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Soil-derived dissolved organic matter (DOM) links soil and water carbon pools and is an important source of photochemically produced reactive intermediates (PPRIs) in aquatic environments. Despite its importance, the variations in photochemical reactivity of soil-derived DOM molecules in producing PPRIs across broad geographical regions, and the factors driving these variations, remain unclear. Herein, we resolved the apparent quantum yields (Φ(PPRIs)) of hydroxyl radicals (•OH), singlet oxygen ( 1 O 2 ), and excited triplet-state DOM ( 3 DOM*) for irradiated DOM from 22 representative soil reference materials in China, and linked them to soil pH, mineral weathering degree, and DOM characteristics. Generally, the average Φ(PPRIs) values of the soil-derived DOM followed the order of Φ( 3 DOM*) (1.67× 10 -2 ) > Φ( 1 O 2 ) (1.47× 10 -2 ) > Φ(•OH) (7.31× 10 -5 ). The DOM from less weathered soils showed higher Φ(•OH) and Φ( 3 DOM*) and comparable Φ( 1 O 2 ) than that from more weathered soils. The differences were mainly regulated by the abundance of humic-, lignin-, tannin-, and aromatic-like compounds, as indicated by the correlation and random forest model analyses. Partial least squares and multiple linear regression analyses identified DOM molecular weight, nominal oxidation state of carbon, and soil chemical index of alteration as effective predictors of •OH yields. Soil chemical index of alteration emerged as a prioritized predictor of 3 DOM* yields, while the electron-donating capacity and humic-like compound content of the soil-derived DOM were effective predictors of 1 O 2 yields. This study advances our understanding of how mineral weathering processes regulate the photochemical reactivity of soil-derived DOM in the aquatic environment across wide geographical regions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Nitrogen-containing organic compounds (NOCs) may potentially contribute to aqueous secondary organic aerosols, yet the different formation of NOCs in aerosol particles and cloud droplets remains unclear. With the in-situ measurements performed at a mountain site (1690 m a.s.l.) in southern China, we investigated the formation of NOCs in the cloud droplets and the cloud-free particles, based on their mixing state information of NOCs-containing particles by single particle mass spectrometry. The relative abundance of NOCs in the cloud-free particles was significantly higher than those in cloud residual (cloud RES) particles. NOCs were highly correlated with carbonyl compounds (including glyoxalate and methylglyoxal) in the cloud-free particles, however, limited correlation was observed for cloud RES particles. Analysis of their mixing state and temporal variations highlights that NOCs was mainly formed from the carbonyl compounds and ammonium in the cloud-free particles, rather than in the cloud RES particles. The results support that the formation of NOCs from carbonyl compounds is facilitated in concentrated solutions in wet aerosols, rather than cloud droplets. In addition, we have identified the transport of biomass burning particles that facilitate the formation of NOCs, and that the observed NOCs is most likely contributed to the light absorption. These findings have implications for the evaluation of NOCs formation and their contribution to light absorption., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Sediment-derived dissolved organic matter (SDOM) is instrumental in the cycling of nutrients and heavy metals within lakes, influencing ecological balance and contaminant distribution. Given the influence of photodegradation on the alteration and breakdown of SDOM, further understanding of this process is essential. In this research, the properties of the SDOM photodegradation process and its metal-binding reactions in Nansi Lake were analyzed using the EEM-PARAFAC and 2D-SF/FTIR-COS techniques. Our study identified three sorts of humic-like components and one protein-like component in SDOM, with the humic-like material accounting for 71.3 ± 5.19% of the fluorescence intensity (F max ). Photodegradation altered the abundance and structure of SDOM, with a 41.6 ± 5.82% decrease in a 280 and a 29.1 ± 9.31% reduction in F max after 7 days, notably reducing the protein-like component C4 by 54.0 ± 5.17% and the humic-like component C2 by 48.5 ± 2.54%, which led to SDOM being formed with lower molecular weight and aromaticity. After photodegradation, the LogK Cu values for humic-like and protein-like substances decreased (humic-like C2: LogK Cu : 1.35 ± 0.10-1.11 ± 0.15, protein-like C4: 1.49 ± 0.14-1.29 ± 0.34), yet the preferential binding sequence of protein-like materials and specific functional groups with Cu 2+ such as aliphatic C-OH, amide (I) C=O and polysaccharide C-O groups remained unaltered. Our results enhance the knowledge of light-induced SDOM alterations and offer insights into SDOM-metal interactions in aquatic ecosystems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Soil dissolved organic matter (SDOM) is an important part of the DOM pool in terrestrial systems, influencing the transport and fate of many pollutants. In this study, SDOMs from different regions across China were compared by a series of spectroscopic methods, including UV-vis spectroscopy, fluorescence spectroscopy, and Fourier transform infrared (FTIR) spectroscopy, and the hydrophobicity was quantified by partition coefficients of SDOM in the aqueous two-phase system (K ATPS ). The molecular weight, aromaticity, and hydrophobicity of SDOM from different regions exhibited strong heterogeneity, K ATPS combined with UV-vis and fluorescence indices can be readily used for differentiating heterogeneous SDOM, and SDOMs were compositionally and structurally different from DOMs in aquatic systems based on spectral characterization. Importantly, the two-phase system (TPS) model has only been validated by DOMs in freshwater systems, and good organic carbon‒water partition coefficient (K OC ) predictive power (RMSE = 0.11) could be provided by the TPS model when applied to heterogeneous SDOM without calibration, showing its broad applicability. Our results demonstrate the applicability of the TPS model for predicting the sorption behavior of terrestrial DOM, broadening the application scope of the TPS model and indicating its potential as a routine model for the risk assessment of hydrophobic organic compounds (HOCs) in organic contaminated sites., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

The urgent need for field detection of uranium in seawater is 2-fold: to provide prompt guidance for uranium extraction and to prevent human exposure to nuclear radiation. However, current methods for this purpose are largely hindered by bulky instrumentation, high costs of developed materials, and severe matrix interferences, which limit their further application in the field. Herein, we demonstrated a portable and label-free strategy for the field detection of uranyl in seawater based on the efficient photocleavage of DNA. Further experiments confirmed the generation of ultraviolet (UV) light-induced reactive oxygen species (ROS), such as O 2 and •OH, which fragmented oligomeric DNA in the presence of uranyl and UV light. Detailed studies showed that DNA significantly enhances uranyl absorption in the UV-visible region, leading to the generation of more ROS. A fluorescence system for the selective detection of uranyl in seawater was established by immobilizing two complementary oligonucleotides with the fluorescent dye SYBR Green I. The strategy of UV-induced photocleavage offers high selectivity, excellent interference immunity, and high sensitivity for uranyl, with a detection limit of 6.8 nM. Additionally, the fluorescence can be visually detected using a 3D-printed miniaturized device integrated with a smartphone. This method has been successfully applied to the on-site detection of uranyl in seawater in 18 Chinese coastal cities and along the coast of Hainan Island within 3 min for a single sample. The sample testing and field analysis results indicate that this strategy has promising potential for real-time monitoring of trace uranyl in China's coastal waters. It is expected to be utilized for the rapid assessment of nuclear contamination and nuclear engineering construction.•- and •OH, which fragmented oligomeric DNA in the presence of uranyl and UV light. Detailed studies showed that DNA significantly enhances uranyl absorption in the UV-visible region, leading to the generation of more ROS. A fluorescence system for the selective detection of uranyl in seawater was established by immobilizing two complementary oligonucleotides with the fluorescent dye SYBR Green I. The strategy of UV-induced photocleavage offers high selectivity, excellent interference immunity, and high sensitivity for uranyl, with a detection limit of 6.8 nM. Additionally, the fluorescence can be visually detected using a 3D-printed miniaturized device integrated with a smartphone. This method has been successfully applied to the on-site detection of uranyl in seawater in 18 Chinese coastal cities and along the coast of Hainan Island within 3 min for a single sample. The sample testing and field analysis results indicate that this strategy has promising potential for real-time monitoring of trace uranyl in China's coastal waters. It is expected to be utilized for the rapid assessment of nuclear contamination and nuclear engineering construction.

