Huacheng Xu

Nanjing institute of Geography and Limnology,Nanjing, China · State Key Laboratory of Lake Science and Environment

Dissolved organic matter (DOM) is ubiquitous in natural waters. The ecological role and environmental fate of DOM are highly related to the chemical composition and size distribution. To evaluate size-dependent DOM quantity and quality, water samples were collected from river, lake, and coastal marine environments and size fractionated through a se...

The importance of controlling internal phosphorus (P) pollution in lakes has been recognized by scientists, and the application of P-inactivating materials to immobilize sediment P is often considered. However, sediment resuspension, a typical physical process occurring in lakes, has been demonstrated to increase the uncertainty of immobilization....

The heavy metal Cd can cause severe toxicity on aquatic algae, but there are few studies on the cytotoxicity of heavy metal on algae based on synchrotron radiation technology. In this study, synchrotron radiation-based Fourier transform infrared spectromicroscopy (SR-FTIR) was used to characterize in vivo the toxic effects of Cd on Cosmarium sp. ce...

Dissolved organic matter (DOM) is ubiquitous in natural waters which exhibits obvious effects on the toxicity of heavy metals. However, information on the toxicity of heavy metals in the presence of DOMs with different molecular weights (MWs) was still unclear. In this study, Suwannee river humic acid (SRHA) and algae-derived organic matter (ADOM)...

As an inevitable by-product of potable water production, drinking water treatment residue (DWTR) recycling to make ceramsite can provide both environmental and economic benefits in constructing filtration treatment system for water environment remediation. Given the varied properties of DWTR from different waterworks, this study aims to identify th...

The typical harm effect of algal bloom sedimentation is to increase sulfides level in surroundings, threatening aquatic organisms and human health; whereas, P inactivating materials containing sulfate are commonly attempted to be used to immobilize reactive P or to flocculate excessive algae in water columns for eutrophication control. In this stud...

The classical lake internal phosphorus (P) pollution control using P-inactivating materials is typically carried out by reducing the release of soluble P from sediments to overlying water; however, particulate P loading through sediment resuspension could also cause internal P pollution for algae breeding. Therefore, based on lanthanum modified ben...

Dissolved organic matter (DOM) is ubiquitous in aquatic environments, whose behaviors and fate are highly related to the chemical compositions and size distribution. In this study, the UV-induced photodegradation properties of DOMs with different origins (i.e., macrophyte- and algae-derived) were investigated using absorption and fluorescence spect...

Drinking water treatment residue (DWTR) often exhibits favorable microbial effect on nitrogen (N) removal during recycling as phosphorus (P) adsorbent in environmental remediation. Given the relatively high concentrations of iron (Fe) in DWTR and the importance of Fe-cycling microbial communities to regulate N cycles in nature, this study hypothesi...

Seasonal flooding-drought transformation process of lake sediments lead to changes of dissolved oxygen and redox conditions and the resultant generation of hydroxyl radical (HO•). To date, information on HO• formation and its regulators in seasonal lake sediments is largely unexplored. In this study, a total of nineteen sediments were collected fro...

Fe-based materials used to adsorb P are commonly considered to be limited by the increased Fe lability, while Fe in drinking water treatment residue (DWTR) shows stable P adsorption abilities. Accordingly, this study aimed to gain insight into Fe lability in DWTR as compared to FeCl3 and Fe2(SO4)3 using Fe fractionation, EXAFS, and high-throughput...

Oxygenation of the reduced species has been regarded as the major source for hydroxyl radical (HO•) generation in aquatic environments. Yet, the O2-induced formation of HO• in lake sediments during the flooding/drought transformation process remained largely unexplored. In this study, two types of sediments from Wucheng (WC) and Nanji (NJ) area in...

Heavy metals were typical contaminants in aquatic ecosystems, while their effects on the biotoxicity and metabolism of algal cells in the presence of organic ligands were still unclear. In this study, the contrasting effects of Cu and humic acids (HA) on the growth inhibition, oxidative stress and extracellular secretion of microalga Chlorella vulg...

