveal that the release rate of MnO depends on the surface type, in the decreasing order: SiO > FeO > AlO, resulting from electrostatic interactions between the surface and particles. Moreover, differences in solution pH can lead to variance in the release behavior of MnO nanoparticles. The release rate from surfaces was significantly higher at pH 9.8 that at 4.5, indicating that alkaline conditions were more favorable for the mobilization of MnO in the aquatic environment. In the presence of macromolecular organics, bovine serum albumin (BSA) can inhibit the release of MnO from the surfaces due to attractive forces. In presence of humic acid (HA) and sodium alginate (SA), the MnO nanoparticles were more likely to be mobile, which may be associated with a large repulsive barrier imparted by steric effects.
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http://dx.doi.org/10.1016/j.jes.2019.12.011DOI Listing
April 2020

Phytoplankton community structure in relation to environmental factors and ecological assessment of water quality in the upper reaches of the Genhe River in the Greater Hinggan Mountains.

Environ Sci Pollut Res Int 2019 Jun 25;26(17):17512-17519. Epub 2019 Apr 25.

College of Wildlife Resource, Northeast Forestry University, Harbin, 150040, China.

Phytoplankton assemblages were investigated in 2015 along the seasonal changes of the Genhe River in the Greater Hinggan Mountains. The survey was performed in June (spring), August (summer), and October (autumn) at nine sampling stations to study the community composition, abundance, and biodiversity. The results showed that 61 species belonging to 16 genera were identified, including Bacillariophyta of 31 species, Dinophyta 2 species, Cyanophyta 2 species, Chlorophyta 20 species, Chrysophyta 2 species, and Cryptophyta 1 species; Besides, Bacillariophyta are dominant species. Shannon-Wiener (H') and Pielou (J') indices indicated that phytoplankton community was stable. And these two indices were significantly lower in summer than in spring and autumn. Phytoplankton abundance and biomass show significant differences in each season. The total phytoplankton abundance (1122.3 × 104 ind/L) and biomass (6.5709 mg/L) in summer are much higher than that in spring and autumn. There were few species and low abundance and biomass in the upper reaches of Genhe River; this fact can be explained by the cold climate in the Greater Higgnan Mountains region. Canonical correspondence analysis (CCA) was used to analyze the data. It revealed that Fe, Cu, pH, and water temperature (WT) were responsible for most of the variation in space in the phytoplankton community. These environmental parameters play an essential role in the community structure variation of phytoplankton in the upper reaches of Genhe River, the strong association between phytoplankton community structure and ecological factors is varied in each season.
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http://dx.doi.org/10.1007/s11356-019-05200-3DOI Listing
June 2019

A review on the interactions between engineered nanoparticles with extracellular and intracellular polymeric substances from wastewater treatment aggregates.

Chemosphere 2019 Mar 12;219:766-783. Epub 2018 Dec 12.

Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Faculty of Urban Construction and Environmental Engineering, Chongqing University 400044, China.

Engineered nanoparticles (ENPs) will inevitably enter wastewater treatment plants (WWTPs) due to their widespread application; thus, it is necessary to study the migration and transformation of nanoparticles in sewage treatment systems. Extracellular polymeric substances (EPSs) such as polysaccharides, proteins, nucleic acids, humic acids and other polymers are polymers released by microorganisms under certain conditions. Intracellular polymeric substances (IPSs) are microbial substances contained in the body with compositions similar to those of extracellular polymers. In this review, we summarize the characteristics of EPSs and IPSs from sewage-collecting microbial aggregates containing pure bacteria, activated sludge, granular sludge and biofilms. We also further investigate the dissolution, adsorption, aggregation, deposition, oxidation and other chemical transformation processes of nanoparticles, such as metals, metal oxides, and nonmetallic oxides. In particular, the review deeply analyzes the migration and transformation mechanisms of nanoparticles in EPS and IPS matrices, including physical, chemical, biological interactions mechanisms. Moreover, various factors, such as ionic strength, ionic valence, pH, light, oxidation-reduction potential and dissolved oxygen, influencing the interaction mechanisms are discussed. In recent years, studies on the interactions between EPSs/IPSs and nanoparticles have gradually increased, but the mechanisms of these interactions are seldom explored. Therefore, developing a systematic understanding of the migration and transformation mechanisms of ENPs is significant.
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http://dx.doi.org/10.1016/j.chemosphere.2018.12.044DOI Listing
March 2019

Deposition Kinetics of Colloidal Manganese Dioxide onto Representative Surfaces in Aquatic Environments: The Role of Humic Acid and Biomacromolecules.

Environ Sci Technol 2019 01 11;53(1):146-156. Epub 2018 Dec 11.

Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Faculty of Urban Construction and Environmental Engineering, National Centre for International Research of Low-Carbon and Green Buildings , Chongqing University , Chongqing 400044 , China.

The initial deposition kinetics of colloidal MnO on three representative surfaces in aquatic systems (i.e., silica, magnetite, and alumina) in NaNO solution were investigated in the presence of model constituents, including humic acid (HA), a polysaccharide (alginate), and a protein (bovine serum albumin (BSA), using laboratory quartz crystal microbalance with dissipation monitoring equipment (QCM-D). The results indicated that the deposition behaviors of MnO colloids on three surfaces were in good agreement with classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Critical deposition concentrations (CDC) were determined to be 15.5 mM NaNO and 9.0 mM NaNO when colloidal MnO was deposited onto silica and magnetite, respectively. Both HA and alginate could largely retard the deposition of MnO colloids onto three selected surfaces due to steric repulsion, and HA was more effective in decreasing the deposition rate relative to alginate. However, the presence of BSA can provide more attractive deposition site and thus lead to greater deposition behavior of MnO colloids onto surfaces. The dissipative properties of the deposited layer were also influenced by surface type, electrolyte concentration, and organic matter characteristics. Overall, these results provide insights into the deposition behavior of MnO colloids on environmental surfaces and have significant implications for predicting the transport potential of common MnO colloids in natural environments and engineered systems.
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http://dx.doi.org/10.1021/acs.est.8b04274DOI Listing
January 2019

Deposition of engineered nanoparticles (ENPs) on surfaces in aquatic systems: a review of interaction forces, experimental approaches, and influencing factors.

