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Sample records for effluent dissolved organic

  1. Bioavailability and characterization of dissolved organic nitrogen and dissolved organic phosphorus in wastewater effluents.

    PubMed

    Qin, Chao; Liu, Haizhou; Liu, Lei; Smith, Scott; Sedlak, David L; Gu, April Z

    2015-04-01

    There is still a great knowledge gap in the understanding of characteristics and bioavailability of dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) in wastewater effluents, which surmise implications related to both discharge regulation and treatment practice. In this study, we simultaneously investigated the characteristics and bioavailability of both DON and DOP, with separated hydrophilic versus hydrophobic fractions, in highly-treated wastewater effluents for the first time. The tertiary effluents from two wastewater treatment plants were separated into two fractions by XAD-8 resin coupled with anion exchange resin based on the hydrophobicity. Results showed that the majority of DON was present in hydrophilic forms while more DOP existed in hydrophobic forms. Hydrophilic DON contributed to 64.0%-72.2% of whole DON, while hydrophobic DOP accounted for 61.4%-80.7% of total DOP for the two plants evaluated. The effluents and their fractions were then subject to bioavailability assay based on 14-day algae growth. The results indicated that majority (~73-75%) of the effluent DOP, particularly the hydrophobic fraction with lower C/P ratio was more likely to be bioavailable for algal growth. The bioavailable fraction of DON varied widely (28%-61%) for the two plants studied and the hydrophilic fraction with lower C/N ratio seemed to exhibit higher bioavailability than the hydrophobic portion. The differences in bioavailable DON and DOP distributions of effluents from those two plants could be attributed to different receiving effluent compositions and wastewater treatment processes. In addition, fluorescence excitation-emission matrices (EEMs) combined with parallel factor analysis (PARAFAC) were used to characterize the dissolved organic matter (DOM) in wastewater effluent, which provided insights into the nature of organic matter in wastewater samples with different characteristics and originating sources. PMID:25527968

  2. Effluent dissolved organic nitrogen and dissolved phosphorus removal by enhanced coagulation and microfiltration.

    PubMed

    Arnaldos, Marina; Pagilla, Krishna

    2010-10-01

    Plants aiming to achieve very low effluent nutrient levels (<3 mg N/L for N, and <0.1 mg P/L for P) need to consider removal of effluent fractions hitherto not taken into account. Two of these fractions are dissolved organic nitrogen (DON) and dissolved non-reactive phosphorus (DNRP) (mainly composed of organic phosphorus). In this research, enhanced coagulation using alum (at doses commonly employed in tertiary phosphorus removal) followed by microfiltration (using 0.22 μm pore size filters) was investigated for simultaneous effluent DON and dissolved phosphorus (DP) fractions removal. At an approximate dose of 3.2 mg Al(III)/L, corresponding to 1.5 Al(III)/initial DON-N and 3.8 Al(III)/initial DP-P molar ratios, maximum simultaneous removal of DON and DP was achieved (69% for DON and 72% for DP). At this dose, residual DON and DP concentrations were found to be 0.3 mg N/L and 0.25 mg P/L, respectively. Analysis of the trends of removal revealed that the DNRP removal pattern was similar to that commonly reported for dissolved reactive phosphorus. Since this study involved intensive analytical work, a secondary objective was to develop a simple and accurate measurement protocol for determining dissolved N and P species at very low levels in wastewater effluents. The protocol developed in this study, involving simultaneous digestion for DON and DNRP species, was found to be very reliable and accurate based on the results. PMID:20643469

  3. Abiotic effects on effluent dissolved organic nitrogen along an estuarine transect.

    PubMed

    Funkey, Carolina P; Latour, Robert J; Bronk, Deborah A

    2015-03-01

    Biological nutrient removal is a process commonly used in water resource recovery facilities to reduce dissolved inorganic nitrogen (DIN) concentrations in effluent; this process is less effective at removing all of the effluent dissolved organic nitrogen (EDON). The goal of this study was to investigate the fate of EDON after it undergoes the disinfection process and enters receiving waters. The authors quantified the abiotic effects of effluent exposure to sunlight, increased salinity, and a combination of the two factors. Effluent dissolved organic nitrogen showed significant breakdown during the disinfection process (UV and chlorine) and when exposed to sunlight and increasing salinity. Approximately 7% of the EDON was transformed to DIN and dissolved primary amines after exposure to 9 hours of sunlight and a salinity increase from 0 to 33. The production of DIN and primary amines should be taken into account when considering sources of labile nitrogen to aquatic ecosystems. PMID:25842537

  4. Method for removing and decolorizing aqueous waste effluents containing dissolved or dispersed organic matter

    DOEpatents

    Case, F.N.; Ketchen, E.E.