Dissolved organic matter (DOM) plays an essential role in many geochemical processes, however its complexity, chemical diversity, and molecular composition are poorly understood. Soil samples were collected from 500 vegetable fields in administrative regions of mainland China, of which 122 were selected for further investigation. DOM properties were characterized by three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) (field intensity is 15 Tesla). Our results indicated that the main constituents were UVA humic-like substances, humic-like substances, fulvic acid-like substances, and tyrosine-like substances. A total of 10,989 molecular formulae with a mass range of 100.04 to 799.59 Da were detected, covering the mass spectrometric information of the soil samples from 27 different regions. CHO and CHON molecules were dominant in DOM, whereas lignin, tannins, and aromatic substances served as the main components. The results of cluster analysis revealed that the soil properties in Jiangxi Province were considerably different from those in other regions. The key backgrounds of the DOM molecular characteristics in the vegetable-field soil samples across mainland China were provided at the molecular level, with large abundance and great variability., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Sulfamerazine (SM) is a commonly used antibiotic and have been widely used to control various bacterial infectious diseases. The structural composition of colored dissolved organic matter (CDOM) is known to be a major factor that influences the indirect photodegradation of SM, yet the influence mechanism remains unknown. In order to understand this mechanism, CDOM from different sources was fractionated using ultrafiltration and XAD resin, and characterized using UV-vis absorption and fluorescence spectroscopy. The indirect photodegradation of SM in these CDOM fractions was then investigated. Humic acid (JKHA) and Suwannee River natural organic matter (SRNOM) were used in this study. The results showed that CDOM could be divided into four components (three humic-like components and one protein-like component), and terrestrial humic-like components C1 and C2 were found to be the main components that promote SM indirect photodegradation due to their high aromaticity. The indirect photodegradation of SM was much faster in low molecular weight (MW) solutions, whose structures were dominated by greater aromaticity and terrestrial fluorophores in JKHA and higher terrestrial fluorophores in SRNOM. The HIA and HIB fractions of SRNOM contained large aromaticity and high fluorescence intensities of C1 and C2, resulting in a greater indirect photodegradation rate of SM. The HOA and HIB fractions of JKHA had abundant terrestrial humic-like components and contributed more to SM indirect photodegradation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Cancer, the second largest human disease, has become a major public health problem. The prediction of chemicals' carcinogenicity before their synthesis is crucial. In this paper, seven machine learning algorithms (i.e., Random Forest (RF), Logistic Regression (LR), Support Vector Machines (SVM), Complement Naive Bayes (CNB), K-Nearest Neighbor (KNN), XGBoost, and Multilayer Perceptron (MLP)) were used to construct the carcinogenicity triple classification prediction (TCP) model (i.e., 1A, 1B, Category 2). A total of 1444 descriptors of 118 hazardous organic chemicals were calculated by Discovery Studio 2020, Sybyl X-2.0 and PaDEL-Descriptor software. The constructed carcinogenicity TCP model was evaluated through five model evaluation indicators (i.e., Accuracy, Precision, Recall, F1 Score and AUC). The model evaluation results show that Accuracy, Precision, Recall, F1 Score and AUC evaluation indicators meet requirements (greater than 0.6). The accuracy of RF, LR, XGBoost, and MLP models for predicting carcinogenicity of Category 2 is 91.67%, 79.17%, 100%, and 100%, respectively. In addition, the constructed machine learning model in this study has potential for error correction. Taking XGBoost model as an example, the predicted carcinogenicity level of 1,2,3-Trichloropropane (96-18-4) is Category 2, but the actual carcinogenicity level is 1B. But the difference between Category 2 and 1B is only 0.004, indicating that the XGBoost is one optimum model of the seven constructed machine learning models. Besides, results showed that functional groups like chlorine and benzene ring might influence the prediction of carcinogenic classification. Therefore, considering functional group characteristics of chemicals before constructing the carcinogenicity prediction model of organic chemicals is recommended. The predicted carcinogenicity of the organic chemicals using the optimum machine leaning model (i.e., XGBoost) was also evaluated and verified by the toxicokinetics. The RF and XGBoost TCP models constructed in this paper can be used for carcinogenicity detection before synthesizing new organic substances. It also provides technical support for the subsequent management of organic chemicals., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Industrial waste salt is classified as hazardous waste to the environment. The organic impurity and its occurrence in industrial waste salt affect the salt resource utilization. In this paper, composition quantitative analysis, XRD, TG-DSC, SEM/FIB-SEM coupled with EDS, FTIR, XPS and GC-Ms were chosen to investigate the organic impurity and its occurrence in industrial waste salt. The organic impurities owe small proportion (1.77%) in the specimen and exhibit weak thermal stability within the temperature of 600°C. A clear definition of organic impurity, including 11 kinds of organic compounds, including aldehyde, benzene and its derivatives etc., were detected in the industrial waste salt. These organic impurities, owing (C-O/C-O-C, C-OH/C = O, C-C/CHx/C = C etc.)-containing function group substance, are mainly distributed both on the surface and inside of the salt particles. Meanwhile, the organic substance may combine with metal cations (Ni2+, Mg2+, Cu2+ etc.) through functional groups, such as hydroxide, carbonyl etc., which increases its stability in the industrial waste salt. These findings provide comprehensive information for the resource utilization of industrial waste salt from chemical industry etc., Competing Interests: The authors of this paper have read the journal’s policy and have the following competing interests: Zongwen Zhao, Wenbin Xu, Zhongbing Wang, Weining Qin, Xinglin Guo, and Jiang Long are paid employees of Dongjiang Environmental Co., Ltd. Jie Lei is paid employees of Green Eco-Manufacture Co., Ltd. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Cooking emissions are both indoor and outdoor sources for fine particulate matter (PM2.5) but their contributions are often ignored. The PM2.5-bound organic compounds, including alkanols, alkanes, monocarboxylic acids, dicarboxylic acids, and polycyclic aromatic hydrocarbons (PAHs) were determined in the emissions from the most popular types of restaurants in the capital city of northwestern China. The mean concentration of total quantified organic compounds (Σ PM_O ) ranged from 1112 to 32,016 ng m-3, with the maximum for the Chinese barbecue restaurants. The Σ PM_O accounted for an average of 11% of PM 2.5 mass, demonstrating their significances in the cooking emissions. Hexadecanoic acid (C 16 ) and 1-hexadecanol (C 16 ) were considered as the tracers for stir-frying, steaming, and boiling which are usually applied in the traditional Chinese cuisines; 1-undecanol (C 11 ), 9-fluorenone, and indeno[1,2,3-cd]pyrene were found to be potential markers for grilling and deep-frying which are widely applied in the Western style cooking method. The PAH diagnostic ratios also illustrated their representatives to distinguish the emissions from traditional Chinese cuisines and the Western-style restaurants. The estimated carcinogenic risks for the restaurants that consumed a large amount of oils and employed high temperature cooking methods (e.g., barbecuing and deep-frying) were 2.6-4.2 times exceeded the international safety limit. The organic profiles obtained in this study could be contributed to refine PM 2.5 source apportionment in urban areas in northwestern China. The estimations of potential cancer risks urge the establishment of more stringent legislations to protect the health of the catering staffs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Most scientists consider that sonochemistry became recognised as a discrete subject in the 1980's - some 40 years ago which coincidentally is when my own interests in the subject began. This review briefly outlines how I first became involved in sonochemistry and then in its development. However its main theme is the way in which my links with China through sonochemistry have developed from their beginnings in 1990. This was the subject of my presentation at AOSS4 and involves a range of topics which started with the extraction of natural products and surface treatment but later expanded to include therapeutic ultrasound and environmental protection., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

