Effect of environmental level of methomyl on hatching, morphology, immunity and development related genes expression in zebrafish (Danio rerio) embryo.

The extensive use of carbamate pesticides has led to a range of environmental and health problems, such as surface and groundwater contamination, and endocrine disorders in organisms. In this study, we focused on examining the effects of toxic exposure to the carbamate pesticide methomyl on the hatching, morphology, immunity and developmental gene expression levels in zebrafish embryos. Four concentrations of methomyl (0, 2, 20, and 200 µg/L) were administered to zebrafish embryos for a period of 96 h. The study found that exposure to methomyl accelerated the hatching process of zebrafish embryos, with the strongest effect recorded at the concentration of 2 µg/L. Methomyl exposure also trigged significantly reductions in heart rate and caused abnormalities in larvae morphology, and it also stimulated the synthesis and release of several inflammatory factors such as IL-1ß, IL-6, TNF-α and INF-α, lowered the IgM contents, ultimately enhancing inflammatory response and interfering with immune function. All of these showed the significant effects on exposure time, concentration and their interaction (Time × Concentration). Furthermore, the body length of zebrafish exposed to methomyl for 96 h was significantly shorter, particularly at higher concentrations (200 µg/L). Methomyl also affected the expression levels of genes associated with development (down-regulated igf1, bmp2b, vasa, dazl and piwi genes), demonstrating strong developmental toxicity and disruption of the endocrine system, with the most observed at the concentration of 200 µg/L and 96 h exposure to methomyl. The results of this study provide valuable reference information on the potential damage of methomyl concentrations in the environment on fish embryo development, while also supplementing present research on the immunotoxicity of methomyl.

A novel process for food waste recycling: A hydrophobic liquid mulching film preparation.

Appropriate and effective recycling of food waste (FW) has become increasingly significant with the promotion of garbage classification in China. In this study, a novel and green process was developed to recycle FW to prepare a biodegradable composite liquid mulching film (LMF) through crosslinking with sodium alginate (SA). The solid phase of FW was obtained as the raw material after hydrothermal pretreatment to remove pathogens and salts, and to improve the reactivity of active components at a moderate temperature. The prepared LMF had a hydrophobic surface and compact structure due to the lipid in FW and the acetalization reaction and hydrogen bonds among SA, glutaraldehyde and multi-active components of FW, resulting in enhanced water vapor barrier properties. The minimum water vapor permeability of the prepared LMF reached (8.23 ± 0.05) ✕ 10-12 g cm/(cm2·s·Pa) with 1.82 wt % of plasticizer, 0.74 wt% of crosslinker and a mass ratio of HTP-FW to SA of 3.56:1. The prepared LMF showed good mechanical properties and could maintain its integrity after spraying it on the soil surface for 31 days. In addition, it could effectively prevent the loss of soil moisture and heat, promote the seed germination of Chinese cabbage and achieve 89.14% of weight loss after burying in the soil for 27 days. This study provides a high value-added route to convert the FW to a hydrophobic LMF with superior properties, which addresses not only the problem of food waste but also the pollution of plastic mulching film.

Transcriptome profiling reveals differential expression of immune-related genes in gills of hybrid yellow catfish (Tachysurus fulvidraco ♀ × Pseudobagrus vachellii ♂) under hypoxic stress: Potential NLR-mediated immune response.

