Dissolved Organic Matter Fluorescence Spectra Research Articles

Relationship between non-point source pollution and fluorescence fingerprint of riverine dissolved organic matter is season dependent

The source identification of water pollution and quantification of pollution sources are vital for water environment management. Dissolved organic matter (DOM) affects the form, solubility, and toxicity of pollutants, so the migration and transformation of DOM are crucial for water quality assessment. Therefore, the aim of this study was to identify pollution sources and quantify their contribution in water environments using fluorescence fingerprint of DOM. The Danjiangkou Reservoir and its main tributaries were selected as the study area. The DOM fluorescence components of pollution source samples were analyzed and the quantitative relationship between DOM spectral indices and nitrate isotopes (δ15N-NO3− and δ18O-NO3−) was established. It was found that humic-like substances were mainly derived from non-point source (NPS) pollution and protein-like substances were from point source (PS) pollution. The fluorescence index (FI) of DOM was positively correlated with PS pollution and negatively correlated with NPS pollution. The quantitative relationship between three-dimensional (3D) fluorescence spectra characteristics of DOM and water quality indicators or NPS pollution was established, which realized the convenient quantitative evaluation of pollution load and pollution source contribution using DOM fluorescence spectra characteristics. The strength of the correlation between DOM fluorescence spectra characteristics and water quality indicators (or NPS pollution) was affected by seasonal rainfall due to changes in the contribution of PS and NPS pollution. This study provides a new approach for source identification of water pollution and quantification of pollution sources using 3D fluorescence fingerprint of DOM.

Dissolved organic matter in hand-dug well water as groundwater quality indicator: assessment using laser-induced fluorescence spectroscopy and multivariate statistical techniques

In groundwater, dissolved organic matter (DOM), a complex material, is a contaminant of concern owing to its ability to influence water quality and stimulate microbial metabolism. Using a 445-nm diode laser-induced fluorescence (LIF) spectroscopy, DOM contamination levels have been investigated of well water samples fetched from ten privately owned hand-dug wells during dry and wet seasons of 2016, 2017 and 2018, in Ghana. The results showed spatio-temporal heterogeneities in the LIF spectra, and the fluorescence intensity peaks were generally higher and broader during the wet season than the dry season. In this study, DOM fluorescence spectra at an emission wavelength band of 460–650 nm showed two distinct broad peak shoulders within 480–500 nm and 550–570 nm, engulfing the water Raman peak at 527 ± 2 nm for all the water samples studied. Furthermore, principal component analysis and cluster analysis were used to differentiate the 2016 water samples based on their DOM contamination levels. In each case, three groups or clusters were identified based on their similarities and dissimilarities. The study revealed humic DOM substances as the most typical well water fluorophores. Applying the K-nearest neighbour algorithm as a classifier method for the classification of 30 water samples studied in 2016, 16.7% (5/30) were classified as very good drinking water, 46.7% (14/30) as good, 26.7% (8/30) as fairly good, and 10% (3/30) as bad drinking water samples. In general, levels of dissolved organic matter contamination increased over the study period during the rainy seasons for wells situated in close proximity to septic tanks, refuse dumps, public toilets and in wetlands. Thus, in the study the fluorescence intensity depends on the sampling site and the season, and indicates the DOM contamination level.

Tracking and analysis of DBP precursors’ properties by fluorescence spectrometry of dissolved organic matter