Organophosphate ester contaminants, including organophosphate pesticides (OPPs) and organophosphate flame retardants (OPFRs) are ubiquitous in surface water and pose a significant risk to aquatic organisms, thus it is important to develop effective methods for long-term monitoring of these emerging compounds. Polar organic chemical integrative sampler (POCIS) has become a promising monitoring tool for waterborne contaminants, yet recent studies found that the commonly used polyethersulfone (PES) membrane strongly sorbed some moderately hydrophobic compounds, resulting in long lag-phase for chemical accumulation in POCIS. In the present study, 0.45-μm nylon membranes was selected as POCIS diffusion-limiting membrane to design a new POCIS-Nylon configuration for analyzing moderately hydrophobic OPPs and OPFRs in water. The POCIS-Nylon had negligible lag-phase due to low sorption of OPPs and OPFRs to nylon membrane. Meanwhile, linear accumulation time and sensitivity for target contaminants using POCIS-Nylon retained similar to the traditional POCIS. Water velocity and chemical concentration had little impact on sampling rate (R s ), validating that the POCIS-Nylon was suitable for various water conditions. Finally, the occurrence of OPPs and OPFRs in urban waterways of Guangzhou, China was evaluated using the POCIS-Nylon with R s values that were calibrated in the laboratory. The average concentration of OPPs was 4.97 ± 1.35 ng/L (range: 2.64 ± 1.28-6.54 ± 0.18 ng/L) and the average concentration of OPFRs was 400 ± 88 ng/L (range: 316 ± 24-615 ± 36 ng/L) across nine sampling sites. The present study provides a way to resolve the inherent challenge of accumulating hydrophobic substances by POCIS., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Soil dissolved organic matter (DOM) plays an essential role in the Three Gorges Reservoir (TGR) as a linkage between terrestrial and aquatic systems. In particular, the reducing capacities of soil DOM influence the geochemistry of contaminants such as mercury (Hg). However, few studies have investigated the molecular information of soil DOM and its relationship with relevant geochemical reactivities, including redox properties. We collected samples from eight sites in the TGR areas and studied the link between the molecular characteristics of DOM and their electron donation capacities (EDCs) toward Hg(II). The average kinetic rate and EDC of soil DOM in TGR areas were (0.004 ± 0.001) hr -1 and (2.88 ± 1.39) nmol e - /mg DOM bulk , respectively. Results suggest that higher EDCs and relatively rapid kinetics were related to the greater electron donating components of lignin-derived and perhaps pyrogenic DOM, which are the aromatic constituents that influenced the reducing capacities of DOM in the present study. Molecular details revealed that even the typical autochthonous markers are important for the EDCs of DOM as well, in contrast to what is generally assumed. More studies identifying specific DOM molecular components involved in the abiotic reduction of Hg(II) are required to further understand the relations between DOM sources and their redox roles in the environmental fate of contaminants., (Copyright © 2019. Published by Elsevier B.V.)

Dissolved organic matter (DOM) is a critical component of high-strength organic wastewater, and the study of them from molecular perspective could improve the removal efficiency. Leachate samples were collected from China's largest two stage anaerobic/aerobic membrane bioreactor and nanofiltration (A/O-MBR-NF) process, with the treatment capacity of 5000 t/d, and characterized by electrospray ionization (ESI) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) from molecular perspective. High molecular weight (m/z > 500) compounds with 40-50 carbon atoms and 15-20 double bond equivalence (DBE) were biodegraded into medium molecular weight compounds with 10-20 carbon atoms and ∼10 DBE. Contribution of lipids and unsaturated hydrocarbons compounds in DOM turned into 42.1% and 2.5%, respectively, while contribution of condensed aromatics in DOM dramatically increased to 15.4% in leachates along the A/O-MBR process. Most of DOM was converted into higher polymerization degree and accumulated in concentrated leachate (CL). Sulfur-containing compounds, whose relative peak ratio accounted for 56.4%, were regarded as recalcitrant DOM in CL. Increase of retention time in anaerobic unit for raw leachate might be useful for decomposing the long-chain organic compounds, which could also reduce loadings for the following A/O-MBR process. Well-focus techniques such as sulfur-oxidation bacteria could be introduced into the MBR unit for better removing organo-sulfur compounds. Advanced oxidation processes for CL degradation would be efficiency for the removal of recalcitrant DOM. Thus, leachate could be disposed in a zero-discharge way based on the practical experience of such a typical working treatment process., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

To identify whether the iron (Fe) mining area in the Jiulongjiang River basin (JRB) has an influence on the mercury in the forest soil, the spatial distribution patterns of mercury's behavior on different controlling factors were analyzed, and a potential ecological risk assessment was done. A total of 107 soil samples were collected from two forest soil profiles, one profile near the Fe mining area and the other far from it. The soil near the mining area had a moderate potential ecological risk with high Fe content rich in the upper layer of soil (<70 cm), whereas soil collected far from the mining area had a low potential ecological risk. These results indicated that the rise of iron content in the soil near the mining area was beneficial to the enrichment of mercury, probably causing damage to the forest ecosystem. Both soil organic carbon (SOC) and Fe content have strong positive correlations with THg content, controlling the mercury behavior in the upper layer (<70 cm) and a lower layer (>70 cm) of soil, respectively. The high Fe content in the upper layer of soil will compete for the adsorption of mercury by SOC, leading to the poor correlation between SOC and THg.

The volatility of atmospheric aerosols greatly influences the gas-particle partitioning, chemical mechanisms and lifetime of aerosols. Due to the complex composition, the volatility of organic aerosol is one of the major sources of uncertainty in measuring and modeling ambient aerosols. Despite high aerosol loading in the atmosphere in China, especially in winter, few field measurements were conducted targeting the volatility of ambient organic aerosol (OA). With the deployment of a thermodenuder-aerosol mass spectrometer (TD-AMS) system, the volatility of non-refractory submicron aerosols (NR-PM 1 ) were measured on an island near the coastal line for the regional air in wintertime in southern China. NO 3 - and Cl - showed the highest volatility in the NR-PM 1 chemical species, while SO 4 2- showed the least volatility. Organic aerosol showed a moderate volatility, evaporating at a stable rate (0.57% °C -1 ) at temperatures lower than 150 °C and keeping a stable volatility when its loading increases, which could be an advantage for parameterization of OA in air quality models. Based on both positive matrix factorization and chemical mass balance modeling of OA composition, biomass burning OA was found to be the most volatile factor, followed by hydrocarbon-like OA and more-oxidized oxygenated OA. By summarizing the OA volatility measured in this study and in the literature, we found that the volatilities of different OA factors at different locations do not have a clear relationship with the OA oxidation state, possibly due to the vague understanding of local OA aging mechanisms and mixing states., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The molecular structure of soil organic matter (SOM) is closely related to the structure and functions of the rhizosphere community. In this study, a microcosm experiment was conducted to investigate the effect of straw-derived biochar on the structural differentiation of SOM and rhizosphere bacterial communities. 13 C NMR spectra showed that the relative abundance of carboxyl, alkyl, N-alkyl, O-alkyl and methoxyl groups decreased by 22%, 31%, 27%, 27% and 27%, respectively, and the relatively stable structure of aryl and O-aryl groups increased by 213% and 41%, respectively. In addition, network-based analysis showed that biochar amendment not only improved the network connectivity of the rhizosphere bacteria, but also enhanced the linkage between bacteria and the molecular structure of SOM. The topological properties of the network, including the number of edges, network density, and average clustering coefficient, were increased by 79%, 15% and 22%, respectively. Moreover, modularization analysis and structural equation model indicated that rhizosphere bacterial network was the important bio-factor affecting the content of labile carbon., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Bisphenol S (BPs) has been found in a variety of common consumer products surrounding human living, despite the fact that it could damage the human digestive system and genital system. In China, straw-returning to the field is a common soil improvement technology used to increase the concentration of dissolved organic matter (DOM), which plays an important role in the natural environment as a microreactor of contaminants. Additionally, the biochar obtained by the straw is an effective soil conditioner. DOM is a key influencing factor when biochar is employed as the conditioner of BPs contaminated soil. However, the BPs adsorption behavior on the Ferralsol affected by DOM and biochar is also unclear. Hence, DOM was prepared and the effect of DOM on the BPs adsorption behavior on soil and biochar modified soil was investigated. DOM was characterized by Elemental analysis, Fourier transforming infrared spectra (FT-IR), and three-dimensional excitation-emission matrix spectra (3D-EEM). The results of the adsorption experiments indicated that both biochar and DOM could improve the BPs adsorption capacity in Ferralsol, while DOM suppressed the BPs adsorption capacity of biochar modified soil, indicating that DOM and BPs could not be applied at the same time for BPs adsorption.