Fish gills are the primary organ that respond to sudden changes in the dissolved oxygen (DO) level in the aquatic environment. Hypoxic stress impairs the normal function of gill tissues. However, little is known about the mechanisms of the response of yellow catfish gills to hypoxic stress. In this study, we compared transcriptomic and physiological changes in gill tissues of hybrid yellow catfish (Tachysurus fulvidraco ♀ × Pseudobagrus vachellii ♂) between a hypoxia-treated group (DO: 1.5 mg/L) and a control group (DO: 6.5 mg/L). In fish in the hypoxia-treated group, gill filaments underwent adaptive changes, and the number of vacuoles in gill tissues increased. Exposure to hypoxic conditions for 96 h resulted in increased anaerobic metabolism and decreased antioxidant and immune capacity in gill tissues. Transcriptome analyses revealed 1556 differentially expressed genes, including 316 up-regulated and 1240 down-regulated genes, between fish in the hypoxia-treated and control groups. Functional analyses indicated that the main pathway enriched with differentially expressed genes was immune response, followed by energy metabolism and signal transduction. Under hypoxic stress, the transcript levels of genes involved in the NOD-like receptor signaling pathway initially increased rapidly but then decreased over time, suggesting that the NOD-like receptor-mediated immune response plays an essential role in hypoxia tolerance and resistance in hybrid yellow catfish. Our results provide novel insights into which immune-related genes and pathways are activated under hypoxic stress, and reveal details of early adaptation of the immune response and defense mechanisms under hypoxic stress.

[Study on ecological stereoscopic cultivation mode of Amomum villosum-Dimocarpus longan].

In order to set up a technical standard for planting Amomum villosum in wood forest in the future, we analyzed the relationship between the ecological factors and the yield of A. villosum planted in five Dimocarpus imocarpus longan wood forests and five miscellaneous wood forests in Yangchun city, to find out the dominant factors that affect the yield of A. villosum. The results showed that agricultural measures of fertilization, artificial irrigation and removing the old plants were positively correlated with the yield of A. villosum, the pesticide spraying and soil pH value were negatively correlated with the yield of A. villosum. But the effects of ecological factors on the yield were not significantly. High yield regions are generally located in the ravine, two sides of mountain stream and other places where water is more adequate. The slope of cultivated field with high yield is generally less than 30°, lighting and ventilation are more appropriate; soil type is generally sandy or loam, shade density is generally about 50%, and pollinators are many in quantity and variety. And we found that there was a large difference in mineral nutrient contents of soils among ten plantations. Results indicate that the yield of A. villosum is determined by the combination of each ecological factor. Suitable light intensity, moisture, ventilation and reasonable fertilization are conductive to increase the yield of A. villosum, but the use of pesticides and soil alkalization hinder the increase of A. villosum production. Too high shade density and the abuse of pesticides may be the main reason for limiting the yield of A. villosum planted in D. longan wood forests. This study has obtained key techniques of the ecological stereoscopic cultivation mode of A. villosum-D. longan, which lays a theoretical foundation for the guidance of farmers in planting A. villosum in the D. Longan forest in the future.

Degradation of toluene-2,4-diamine by persulphate: kinetics, intermediates and degradation pathway.

In this study, the degradation of toluene-2,4-diamine (TDA) by persulphate (PS) in an aqueous solution at near-neutral pH was examined. The result showed that the degradation rate of TDA increased with increasing PS concentrations. The optimal dosage of PS in the reaction system was determined by efficiency indicator (I) coupling in the consumption of PS and decay half-life of TDA. Calculation showed that 0.74 mM of PS was the most effective dosage for TDA degradation, at that level the maximum I of 24.51 was obtained. PS can oxidize TDA for an extended reaction time period. Under neutral condition without activation, four degradation intermediates, 2,4-diamino-3-hydroxy-5-sulfonicacidtoluene, 2,4-diaminobenzaldehyde, 2,4-bis(vinylamino)benzaldehyde and 3,5-diamino-4-hydroxy-2-pentene, were identified by high-performance liquid chromatography-mass spectrometry. The tentative degradation pathway of TDA was proposed as well. It was found that hydroxyl radical played an important role in degradation of TDA with the activation of Fe2+, whereas PS anion and sulphate radicals were responsible for the degradation without activation of Fe2+.

[Influence of the Composition of the Initial Mixtures on the Physicochemical and Biological Properties and Spectral Characteristics of Composts].