Disinfection by-products (DBPs) play a significant role in human health. Identification of the precursor of DBPs, which constitutes dissolved organic matter (DOM), can help optimize the processes in a drinking water treatment plant (DWTP). This is very important for obtaining more safe water. In this context, a one-year study was performed in a DWTP. Fluorescence spectra of DOM were quantified for determining DOM composition and properties, and the corresponding DBPs formation was analyzed. Hydrophobic neutral and acidic compounds were found to be the two predominant substances forming DBPs, which also were dominant in the DOM. Coagulation and sedimentation were not effective in DOM elimination. Besides, sand filtration caused organic compounds to increase by 14.8% on average, especially 28.59% for aromatic protein II and 18.7% for soluble microbial product-like compounds, which was due to metabolism by microorganisms present in the filter. Carbonaceous DBPs were elevated from 34.8 μg/L in source water to 42.5 μg/L in effluent, along with organic compounds increasing in filtration, and nitrogenous DBPs were under detection in winter. All DBPs appeared at a high level in summer. Accordingly, enhanced coagulation process and measures that can avoid the release of organic compounds during filtration have been suggested. As the source water was rarely affected by human activities in the study area and owing to the wide use of traditional treatment process, the data of this research can be regarded as environmental background values and the results are considered as a significant reference.

Roxarsone binding to soil-derived dissolved organic matter: Insights from multi-spectroscopic techniques

The fate and transport of roxarsone (ROX), a widely used organoarsenic feed additive, in soil is significantly influenced by the ubiquitous presence of soil-derived dissolved organic matter (DOM). In this study, fluorescence quenching titration and two-dimensional correlation spectroscopy (2D-COS) were employed to study ROX binding to DOM. Binding mechanisms were revealed by fluorescence lifetime measurement and Fourier transform infrared spectroscopy (FTIR). Humic- and protein-like fluorophores were identified in the excitation-emission matrix and synchronous fluorescence spectra of DOM. The conditional stability constant (log KC) for ROX binding to DOM was found to be 5.06, indicating that ROX was strongly bound to DOM. The binding order of ROX to DOM fluorophores revealed by 2D-COS followed the sequence of protein-like fluorophore ≈ the longer wavelength excited humic-like (L-humic-like) fluorophore > the shorter wavelength excited humic-like (S-humic-like) fluorophore. 2D-COS resolved issues with peak overlapping and allowed further exploration of the interaction between ROX and DOM. Results of fluorescence lifetime and FTIR spectra demonstrated that ROX interacted with DOM through the hydroxyl, amide II, carboxyl, aliphatic CH, and NO2 groups, yielding stable DOM-ROX complexes. The strong interaction between ROX and DOM implies that DOM plays an important role in the environmental fate of ROX in soil.

A new fluorescence index with a fluorescence excitation-emission matrix for dissolved organic matter (DOM) characterization

AbstractA series of fluorescence approaches have been employed to characterize the composition, transformation, and biogeochemical cycles of aquatic dissolved organic matter (DOM). However, there is no consensus on the protocols for elucidating DOM fluorescence spectra from protein-like (young DOM) to humic-like (old DOM) types, which are associated with the intrinsic fluorescence properties involved in the excitation/emission and detection of DOM. The central objective of this study was to evaluate the excitation–emissions matrices (EEMs)-average area of fluorescence intensity response using DOM fluorescence spectra collected on six different DOM surrogates using high-performance size-exclusion chromatography techniques. We evaluated criteria and protocols of a new Y fluorescence index (YFI) for comparison with McKnight fluorescence index (MFI), in which 280 nm excitation coincides with independent inferences with response to emission wavelengths from 350 to 450 nm. Our results demonstrate that YFI had s...