Dissolved organic matter (DOM) is ubiquitous in aquatic ecosystem and characterized by a wide range of molecular weight (MW) distribution. In this study, a total of nine bulk DOM samples, including five International Humic Substances Society (IHSS) standards and four naturally collected samples, were fractionated into low MW (LMW-, <1 kDa) and high...

Hydroxyl radical (HO•) in natural waters plays a critical role in contaminant transformation and ecosystem health. In this study, the photogeneration and steady-state concentration of HO• in different aquatic environments (e.g., river and lake) along the middle-lower Yangtze region, China, were evaluated. The results showed that, compared to lake s...

The overgrowth of macrophytes has become serious due to increasing eutrophication in shallow lakes. The primary degradation processes of macrophytes litter, including photodegradation and biodegradation, induce considerable patchiness in the concentration and bioavailability of dissolved organic matter (DOM). In this study we investigated the compo...

Anaerobic ammonium oxidation coupled to ferric iron reduction (Feammox) has been assumed to play an important role in nitrogen removal from ecosystems. This study assessed the potential role of Feammox in nitrogen transformation in eutrophic lake sediment using an isotope tracing technique in sediment slurry incubation experiments. Feammox was disc...

The loading of La can substantially enhance the adsorption capability of drinking water treatment residue (DWTR) for better recycling. Normally, the modification was based on incubation of DWTR and La solution at a certain ratio, following by solid-liquid separation and drying processes. This study attempted to simplify La loading procedures by ado...

This study proposed a scheme for drinking water treatment residue (DWTR) pretreatment to eliminate concerns about potential unfavorable effects caused by excessive release of nutrients (typically N) during recycling in restoration of a water environment with relatively low pollution (e.g., eutrophic surface water). Inspired by soil washing, the pre...

The separation and recovery of pollutant-loaded magnetic carbon materials from organic contaminated environment is recently concerned, but the change of sorption ability and mechanism of activated carbon and biochar caused by magnetic particles modification still need to be explored. Here, the magnetic modification of two coconut shell-, coal-deriv...

Dissolved organic matter (DOM) in aquatic environment significantly influences the behavior and fate of heavy metals via binding, complexation and thus changes the metal speciation; however detailed interfacial processes and mechanisms are still unclear. Here, differential absorbance and fluorescence spectra and two dimensional UV-FTIR heterospectr...

Knowledge of the dynamic changes in molecular size of natural colloidal organic matter (COM) along the aquatic continuum is of vital importance for a better understanding of the environmental fate and ecological role of dissolved organic matter and associated contaminants in aquatic systems. We report here the pH- and cation-dependent size variatio...

Stability of colloidal particles contributes to the turbidity in the water column, which significantly influences water quality and ecological functions in aquatic environments especially shallow lakes. Here we report characterization, origin and aggregation behavior of aquatic colloids, including natural colloidal particles (NCPs) and total inorga...

Effects of photochemical and microbial degradation on variations in composition and molecular-size of dissolved organic matter (DOM) from different sources (algal and soil) and the subsequent influence on Cu(II) binding were investigated using UV-Vis, fluorescence excitation-emission matrices coupled with parallel factor analysis, flow field-flow f...

A bacterial strain, designated TH167T, was isolated from cyanobacterial aggregates in eutrophic Lake Taihu in China. Cells were observed to be slightly curved rod-shaped, motile by gliding, aerobic, Gram-stain-negative, proteorhodopsin-containing. Optimal growth was obtained at pH 7.0 (range: 6.0-9.0), 28 °C (range: 4-32 °C) and 0 % (w/v) NaCl (ran...

Dissolved organic matter (DOM) is ubiquitous and plays an important role in regulating water quality, ecological function, and the fate and transport of trace elements and pollutants in aquatic environments. Both the colloidal precursors (i.e. <1 kDa) and bulk DOM collected from a freshwater estuary were incubated in the dark for 21 days to examine...