In this work, biogas residues, the remnant of the anaerobic digestion, was used for composting with livestock manure as the co-substrate. It is important for improving the soil quality in China, because the negative influence of biogas residues being utilized directly as organic fertilizer (a mainstream way of disposing biogas residues in China) on the soil could be eliminated or mitigated via composting. The composition of composting substrate has a great influence on the composting process. To explore the influence of the composition of the initial mixtures on the physicochemical properties and spectroscopic characteristics of composts, fifteen co-composting of biogas residue, pig manure and chicken manure, with different material ratios, were carried out. Physicochemical and biological indicators were determined. Meanwhile, spectroscopic methods, such as UV-Vis, synchronous fluorescence and 3D-EEM spectra were used for identifying characteristic spectral parameters companied with FRI and PARAFAC. Therefore, spectroscopic characteristics of composts were characterized. The relationship between physicochemical properties of composts and the composition of the initial mixtures was established using CCA. Similarly, that between spectroscopic characteristics of composts and the composition of the initial mixtures was also established. The results showed that: physicochemical properties of composts exhibits a significant correlation with the composition of the initial mixtures. A significant correlation between spectroscopic characteristics of composts and the composition of the initial mixtures was also observed. In the two CCA, the former four axes account for 83.9% and 97.5% of the total sample variation. The influence of enviro nmental factors on physicochemical properties of composts was in the order of pig manure amount>chicken manure amount>biogas residue amount and that on spectroscopic characteristics of composts was in the order of biogas residue amount>pig manure amount>chicken manure amount. Carbon-rich raw materials favor the maturation of compost. A high proportion of nitrogen-rich raw materials does not lead to the accumulation of ammonia in compost. A low proportion of biogas residue favors the formation of humic substances during the co-composting of biogas residue and livestock manure. In summary, the evaluation of compost fermentation effect should synthetically consider physic-chemical, biological indicators and spectral parameters instead of a single index.

Catheter ablation versus medical therapy for atrial fibrillation with prior stroke history: a prospective propensity score-matched cohort study.

BACKGROUND: Patients with atrial fibrillation (AF) and prior stroke history have a high risk of cardiovascular events despite anticoagulation therapy. It is unclear whether catheter ablation (CA) has further benefits in these patients. METHODS: AF patients with a previous history of stroke or systemic embolism (SE) from the prospective Chinese Atrial Fibrillation Registry study between August 2011 and December 2020 were included in the analysis. Patients were matched in a 1:1 ratio to CA or medical treatment (MT) based on propensity score. The primary outcome was a composite of all-cause death or ischemic stroke (IS)/SE. RESULTS: During a total of 4.1 ± 2.3 years of follow-up, the primary outcome occurred in 111 patients in the CA group (3.3 per 100 person-years) and in 229 patients in the MT group (5.7 per 100 person-years). The CA group had a lower risk of the primary outcome compared to the MT group [hazard ratio (HR) = 0.59, 95% CI: 0.47-0.74, P < 0.001]. There was a significant decreasing risk of all-cause mortality (HR = 0.43, 95% CI: 0.31-0.61, P < 0.001), IS/SE (HR = 0.73, 95% CI: 0.54-0.97, P = 0.033), cardiovascular mortality (HR = 0.32, 95% CI: 0.19-0.54, P < 0.001) and AF recurrence (HR = 0.33, 95% CI: 0.30-0.37, P < 0.001) in the CA group compared to that in the MT group. Sensitivity analysis generated consistent results when adjusting for time-dependent usage of anticoagulants. CONCLUSIONS: In AF patients with a prior stroke history, CA was associated with a lower combined risk of all-cause death or IS/SE. Further clinical trials are warranted to confirm the benefits of CA in these patients.

Elemental and spectroscopic methods with chemometric analysis for characterizing composition and transformation of dissolved organic matter during chicken manure composting.

Dissolved organic matter was extracted from chicken manure after 1, 8, 16, 28 and 40 days of composting and characterized by combining elemental and spectroscopic methods with chemometric analysis to investigate the evolution of composting materials. The elemental and spectroscopic analysis results showed that the composting process was characterized by the biodegradation of aliphatics, polysaccharide and proteins, as well as by the synthesis of aromatic structures, humic-like substances and macromolecules. Principal component analysis and correlation analysis indicated that the data from elemental and spectroscopic analysis fell into three main groups, and corresponded to the biodegradation, aromatization, and humification and polymerization state of the composting materials. Hierarchical cluster analysis indicated rapid biodegradation of organic matter during the first eight days, and the formation of aromatic structures, humic-like materials and macromolecules in dissolved organic matter after eight days.