    1975-10-14

    A method is provided for treating organic waste material dissolved or dispersed in an aqueous effluent, which comprises contacting the effluent with an inert particulate carbonaceous sorbent at an oxygen pressure up to 2000 psi, irradiating the resultant mixture with high energy radiation until a decolorized liquid is produced, and then separating the decolorized liquid.

  5. Effect of dissolved organic matter from treated effluents on sorption of atrazine and prometryn by soils

    SciTech Connect

    Seol, Y.; Lee, L.S.

    2000-01-02

    The apparent enhanced transport of soil-applied atrazine following irrigation of treated effluents has been hypothesized to be from complexation of atrazine with effluent-borne dissolved organic matter (DOM). Under long-term effluent irrigation, even small DOM-induced decreases in pesticide sorption can result in significant enhanced pesticide movement due to cumulative effects. The effect of atrazine and prometryn association with DOM extracted from municipal wastewater (MW), swine-derived lagoon wastewater (SW), and dissolved Aldrich humic acid (HA) on sorption by two soils was measured in batch equilibration studies. Individual association of pesticides to DOM, sorption of DOM to soil, and pesticide sorption by soil were also quantified. Pesticide association to DOM normalized to organic carbon (OC) ranged from 30 to 1000 L/kg OC. DOM sorption by soil ranged from 1.5 to 10 L/kg with a silt loam having a higher affinity for the DOM than the sandy loam. DOM up to 150 mg OC/L did not significantly suppress sorption by soils of either atrazine or prometryne in agreement with predictions using the independently measured binary distribution coefficients in a model that assumed linear equilibrium behavior among pesticide, soil, and DOM. A sensitivity analysis was performed using the same model to identify what combination of soil, pesticide, and DOC variables may suppress sorption, resulting in facilitated transport. Results from the sensitivity analysis are presented and the potential for effluent properties other than DOM to facilitate pesticide transport is discussed.

  6. Characterization of fluorescent-dissolved organic matter and identification of specific fluorophores in textile effluents.

    PubMed

    Li, Wentao; Xu, Zixiao; Wu, Qian; Li, Yan; Shuang, Chendong; Li, Aimin

    2015-03-01

    This study focused on the characterization of fluorescent-dissolved organic matter and identification of specific fluorophores in textile effluents. Samples from different textile wastewater treatment plants were characterized by high-performance liquid chromatography and size exclusion chromatography as well as fluorescence excitation-emission matrix spectra. Despite the highly heterogeneous textile effluents, the fluorescent components and their physicochemical properties were found relatively invariable, which is beneficial for the combination of biological and physicochemical treatment processes. The humic-like substance with triple-excitation peaks (excitation (Ex) 250, 310, 365/emission (Em) 460 nm) presented as the specific fluorescence indicator in textile effluents. It was also the major contributor to UV absorbance at 254 nm and resulted in the brown color of biologically treated textile effluents. By spectral comparison, the specific fluorophore in textile effluents could be attributed to the intermediate structure of azo dyes 1-amino-2-naphthol, which was transferred into the special humic-like substances during biological treatment. PMID:25277708

  7. Impacts of powdered activated carbon addition on trihalomethane formation reactivity of dissolved organic matter in membrane bioreactor effluent.

    PubMed

    Ma, Defang; Gao, Yue; Gao, Baoyu; Wang, Yan; Yue, Qinyan; Li, Qian

    2014-12-01

    Characteristics and trihalomethane (THM) formation reactivity of dissolved organic matter (DOM) in effluents from two membrane bioreactors (MBRs) with and without powdered activated carbon (PAC) addition (referred to as PAC/MBR and MBR, respectively) were examined to investigate the effects of PAC addition on THM formation of MBR effluent during chlorination. PAC addition increased the specific UV absorbance. Hydrophobic DOM especially hydrophobic acids in PAC/MBR effluent (50%) were more than MBR effluent (42%). DOM with molecular weight <1 kDa constituted 12% of PAC/MBR effluent DOM, which was less than that of MBR effluent (16%). Data obtained from excitation and emission matrix fluorescence spectroscopy revealed that PAC/MBR effluent DOM contained more simple aromatic protein, but had less fulvic acid-like and soluble microbial by-product-like. PAC addition reduced the formation of bromine-containing THMs during chlorination of effluents, but increased THM formation reactivity of effluent DOM. PMID:25150685

  8. Dissolved effluent organic matter: Characteristics and potential implications in wastewater treatment and reuse applications.