China is a major textile manufacturer in the world; as a result, large quantities of dyeing effluents are generated every year in the country. In this study, the performances of two cationic starch-based flocculants with different chain architectures, i.e., starch-graft-poly[(2-methacryloyloxyethyl) trimethyl ammonium chloride] (STC-g-PDMC) and starch-3-chloro-2-hydroxypropyl trimethyl ammonium chloride (STC-CTA), in flocculating dissolved organic matter (DOM) in dyeing secondary effluents were investigated and compared with that of polyaluminum chloride (PAC). In the exploration of the flocculation mechanisms, humic acid (HA) and bovine serum albumin (BSA) were selected as main representatives of DOM in textile dyeing secondary effluents, which were humic/fulvic acid-like and protein-like extracellular matters according to the studied wastewater's characteristics based on its three-dimensional excitation-emission matrix spectrum. According to experimental results of the flocculation of both the real and synthetic wastewaters, STC-g-PDMC with cationic branches had remarkable advantages over STC-CTA and PAC because of the more efficient charge neutralization and bridging flocculation effects of STC-g-PDMC. Another interesting finding in this study was the reaggregation phenomenon after restabilization at an overdose during the flocculation of BSA effluents by STC-g-PDMC at a very narrow pH range under a nearly neutral condition. This phenomenon might be ascribed to the formation of STC-g-PDMC/BSA complexes induced by some local charge interactions between starch-based flocculant and the amino acid fragments of protein due to charge patch effects., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

In this work, a biosensor based on luminescence resonance energy transfer (LRET) from NaYF4:Yb,Tm upconversion nanoparticles (UCNPs) to SYBR Green I has been developed. The aptamers are covalently linked to UCNPs and hybridized with their complementary strands. The subsequent addition of SYBR Green allows SYBR Green I to insert into the formed double-stranded DNA (dsDNA) duplex and brings the energy donor and acceptor into close proximity, leading to the fluorescence of UCNPs transferred to SYBR Green I. When excited at 980 nm, the UCNPs emit luminescence at 477 nm, and this energy is transferred to SYBR Green I, which emits luminescence at 530 nm. In the presence of oxytetracycline (OTC), the aptamers prefer to bind to its corresponding analyte and dehybridize with the complementary DNA. This dehybridization leads to the liberation of SYBR Green I, which distances SYBR Green I from the UCNPs and recovers the UCNPs' luminescence. Under optimal conditions, a linear calibration is obtained between the ratio of I530 to I477 nm (I530/I477) and the OTC concentration, which ranges from 0.1 to 10 ng/ml with a limit of detection (LOD) of 0.054 ng/ml., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Eddies play a critical role in regulating the biological pump by pumping new nutrients to the euphotic zone. However, the effects of cyclonic eddies on particle export are not well understood. Here, biogenic silica (BSi) and particulate organic carbon (POC) exports were examined inside and outside a decaying cyclonic eddy using 234Th-238U disequilibria in the tropical South China Sea. For the eddy and outside stations, the average concentrations of BSi in the euphotic zone were 0.17±0.09 μmol L-1 (mean±sd, n = 20) and 0.21±0.06 μmol L-1 (n = 34). The POC concentrations were 1.42±0.56 μmol L-1 (n = 34) and 1.30±0.46 μmol L-1 (n = 51). Both BSi and POC abundances did not show change at the 95% confidence level. Based on the 234Th-238U model, BSi export fluxes in the eddy averaged 0.18±0.15 mmol Si m-2 d-1, which was comparable with the 0.40±0.20 mmol Si m-2 d-1 outside the eddy. Similarly, the average POC export fluxes were 1.5±1.4 mmol C m-2 d-1 and 1.9±1.3 mmol C m-2 d-1 for the eddy and outside stations. From these results we concluded that cyclonic eddies in their decaying phase have little effect on the abundance and export of biogenic particles.

A combined treatment process of air stripping+Fenton+sequencing batch reactor (SBR)+ coagulation was performed to remove the pollutants in landfill leachate. Molecular weight (MW) distribution and fractions of dissolved organic matter (DOM) were discussed to study the characteristics. The experiment showed that the removal rate of chemical oxygen demand (COD), five day biological oxygen demand (BOD5) and ammonia nitrogen (NH3N) by the combined process were 92.8%, 87.8% and 98.0%, respectively. Humic acid (HA) and fulvic acid (FA) were the main fractions in raw leachate with 81.8% of the total COD concentration, while hydrophilic organic matter (HyI) was the dominant fraction in the final effluent of the combined process with 63.5% of the total COD concentration. After the combined treatment process, the removal rate of DOM and fractions HA, FA, HyI were 91.9%, 97.1%, 95.8% and 71.7%, respectively. Organic matters of MW<2k and MW>100k were removed with 90.5% and 97.9% COD concentration after the treatment. The ultraviolet-visible spectra (UV-vis), Fourier transform infrared spectra (FTIR) and three-dimensional excitation-emission matrices spectra (EEMs) indicated that benzene materials and phenol compounds were preferentially removed in air stripping. High MW matters, aromatic rings, conjugated moieties and some functional groups were mainly removed by Fenton. While smallMW fractions, carboxylic acids, alcohols and protein-like materials were preferentially biodegraded via SBR. Fulvic-like and humic-like materials were mainly destroyed via Fenton oxidation and coagulation., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

This study investigated the partitioning behavior of dissolved organic matter (DOM) in liquid and ice phases, as well as the changes in the optical properties and chlorine reactivity of DOM during the freezing processes of water. DOM was rejected from the ice phase and accumulated in the remaining liquid phase during water freezing. Moreover, the decrease in freezing temperature, as well as the increase in dissolved organic carbon (DOC) concentration of feed water, caused an increase in DOM captured in the ice phase. The ultraviolet-absorbing compounds, trihalomethane precursors, as well as fulvic acid- and humic acid-like fluorescent materials, were more liable to be to be rejected from the ice phase and were more easily retained in the unfrozen liquid phase during water freezing, as compared with organics (on average) that comprise DOC. In addition, it was also found a higher accumulation of these organics in the unfrozen liquid phase during water freezing at higher temperature. The freeze/thaw processes altered the quantity, optical properties, and chlorine reactivity of DOM. The decrease in ultraviolet light at 254 nm as well as the production of aromatic protein- and soluble microbial byproduct-like fluorescent materials in DOM due to freeze/thaw were consistently observed. On the other hand, the changes in DOC, trihalomethane formation potential, and fulvic acid- and humic acid-like fluorescence caused by freeze/thaw varied significantly between samples., (Copyright © 2014. Published by Elsevier B.V.)

Background: Halotolerant bacteria are excellent sources for selecting novel enzymes. Being intrinsically stable and active under high salinities, enzymes from these prokaryotes have evolved to function optimally under extreme conditions, making them robust biocatalysts with potential applications in harsh industrial processes., Results: A halotolerant strain LY19 showing lipolytic activity was isolated from saline soil of Yuncheng Salt Lake, China. It was identified as belonging to the genus of Salimicrobium by 16S rRNA gene sequence analysis. The extracellular enzyme was purified to homogeneity with molecular mass of 57 kDa by SDS-PAGE. Substrate specificity test revealed that the enzyme preferred short-chain p-nitrophenyl esters and exhibited maximum activity towards p-nitrophenyl butyrate (p-NPB), indicating an esterase activity. The esterase was highly active and stable over broad temperature (20°C-70°C), pH (7.0-10.0) and NaCl concentration (2.5%-25%) ranges, with an optimum at 50°C, pH 7.0 and 5% NaCl. Significant inhibition of the esterase was shown by ethylenediaminetetraacetic acid (EDTA), phenylmethylsulfonyl fluoride (PMSF) and phenylarsine oxide (PAO), which indicated that it was a metalloenzyme with serine and cysteine residues essential for enzyme activity. Moreover, the esterase displayed high activity and stability in the presence of hydrophobic organic solvents with log P(ow) ≥ 0.88 than in the absence of an organic solvent or in the presence of hydrophilic solvents., Conclusions: Results from the present study indicated the novel extracellular esterase from Salimicrobium sp. LY19 exhibited thermostable, alkali-stable, halotolerant and organic solvent-tolerant properties. These features led us to conclude that the esterase may have considerable potential for industrial applications in organic synthesis reactions.

