Organic Matter In Groundwater Research Articles

Waste-derived permeable reactive barrier to treat heavy metals and organic matter in groundwater affected by landfill leachate

Waste-derived permeable reactive barrier to treat heavy metals and organic matter in groundwater affected by landfill leachate

Spectral characterization of dissolved organic matter in groundwater to assess mixing with oil-field water near selected oil fields, southern California

Samples of oil-field water (oil wells, injectate, disposal ponds) and groundwater near selected oil and gas fields in southern California were analyzed for dissolved organic carbon (DOC) concentration and by optical spectroscopic techniques (i.e., absorbance and fluorescence) to assess whether these measurements can be used to distinguish between oil-field water (Oil Field), native groundwater (WGnat), and native groundwater mixed with oil-field water from surface (WGsurf) or subsurface sources (WGsub), and if so whether commonly reported optical measurements can be used as a screening tool to identify such water. Concentrations of DOC were significantly (p < 0.0001) higher (67 to 2934 mg C L−1) in oil-field water compared to native groundwater samples (<5.0 mg C L−1). Individual optical properties varied by water category and frequently overlapped. However, multivariate statistical analysis showed that when evaluated in combination, 10 optical properties were determined by discriminant analysis to be significant (p < 0.05) in distinguishing among water categories. Principal component analysis of those 10 optical properties showed that these properties can be used to successfully distinguish Oil Field samples from WGnat, WGsurf, and WGsub even when mixing fractions are low (approximately 10 %).

Humic substances derived from unconventional resources: extraction, properties, environmental impacts, and prospects.

Humic substances comprise up to 70% of the total organic matter in soils, between 50 and 80% of the dissolved organic matter in water, and about 25% of dissolved organic matter in groundwater. Elucidation of the complex structure and properties of humic substances requires advanced analytical tools; however, they are of fundamental importance in medicine, agriculture, technology, and the environment, at large. Although they are naturally occurring, significant efforts are now being directed into their extraction owing to their relevance in improving soil properties and other environmental applications. In the present review, the different fractions of humic substances were elucidated, underlying the mechanisms by which they function in soils. Furthermore, the extraction processes of humic substances from various feedstock were illustrated, with the alkali extraction technique being the most widely used. In addition, the functional group and elemental composition of humic substances were discussed. The similarities and/or variations in the properties of humic substances as influenced by the source and origin of feedstock were highlighted. Finally, the environmental impacts of humic substances were discussed while highlighting prospects of humic acid production. This review offers enormous potential in identifying these knowledge gaps while recommending the need for inter- and multidisciplinary studies in making extensive efforts toward the sustainable production of humic substances.

An untargeted exometabolomics approach to characterize dissolved organic matter in groundwater of the Samail Ophiolite.

The process of serpentinization supports life on Earth and gives rise to the habitability of other worlds in our Solar System. While numerous studies have provided clues to the survival strategies of microbial communities in serpentinizing environments on the modern Earth, characterizing microbial activity in such environments remains challenging due to low biomass and extreme conditions. Here, we used an untargeted metabolomics approach to characterize dissolved organic matter in groundwater in the Samail Ophiolite, the largest and best characterized example of actively serpentinizing uplifted ocean crust and mantle. We found that dissolved organic matter composition is strongly correlated with both fluid type and microbial community composition, and that the fluids that were most influenced by serpentinization contained the greatest number of unique compounds, none of which could be identified using the current metabolite databases. Using metabolomics in conjunction with metagenomic data, we detected numerous products and intermediates of microbial metabolic processes and identified potential biosignatures of microbial activity, including pigments, porphyrins, quinones, fatty acids, and metabolites involved in methanogenesis. Metabolomics techniques like the ones used in this study may be used to further our understanding of life in serpentinizing environments, and aid in the identification of biosignatures that can be used to search for life in serpentinizing systems on other worlds.

RISK ASSESSMENT OF SOIL ORGANIC POLLUTANTS SURVEY AT A CERTAIN OIL DEPOT SITE IN GUANGZHOU

In order to investigate the pollution situation of the relocation site of an oil depot in Guangzhou, based on the health risk assessment theory, the investigation and monitoring of soil and groundwater organic pollutants in the site was conducted, and the health risk assessment was carried out combined with the monitoring data.24 types of pollution factors, including 1,3,5-trimethyl benzene, were detected and the maximum concentration accounted for 67% of the screening value; toluene and extractable petroleum hydrocarbon (C10-C40) were detected in the plot, and the maximum concentration accounted for 1%~2% of the screening value. The results show that the maximum risk area of the legacy site is the oil depot area, with soil and groundwater organic matter; the maximum concentration of organic pollutants in the site (≤10-6)Or non-carcinogenic hazard entropy (≤1), and the future exposure receptor is not affected by the health risk of the soil and groundwater organic pollutants in the site.