    PubMed

    Michael-Kordatou, I; Michael, C; Duan, X; He, X; Dionysiou, D D; Mills, M A; Fatta-Kassinos, D

    2015-06-15

    Wastewater reuse is currently considered globally as the most critical element of sustainable water management. The dissolved effluent organic matter (dEfOM) present in biologically treated urban wastewater, consists of a heterogeneous mixture of refractory organic compounds with diverse structures and varying origin, including dissolved natural organic matter, soluble microbial products, endocrine disrupting compounds, pharmaceuticals and personal care products residues, disinfection by-products, metabolites/transformation products and others, which can reach the aquatic environment through discharge and reuse applications. dEfOM constitutes the major fraction of the effluent organic matter (EfOM) and due to its chemical complexity, it is necessary to utilize a battery of complementary techniques to adequately describe its structural and functional character. dEfOM has been shown to exhibit contrasting effects towards various aquatic organisms. It decreases metal uptake, thus potentially reducing their bioavailability to exposed organisms. On the other hand, dEfOM can be adsorbed on cell membranes inducing toxic effects. This review paper evaluates the performance of various advanced treatment processes (i.e., membrane filtration and separation processes, activated carbon adsorption, ion-exchange resin process, and advanced chemical oxidation processes) in removing dEfOM from wastewater effluents. In general, the literature findings reveal that dEfOM removal by advanced treatment processes depends on the type and the amount of organic compounds present in the aqueous matrix, as well as the operational parameters and the removal mechanisms taking place during the application of each treatment technology. PMID:25917290

  9. Effects of dissolved organic matter size fractions on trihalomethanes formation in MBR effluents during chlorine disinfection.

    PubMed

    Ma, Defang; Gao, Baoyu; Sun, Shenglei; Wang, Yan; Yue, Qinyan; Li, Qian

    2013-05-01

    In this study, effects of dissolved organic matter (DOM) size fractions on trihalomethanes (THMs) formation in MBR effluents during chlorination were investigated by fractionating DOM into >100, 30-100, 10-30, 5-10 and <5 kDa fractions using ultrafiltration (UF) membranes based on molecular weight (MW). Fractions of MW>30 kDa constituted 87% of DOM and were the main THMs precursors, which exhibited higher specific ultraviolet absorbance (SUVA) and THMs formation potential (THMFP) and should be reduced to control THMs formation. For these fractions, THMs formation was mostly attributed to slow chlorine decay, and THMs yield coefficients were low because halogenated intermediates derived from the macromolecular DOM were difficult to decompose to produce THMs. Moreover, there was a strong linear correlation between dissolved organic carbon (DOC) concentration and THMFP (R(2)=0.981), as well as between the SUVA and specific THMFP (R(2)=0.993) in all fractions. PMID:23567728

  10. Dissolved organic matter removal using magnetic anion exchange resin treatment on biological effluent of textile dyeing wastewater.

    PubMed

    Fan, Jun; Li, Haibo; Shuang, Chendong; Li, Wentao; Li, Aimin

    2014-08-01

    This study investigated the removal of dissolved organic matter (DOM) from real dyeing bio-treatment effluents (DBEs) with the use of a novel magnetic anion exchange resin (NDMP). DOMs in two typical DBEs were fractionized using DAX-8/XAD-4 resin and ultrafiltration membranes. The hydrophilic fractions and the low molecular weight (MW) (<3kDa) DOM fractions constituted a major portion (>50%) of DOMs for the two effluents. The hydrophilic and low MW fractions of both effluents were the greatest contributors of specific UV254 absorbance (SUVA254), and the SUVA254 of DOM fractions decreased with hydrophobicity and MW. Two DBEs exhibited acute and chronic biotoxicities. Both acute and chronic toxicities of DOM fractions increased linearly with the increase of SUVA254 value. Kinetics of dissolved organic carbon (DOC) removal via NDMP treatment was performed by comparing it with that of particle active carbon (PAC). Results indicated that the removal of DOC from DBEs via NDMP was 60%, whereas DOC removals by PAC were lower than 15%. Acidic organics could be significantly removed with the use of NDMP. DOM with large MW in DBE could be removed significantly by using the same means. Removal efficiency of NDMP for DOM decreased with the decrease of MW. Compared with PAC, NDMP could significantly reduce the acute and chronic bio-toxicities of DBEs. NaCl/NaOH mixture regenerants, with selected concentrations of 10% NaCl (m/m)/1% NaOH (m/m), could improve desorption efficiency. PMID:25108712