Growth performance, physiological parameters, and transcript levels of lipid metabolism-related genes in hybrid yellow catfish (Tachysurus fulvidraco ♀ × Pseudobagrus vachellii ♂) fed diets containing Siberian ginseng.

In high-density aquaculture, fish health can suffer because of excessive feeding, which causes fatty liver disease. Siberian ginseng (Acanthopanax senticosus) has been used as a feed additive to promote animal growth, immunity, and lipid metabolism. In this study, we explored the effects of A. senticosus on the physiology of hybrid yellow catfish (Tachysurus fulvidraco ♀ × Pseudobagrus vachellii ♂). A control group and five groups fed diets containing A. senticosus (0.5, 1, 2, 4, and 8 g A. senticosus/kg feed) were established and maintained for 8 weeks. Dietary supplementation with A. senticosus at 4 g/kg promoted growth of the hybrid yellow catfish. Serum total cholesterol (TC) and triacylglycerol (TG) levels at 2 g/kg A. senticosus (TC: 1.31 mmol/L; TG: 1.08 mmol/L) were significantly lower than in the control group (TC: 1.51 mmol/L; TG: 1.41 mmol/L), and 4 g/kg A. senticosus (17.20 µmol/g tissue) reduced the liver TG level compared with the control group (21.36 µmol/g tissue) (P <0.05). Comparative transcriptomic analysis of liver tissue between the control group and the group showing optimum growth (4 g/kg A. senticosus) revealed 820 differentially expressed genes and 44 significantly enriched pathways, especially lipid metabolism pathways such as unsaturated fatty acid and fatty acid metabolism. The transcript levels of five lipid metabolism-related genes were determined by quantitative real-time PCR. The results showed that 2-4 g/kg A. senticosus supplementation reduced the FADS2, ELOVL2, CYP24a, and PLPP3 transcript levels and 4 g/kg A. senticosus increased the DIO2 transcript level (P <0.05), leading to altered synthesis of TG and thyroxine and reduced fat deposition in the liver. Our results show that dietary A. senticosus affects the regulation of fat metabolism and promotes the growth of hybrid yellow catfish. A. senticosus is a healthy feed additive, and the appropriate dietary supplementation rate is 2-4 g/kg.

[Quantitative fluorescence characterization of organic matter stability during chicken manure composting].

Due to its high sensitivity, good selectivity and nondestructive nature, fluorescence spectroscopy was widely applied to characterize the nature of dissolved organic matter (DOM) from different source since the last decade. In the present study, dissolved organic matter (DOM) extracted from chicken manure samples during composting progress was quantitatively characterized by fluorescence analysis techniques and mathematical analysis methods. The results showed that, the ratio between the fluorescence intensities at 330 nm (humic-like matter) and 280 nm(protein-like matter) (I330/I280) in synchronous-scan excitation mode spectra, the area of a fluorescence spectrum obtained by excitation at the blue wavelength of 465 nm(A470-640), and the ratio between the area of the last quarter (435-480 nm) and the area of the first quarter (300-345 nm) of the emission spectrum (A435-480 nm/A300-345 nm) by exciting the sample with ultraviolet radiation of 240 nm, all increased during composting, and the humification degree of compost increased as well. Three-dimensional excitation emission matrix fluorescence spectroscopy showed that the intensity of protein-like matter decreased during composting progress and diminished at the end, while that of fulvic-like matter increased all the time. The ratio between the intensity of the ultraviolet fulvic-like fluorescence (Peak A) and that of the visible fulvic-like fluorescence gamma (A, C) showed an overall significant downward trend during composting, but fluctuated in the progress. The correlation analysis showed that, I330/I280, A470-640 and A435-480 nm/A300-345 nm were all significant correlative, while gamma (A, C) was not correlative with the above-mentioned three parameters at 0. 05 level due to effect by other factors. The results show that, I330/I280, A470-640 and A435-480 nm/A300-345 nm can be effectively used in the process of the evaluation of humification degree during composting.