We compared extracts and toxicities of organic compounds (OCs) in drinking water concentrated by composite XAD-2/8 resin (mixed with an equal volume of XAD-2 and XAD-8 resins) with those extracted by single XAD-2 (non-polar) and XAD-8 (polar) resins. Drinking water was processed from raw water of the Han River and the Yangtze River in Wuhan section, China. The extraction efficiency of all resins was controlled at 30%. The types of extracted OCs were detected by gas chromatography-mass spectrometry, and the cytotoxicity and genotoxicity were assessed by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and comet assays, respectively, in human hepatoma HepG2 cells. Our results showed that XAD-2/8 extracted a larger variety of OCs, compared with XAD-8 and XAD-2. The cytotoxicity and genotoxicity of extracted OCs were in the order of XAD-8> XAD-2/8> XAD-2 at almost all tested concentrations after 24 h treatment (P < 0.05). Our findings suggest that single XAD resin selectively extracts either polar or non-polar OCs, which would lead to over- or under-estimation of the toxicity of drinking water. Nevertheless, composite resin extracts both polar and non-polar OCs, and could be utilized as a useful extraction technique to evaluate the level and toxicity of OCs in drinking water.

Phosphorus fractions, organic matter and particle size of the surface sediment from Chaohu Lake were analyzed for spatial distribution and the risk of phosphorus release. The result showed that total phosphorus (TP) of surface sediment was 790 mg x kg(-1), which was 55% higher than that in 1980s, with 386 mg x kg(-1) higher in western lake and 211 mg x kg(-1) higher in eastern lake. NaOH-Pi of sediment ranged from 55 to 648 mg x kg(-1), and occupied average 25% of TP. NaOH-Po of sediment ranged from 27 to 468 mg x kg(-1), and occupied average 17% of TP. NaOH-Pi and NaOH-Po in western lake were 331 mg x kg(-1) and 225 mg x kg(-1), which were significantly higher than those in eastern lake. Ca-P and Res-P accounted for 18% and 40% of TP, and were equably distributed in the lake. TP, NaOH-Pi and NaOH-Po of sediment in the western lake increased intensively with the depth, while Ca-P and Res-P showed no significant change in the vertical profile in the lake. Profile of phosphorus fractions showed that NaOH-Pi and NaOH-Po were the dominant factions of the increasing phosphorus sedimentation in the western lake. Phosphorus of sediment in the western lake will release more easily to the water with higher organic matter and higher content of sandy silt.

Photo-production of dissolved inorganic carbon (DIC) from chromophoric dissolved organic matter (CDOM) is an important transformation process in marine carbon cycle, but little is known about this process in Chinese coastal systems. This study investigated an estuarine water sample and a coastal seawater sample from the subtropical waters in southeast of China. Water samples were exposed to natural sunlight and the absorption and fluorescence of CDOM as well as the DIC concentration were measured in the summer of 2009. The estuarine water had higher CDOM level, molecular weight and proportion of humic-like fluorescent components than the seawater that exhibited abundant tryptophan-like fluorescent component. After a 3-day irradiation, the CDOM level decreased by 45% in the estuarine water and 20% in the seawater, accompanied with a decrease in the molecular weight and aromaticity of DOM which was inferred from an increase in the absorption spectral slope parameter. The photo-degradation rates of all the five fluorescent components were also notable, in particular two humic-like components (C4 and C5) were removed by 78% and 69% in the estuarine water and by 69% and 56% in the seawater. The estuarine water had a higher photo-production rate of DIC than the seawater (4.4 vs. 2.5 micromol/(L x day)), in part due to its higher CDOM abundance. The differences in CDOM compositions between the two types of waters might be responsible for the higher susceptibility of the estuarine water to photo-degradation and hence could also affect the photo-production process of DIC.

In July-December 2010, a complete factor-controlled experiment was conducted to study the effects of litter and mineral nitrogen addition on soil organic matter decomposition (soil respiration) at the depths of 0-10 cm and 20-30 cm in Dinghu Mountain National Reserve. Coniferous needle litter and broadleaved litter were added, respectively, and 70 g N x m(-2) x yr(-1) of NH4 NO3 was applied to simulate soil nitrogen saturation whereas soil mineral nitrogen was removed by ion-exchange membrane to simulate the decreased nitrogen absorption by root. The addition of both needle litter and broadleaved litter increased the respiration rate of soil-litter system significantly from July to November, but this effect disappeared in December. Both mineral nitrogen application and soil mineral nitrogen removal increased the soil-litter respiration significantly. These results suggest that litter decomposed completely in a short period therefor had limited effects on soil organic matter decomposition and accumulation, and thus, foliar litters could be not the major source of soil organic matter, whereas soil mineral nitrogen removal could obviously promote the soil organic matter decomposition in the system.

In 2006-2007, a field trial was conducted to study the effects of applying three kinds of organic-inorganic compound fertilizers [rapeseed cake compost plus inorganic fertilizers (RCC), pig manure compost plus inorganic fertilizers (PMC), and Chinese medicine residues plus inorganic fertilizers (CMC)] on the crop growth and nitrogen (N) use efficiency of rice-wheat rotation system in South Jiangsu. Grain yield of wheat and rice in the different fertilization treatments was significantly higher than the control (no fertilization). In treatments RCC, PMC and CMC, the wheat yield was 13.1%, 32.2% and 39.3% lower than that of the NPK compound fertilizer (CF, 6760 kg x hm(-2)), respectively, but the rice yield (8504-9449 kg x hm(-2)) was significantly higher than that (7919 kg x hm(-2)) of CF, with an increment of 7.4%-19.3%. In wheat season, the aboveground dry mass, N accumulation, and N use efficiency in treatments RCC, PMC, and CMC were lower than those of CF, but in rice season, these parameters were significantly higher than or as the same as CF. In sum, all the test three compound fertilizers had positive effects on the rice yield and its nitrogen use efficiency in the rice-wheat rotation system, being most significant for RCC.

Chromophoric dissolved organic matter (CDOM) is an important optically active substance that transports nutrients, heavy metals, and other pollutants from terrestrial to aquatic systems and is used as a measure of water quality. To investigate how the source and composition of CDOM changes in both space and time, we used chemical, spectroscopic, and fluorescence analyses to characterize CDOM in Lake Tianmuhu (a drinking water source) and its catchment in China. Parallel factor analysis (PARAFAC) identified three individual fluorophore moieties that were attributed to humic-like and protein-like materials in 224 water samples collected between December 2008 and September 2009. The upstream rivers contained significantly higher concentrations of CDOM than did the lake water (a(350) of 4.27±2.51 and 2.32±0.59 m(-1), respectively), indicating that the rivers carried a substantial load of organic matter to the lake. Of the three main rivers that flow into Lake Tianmuhu, the Pingqiao River brought in the most CDOM from the catchment to the lake. CDOM absorption and the microbial and terrestrial humic-like components, but not the protein-like component, were significantly higher in the wet season than in other seasons, indicating that the frequency of rainfall and runoff could significantly impact the quantity and quality of CDOM collected from the catchment. The different relationships between the maximum fluorescence intensities of the three PARAFAC components, CDOM absorption, and chemical oxygen demand (COD) concentration in riverine and lake water indicated the difference in the composition of CDOM between Lake Tianmuhu and the rivers that feed it. This study demonstrates the utility of combining excitation-emission matrix fluorescence and PARAFAC to study CDOM dynamics in inland waters., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