Molecular Linkage of Dissolved Organic Matter in Groundwater with Prevalence of Chronic Kidney Disease with Unknown Etiology

Molecular Linkage of Dissolved Organic Matter in Groundwater with Prevalence of Chronic Kidney Disease with Unknown Etiology

Identifying carbon processing based on molecular differences between groundwater and water-extractable aquifer sediment dissolved organic matter in a Quaternary alluvial-lacustrine aquifer

Dissolved organic matter in groundwater (GDOM) plays an important role in many biogeochemical processes. The molecular composition of GDOM varies with the source and processing pathways, and also affects its reactivity. Sedimentary organic matter (SOM) is a key carbon source in groundwater, but its association with GDOM remains unclear. In this study, Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS) and comprehensive data analysis were used to identify the molecular characteristics of SOM and the fate of DOM in groundwater by comparing the differences between the GDOM with depth-matched water-extractable aquifer SOM (WEOM; the most bioavailable and dynamic pool of organic carbon in SOM) in a Quaternary alluvial-lacustrine aquifer with abundant SOM in Jianghan Plain, central China. The results show that WEOM is a key carbon source in groundwater as reflected by the strong correlation (rs = 0.76, P = 0.028) of the DOC content between GDOM and WEOM, and the large proportion (70.64 ± 14.09%) of common compounds present both in GDOM and WEOM. However, the molecular compositions of GDOM and WEOM are significantly different even for common compounds when considering the relative abundance. WEOM contains relatively high abundance of low molecular weight and thermodynamically more favorable components for microbial oxidation (aminosugars and carbohydrates), making WEOM an energetic carbon source for groundwater that can fuel reduction half-reactions such as iron oxide reduction. Although the hydrochemical compositions and the DOC content of groundwater are quite different, the molecular composition of GDOM is relatively similar and enriched in oxygen-poor highly unsaturated and phenolic compounds compared with WEOM. This indicates that organic matter is gradually processed into stable components with relatively medium aromaticity, low average nominal carbon oxidation state, low O/C and medium H/C; these transformations occur through adsorption to minerals and biodegradation after being mobilized from aquifer sediment into groundwater. We identified the processing pathways of GDOM based on comprehensive comparisons of molecular compositions between aquifer WEOM and GDOM, and highlight the combined influence of aquifer SOM and processing pathways on the GDOM molecular compositions in the alluvial-lacustrine aquifer with abundant aquifer SOM.

Analysis of the Three-Dimensional Fluorescence Spectroscopy Characteristics of Dissolved Organic Matter in Groundwater from a Subtropical Cave in Dry Season—Daxiao Cave in South China Karst

Groups in dissolved organic matter (DOM) emit fluorescence information at characteristic wavelengths when irradiated by excitation waves, which can reveal the geochemical behavior of dissolved organic matter in the environment and its sources, but there are few relevant studies in cave groundwater systems. In order to investigate the relationship between drip hydrochemistry characteristics and DOM in cave systems after subsurface leakage, in this study, from the perspective of dissolved organic matter in the karst cave water system, the groundwater in the dry season of Daxiao Cave was selected as the research object. Five drip points and one water pool (DX-1, DX-2, DX-3, DX-4, DX-5, and DX-C) in Daxiao Cave were monitored and consecutively sampled for four months. The parallel factor analysis method (PARAFAC), three-dimensional (3D) fluorescence parameters, and excitation-emission matrix fluorescence spectroscopy (EEM), combined with the hydrochemistry characteristics of the drip water and correlation analysis, were used to analyze the 3D fluorescence spectral characteristics of the DOM of the drip water of Daxiao Cave and their influencing factors. The results show that (1) the hydrochemistry type of the drip water in Daxiao Cave was within the Ca–Mg–HCO3 type, and Ca2+, Mg2+, and HCO3− were the dominant ions in Daxiao Cave; (2) the fluorescence fractions of drip water in dry season caves were dominated by C1 (humus-like), C2 (tryptophan-like), and C3 (tyrosine-like), and the fluorescence fractions of drip water DOM were controlled by protein fluorophores; (3) the DOM in the drip water of Daxiao Cave in the dry season was controlled in part by subsurface leakage and was largely the result of microbial degradation; and (4) the DOM of the drip water may be influenced by the chemical composition of the water, but the exact process is not clear.