[Study on the characteristic UV absorption parameters of dissolved organic matter extracted from chicken manure during composting].

The characteristic parameters obtained from UV-Visible spectra of dissolved organic matter (DOM) during composting were studied in the present paper. The results showed that, during composting progress, the non-humic substances were translated into humus substances, and the aromatization, humification degree and molecular weight of the humus substances increased, while the fatty chains linked with the benzene ring structure were cleavaged into carbonyl, carboxyl and other functional groups. The correlation analysis showed that, when DOM concentration (DOC) from all samples was the same, the specific ultraviolet absorbance values at 254 and 280 nm (SUVA254 and SUVA280, respectively), and the area of a spectrum obtained from 226 to 400 nm (A(226-400)) showed significant positive correlation, furthermore, they were all significantly negatively correlated with the concentration of DOM (DOC), but the correlation between A(226-400) and DOC was the best; The ratio between the absorbance value at 253 nm and that at 203 nm (E253/E203) was significantly correlative with SUVA254, SUVA280 and A 226-400, though the correlation between E253/E203 and DOC was not as good as the other three characteristic parameters; The ratio between the absorbance value at 250 nm and that at 365 nm (E250/E365) and the ratio between the absorbance value at 465 nm and that at 665 nm(E250/E365) were not correlated with the other parameters. The results showed that, the stability of DOM extracted from chicken manure increased during composting, and the complex ability between DOM and heavy metals enhanced as well; A(226-400) reflects the changes of compost maturity best in all UV-Visible spectral absorption parameters studied in this paper.

[Effect of pH on the fluorescence characteristic of dissolved organic matter in landfill leachate].

Due to its high sensitivity, good selectivity and nondestructivity nature, fluorescence technique is suitable to the study of DOM. In the present study, fluorescence characteristics of dissolved organic matter (DOM) from three different ages of landfill leachate (1a, 5a, 10a) under different pH value were investigated. The fluorescence synchronous scan spectroscopy showed that, in addition to the characteristic each age of landfill leachate owned separately, DOM from three ages of landfill leachate shared some common characteristics with the change in pH as follows: the fluorescence peaks of DOM exhibited in synchronous scan spectroscopy from 1 and 5-year-old leachate showed the maximum fluorescence intensity at pH 5, while that of DOM from 10-year-old landfill leachate appeared at pH 12, and the fluorescence intensity of most fluorescence peaks of DOM from 10-year-old landfill leachate exhibited in synchronous scan spectroscopy at pH 4 ranked second. The three-dimensional fluorescence excitation-emission matrix spectroscopy (3DEEM) suggested that the fluorescence intensity of the protein-like peaks of DOM from all three ages of landfill leachate increased with pH value increasing, and the maximum fluorescence occurred at pH 10, while that of DOM from 10-year-old appeared at pH 8; the fluorescence intensity of the visible fulvic-like peaks of DOM from all three ages of landfill leachate was enhanced with pH increasing, and exhibited the maximum fluorescence intensity at pH 10, while the relation curve between the fluorescence intensity of the UV fulvic-like and pH value of DOM from all three year ages of landfill leachate exhibited two peaks, one occurred at pH 4, and the other appeared at pH 10. 3 DEEM also indicated that compared to the fluvic-like matter, the protein-like matter was more easily influenced by pH value. The relation between the r(A,C) value and pH value suggested that the former relied on the latter. If we would compare the r(A,C) values of DOM originating differently, the authors should compare each other under the same pH value.

[Comparison of two spectral mixture analysis models].