This report describes a one-step real-time polymerase chain reaction assay based on SYBR Green I for detection of a broad range of duck circovirus (DuCV). Align with all DuCV complete genome sequences and other Genus Circovirus download from the GenBank (such as goose circovirus, pigeon circovirus), the primers targets to the replicate gene of DuCV were designed. The detection assay was linear in the range of 1.31 × 102-1.31 × 107 copies/μL. The reaction efficiency of the assay using the slope (the slope was -3.349) and the Y-intercept was 37.01 from the linear equation was estimated to be 0.99 and the correlation coefficient (R2) was 0.993. A series of experiments were carried out to assess the reproducibility, sensitivity, and specificity of the assay, following by the low intra-assay and inter-assay CVs for CT values obtained with the standard plasmids. The intra-assay CVs were equal or less than 1.89% and the inter-assay CVs were equal or less than 1.26%. There was no cross-reaction occurred with nucleic acids extracted from RA (Riemerella anatipestifer), E. coli (Escherichia coli), Duck Cholera (Pasteurella multocida), Avian influenza virus, avian paramyxovirus, Muscovy duck parvovirus, Duck reovirus, Duck hepatitis A virus as control templates. The nucleic acids extracted from samples of healthy ducks were used as negative controls. The assay was specific and reproducible. The established real time PCR was used to detect 45 DuCV-negative samples, which were tested using conventional PCR under the developed optimal conditions, each 15 for embryonated eggs, non-embryonated budgerigar eggs, newly hatched duck, the mixture of the lung, liver, spleen which were analysis for the presence of DuCV DNA, to conform that whether the DuCV can be transmitted vertically. Meanwhile, no positive result was shown by the real-time PCR method. The SYBR Green I-based quantitative PCR can therefore be practically used as an alternative diagnostic tool and a screening method for ducks infected with duck circovirus.

The aim of this study was to investigate the feasibility of PAC-MBR process treating municipal secondary effluent. Two laboratory-scale submerged MBRs (SMBR) with and without PAC addition were continuously operated in parallel for secondary effluent treatment. Approximately 63%TOC, 95% NH(4)(+)-N and 98% turbidity in secondary effluent were removed by the PAC-MBR process. Most organics in the secondary effluent were found to be low molecular weight (MW) substances, which could be retained in the reactor and then removed to some extent by using PAC-MBR process. Parallel experiments showed that the addition of PAC significantly increased organic removal and responsible for the largest fraction of organic removal. Membrane fouling analysis showed the enhanced membrane performance in terms of sustainable operational time and filtration resistances by PAC addition. Based on these results, the PAC-MBR process was considered as an attractive option for the reduction of pollutants in secondary effluent., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The soil samples were collected from the surface (0-20 cm) soil of the long-term fertilizer experiments in black soil areas in Northeast Location Monitoring Field [fertilizers and organic fertilizers (NPOM), no fertilization (NF)], and indoor culture method was adopted to study the behaviour of aging of the phenanthrene different size of soil aggregates and its contributing factors of aging source analysis. The results show that in the beginning of the aging > 2 mm aggregate fraction was a priority adsorbent, while last stage of the aging < 0.053 mm aggregate fraction was the preferred adsorbent. In the 120-day aging period, the extraction rate of 0.25-0.053 mm and 0.25-2 mm aggregate fraction had no significant difference. The phenanthrene residual content in undisturbed soil of NPOM treatment was 31.13%, while in the NF treatment residual content of undisturbed soil was 27.73%. Average rates of the phenanthrene aging in the NPOM and NF treatments was 0.26% x d(-1) and 0.23% x d(-1). The five major influence factors of the combination of content of the residual phenanthrene based on principal component analysis were analyzed, the results showed that the organic carbon and specific surface area were the mainly factors combined with residual content of phenanthrene. As a consequence, Long-term application of fertilizers was in favour of the aging behaviour of phenanthrene, thereby reducing the activity and toxicity of phenanthrene in the black soil.

In this study, the characteristics of organic phosphorus fractions in sediments of seven lakes with different drainage basin feature, ecological structure, and polluted levels from different regions were investigated, and the relationships between organic phosphorus (Po), inorganic phosphorus (Pi) and bioavailable characters were also discussed. The difference of the related content of Po in different sediments indicated the discrepancy of phosphorus sources and biogeochemical cycles in different lakes. Organic matter (OM) was significantly correlated with Po (R2 = 0.80, p < 0.01), and except for Lake Qilu, OM was significantly correlated with labile Po, moderately labile Po and nonlabile Po in all studied sediments (R2 were 0.85, 0.52, 0.80 respectively, p < 0.01). The moderately labile Po and nonlabile Po were the main fraction of Po in all studied lakes, and the relative contributions to total Po were 15.12%-66.73% and 27.99%-77.72%, respectively. The mean proportion of labile Po was 6.1% in studied sediments. The rank order of Po fractions was residual Po > HCl-Po > fulvic acid-Po > humic acid-Po > NaHCO3-Po with mean relative proportion 8.3:3.1:2.2:1.8:1.0. Labile Po was significantly correlated with total phosphorus (TP), Pi , Po, NaHCO3-Pi and NaOH-Pi . Furthermore, Labile Po was also significantly correlated with T), Po and NaOH-Pi in all studied sediments, which suggested that labile Po was transformed into bioavailable phosphorus and the nonlabile Po may become a potential source of available phosphorus, although it was considered as highly resistant fraction.

Polyvinylidene fluoride (PVDF) flat ultrafiltration membranes modified by nano-sized alumina (Al₂O₃) particles were prepared by phase inversion process and their properties and anti-fouling performances were examined. The influence of three types of natural organic matters on the modified membrane fouling was also studied. Raw water was taken from two different locations, i.e., Harbin and Zhaoyuan, of Songhua River. Dissolved organic compounds in the raw water were fractionated using XAD resins into three fractions, i.e., hydrophobic fraction, transphilic fraction, and hydrophilic fraction (HPI). The three adsorbed compounds were further eluted and dissolved into distilled water respectively to prepare the feed for the fouling tests. All solutions were adjusted to a concentration of 10.6 mg C/L, which equals to the total organic carbon (TOC) of the raw water. Results show that the addition of nano-Al₂O₃ particulars did not affect the inherent traits of the PVDF membranes, however, its surface hydrophilic properties were improved significantly with the addition of nanoparticles and anti-fouling performance was enhanced as well. The HPIs in the Songhua River were the main foulant, causing more fouling to membrane than hydrophobic and transphilic matters.

The character of dissolved organic matter (DOM) in source waters from two countries (Australia and China) was investigated using an extended fractionation technique by combining resin adsorption, ultrafiltration and high performance size exclusion chromatography. There are distinctive chemical characteristics associated with DOM origins. Australian sourced DOM had higher hydrophobic acid (HoA) content and exhibited a more pronounced humic character, indicating a higher influence from allochthonous organics (decayed plant bodies from vegetated catchments). The higher content of hydrophobic base and neutral components found in Chinese DOM, may be attributed to the effects of increasing pollution caused by the rapid urbanization in China. The molecular weights (MWs) of aquatic HoA are predominantly in the moderate (e.g., 1-10 kDa) or small (e.g., < 1 kDa) ranges. This suggests that aquatic HOA should not be assumed as high MW organics without experimental validation. It is also found that some of the low MW compounds in our samples were hydrophobic, which could explain the observation of low MW organic compounds being able to be removed by conventional treatment processes.

33 total suspended particle samples and 7 size-segregated particle samples were collected over the East China Sea from Nov. to Dec., 2006, Feb. to Mar., 2007 and May. to Jun., 2008. Concentrations of ammonium, nitrate and nitrite in aerosols were measured to investigate their seasonal variation and size distribution. The concentrations of ammonium in aerosols ranged from 2.6 to 646.9 nmol x m(-3) ,with the higher values observed in winter and spring, and the lower values in summer. Nitrate concentrations were from 5.5 to 281.5 nmol x m(-3), presenting the seasonal trend of winter > spring approximately summer. The concentrations of nitrite were very low, less than 0.5 nmol x m(-3). The relative contributions of nitrogen species to total nitrogen varied seasonally in some extent. The contribution of nitrate was comparable with that of ammonium in winter, while the contribution of ammonium was the predominant in spring and summer. The size distribution of nitrate presented clear monthly changes. Most of nitrate existed in the fine particles less than 2.1 microm in Nov. to Dec., and it predominated in the coarse particles with the size of 1.1-4.7 microm and 2.1-7.0 microm, respectively, in Feb. to Mar. and May. to Jun. The size distributions of ammonium in different months were similar, with one peak presenting in the < 1.1 microm fine particles. The air mass back trajectories analysis indicated that the distributions of inorganic nitrogen in aerosols were significantly influenced by the sources and transport pathways of air mass. Both high nitrogen concentration per unit atmospheric volume (nmol x m(-3)) and per unit mass particle (micromol x g(-1)) occurred when the air mass passed over severe pollution region. Both low concentration in atmosphere and particle occurred when the air mass came from clean marine atmosphere. Lower concentration in atmosphere and higher concentration in particle occurred when the air mass originated from the continent and transported long distances over the sea.