Dynamic variations in chemical composition and size distribution of dissolved organic matter (DOM) along the river-lake interface in the Fox River plume were investigated using ultrafiltration, flow field-flow fractionation, UV-Vis and fluorescence spectroscopy and parallel factor analysis. On average, ~67% of bulk dissolved organic carbon (DOC) we...

Occurrence of cyanobacterial harmful algal blooms (CyanoHAB) can induce considerable patchiness in the concentration and bioavailability of dissolved organic matter (DOM), which could influence biogeochemical processes and fuel microbial metabolism. In the present study, a laboratory 4-stage plug-flow bioreactor was used to successfully separate th...

The stability/aggregation propensity of inorganic colloids in eutrophic shallow lakes is of great essence in governing the water transparency and contaminant behavior. In this study, time-resolved dynamic light scattering was employed to investigate the aggregation kinetics of Al2O3 inorganic colloids over a wide range of cyanobacterial extracellul...

Nanoparticle binding with organic ligands in natural waters is important to understand their environmental behavior and fate. In this study, the interaction of two metal oxide nanoparticles (nano-CuO and nano-Fe3O4) with extracellular polymeric substances (EPS) from algal aggregates was studied through using fluorescence emission-excitation matrix...

The hydrodynamic and structural properties of Microcystis extracellular polymeric substances (EPS) in electrolytes with different valences and ionic strengths were investigated via using dynamic light scattering, fluorescence excitation emission matrix coupled with parallel factor (EEM–ARAFAC) analysis, two-dimensional correlation spectroscopy (2D–...

The use of phosphorus (P) inactivating agents to reduce internal P loading from sediment for lake restoration has attracted increasing attention. Reasonably, the physicochemical properties of P inactivating agents may vary with the interference of various environmental factors, leading to the change of control effectiveness and risks. In this study...

A Gram-negative, slightly curved rod-shaped, non-spore-forming diazotrophic bacterium, designated strain TH16T, was isolated from cyanobacterial aggregates taken from eutrophic Lake Taihu, Jiangsu Province, China. The pH range for growth was 5-9 (optimum at pH 7.0), salt range was 0-2% (w/v) NaCl (optimum 0%) and temperature range 20-37℃ (optimum 3...

Metal binding of organic ligands can definitely affect its environmental behavior in waters, while information on the binding heterogeneity with different organic ligands is still lacked till now. In this study, the binding of zinc with organic matters associated with cyanobacterial blooms, including dissolved organic matters (DOM) and attached org...

Water-sediment exchange is a fundamental component of oxyanion cycling in the environment. Yet, many of the (im)mobilization processes overlay complex spatial and temporal redox regimes that occur within millimeters of the interface. Only a few methods exist that can reliably capture these porewater fluxes, with the most popular being high-resoluti...

Information on metal binding with fluorescent substances has been widely studied. By contrast, information on metal binding with non-fluorescent substances remains lacking despite the dominance of these substances in aquatic systems. In this study, the metal binding properties of both fluorescent and non-fluorescent substances were investigated by...

Dissolved organic matter (DOM) affects the toxicity, mobility and bioavailability of metals in aquatic environment. In this study, the interactions between two metals of environmental concern [Cu(II) and Fe(III)] with DOM in a euthrophic algae-rich lake (Lake Taihu, China), including dissolved natural organic matter (NOM) and algal extracellular po...

Cyanobacterial blooms represent a significant ecological and human health problem worldwide. In aquatic environments, cyanobacterial blooms are actually surrounded by dissolved organic matter (DOM) and attached organic matter (AOM) that bind with algal cells. In this study, DOM and AOM fractionated from blooming cyanobacteria in a eutrophic freshwa...

Detailed knowledge of the architecture and molecular structure of biofilms during composting is important for understanding the underlying mechanisms of rapid composting with inoculation. In this study, multiple fluorescent labeling and two-dimensional Fourier transform infrared (FTIR) correlation spectroscopy were used to characterize biofilms dur...