Geochemical modeling of mercury in coastal groundwater

The systematic analysis of groundwater in the Greek island of Skiathos revealed a seasonal increase of total mercury concentrations after the extensive groundwater abstraction during the busy and heavily touristic summer months. This contamination was accompanied by a corresponding increase of the chloride content of groundwater, attributed to seawater intrusion into the freshwater-depleted aquifer within mercury-rich bedrock. The effects of elevated concentrations of chloride anions in the mobilization of mercury and its speciation were addressed by geochemical equilibrium modeling, considering cinnabar (HgS) as the mineral source of mercury. Adsorption onto hydrous ferric oxide (Fe2O3·H2O) was a necessary ingredient of the geochemical model for bringing the calculated concentrations in agreement with field measurements, after optimization of the cinnabar/adsorbent mass ratio to a value of 4.9 × 10−8. The speciation of mercury was found to depend on the acidity and redox status as well as on the chloride content of groundwater. Mercury concentrations in the groundwater of Skiathos rise above the World Health Organization limit of 1 μg L−1 for a seawater intrusion higher than 3 %, with HgCl2 being the dominant species followed by HgClOH, HgCl3− and HgCl42−. The assumed concentration of dissolved organic matter in groundwater had a negligible impact on the mercury speciation and its mobilization by chloride.

Molecular structure and evolution characteristics of dissolved organic matter in groundwater near landfill: Implications of the identification of leachate leakage

Landfills can cause groundwater contamination, the pollution characteristics in groundwater near landfill sites have been extensively investigated, while the rapid identification of leachate leakage remained unclear. Comprehensively characterizing dissolved organic matter (DOM) is crucial for tracing the source, species, and migration of contaminants within groundwater and protecting groundwater sources. Here, we showed that DOM composition from newer landfills was mainly composed of newly-produced tryptophan and tyrosine, and protein-like and humic-like substances were more abundant in landfills that were relatively older. DOM in landfill groundwater was initially dominated by outputs from microbial activities, followed by terrigenous input. Leaked leachate contained an additional dye-derived fluorescent matter at the excitation/emission wavelength of 240–260/440–460 nm that was absent in uncontaminated groundwater. Leachate leakage increased the concentrations of humic-like substance, DOM molecular weight, and microbial activity in the downstream groundwater, resulting in the microorganisms rapidly multiply and secrete large amounts of microbial metabolism by-products, making them suitable indicators of groundwater pollution. Three criteria were proposed to establish an interpretable fluorescence method to identify leachate pollution. The obtained results provide a novel insight into not only the monitoring, early warning, and identification but also the transport, fate and removal or transformation of groundwater leachate in landfills.

Hydrochemistry characters and hydrochemical processes under the impact of anthropogenic activity in the Yiyuan city, Northern China

Water resource is a valuable resource for human beings to survive and maintain social stability and development. However, in recent years, the process of urbanization has been accelerated, and many cities and towns have presented groundwater pollution. To investigate the spatial distribution of hydrochemical components in urban areas after groundwater pollution and the hydrogeochemical effects on surrounding areas, using multifarious methods such as classical statistics, geostatistics, saturation index, and stable isotopes, the hydrogeochemical effects along groundwater flow were analyzed and deduced. The results show that the main ions of the groundwater in the Yiyuan are Ca2+ and HCO3−, it is mainly low-salinity fresh water, and the hydrochemistry type is mainly HCO3–Ca·Mg type. Groundwater pollution in urban areas increases the content of inorganic and organic matter in groundwater, the main ions affected are NO3−, Cl−, Ca2+, and SO42−, and their concentrations increased by 12.3, 22.3, 7.6, and 12.3 mg/L, respectively. In the city, negative cation exchange occurs mainly, after leaving the city, cation exchange occurs mainly. The results of the saturation index calculation indicate that groundwater pollution has little effect on the dissolution and precipitation of minerals. After leaving the town, denitrification, desulphurization, and cation exchange occurs in the underground aquifer, which reduces the concentration of pollutants in the groundwater. The study suggests that a variety of hydrogeochemical processes play an important role in the spontaneous reduction of some pollutant concentrations in groundwater away from the pollution source, while the concentration of other substances may rise.