Bowman-Cole modified organic phosphorus fractionation system was used for the analysis of the phosphorus (P) forms in the sediments in North Canal River. The results showed that the average concentrations variation of total phosphorus (TP), and total organic phosphorus (TOP) in the sediments were 654.9-1285.4 mg x kg(-1) and 241.6-501.1 mg x kg(-1), respectively. TOP accounted for 34.08%-41.86% of TP which was much higher than other regions. The vertical distribution of OP forms changed greatly with the depth in the sediments. Labile organic P (LOP) increased at first (0-10 cm depth) but decreased gradually (10-40 cm). On the contrary, moderately labile organic P (MLOP) showed a degressive trend and nonlabile organic P (NOP) was no change with the depth. MLOP was the major part of TOP which was about 39.03%-85.72% of TOP, and was much higher than LOP (7.73%-24.13%) and NOP (10.14%-35.64%). The dynamic of MLOP in the sediments should be attended because it's easy to transform to LOP resulting in a strong influence on the water quality.

Absorption property of colored dissolved organic material (CDOM) is one of the most important contents to remote sensing of ocean color in estuarine and coastal areas. In this study, the optical properties and mixing behavior of CDOM in surface water of Yangtze Estuary were discussed according to the two surveys in August of 2008 and May of 2009. Based on the research, the absorption coefficient and spectral slope were discussed. It was found that in summer of 2008 CDOM absorption coefficients at 440 nm [a(g) (440)], ranged from 0.20 m(-1) to 0.73 m(-1), while the coefficients in 2009 varied between 0.20 m(-1) and 0.77 m(-1). Statistics showed that the power function model fitted the best in the regression analysis of CDOM absorption spectral. The spectral slopes (S(g2)) of CDOM calculated by the power function model ranged from 5.10 to 7.90 in Summer of 2008 and from 2.95 to 6.11 in Spring of 2009. The highest absorption coefficients of two cruises appeared both in the south passage of the Yangtze Estuary. The absorption coefficient in surfer water was observed varied tremendously in the estuary and the offshore area. And the main reason is affected by the turbidity maximum zone. It is observed that the absorption coefficients of CDOM tended to a homogeneous distribution whilst the layers of water mixed tempestuously, but otherwise it always showed a conservative mixing behavior. Because of the frequent mixture, there is not assured correlativity between S(g2) and a(g) (440). In the offshore area of Yangtze Estuary, the effecting of local production cannot be negligent, which differed from the estuary area. Yet when the hydrological environment was relatively stable, the negative relationship between them was very clear. In conclusion, the optical properties and mixing behavior of CDOM had showed tremendous different characteristics from inside the estuary to outside the estuary because of the influence of complex physical, chemical and hydrology conditions.

The present study aims to further reveal the environmental behavior of mercury on sediments surface. Effects of particle-sizes, pH and concentrations of dissolved organic matter (DOM) on mercury adsorption and desorption to the surface of sediments in the Songhua River were investigated by simulation experiments. A distinct variety of absorption ability among sediments with different particle-sizes was observed. Under this experimental condition, the absorption ability increased inversely with particle-size of sediments. In all absorption systems, mercury adsorption was enhanced when pH increased from 3.5 to 4.5, while mercury adsorption was inhibited significantly with the increasing of pH when pH values were above 4.5. With the increasing of pH values, the desorption of mercury presented a decreasing-increasing trend, the minimum desorption occurred at pH 5. Citric acid inhibited the mercury adsorption, and the intensity was correlated with mercury concentrations. Effects of citric acid on desorption of mercury were also apparently. With the increasing of citric acid concentrations, its effect on desorption presented a trend as enhanced-inhibited-steadied. Therefore, the above factors affected the mercury adsorption and desorption obviously, and it was necessary to take these factors into consideration in conducting the rivers' mercury control and dealing with a sudden pollution incident.

Batch experiments were employed to investigate the sorption and desorption procedures of phenanthrene (Phe) on the river and estuarine sediments. The relationships between sorption parameters and organic matter properties were also discussed. The results indicated that the data on Phe sorption and desorption by different river and estuarine sediments could be fitted well by the linear partitioning and Freundlich model. The linear distribution coefficients (KD) (v) aried from 58 to 743 L x kg(-1). The Freundlich parameters (K(F) and K(FOC)) varied from 75 microg(1-N) x kg(-1) x L(N) to 367 micro(1-N) x kg(-1) x L(N) and from 2253 microg(1-N) x kg(-1) x L(N) to 34743 microg(1-N) x kg(-1) x L(N), respectively. There were significantly positive correlations between K(D) and TOC, TN, DOC, Phe, C/N, DOC/TOC. However, a negative correlation occurred between K(F), K(FOC) values and DOC/TOC ratios. The data on Phe desorption could be better fitted by the Freundlich model than that by linear partitioning model. Except for S1, S8 and S9 samples, the others exhibited obvious sorption and desorption hysteresis. Contents and properties of organic matter were significant as the major factors controlling Phe sorption and desorption to and from the sediments. Considering the frequent impacts of anthropogenic sources on the river and estuarine sediments, the effects of dissolved organic matter on Phe sorption and desorption were perceived to be more important.

Field experiments are conducted separately in Taihu Lake and Chaohu Lake on Apr. and Jun. 2009. The changes in absorption spectra of chromophoric dissolved organic matter (CDOM) characteristics are analyzed using spectral differential analysis technology. According the spectral differential characteristic of absorption coefficient; absorption coefficient from 240 to 450 nm is divided into different stages, and the value of spectral slope S is calculated in each stage. In Stage A, S value of CDOM in Taihu Lake and Chaohu Lake are 0.0166-0.0102 nm(-1) [average (0.0132 +/- 0.0017) nm(-1)], 0.029-0.017 nm(-1) [average (0.0214 +/- 0.0024) nm(-1)]. In Stage B, S values are 0.0187-0.0148 nm(-1) [average (0.0169 +/- 0.001) nm(-1)], 0.0179-0.0055 nm(-1) [average (0.0148 +/- 0.002) nm(-1)]. In Stage C, S values are 0.0208-0.0164 nm(-1) [average (0.0186 +/- 0.0009) nm(-1)], 0.0253-0.0161 nm(-1) [average (0.0197 +/- 0.002) nm(-1)]. The results can be concluded as: (1) Absorption coefficient of water in Taihu Lake, and its contribution to absorption of each component is less than that of water in Chaohu Lake, however the standardized absorption coefficient is larger than that in Chaohu Lake. (2) Both in Taihu Lake and Chaohu Lake, derivative spectra of CDOM absorption coefficient reached valley at 260nm, then rise to top at 290 nm, CDOM absorption coefficient can be delivered into three stages. (3) Generally speaking, content of CDOM in Taihu Lake is less than in Chaohu Lake. (4) pectrum slope (S value) of CDOM is related to composition of CDOM, when content of humic acid in CDOM gets higher, S value of Stage B is the most sensitive value, then is the S value of Stage C. Oppositely, S value of Stage B gets the most sensitive value, then is the S value of Stage A; the least sensitive value is in Stage B.