  11. Removal of fluorescent dissolved organic matter in biologically treated textile effluents by NDMP anion exchange process: efficiency and mechanism.

    PubMed

    Li, Wen-Tao; Xu, Zi-Xiao; Shuang, Chen-Dong; Zhou, Qing; Li, Hai-Bo; Li, Ai-Min

    2016-03-01

    The efficiency and mechanism of anion exchange resin Nanda Magnetic Polymer (NDMP) for removal of fluorescent dissolved organic matter in biologically treated textile effluents were studied. The bench-scale experiments showed that as well as activated carbon, anion exchange resin could efficiently remove both aniline-like and humic-like fluorescent components, which can be up to 40 % of dissolved organic matter. The humic-like fluorescent component HS-Em460-Ex3 was more hydrophilic than HS-Em430-Ex2 and contained fewer alkyl chains but more acid groups. As a result, HS-Em460-Ex3 was eliminated more preferentially by NDMP anion exchange. However, compared with adsorption resins, the polarity of fluorescent components had a relatively small effect on the performance of anion exchange resin. The long-term pilot-scale experiments showed that the NDMP anion exchange process could remove approximately 30 % of the chemical oxygen demand and about 90 % of color from the biologically treated textile effluents. Once the issue of waste brine from resin desorption is solved, the NDMP anion exchange process could be a promising alternative for the advanced treatment of textile effluents. PMID:26578375

  12. Evaluation of ion exchange resins for the removal of dissolved organic matter from biologically treated paper mill effluent.

    PubMed

    Bassandeh, Mojgan; Antony, Alice; Le-Clech, Pierre; Richardson, Desmond; Leslie, Greg

    2013-01-01

    In this study, the efficiency of six ion exchange resins to reduce the dissolved organic matter (DOM) from a biologically treated newsprint mill effluent was evaluated and the dominant removal mechanism of residual organics was established using advanced organic characterisations techniques. Among the resins screened, TAN1 possessed favourable Freundlich parameters, high resin capacity and solute affinity, closely followed by Marathon MSA and Marathon WBA. The removal efficiency of colour and lignin residuals was generally good for the anion exchange resins, greater than 50% and 75% respectively. In terms of the DOM fractions removal measured through liquid chromatography-organic carbon and nitrogen detector (LC-OCND), the resins mainly targeted the removal of humic and fulvic acids of molecular weight ranging between 500 and 1000 g mol(-1), the portion expected to contribute the most to the aromaticity of the effluent. For the anion exchange resins, physical adsorption operated along with ion exchange mechanism assisting to remove neutral and transphilic acid fractions of DOM. The column studies confirmed TAN1 being the best of those screened, exhibited the longest mass transfer zone and maximum treatable volume of effluent. The treatable effluent volume with 50% reduction in dissolved organic carbon (DOC) was 4.8 L for TAN1 followed by Marathon MSA - 3.6L, Marathon 11 - 2.0 L, 21K-XLT - 1.5 L and Marathon WBA - 1.2 L. The cation exchange resin G26 was not effective in DOM removal as the maximum DOC removal obtained was only 27%. The resin capacity could not be completely restored for any of the resins; however, a maximum restoration up to 74% and 93% was achieved for TAN1 and Marathon WBA resins. While this feasibility study indicates the potential option of using ion exchange resins for the reclamation of paper mill effluent, the need for improving the regeneration protocols to restore the resin efficiency is also identified. Similarly, care should be taken

  13. Characteristics and trihalomethane formation reactivity of dissolved organic matter in effluents from membrane bioreactors with and without filamentous bulking.