A spectral mixture analysis experiment was designed to compare the spectral unmixing effects of linear spectral mixture analysis (LSMA) and constraint linear spectral mixture analysis (CLSMA). In the experiment, red, green, blue and yellow colors were printed on a coarse album as four end members. Thirty nine mixed samples were made according to each end member's different percent in one pixel. Then, field spectrometer was located on the top of the mixed samples' center to measure spectrum one by one. Inversion percent of each end member in the pixel was extracted using LSMA and CLSMA models. Finally, normalized mean squared error was calculated between inversion and real percent to compare the two models' effects on spectral unmixing. Results from experiment showed that the total error of LSMA was 0.30087 and that of CLSMA was 0.37552 when using all bands in the spectrum. Therefore, LSMA was 0.075 less than that of CLSMA when the whole bands of four end members' spectra were used. On the other hand, the total error of LSMA was 0.28095 and that of CLSMA was 0.29805 after band selection. So, LSMA was 0.017 less than that of CLSMA when bands selection was performed. Therefore, whether all or selected bands were used, the accuracy of LSMA was better than that of CLSMA because during the process of spectrum measurement, errors caused by instrument or human were introduced into the model, leading to that the measured data could not mean the strict requirement of CLSMA and therefore reduced its accuracy: Furthermore, the total error of LSMA using selected bands was 0.02 less than that using the whole bands. The total error of CLSMA using selected bands was 0.077 less than that using the whole bands. So, in the same model, spectral unmixing using selected bands to reduce the correlation of end members' spectra was superior to that using the whole bands.

[An algorithm for highlightling structure in multispectral remote sensing].

Based on the principle of mineral generation, structures could provide not only passage ways for ore-forming fluid, but also space for them to aggregate. So, it was very important to study the feature of structures in study area before mineral exploration. In order to highlight structures using multispectral remote sensing data, an algorithm integrating principle component analysis (PCA), maximum noise fraction transformation (MNF) and original image data was proposed here. In the algorithm, the original image was firstly transformed by PCA and MNF; then all bands were normalized to reduce errors caused by different band dimensions, and three bands containing detailed structure information were selected to form the false color image in which structures in study area were highlighted. Results of transformation on enhanced thematic mapper (ETM) data acquired on June 27th 2000 in Hatu area, Xinjiang province, China showed that (1) the transformed image was not only more colorful than the original data, but also more gradational than the original data. (2) The color difference among objects was enhanced by the algorithm. (3) Structrues were highlighted by the algorithm. Therefore, the algorithm's effect of highlighting structures in study area was noticeable.

[A target-highlighting method in multispectral remote sensing].

In order to highlight target in multispectral remote sensing and overcome the human error caused by threshold, a new method is proposed here. Image of target similarity is firstly calculated by spectral energy level matching (SEM) algorithm and as a band added to original image; Then, band normalization is performed on the new image to reduce the effects caused by the order of magnitude in different bands; Finally, a false color image that highlights the target is made by RGB composed of the first three bands (3, 2, 1) in MNF transformation. Results from the experiment of highlighting the main rock-type tuffaceous siltstone in Hatu area, Xinjiang province, China show that (1) the new method can highlight target for the increment of target's information and weights during the process of transformation by adding a band representing target's similarity to the original image. Therefore, it overcomes the shortcomings existing in the common transformations on space information-although different objects corresponding to special information space are distinguished, targets the authors wanted can not be highlighted yet; (2) The new method can distinguish more objects than original maximum noise fraction (MNF) transformation because it unifies the tone for the same object's type by suppressing none target information using SEM method; (3) In addition to highlighting tuffaceous siltstone in the study area, the new method can be used widely in other fields such as soil, concrete, altered mineral etc.

[Spectroscopic characterization indicator of landfill in the process of stabilizing].

In the present study, dissolved organic matter (DOM) extracted from landfill of four different ages was studied with fluorescence and ultraviolet-visible spectroscopy in order to explore the possibility of using spectral characteristic changes of DOM as stabilization indicators for landfill. The three-dimensional fluorescence excitation-emission matrix spectroscopy (EEM) displayed that DOM of 0-year-old contained mainly protein-like matter, while DOM extracted from 1, 5 and 10-year-old consisted chiefly of humic matter-like substance, and the intensity change of DOM of 1, 5 and 10-year-old landfill was disordered. Besides, the fluorescence spectroscopy also showed that the r(A,C) value and the fluorescence index f(450/500) of DOM of four different years both decreased with landfill age, which indicated that the low molecular weight fraction of DOM was translated into the high molecular aromatic matter and the degree of humification was enhanced with the time increasing. In addition, the specific ultraviolet-visible absorbance (SUVA) increased with landfill age, which also revealed the law that the degree of humification strengthened with the time increasing, but the change regularity of E4/E6 value of DOM was unconspicuous since the E4/E6 value was easily impacted by some other factors. Therefore, the r(A,C) value, the fluorescence index f(450/500) and the SUVA value of DOM extracted from aged refuse reflected effectively the law of how landfill changed, and could be employed as simple stabilization indicators for aged refuse and closed landfill compartments.