杉木和米槠凋落叶DOM对土壤碳矿化的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 杉木和米槠凋落叶DOM对土壤碳矿化的影响 DOI: 10.5846/stxb201407301532 作者: 作者单位: 福建师范大学地理科学学院;.湿润亚热带山地生态国家重点实验室培育基地,福建师范大学地理科学学院;.湿润亚热带山地生态国家重点实验室培育基地,福建师范大学地理科学学院;.湿润亚热带山地生态国家重点实验室培育基地,福建师范大学地理科学学院;.湿润亚热带山地生态国家重点实验室培育基地,福建师范大学地理科学学院;.湿润亚热带山地生态国家重点实验室培育基地,福建师范大学地理科学学院;.湿润亚热带山地生态国家重点实验室培育基地,福建师范大学地理科学学院;.湿润亚热带山地生态国家重点实验室培育基地 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金(31370615,31130013);高等学校博士学科点专项科研基金(20113503130001)和福建省教育厅重点项目(JA13065) Effects of dissolved organic matter from Cunninghamia lanceolata and Castanopsis carlesii leaf litter on soil C mineralization Author: Affiliation: School of Geographical Science，Fujian Normal University;Cultivation Base of State Key Laboratory of Humid Subtropical Mountain Ecology,School of Geographical Science，Fujian Normal University;Cultivation Base of State Key Laboratory of Humid Subtropical Mountain Ecology,School of Geographical Science，Fujian Normal University;Cultivation Base of State Key Laboratory of Humid Subtropical Mountain Ecology,School of Geographical Science，Fujian Normal University;Cultivation Base of State Key Laboratory of Humid Subtropical Mountain Ecology,School of Geographical Science，Fujian Normal University;Cultivation Base of State Key Laboratory of Humid Subtropical Mountain Ecology,School of Geographical Science，Fujian Normal University;Cultivation Base of State Key Laboratory of Humid Subtropical Mountain Ecology,School of Geographical Science，Fujian Normal University;Cultivation Base of State Key Laboratory of Humid Subtropical Mountain Ecology Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:DOM(Dissolved organic matter)是土壤微生物呼吸的重要底物,凋落物淋溶的DOM对土壤碳矿化具有重要影响。选择中亚热带地区具有代表性的杉木(Cunninghamia lanceolata)和米槠(Castanopsis carlesii)凋落叶作为研究对象,通过两个月的短期室内培养,把不同凋落叶浸提出的DOM添加到培养瓶中,定期测定土壤碳矿化速率,计算土壤碳累积矿化量,探讨两种等浓度等量DOM添加对土壤碳矿化的影响,并分析DOM化学性质在土壤碳矿化过程中的重要性。结果表明:米槠凋落叶浸提得到的DOC(Dissolved organic carbon)和DON(Dissolved organic nitrogen)浓度均显著高于杉木凋落叶的(P < 0.05),而杉木凋落叶浸提得到的DOM的UV吸收值(SUVA254)和HIX(Humification index)均显著低于米槠凋落叶的(P < 0.01)。添加等浓度等量杉木和米槠凋落叶DOM到土壤中均显著增加了土壤碳矿化速率,在第1天内分别比对照高198%和168%,3d后下降到61.8%和44.1%,14d后基本处于平稳状态,表明外源有机物添加对土壤碳矿化的前期影响较大。培养过程中,添加杉木和米槠凋落叶DOM的土壤碳矿化累积量均能采用双因素指数模型进行拟合(r2=0.99),但添加两者凋落叶DOM后土壤碳矿化累积量没有显著差异。 Abstract:The leaching of dissolved organic matter (DOM) from leaf litter, and the subsequent supply of an available carbon pool for microbial growth, can be important factors regulating forest C mineralization. Field studies have shown that with increasing DOM, soil respiration rates increase observably. Numerous studies have assessed the difference of dissolved organic C (DOC) and the C chemistry of solubility during leaching of DOM from different litters. The chemical structure of DOM and the complexity of its molecules were found to correlate with C mineralization. Our objectives were to investigate how differences in chemistry of DOM from Cunninghamia lanceolata and Castanopsis carlesii leaf litter affected soil CO2 fluxes in laboratory incubations. Mineral soils from a depth of 0-10 cm from a 39-year-old C. carlesii plantation forest in Sanming, Fujian, China were incubated for 2 months after adding the same concentrations and amounts of DOM from C. lanceolata and C. carlesii leaf litter. CO2 production was continuously measured during 59 days of laboratory incubation, and soil CO2 evolution patterns were determined by fitting the double exponential model (r2=0.99). Results showed that: (1) C chemistry varied significantly between DOM from C. lanceolata and C. carlesii leaf litter (P < 0.05). UV and fluorescence spectra of DOM from C. lanceolata leaf litter were lower than those of C. carlesii leaf litter, which suggested that DOM from C. lanceolata leaf litter has a lower content of aromatic C. (2) Following additions of DOM from C. lanceolata and C. carlesii leaf litter to soils, rates of C mineralization increased by 198% and 168%, respectively, decreased to 61.8% and 44.1%, respectively, by day 3 and then decreased progressively. This indicated that an increase in soil C mineralization induced by the addition of external DOM to soil was short-term. (3) There was no significant difference in the cumulative mineralized C between the addition of DOM from C. lanceolata and C. carlesii leaf litter. Further research should be done to investigate the reasons for this lack of a significance difference. 参考文献 相似文献 引证文献