    PubMed

    Xia, Chufan; Ma, Defang; Gao, Baoyu; Hu, Xinxiao; Yue, Qinyan; Meng, Yingjie; Kang, Shuyu; Zhang, Bei; Qi, Yuanfeng

    2016-07-01

    In this study, synthetic wastewater was treated by two identical membrane bioreactors (MBRs): the normal sludge MBR (NS-MBR) and the bulking sludge MBR (BS-MBR). Effects of filamentous bulking on the characteristics and trihalomethane (THM) formation reactivity of MBR effluent dissolved organic matter (EfOM) were investigated. Filamentous sludge bulking had no significant influence on the regulated MBR effluent water quality except NO2-N and NO3-N. NS-MBR effluent had more low molecular weight (LMW) (<5kDa) EfOM (92.43%) than BS-MBR (75.18%). About two-thirds of EfOM from BS-MBR were hydrophilic substances. On the contrary, EfOM from NS-MBR exhibited higher hydrophobicity. The ratio of polysaccharides and proteins in MBR effluents increased after filamentous bulking. There were more protein-like materials, fulvic acid-like and humic acid-like in BS-MBR EfOM. The THM formation reactivity of BS-MBR EfOM was 30.15% of NS-MBR EfOM, whereas BS-MBR EfOM exhibited higher formation reactivity of bromine containing species. PMID:27017128

  14. Dissolved Organic Nitrogen Inputs from Wastewater Treatment Plant Effluents Increase Responses of Planktonic Metabolic Rates to Warming.

    PubMed

    Vaquer-Sunyer, Raquel; Conley, Daniel J; Muthusamy, Saraladevi; Lindh, Markus V; Pinhassi, Jarone; Kritzberg, Emma S

    2015-10-01

    Increased anthropogenic pressures on coastal marine ecosystems in the last century are threatening their biodiversity and functioning. Global warming and increases in nutrient loadings are two major stressors affecting these systems. Global warming is expected to increase both atmospheric and water temperatures and increase precipitation and terrestrial runoff, further increasing organic matter and nutrient inputs to coastal areas. Dissolved organic nitrogen (DON) concentrations frequently exceed those of dissolved inorganic nitrogen in aquatic systems. Many components of the DON pool have been shown to supply nitrogen nutrition to phytoplankton and bacteria. Predictions of how global warming and eutrophication will affect metabolic rates and dissolved oxygen dynamics in the future are needed to elucidate their impacts on biodiversity and ecosystem functioning. Here, we experimentally determine the effects of simultaneous DON additions and warming on planktonic community metabolism in the Baltic Sea, the largest coastal area suffering from eutrophication-driven hypoxia. Both bacterioplankton community composition and metabolic rates changed in relation to temperature. DON additions from wastewater treatment plant effluents significantly increased the activation energies for community respiration and gross primary production. Activation energies for community respiration were higher than those for gross primary production. Results support the prediction that warming of the Baltic Sea will enhance planktonic respiration rates faster than it will for planktonic primary production. Higher increases in respiration rates than in production may lead to the depletion of the oxygen pool, further aggravating hypoxia in the Baltic Sea. PMID:26356812

  15. Dissolved organic matter removal during coal slag additive soil aquifer treatment for secondary effluent recharging: Contribution of aerobic biodegradation.

    PubMed

    Wei, Liangliang; Li, Siliang; Noguera, Daniel R; Qin, Kena; Jiang, Junqiu; Zhao, Qingliang; Kong, Xiangjuan; Cui, Fuyi

    2015-06-01

    Recycling wastewater treatment plant (WWTP) effluent at low cost via the soil aquifer treatment (SAT), which has been considered as a renewable approach in regenerating potable and non-potable water, is welcome in arid and semi-arid regions throughout the world. In this study, the effect of a coal slag additive on the bulk removal of the dissolved organic matter (DOM) in WWTP effluent during SAT operation was explored via the matrix configurations of both coal slag layer and natural soil layer. Azide inhibition and XAD-resins fractionation experiments indicated that the appropriate configuration designing of an upper soil layer (25 cm) and a mixture of soil/coal slag underneath would enhance the removal efficiency of adsorption and anaerobic biodegradation to the same level as that of aerobic biodegradation (31.7% vs 32.2%), while it was only 29.4% compared with the aerobic biodegradation during traditional 50 cm soil column operation. The added coal slag would preferentially adsorb the hydrophobic DOM, and those adsorbed organics could be partially biodegraded by the biomass within the SAT systems. Compared with the relatively lower dissolved organic carbon (DOC), ultraviolet light adsorption at 254 nm (UV-254) and trihalomethane formation potential (THMFP) removal rate of the original soil column (42.0%, 32.9%, and 28.0%, respectively), SSL2 and SSL4 columns would enhance the bulk removal efficiency to more than 60%. Moreover, a coal slag additive in the SAT columns could decline the aromatic components (fulvic-like organics and tryptophan-like proteins) significantly. PMID:25845997

  16. Dissolved organic matter from treated effluent of a major wastewater treatment plant: characterization and influence on copper toxicity.