Removal of Naturally Occurring Strontium by Nanofiltration/Reverse Osmosis from Groundwater.

Removal of naturally occurring strontium (Sr) from groundwater is vital as excessive exposure may lead to bone growth problems in children. Nanofiltration/reverse osmosis (NF/RO) is commonly used in groundwater treatment due to the high effectiveness and simple maintenance of these pressure driven membrane processes. In this research, a pilot-scale NF/RO system was used to desalinate a natural groundwater sample containing high Sr concentration (10.3 mg/L) and “old” groundwater organic matter (70.9 mg/L) from Esilalei in northern Tanzania to understand the removal of strontium by NF/RO. The impact of applied pressure (10–15 bar) and groundwater pH (3–12) on the membrane performance including permeate flux, strontium and total organic carbon (TOC) flux and removal was investigated. Increasing applied pressure was found to enhance the flux by increasing the driving force and enhance Sr and TOC removal by dilution effect (water flux higher than Sr passage). The alkaline pH caused severe flux decline likely due to membrane fouling and scaling, while it slightly enhanced Sr removal of RO membranes, but weakened the TOC removal. In contrast, acidic and neutral pH of groundwater enhanced TOC removal. These findings suggest that appropriately high applied pressure and acidic pH condition of groundwater are recommended to apply to the NF/RO membrane system in groundwater desalination to achieve better membrane performance.

Algal softening followed by ozonation: The fate of persistent micropollutants and natural organic matter in groundwater

A proof-of-concept study evaluates the performance of a novel strategy using photosynthetic microorganisms to soften groundwater instead of using caustic chemicals. The microalga Scenedesmus quadricauda was used to increase the pH of the groundwater via natural photosynthesis. This work applied softening as a pretreatment to ozonation of hard groundwater and mainly focused on investigating the multiple effects of algal softening on the degradation of persistent micropollutants upon subsequent ozonation. The algae-induced alkaline conditions (pH > 10) were favorable to catalyze the formation of OH radicals directly from O3 molecules. Moreover, algal softening removed the strong radical-scavenging carbonate species (HCO3− and CO32−) to a much greater extent than that achieved by chemical softening, which was attributed to the combination of mineral carbonation and metabolic CO2 reduction. The fate of the natural organic matter (NOM) was characterized with spectroscopy, chromatography, and bioassay, which indicates that algal treatment decomposed the NOM to be less susceptible to attack by OH radicals. Consequently, the ozonation of alkaline groundwater achieved a better removal of the micropollutant residues in groundwater. Carbamazepine and diclofenac were used as model chemicals of persistent groundwater contaminants and were almost completely removed with an addition of 1.25 mg O3 L−1 (0.63 mg-O3 mg-C−1).

Indices of the dual roles of OM as electron donor and complexing compound involved in As and Fe mobilization in aquifer systems of the Datong Basin

Organic matter (OM) acts as a source of carbon and is strongly implicated in biogeochemical processes, such as metal complexation and redox reactions. To illustrate the effects of OM on As mobilization in aquifers, this study characterized fluorescence features and hydrochemical properties of OM in sediments and groundwater from an As-affected field site located in the Datong Basin. Fluorescence analysis showed sediment and groundwater OM are dominated by oxidized and reduced quinone-like compounds; shorter emission wavelengths observed in groundwater indicated more labile and protein-like organic substances than in sediments. Dissolved As concentrations were positively correlated with dissolved Fe and HCO3− concentrations in middle and deep groundwater, suggesting labile OM degradation promotes the release of As and Fe from sediments into the groundwater. This result also demonstrated more bioavailable OM occurs in groundwater and that labile OM degradation promotes As release. Grain size distribution results indicated sedimentary As, Fe and OM are associated with fine-grained fractions. Sedimentary As content was significantly and positively correlated with Fe2O3 and OM content, suggesting the potential existence of As–Fe-OM ternary complexation; this was further supported by the results of Fourier-transform infrared (FTIR) spectra and extraction experiments. In addition, the ratio of dissolved reduced quinone-like compounds to oxidized quinone-like compounds was positively correlated with both dissolved As and HCO3− concentrations, implying quinone-like compounds participate in the complexation and influence As mobilization. In the reducing environment, labile OM served as the electron donor to maintain microbial respiration and mediated reductive dissolution of Fe minerals. As–Fe-OM ternary complexation in sediments and microbial reduction have a potentially strong impact on As enrichment in groundwater, and therefore are important considerations for regulating As contamination.