This study is focused on the pollutant level of sediments after 20 years continuous rehabilitation in Yundang Lagoon, Xiamen Bay, one of the most developed harbors in China. The modified BCR fractionation scheme was employed in sediments for the partition of particulating metals and metalloids. Moreover, the potential environment risks of these pollutants were evaluated by using Håkanson indexes. The results showed that the sediments were slightly contaminated by Cu, Pb, Zn, Cr, Ni, Mn, Ag, As and Se. A major portion (30-46%) of Mn was strongly associated with the acid soluble fraction. Copper (Cu), Cr and Ni exhibit significant oxidisable fraction (from 22 to 32%), Pb, Cr, As, Zn, Se and Ag showed considerable concentration (>50%) in the residual phase. Environment risk evaluation showed that the pollution in Yundang Lagoon is moderate and the ranking of the contaminants followed the order: As>Ni>Pb>Cu>Cr>Zn. Importantly, though these results indicate that the concentrations of heavy metals in sediments here are also higher than the sediment quality guidelines and may pose a potential threat to these areas and so the efforts in remediation should be continued., ((c) 2009 Elsevier B.V. All rights reserved.)

Over the last 20 years, China has successfully established a modern biotechnology industry from almost nothing. Presently, China is a major producer of a vast array of products involving bioprocesses, for some China is even the world's top producer. The ever-increasing list of products includes organic acids, amino acids, antibiotics, solvents, chiral chemicals, biopesticides, and biopolymers. Herein, the research and development of bioprocesses in China will be reviewed briefly. We will concentrate on three categories of products: small molecules produced via fermentation, biopolymers produced via fermentation and small chemicals produced by enzyme-catalyzed reactions. In comparison with the traditional chemical process, in which, nonrenewable mineral resources are generally used, products in the first and second categories noted above can use renewable bioresources as raw materials. The bioprocesses are generally energy saving and environmentally benign. For products developed via the third category, although the raw materials still need to be obtained from mineral resources, the biocatalysts are more effective with higher selectivity and productivity, and the bioprocesses occur under ambient temperature and pressure, therefore, these are "green processes." Most of the products such as citric acid, xanthan and acrylamide etc., discussed in this paper have been in large-scale commercial production in China. Also introduced herein are three scientists, Prof. Shen Yinchu, Prof. Ouyang Pingkai and Prof. Chen Guoqiang, and six enterprises, Anhui Fengyuan Biochemical Co. Ltd., Shandong Hiland Biotechnology Co. Ltd., Shandong Fufeng Fermentation Co. Ltd., Shandong Bausch & Lomb-Freda Pharmaceutical Co. Ltd., Zhejiang Hangzhou Xinfu Pharmaceutical Co. Ltd., and Changzhou Changmao Biochemical Engineering Co. Ltd.; they have all contributed a great deal to research and development in the commercialization of bioprocesses.

Sediment cores taken from Taihu Lake, East China were analyzed for polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and polybrominated biphenyl ethers (PBDEs). The results showed a general sharp increase of HCH, DDT, PAH and PBDE concentrations in the surface layers, corresponding to a sedimentation time of 1980 and 1990 onward in the Meiliang Bay and Xukou Bay, respectively. The source of PAHs has largely transferred from petrogenic to pyrogenic origin, and good relationships were observed between sediment PAH concentrations and the regional gross domestic product. The sharp increase of DDTs in recent years may be related to the mobilization and migration of these chemicals from surface soil to lake sediment, as a result of enhanced soil run-off due to large scale land transform, as well as the contribution of current usage of dicofol and DDT-containing anti-fouling paints.

Field measurements were conducted in four representative rural areas across China to determine carbonaceous aerosol emissions from combustion of household biofuel. Results showed that the size distribution of both black carbon (BC) and organic carbon (OC) peaked at 0.26-0.38 microm. OC accounted for a significant fraction of fine particles from wheat residue combustion across all size categories, whereas both BC and OC accounted for a significant fraction of fine particles from fuel wood combustion across all size categories. The emission factors for crop wastes are 0.43 +/- 0.32 and 1.93 +/- 1.00 g/kg for BC and OC, respectively. The emission factors for woody fuel were 1.49 +/- 0.69 g/kg and 1.13 +/- 0.40 g/kg for BC and OC, respectively. Woody fuel BC-to-PM2.5 ratios were significantly higher than the ratios from crop waste, ranging from 36.40 to 71.18%, relative to crop waste BC-to-PM2.5 ratios which ranged from 1.70 to 33.52%. Woody fuel also had high BC-to-OC ratios, ranging from 0.95 to 2.51. Woody fuel combustion accounts for approximately two-thirds of China's estimated 430 Gg of BC emissions and crop waste combustion accounts for approximately 80% of China's 922 Gg of OC emissions from household biofuel combustion in 2005.

The use of coal briquettes and improved stoves by Chinese households has been encouraged by the government as a means of reducing air pollution and health impacts. In this study we have shown that these two improvements also relate to climate change. Our experimental measurements indicate that if all coal were burned as briquettes in improved stoves, particulate matter (PM), organic carbon (OC), and black carbon (BC) could be annually reduced by 63 +/- 12%, 61 +/- 10%, and 98 +/- 1.7%, respectively. Also, the ratio of BC to OC (BC/OC) could be reduced by about 97%, from 0.49 to 0.016, which would make the primary emissions of household coal combustion more optically scattering. Therefore, it is suggested that the government consider the possibility of: (i) phasing out direct burning of bituminous raw-coal-chunks in households; (ii) phasing out simple stoves in households; and, (iii) financially supporting the research, production, and popularization of improved stoves and efficient coal briquettes. These actions may have considerable environmental benefits by reducing emissions and mitigating some of the impacts of household coal burning on the climate. International cooperation is required both technologically and financially to accelerate the emission reduction in the world.

Normalized spectrum of photosynthesis available radiation (PAR), which was absorbed by all kinds of medium per unit volume of water at different depths, was calculated by the data from downward and upward irradiance and absorption coefficients of phytoplankton, non-algae particles and chromophoric dissolved organic matter (CDOM) in 41 locations in Lake Taihu from July 29 to August 1, 2006. The results showed that there were two peaks at about 450 nm and 675 nm in the normalized spectrum of PAR absorbed by phytoplankton per unit volume of water, respectively. With the increasing of the depth, the peak at about 450 nm gradually weakened, and red-shift appeared from 450 nm. The above phenomena were much more obvious in the algae-type zone and the center of Lake Taihu. The PAR absorbed by phytoplankton per unit volume of water was shift to 600-700 nm which mainly originated from 400-500 nm to 600-700 nm. The transitional speed was slower in the grass-type zone but it was faster in Meiliang Bay(algae-type zone)and the center of Lake Taihu. In the above water, the PAR absorbed by non-algae particles per unit volume of water mainly originated from 400-500 nm, but energy source gradually shifted to 500-600 nm with the increasing of depth. The variable characteristics of normalized spectrum of PAR absorbed by CDOM per unit volume of water were similar to that of non-algae particles. However, the advantage in grass-type zone which CDOM per unit volume of water absorbed PAR between 500 and 600 nm was less significant than that of non-algae particles per unit volume of water.

With XAD-series and ion exchange resins, dissolved organic matter (DOM) from Lake Hongfeng in Southwestern China Plateau was isolated into 6 fractions, i.e., humic acid (HA), fulvic acid (FA), hydrophobic neutrals (HON), hydrophilic acids (HIA), hydrophilic bases (HIB) and hydrophilic neutrals (HIN). Those fractions were characterized by high performance size exclusion chromatography, fluorescence spectroscopy and UV absorbance. Among the 6 fractions, FA was predominant and accounted for 51% of the total DOM. The weight-average (Mw) and number-averaged (Mn) molecular weight of these fractions ranged from 1688 to 2355 Da and from 1338 to 1928 Da, respectively. A strong correlation was observed between specific UV absorbance at 280 nm, E2/E3 (absorbance at 250 nm to 365 nm), and the molecular weight for DOM fractions. UV-Vis fulvic-like fluorescence peaks were found in all fractions. Protein-like fluorescence peaks existed in HON may indicate that microbial activity was severely in Lake Hongfeng. There was a significant relationship between fluorescence intensities and specific UV absorbance at 254 nm for those DOM fractions, suggesting their similar luminescence characteristics. The values of fluorescence index (f450/500) indicated that hydrophobic fractions may derive from terrestrial sources, and the hydrophilic fractions from microbial and terrestrial origins. Those results suggest that there were inter-relationships between molecular weight, fluorescence and absorbance characteristics, and also subtle consistencies between the hydrophilic and hydrophobic properties and the sources for these 6 fractions from Lake Hongfeng.