Influences of Different Inoculation Methods on Fluorescence Characteristics of DOM in Solid Waste Composting

In order to determine better inoculation methods of compound microorganisms in solid waste composting, biochemical parameters and dissolved organic matter (DOM) during the process of composting with five different inoculation methods were tested and analyzed. The results show that temperature, pH value, and synchronous fluorescence spectra of DOM in the composting piles of the five deals exhibits a certain trend with composting time increasing, in which macromolecules with complex structures and humic substances gradually increase. Overall, the temperature increases first and then decreases, and pH value is nearly stable at slightly alkaline range by the end of composting. Complex macromolecules and humic substances increase, and DOM properties tend to stabilize. Meanwhile, humification index (IA/IC, %PLF, and %HLF) of the five deals of compost also experienced significant changes. With the decrease of protein-like substances, the content of humus correspondingly increase, i.e. with composting time increasing, low-molecular-weight organic matter in the compost gradually transforms into stable high-molecular-weight humic substances, which suggests increasing aromaticity and distinctive complexity of DOM. From a comprehensive comparison of the relevant parameters and indicators, the deal of inoculating compound microorganisms at the start time or after the high-temperature phase could notably speed up the humification process in solid waste composting.

Novel insights into destruction mechanisms in a hybrid membrane process for simultaneous sludge thickening and digestion by characterization of dissolved organic matter

Three-dimensional excitation–emission matrix (EEM) fluorescence spectroscopy and gel filtration chromatography (GFC) were employed to characterize dissolved organic matter (DOM) in a hybrid membrane process for simultaneous sludge thickening and digestion (MSTD). The MSTD process was operated under a sequencing batch mode, and the operating time of each cycle was 15 d from the initial fresh sludge to the final thickened and digested sludge. Results showed that the molecular weight (MW) distribution of DOM in sludge supernatant became broader after the MSTD process, and three main peaks including Peak A and Peak B related to protein-like substances and Peak C associated with humic acid-like substances could be identified from the EEM fluorescence spectra of all DOM samples in the MSTD process. The quantitative analysis of the fluorescence spectra of DOM in sludge supernatant showed that the fluorescence intensity (FI) of Peak A and Peak B in sludge supernatant correlated well with the concentration of soluble protein, MLSS destruction efficiency and mean particle size, suggesting that the variations of EEM fluorescence spectra of DOM in sludge supernatant could be used to evaluate the floc destruction mechanisms of the MSTD process. It was also found that the FI of Peak A slightly increased before 8 d but rapidly went up after 8 d, and the FI of Peak B changed slightly before 8 d but increased after 8 d, which implied that the floc destruction mechanisms were varied in one cycle of the MSTD process.

Growth and photosynthesis responses of Phaeodactylum tricornutum to dissolved organic matter from salt marsh plant and sediment