Enhanced knowledge on extracellular polymeric substances (EPSs) of mucilaginous cyanobacterial blooms could improve our understanding of its ecological significance. This study for the first time investigated the extraction and fractionation of EPS matrix from cyanobacterial blooms in a eutrophic freshwater lake, and the changes in chemical composi...

This is the first attempt to report the gaseous nitrogen emissions from landfill leachate filtration methods by irrigating the aged refuse. A first-order reaction model was a good fit for the increase in ammonia emissions from aged refuse, clay and sandy soil incubated for 120h after adding the leachate-N solution. The emissions of ammonia and N2O...

Investigations on the extracellular polymeric substances (EPS) are crucial for better understanding the growth and proliferation of cyanobacterium Microcystis aeruginosa. In this study, a combined approach of fractionation procedure and parallel factor (PARAFAC) analysis were applied to characterize the EPS of M. aeruginosa. Physicochemical analysi...

To investigate the influences of alkaline pretreatment on anaerobic digestion (AD) and sludge dewaterability after AD, waste activated sludge was adjusted to different pH values (8, 9, 10, 11, 12) and placed at ambient temperature for 24 hr. The samples were then adjusted to the initial pH and subjected to 25 days of AD. The results showed that, wh...

Phosphorus (P) is an element vital for all living organisms, yet the world's reserves of phosphate rock are becoming depleted. This study investigated an effective P recovery method from sludge ash via struvite precipitation. Results showed that more than 95% of the total P content was extracted from sludge ash by applying 0.5 mol/L HCl at a liquid...

To investigate the effect of ultrasonic pretreatment on anaerobic digestion and sludge dewaterability and further to probe into the influencing factors on sludge dewaterability, sludge flocs were stratified into four fractions: (1) slime; (2) loosely bound extracellular polymeric substances (LB-EPS); (3) tightly bound EPS (TB-EPS); and (4) EPS-free...

Previous publications on phosphorus (P) in sewage sludge and sludge ash have mostly focused on the total contents, while information on the fraction distribution of P is rarely examined. In this study, P in sewage sludge was, for the first time, fractioned into NH4Cl-P, BD-P, NaOH-P, HCl-P and Res-P via increasing chemical reagents. Its speciation...

Aerobic granules seeded with activated sludge flocs and pellets (obtained from activated sludge flocs) were cultivated in two sequencing batch reactors and their characteristics were compared. Compared with granules seeded with activated sludge flocs, those seeded with pellets had shorter start-up time, larger diameter, better chemical oxygen deman...

Dewatered sewage sludge is often stored still before further processing and final disposal. This study showed that anaerobic storage of dewatered sewage sludge could hydrolyze organic matter from the sludge matrix, and increase soluble organic acid content from 90 to 2400 mg/L and soluble organic carbon content from 220 to 1650 mg/L. Correspondingl...

Effect of ultrasonic pretreatment on sludge dewaterability was determined and the fate of extracellular polymeric substances (EPS) matrix in mesophilic anaerobic digestion after ultrasonic pretreatment was studied. Characteristics of proteins (PN), polysaccharides (PS), excitation-emission matrix (EEM) fluorescence spectroscopy and molecular weight...

The responses of two different types of aerobic granules to storage, granule A seeded with activated sludge flocs and granule B seeded with pellets (cells), were investigated in this study. After 3-week storage, the surface of granule B remained compact and smooth while obvious crevices were observed on that of granule A. Compared with granule B, g...

Three-dimensional excitation emission matrix (EEM) fluorescence spectroscopy and gel-permeating chromatography (GPC) were employed to characterize the extracellular polymeric substances (EPS) in aerobic granulation. EPS matrix in this study was stratified into four fractions: (1) supernatant, (2) slime, (3) loosely bound EPS (LB-EPS), and (4) tight...

The present study evaluated the sludge dewaterability and further explored the relationship between the sludge dewaterability and the molecule weights (MW) of organic matters in the different fractions of sludge flocs. The sewage sludge was sampled and fractionated into four fractions: (1) slime, (2) loosely bound extracellular polymeric substances...