[Fluorescence spectroscopic chracterization of the complexation between mercury(II) and dissolved organic matter].

In this study, conventional fluorescence spectroscopy in the excitation, emission and synchronous scan modes and three-dimensional fluorescence spectroscopy in the form of excitation-emission matrix of fluorescence intensity as a function of excitation and emission wavelengths were applied to study the complexation between DOM extracted from landfill leachates and Hg(II) ions. The emission spectrum of DOM exhibited a broad peak with a center at 425 nm and a disorder change of the peak with increasing Hg(II) concentrations, which suggested that the structure of DOM was comparatively simple and the fluorescence character of DOM-Hg(II) complexes resulted from interaction of all fluorescence groups. The excitation spectrum of DOM showed that the intensities of two peaks at 392 and 458 nm both decreased with the addition of Hg(II), indicating that different sources, hydroxy and amido groups, were all involved in the DOM-Hg(II) complexation process. Synchronous-scan excitation spectra of DOM-Hg(II) complexation showed that Hg(II) not only produced fluorescence quenching effect, but also enhanced the rigid structure of DOM at a low concentration. The three-dimensional fluorescence spectra of DOM-Hg(II) showed that the peaks A and B reduced strongly and the two peaks tended to shift toward longer wavelength with the concentrations of Hg(II) increasing. These results indicated that protein-like matter reacted with Hg(II) and there was a charge-transfer transition either between energy level in its ligand and a mercury energy level or between two mercury energy levels at the same time. Besides, the decrease in fluorescence intensity of peaks C and D in three-dimensional fluorescence spectra suggested that carbonyl and carboxyl formed bonds with Hg(II) when DOM was complexed with Hg(II).

[Study on three-dimensional fluorescence spectroscopy characteristics of humic acid during composting with microbes inoculation].

Composting is one of the municipal solid wastes (MSW) treatment ways. In order to increase composting humification process, in the present study, inoculation microbes were used in MSW composting. The experiment design included RUNck with no microbes inoculation and RUNmic with microbes inoculation. The inoculation microbes were composed of Bacillus casei, Lactobacillus buchneri, Candida rugopelliculosa and Trichoderma. During composting, samples were taken from MSW composting, and humic acid (HA) was extracted from composting and purified, the three-dimensional-excitation emission matrix fluorescence spectroscopy (3DEEM) characteristics and elemental analysis of the HA were determined, and the effect of inoculation microbes on the degree of humification of composting was studied. At initial stage of MSW composting, HA 3DEEM exhibited a peak of fulivc-like at an Ex/Em wavelength pair of 330/440 nm (peak a), and with MSW composting process, the excitation wavelength of peak a shifted from 330 to 350 nm. And a new peak of humic-like reformed nearby an Ex/Em wavelength pair of 390/470 nm (peak b). At 336 h of MSW composting, compared with RUNck (with no micromial inoculation), the fluorescence intensity of peak a (fulivc-like) nearby an Ex/Em wavelength pair of 350/440 in RUNmic (with microbial inoculation) was decreased, while that of peak b (humic-like) nearby an Ex/Em wavelength pair of 390/470 was slightly increased; the excitation and emission wavelength of peak a and peak b all shifted to long wavelengths. Elemental analysis indicated that C/H and O/C of HA molecule in RUNck increased by 9.68% and 10.91% respectively; and those of RUNmic increased by 11.11% and 20.37% at 336 h of MSW composting, respectively. The changes in HA 3DEEM and parameters of elemental analysis occurred in RUNmic at the final stage of composting, because degraded molecules, by the intense microbiological activity during composting, became reorganized to form more condensed compounds, richer in aromatic components. These results all led to the similar conclusion that inoculation microbes composting would accelerate the degree of HA humification, and increase the efficiency of composting.