Characterisation of shallow groundwater dissolved organic matter in aeolian, alluvial and fractured rock aquifers

Groundwater organic matter is processed within aquifers through transformations such as the adsorption of dissolved organic matter (DOM) to minerals and biodegradation. The molecular character of DOM varies according to its source and this can impact its bioavailability and reactivity. Whilst the character of DOM in riverine and oceanic environments is increasingly well understood, the sources, character and ultimately the fate of groundwater DOM remains unclear. Here we examine groundwater DOM from contrasting hydrogeological settings in New South Wales, Australia. For the first time, we identify the distinct molecular composition of three groundwater DOM end-members including a modern terrestrial input, an aged sedimentary peat source, and an aged stable by-product pool. We also identify and characterise the processing pathway of DOM in semi-arid, low sedimentary organic carbon (OC) environments. Based on size exclusion chromatography, ultrahigh-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS), isotopic analyses (13C, 14C and 3H) and principle component analysis (PCA), we show that in higher rainfall temperate coastal peatland environments, large amounts of aged sedimentary organic carbon can leach into groundwater resulting in higher molecular weight (500 g mol−1 < molecular weight > 1000 g mol−1) and highly aromatic groundwater DOM with high O/C ratios and low H/C ratios. We show that in semi-arid environments with low rainfall rates and high groundwater residence times, groundwater dissolved organic carbon (DOC) is processed into increasingly low molecular weight (<350 g mol−1), low aromaticity DOM with low O/C ratios and high H/C ratios by subsurface processing mechanisms such as biodegradation and adsorption. We provide the first comprehensive study of groundwater DOM characterisation based on multiple analytical techniques, and highlight the impact of source inputs and processing on groundwater DOM composition at a molecular level.

Quantification of TCE Co‐Oxidation in Groundwater Using a 14C–Assay

AbstractBacteria that degrade natural organic matter in groundwater contain oxygenase enzymes that can co‐oxidize trichloroethene (TCE). This degradation pathway is promising for large dilute plumes, but its evaluation is limited because the density of the bacteria with oxygenase enzymes has not been correlated to field scale rates of degradation. A 14C–TCE assay was developed to determine pseudo first‐order rate constants for the aerobic co‐oxidation of TCE in groundwater. The assay involved incubating 14C–TCE in samples of groundwater contained in 160 mL serum bottles, and monitoring the accumulation of radiolabel in degradation products. A first‐order rate constant for co‐oxidation was extracted from the rate of accumulation of 14C in products, accounting for volumetric changes in the serum bottles due to sampling and subsequent changes to the distribution of TCE between the aqueous and gaseous phases. Of the groundwater samples evaluated from 19 wells at five sites, eight samples at three sites had 14C product accumulation rates that exceeded the accumulation rate in filter‐sterilized groundwater controls. First‐order rate constants ranged from 2.65 to 0.0066 year−1, which is equivalent to half‐lives of 0.26 to 105 years. Groundwater samples from a few of the wells in which co‐oxidation occurred had volatile organic contaminants in addition to TCE; their presence may have induced the oxygenase enzymes that are needed for TCE co‐oxidation. 14CO2 represented ~37% to 97% of the 14C products that accumulated; the balance of the products was soluble and non‐volatile.

Analysis of the Characteristics of Groundwater Quality in a Typical Vegetable Field, Northern China

This study explores the impact of facility farming on the origin and composition of groundwater and on the distribution characteristics of inorganic salts, heavy metals, and dissolved organic matter in groundwater in a typical greenhouse vegetable planting area in North China plains. The methods used include conventional analysis, UV-Visible, and fluorescence spectroscopy combined with parallel factor analysis, principle components analysis, and two-dimensional (2D) hetero-spectral correlation spectra techniques. The results showed that the hydrochemistry type of groundwater in the facility vegetable field was Cl-SO4, the nitrogen content was higher than the National Groundwater V Class Quality Standard (GB/T14848-93), and the heavy metal content was lower than the National Drinking Water Standard (GB5749-2006). The nitrification process was blocked due to a strongly reducing atmosphere and shallow depth in groundwater, which caused high concentrations of NH4+-N. Part of the toxic sulfur-containing metal content increased after the application of inorganic fertilizers. The sources of dissolved organic matter in groundwater were similar; the organic manure components which leach into groundwater were recently produced by microbial metabolism. The main components of dissolved organic matter were small-molecule-biodegradable protein-like substances and the fulvic-like content binding to them. The fulvic-like content that bound to protein-like content in vegetable planting groundwater was stable, while the protein-like content was greatly influenced by the cultivation process of the organic manure application. In the process of vegetable planting, organic manure should be applied scientifically and the supervision of the planting area is crucial.