The effects of allochthonous dissolved organic matter (DOM) on the growth and photosynthesis of Phaeodactylum tricornutum were investigated. P. tricornutum incubated in f/2 medium was exposed to DOM additives, which were extracted from the plant and sediment samples of a salt marsh in North Branch of the Yangtze estuary, China. During 12 days incubation, the chlorophyll fluorescence parameters of P. tricornutum were measured by a Phyto-PAM phytoplankton analyzer. Spectral properties of DOM in algae filtrates were also observed. The concentrations of chlorophyll a, active chlorophyll a, and the maximum quantum yield of photosystem II significantly decreased after four days of incubation, suggesting that the growth and photosynthetic efficiency of P. tricornutum were inhibited. After adding sediment-DOM extract, both a 250/ a 365 (the ratio of the absorption coefficients at 250 and 365 nm) and S values (spectral slope coefficients) of algae filtrates declined in the first two days, which demonstrated a loss of low molecular weight DOM. Parallel factor analysis of fluorescence spectra of DOM in algae filtrates revealed that DOM could be classified into two humic-like and two protein-like components. The fluorescence intensity of tyrosine-like component originating from algae increased significantly during incubation. This study supports the hypothesis that allochthonous DOM derived from salt marsh plant and sediment have a strong influence on the adjacent aquatic ecosystems.

Using fluorescence spectroscopy to trace seasonal DOM dynamics, disturbance effects, and hydrologic transport in the Florida Everglades

Dissolved organic matter (DOM) quality reflects numerous environmental processes, including primary production and decomposition, redox gradients, hydrologic transport, and photochemistry. Fluorescence spectroscopy can detect groups of DOM compounds sensitive to these processes. However, different environmental gradients (e.g., redox, DOM provenance) can have confounding effects on DOM fluorescence spectra. This study shows how these confounding effects can be removed through discriminant analyses on parallel factor modeling results. Using statistically distinct end‐members, we resolve spatiotemporal trends in redox potential and DOM provenance within and between adjacent vegetation communities in the patterned ridge and slough landscape of the Everglades, where biogeochemical differences between vegetation communities affect net peat accretion rates and persistence of landscape structure. Source discrimination of DOM in whole‐water samples and peat leachates reveals strong temporal variability associated with seasonality and passage of a hurricane and indicates that hurricane effects on marsh biogeochemistry persist for longer periods of time (&gt;1 year) than previously recognized. Using the DOM source signal as a hydrologic tracer, we show that the system is hydrologically well mixed when surface water is present, and that limited transport of flocculent detritus occurs in surface flows. Redox potential discrimination shows that vertical redox gradients are shallower on ridges than in sloughs, creating an environment more favorable to decomposition and diagenesis. The sensitivity, high resolution, rapidity, and precision of these statistical analyses of DOM fluorescence spectra establish the technique as a promising performance measure for restoration or indicator of carbon cycle processes in the Everglades and aquatic ecosystems worldwide.

Effects of chlorination on the properties of dissolved organic matter and its genotoxicity in secondary sewage effluent under two different ammonium concentrations

Recently, NH4+ has been reported to induce potential risks during wastewater chlorination. Thus, the effects of chlorination on genotoxicity and fluorescence spectra of secondary sewage effluents, were investigated in this study before and after adding a high NH4+ quantity. Chlorination decreased the genotoxicity of secondary sewage effluent, while the presence of a high level of NH4+ inhibited this decrease. By further ultrafiltration following XAD-8 resin fractionation, it was found that, with a high NH4+ concentration, the genotoxicity in the fraction of hydrophobic acids (HOA) increased after chlorination and a sub-fraction of HOA with molecular weight less than 1kDa was the key fraction resulting in this increase. Similar to genotoxicity changes, NH4+ was also found to influence the changes in fluorescence spectra during chlorination. After chlorination, the fluorescence intensity of the dissolved organic matter (DOM) notably decreased, and the emission band of DOM fluorescence spectra shifted to a lower wavelength. However, the presence of NH4+ inhibited both the decrease in intensity and shift. The changes in fluorescence spectra suggested that the fluorescent structure of secondary effluent may decompose during chlorination, but NH4+ could inhibit this decomposition.