    PubMed

    Pernet-Coudrier, Benoît; Clouzot, Ludiwine; Varrault, Gilles; Tusseau-Vuillemin, Marie-Hélène; Verger, Alain; Mouchel, Jean-Marie

    2008-09-01

    A combination of reverse osmosis (RO) concentration and DAX-8/XAD-4 resin adsorption techniques is used to isolate the various constituents of urban dissolved organic matter (DOM) from inorganic salts. Three fractions: hydrophobic (HPO), transphilic (TPI) and hydrophilic (HPI) accounting respectively for 35%, 20% and 45% of extracted carbon, are isolated from effluents of a major French wastewater treatment plant. This atypical DOC distribution, in comparison with natural water where the HPO fraction dominates, shows the significance of HPI fraction which often gets neglected because of extraction difficulties. A number of analytical techniques (elemental, spectroscopic: UV, FTIR) allow highlighting the weak aromaticity of wastewater effluent DOM (EfOM) due to fewer degradation and condensation processes and the strong presence of proteinaceous structures indicative of intense microbial activity. Copper toxicity in the presence of DOM is estimated using an acute toxicity test on Daphnia Magna (Strauss). Results reveal the similar protective role of each EfOM fraction compared to reference Suwannee river fulvic acid despite lower EfOM aromaticity (i.e. specific UV absorbance). The environmental implications of these results are discussed with respect to the development of site-specific water quality criteria. PMID:18632131

  17. Bioavailability of Dissolved Organic Nitrogen Originating From Natural Sources and Wastewater Effluent in the Truckee River

    NASA Astrophysics Data System (ADS)

    Bertrando, N.; Qualls, R. G.; Dean, K. L.; Springer, M.; Brisbin, M.

    2008-12-01

    It has been suggested that implementation of the Clean Water Act might be further refined to recognize differences in biological availability of Nitrate-N, Ammonium-N, and Dissolved Organic-N (DON) in the regulation of Total Nitrogen (TN) Total Maximum Daily Loads (TMDL). This study was conducted to assess whether wastewater DON has a different bioavailable fraction than natural DON and how the bioavailable fraction of DON in river water varies seasonally across an urban gradient. Since the variety of constituents in DON have not been thoroughly identified and may vary based on source, 67 day bioassays were performed to measure the fraction of DON that is mineralized or converted to particulate matter. To assess the importance of N additions to the Truckee River, algal nutrient limitation assays were performed across the urban gradient. Seasonal bioassays in 2007 demonstrated that wastewater derived DON consistently had a higher bioavailable fraction (23-51 %) than naturally derived DON (~ 0 %). However during summer 2007 the fraction of bioavailable DON was similar for wastewater and natural sources (40 % and 43 %, respectively). DON derived from urban runoff had the highest degree of variation in bioavailability (3-70 %) as opposed to the more consistent bioavailability of wastewater DON. Downstream from the wastewater infall, the bioavailable fraction of DON varied seasonally (0-42 %). Algal nutrient limitation assays demonstrated significant N+P limitation across the urban gradient during the spring and summer but no limitation was observed for winter. A significant N limitation was seen for sites below the urban gradient during the summer season. It appears that wastewater DON consistently has a bioavailable fraction and a recalcitrant fraction (minimum 48 %) which suggests TMDLs could be altered to regulate the bioavailable fraction of TN. The occurrence of N limitation for in-river algal production during the summer season suggests that appropriate N TMDLs

  18. Changes in dissolved organic matter composition and metabolic diversity of bacterial community during the degradation of organic matter in swine effluent.