Environ Sci Pollut Res Int 2018 Nov 28;25(33):33056-33081. Epub 2018 Sep 28.

Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Faculty of Urban Construction and Environmental Engineering, Chongqing University, Chongqing, 400044, China.

The growing development of nanotechnology has promoted the wide application of engineered nanomaterials, raising immense concern over the toxicological impacts of nanoparticles on the ecological environment during their transport processes. Nanoparticles in aquatic systems may undergo deposition onto environmental surfaces, which affects the corresponding interactions of engineered nanoparticles (ENPs) with other contaminants and their environmental fate to a certain extent. In this review, the most common ENPs, i.e., carbonaceous, metallic, and nonmetallic nanoparticles, and their potential ecotoxicological impacts on the environment are summarized. Colloidal interactions, including Derjaguin-Landau-Verwey-Overbeek (DLVO) and non-DLVO forces, involved in governing the depositional behavior of these nanoparticles in aquatic systems are outlined in this work. Moreover, laboratory approaches for examining the deposition of ENPs on collector surfaces, such as the packed-bed column and quartz crystal microbalance (QCM) method, and the limitations of their applications are outlined. In addition, the deposition kinetics of nanoparticles on different types of surfaces are critically discussed as well, with emphasis on other influencing factors, including particle-specific properties, particle aggregation, ionic strength, pH, and natural organic matter. Finally, the future outlook and challenges of estimating the environmental transport of ENPs are presented. This review will be helpful for better understanding the effects and transport fate of ENPs in aquatic systems. Graphical abstract ᅟ.
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http://dx.doi.org/10.1007/s11356-018-3225-2DOI Listing
November 2018

Effective removal of trace thallium from surface water by nanosized manganese dioxide enhanced quartz sand filtration.

Chemosphere 2017 Dec 12;189:1-9. Epub 2017 Sep 12.

State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, China.

Thallium (Tl) has drawn wide concern due to its high toxicity even at extremely low concentrations, as well as its tendency for significant accumulation in the human body and other organisms. The need to develop effective strategies for trace Tl removal from drinking water is urgent. In this study, the removal of trace Tl (0.5 μg L) by conventional quartz sand filtration enhanced by nanosized manganese dioxide (nMnO) has been investigated using typical surface water obtained from northeast China. The results indicate that nMnO enhanced quartz sand filtration could remove trace Tl(I) and Tl(III) efficiently through the adsorption of Tl onto nMnO added to a water matrix and onto nMnO attached on quartz sand surfaces. Tl(III)-HA complexes might be responsible for higher residual Tl(III) in the effluent compared to residual Tl(I). Competitive Ca cations inhibit Tl removal to a certain extent because the Ca ions will occupy the Tl adsorption site on nMnO. Moreover, high concentrations of HA (10 mgTOC L), which notably complexes with and dissolves nMnO (more than 78%), resulted in higher residual Tl(I) and Tl(III). Tl(III)-HA complexes might also enhance Tl(III) penetration to a certain extent. Additionally, a higher pH level could enhance the removal of trace Tl from surface water. Finally, a slight increase of residual Tl was observed after backwash, followed by the reduction of the Tl concentration in the effluent to a "steady" state again. The knowledge obtained here may provide a potential strategy for drinking water treatment plants threatened by trace Tl.
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http://dx.doi.org/10.1016/j.chemosphere.2017.09.039DOI Listing
December 2017

Significantly improving trace thallium removal from surface waters during coagulation enhanced by nanosized manganese dioxide.

Chemosphere 2017 Feb 24;168:264-271. Epub 2016 Oct 24.

Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Faculty of Urban Construction and Environmental Engineering, Chongqing University, China.

Thallium (Tl) is an element of high toxicity and significant accumulation in human body. There is an urgent need for the development of appropriate strategies for trace Tl removal in drinking water treatment plants. In this study, the efficiency and mechanism of trace Tl (0.5 μg/L) removal by conventional coagulation enhanced by nanosized manganese dioxide (nMnO) were explored in simulated water and two representative surface waters (a river water and a reservoir water obtained from Northeast China). Experimental results showed that nMnO significantly improve Tl(I) removal from selected waters. The removal efficiency was dramatically higher in the simulated water, demonstrating by less than 0.1 μg/L Tl residual. The enhancement of trace Tl removal in the surface waters decreased to a certain extent. Both adjusting water pH to alkaline condition and preoxidation of Tl(I) to Tl(III) benefit trace Tl removal from surface waters. Data also indicated that competitive cation of Ca decreased the efficiency of trace Tl removal, resulting from the reduction of Tl adsorption on nMnO. Humic acid could largely low Tl removal efficiency during nMnO enhanced coagulation processes. Trace elemental Tl firstly adsorbed on nMnO and then removed accompanying with nMnO settling. The information obtained in the present study may provide a potential strategy for drinking water treatment plants threatened by trace Tl.
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http://dx.doi.org/10.1016/j.chemosphere.2016.10.054DOI Listing
February 2017
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