Changes in Spectroscopic and Molecular Weight Characteristics of Dissolved Organic Matter in a River During a Storm Event

Changes in dissolved organic matter (DOM) characteristics were investigated during a storm event in the Kyungan River using UV-visible, fluorescence spectroscopy, resin fractionation, and size exclusion chromatography (SEC). Water samples were collected at nine sampling times to reflect a variation of the river water level. A dramatic increase was observed for chemical oxygen demand (COD) versus biochemical oxygen demand, suggesting that non-biodegradable organic components may be more contained in the organic matters driven by the storm. Specific UV absorbance values increased from 2.15 to 3.16 L/mgC-m, reaching the maximum level at the highest water level. The storm runoff resulted in the reduction of protein-like fluorescence (PLF), the increase of fulvic-like and humic-like fluorescence for the synchronous fluorescence spectra of DOM. Weight-average molecular weight (MWw) values increased from 1,100 to 1,510 Da due to the increment of high MW fractions in the SEC chromatograms. Overall changes in DOM composition may be explained by the inflow of soil-derived DOM from the upstream basins brought by the storm. The humification index (HIX) exhibited a positive correlation with MWw values, suggesting that HIX may be suggested to a prediction descriptor for DOM MW during the storm event. PLF presented a negative correlation with DOM MW, suggesting that protein-like fluorescent compounds are associated with low MW components in the river. More input of humic substances by the storm runoff appears to shift DOM into a higher MW value as revealed by a positive correlation between MWw and hydrophobic fraction.

Effect of instrument‐specific response on the analysis of fulvic acid fluorescence spectra

Fluorescence spectroscopy has been extensively employed to characterize the source, age, and reactivity of aquatic dissolved organic matter (DOM). However, there is no consensus on the protocols for collecting and correcting DOM fluorescence spectra for the instrument‐specific response associated with each component on a fluorometer involved in the excitation of DOM and the resulting detection of DOM emission. The central objective of this study was to evaluate the removal of instrument‐specific response from DOM fluorescence spectra collected on three different fluorometers using manufacturer‐provided emission and excitation correction files. We evaluated criteria and protocols for comparison of removal of instrument response, using quinine sulfate, a well‐characterized fluorophore, as well as the International Humic Substance Society's microbially and terrestrially derived reference end‐member fulvic acids: Pony Lake and Suwannee River fulvic acids, respectively. Our results demonstrate that sample spectra collected on different fluorometers differed significantly before correction. Although the effectiveness of manufacturer‐provided correction factors in removal of instrument response from sample spectra varied by instrument, spectral overlap of the same sample on multiple instruments improved after correction. Our results suggest that conclusions based on analysis of trends within a dataset of DOM fluorescence spectra should be expected to be independent of the fluorometer employed.

Dissolved Organic Matter Characterization Using Multiway Spectral Decomposition of Fluorescence Landscapes

Dissolved organic matter (DOM) plays an important role in many soil ecosystem functions. Multidimensional fluorescence spectroscopy of DOM with parallel factor analysis (PARAFAC) of the resulting spectral landscape has been successful in characterizing DOM from a variety of aquatic sources. This study was conducted to assess the multiway PARAFAC approach for quantitatively characterizing the fluorescent landscapes of DOM from aqueous extracts of soils and soil amendments. The DOM was extracted from plant biomass representative of crop, wetlands, and tree species; animal manures; and soils from controlled studies of cropping systems with known histories of organic amendments. The fluorescence landscape spectra were collected in the excitation range from 240 to 400 nm and emission range from 300 to 500 nm in 3‐nm increments. The excitation and emission spectra modeled from the PARAFAC analysis showed that the plant biomass, animal manure, and soil DOM contained five fluorescing components: tryptophan‐like (peak location at excitation 270 nm, emission 354 nm), tyrosine‐like (273/309 nm), and three humic‐substance‐like components (&gt;240/465 nm, 306/405 nm, and 315/447 nm). Principal component analysis of the concentration loading showed that the soil‐derived DOM was very similar despite the different types and quantities of organic amendments incorporated in the different cropping systems. This study shows that PARAFAC analysis of multidimensional fluorescence spectra can model the chemical profile of terrestrial DOM in a chemically meaningful way. This represents a significant advance over current approaches to interpreting the complex DOM fluorescence spectra.