Humic acid removal from micro-polluted source water using gas phase surface discharge plasma at different grounding modes

Humic acid (HA) was a predominant natural organic matter in ground water and surface waters. The removal of HA from micro-polluted source water using a gas phase surface discharge plasma at different grounding modes was studied, and three kinds of grounding modes (iron wire mesh, aluminized paper, and water) were selected. The experimental results illustrated that approximately 95.3% of HA in water was removed within 30 min’s discharge plasma treatment in the iron wire mesh electrode system, and it was 89.5% and 84.6% in the aluminized paper electrode system and water electrode system, respectively; although the strongest streamer discharge and the highest ozone equivalent concentration were both observed in the iron wire mesh electrode system. The discharge plasma treatment resulted in a relatively more homogeneous surface topography in the HA molecules as analyzed by scanning electron microscope (SEM), especially in the iron wire mesh electrode system and in the aluminized paper electrode system. The decomposition process of HA at different grounding modes was analyzed and compared via the evolution of the UV–Vis spectrum, dissolved organic carbon (DOC), specific ultraviolet absorbance (SUVA) and UV absorption ratios with treatment time. In addition, the HA removal efficacy in this study was comparable with those of some other techniques.

Vertical Distribution Characteristics of Dissolved Organic Matter in Groundwater and Its Cause

Dissolved organic matter (DOM) can change the species, migration and transformation of foreign pollutants in groundwater, and the investigations of its composition and distribution characteristics play a role in environment protection. The groundwater DOMs were obtained at the depths of 1.2, 1.5 and 1.8 m, and its origin, composition, concentration, distribution characteristics and influencing factors were studied using UV-Vis and fluorescence spectra combined with parallel factor analysis and principle components analysis. The results showed that, DOM in the groundwater originated from both terrigenous input and microbial activities, and was comprised of humic-like matter, heterogeneous component, and protein-like matter. Humic-like matter and heterogeneous components showed a high concentration at 1.5 m and a low one at 1.2 m, whereas the protein-like matter exhibited a low concentration at 1.5 m and a high one at 1.2 m. The groundwater DOM at 1.5 m exhibited the highest aromaticity, humification, molecular weight and polar functional group content, while that at 1.2 m depth showed the lowest aromaticity, humification, molecular weight and polar functional group content. The vertical distribution of DOM in groundwater was related to aromaticity, humification, molecular weight and polar functional group, and the DOM with high aromaticity, humification, molecular weight and polar functional group resisted to biodegradation, and could easily enter into the bottom layer groundwater.

Investigating the effect of landfill leachates on the characteristics of dissolved organic matter in groundwater using excitation-emission matrix fluorescence spectra coupled with fluorescence regional integration and self-organizing map.

For the purpose of investigating the effect of landfill leachate on the characteristics of organic matter in groundwater, groundwater samples were collected near and in a landfill site, and dissolved organic matter (DOM) was extracted from the groundwater samples and characterized by excitation-emission matrix (EEM) fluorescence spectra combined with fluorescence regional integration (FRI) and self-organizing map (SOM). The results showed that the groundwater DOM comprised humic-, fulvic-, and protein-like substances. The concentration of humic-like matter showed no obvious variation for all groundwater except the sample collected in the landfill site. Fulvic-like substance content decreased when the groundwater was polluted by landfill leachates. There were two kinds of protein-like matter in the groundwater. One kind was bound to humic-like substances, and its content did not change along with groundwater pollution. However, the other kind was present as "free" molecules or else bound in proteins, and its concentration increased significantly when the groundwater was polluted by landfill leachates. The FRI and SOM methods both can characterize the composition and evolution of DOM in the groundwater. However, the SOM analysis can identify whether protein-like moieties was bound to humic-like matter.