[Study on spectral characteristic of dissolved organic matter fractions extracted from municipal solid waste landfill leachate].

In the present study, the samples of landfill leachate of 0, 5, 10-year-old were respectively taken from landfill plant. Based on a modified Leenheer fractionation scheme, dissolved organic matter (DOM) extracted from landfill leachate of three different ages was fractioned according to their polarities and charge characteristics by using XAD-8 resin, and the fractions of hydrophobic acid (HOA), neutral (HON) and hydrophilic matter (HIM) were obtained, Then the fluorescence and UV spectra of DOM fractions were determined. The fluorescence synchronous scan spectra of DOM fractions exhibited a primary peak at 280 nm for 0-year-old, while the primary peak exhibited at 340nm for 5 and 10 year-old, suggesting that DOM fractions contained mainly protein-like matter at initial stage of landfill, and with the increase in landfill ages, aromatic structures of DOM fractions in leachate were enriched. Among the DOM fractions of HOA, HON and HIM at different ages of landfill leachate, the fluorescence and UV spectra all indicated that the molecular weight, content of aromatic compounds and degree of condensation were all in the order of HOA>HON>HIM. The ratio of UV absorbance at 253 nm to that at 203 nm (A253/A203) showed, that the substituent on the aromatic ring of HOA and HON fractions consisted mainly of carbonyl, carboxyl and hydroxyl; while that of HIM consisted of aliphatic chains, and the content of aromatic compounds was lower than that of HOA and HON; which implied that the HIM displayed a lower molecular weight and simpler structure compared to HOA and HON. Altogether, the results obtained from fluorescence and UV spectra indicate that the degree of aromatization increased in DOM fractions of leachate with the landfill ages, in the following order: HOA > HON > HIM.

[Study on fluorescence characteristic of dissolved organic matter from municipal solid waste landfill leachate].

In the present study, the samples of leachate of 0, 5, 10-years-old landfill were respectively taken from landfill plant, the dissolved organic matter (DOM) was extracted from landfill leachate, and the fluorescence spectra of DOM were determined. The fluorescence synchronous scan spectra of DOM in 0-year-old leachate exhibited a primary peak at 335 nm, a secondary peak at 455 nm, and a shoulder peak at 385 nm. While the fluorescence intensities of DOM at different peaks were decreased for 5-year-old leachate, especially those of the peaks at shorter wavelengths (335 and 385 nm) which may be ascribed that the simpler structural components were decreased sharply. Compared with 5-year-old leachate, the fluorescence intensity of DOM in 10-year-old leachate decreased slightly. Three-dimensional excitation emission matrix fluorescence spectra (3DEEM) of DOM in 0-year-old leachate exhibited two peaks at Ex/Em wavelength pairs of 270/355 and 220/350, respectively, which were all associated with protein-derived compounds, while the peaks of protein-like disappeared in 5-year-old leachate, and new peaks of complex structural fulvic acid-like were formed at Ex/Em wavelength pair of 330/412.5 and 250/416.5, respectively. This indicated the component of DOM in the leachate of 5-year-old landfill led to a decrease in low molecular compound, and an increase in high molecular compound compared to that of the 0-year-old. 3DEEM of DOM of 10-year-old leachate was similar to that of DOM in the 5-year-old, but the fluorescence intensity of the peaks of fulvic acid-like in DOM was different, and compared with that of 5-year-old leachate, the peak of DOM in 10-year-old leachate shifted from Ex/Em wavelength pair of 250/416.5 to 250/427.5. This indicated that the DOM formed similar structures, but the structure of fulvic acid-like in DOM of 10-year-old leachate had a greater degree of aromatization and quantity than that of 5-year-old leachate. The results obtained from fluorescence synchronous scan spectroscopy and 3DEEM indicate that aromatic structures of DOM are enriched with the age of landfill leachate.