    PubMed

    Li, Lei; Liu, Ming; Li, Yanli; Ma, Xiaoyan; Tang, Xiaoxue; Li, Zhongpei

    2016-07-01

    In this study, an incubation experiment was conducted with effluent collected from the concentrated swine-feeding operations (CSFOs) located in Yujiang County of Jiangxi Province, China. The purpose of this study was to elucidate the relationships between the composition of dissolved organic matter (DOM) and the community-level physiological profiles (CLPPs) of microorganisms in swine effluent. For all samples examined, the concentrations of dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) were decreased by an average of 58.2 ± 30.4 and 49.2 ± 38.7 %, whereas total dissolved phosphorus (TDP) exhibited an average final accumulation of 141.5 ± 43.0 %. In the original samples, ammonium nitrogen accounted for 88.9 ± 4.9 % of the TDN, which was reduced to a final average of 83.9 ± 9.6 %. Two protein-like (tyrosine and tryptophan) and two humic-like (fulvic acids and humic acids) components were identified using a three-dimensional excitation-emission matrix. With the increase in incubation time, the relative concentrations of two protein-like components in effluent were reduced by an average of 83.2 ± 24.7 %. BIOLOG(™) ECO plates were used to determine the metabolic fingerprint of the bacterial community, and a shift in the utilization patterns of substrates was observed over the study period. Additionally, the Shannon-Wiener index of CLPP was ultimately reduced by an average of 43.5 ± 8.5 %, corresponding to the metabolic diversity of the bacterial community. The redundancy analysis identified significant relationships between environmental parameters and the CLPP of microorganisms. To a certain degree, the DOM compositions were linked with the substrate utilization patterns of the bacterial community during the degradation of organic matter in swine effluent. PMID:27030235

  19. Quantification and characterization of dissolved organic nitrogen in wastewater effluents by electrodialysis treatment followed by size-exclusion chromatography with nitrogen detection.

    PubMed

    Chon, Kangmin; Lee, Yunho; Traber, Jacqueline; von Gunten, Urs

    2013-09-15

    Dissolved organic nitrogen (DON) can act as a precursor of nitrogenous disinfection byproducts during oxidative water treatment. Quantification and characterization of DON are still challenging for waters with high concentrations of dissolved inorganic nitrogen (DIN, including ammonia, nitrate and nitrite) relative to total dissolved nitrogen (TDN) due to the cumulative analytical errors of independently measured nitrogen species (i.e., DON = TDN - NO2(-) - NO3(-) - NH4(+)/NH3) and interference of DIN species to TDN quantification. In this study, a novel electrodialysis (ED)-based treatment for selective DIN removal was developed and optimized with respect to type of ion-exchange membrane, sample pH, and ED duration. The optimized ED method was then coupled with size-exclusion chromatography with organic carbon, UV, and nitrogen detection (SEC-OCD-ND) for advanced DON analysis in wastewater effluents. Among the tested ion-exchange membranes, the PC-AR anion- and CMT cation-exchange membranes showed the lowest DOC loss (1-7%) during ED treatment of a wastewater effluent at ambient pH (8.0). A good correlation was found between the decrease of the DIN/TDN ratio and conductivity. Therefore, conductivity has been adopted as a convenient way to determine the optimal duration of the ED treatment. In the pH range of 7.0-8.3, ED treatment of various wastewater effluents with the PC-AR/CMT membranes showed that the relative residual conductivity could be reduced to less than 0.50 (DIN removal >90%; DIN/TDN ratio ≤ 0.60) with lower DOC losses (6%) than the previous dialysis and nanofiltration methods (DOC loss >10%). In addition, the ED method is shorter (0.5 h) than the previous methods (>1-24 h). The relative residual conductivity was further reduced to ≈ 0.20 (DIN removal >95%; DIN/TDN ratio ≤ 0.35) by increasing the ED duration to 0.7 h (DOC loss = 8%) for analysis by SEC-OCD-ND, which provided new information on distribution and ratio of organic carbon and

  20. Concentration, composition, bioavailability, and N-nitrosodimethylamine formation potential of particulate and dissolved organic nitrogen in wastewater effluents: A comparative study.

    PubMed

    Hu, Haidong; Ma, Haijun; Ding, Lili; Geng, Jinju; Xu, Ke; Huang, Hui; Zhang, Yingying; Ren, Hongqiang

    2016-11-01

    Wastewater-derived organic nitrogen (org-N) can act as both nutrients and carcinogenic nitrogenous disinfection byproduct precursors. In this study, the concentration, composition, bioavailability, and N-nitrosodimethylamine (NDMA) formation potential of particulate organic nitrogen (PON) from three different municipal wastewater treatment plants were characterized and compared with that of effluent dissolved organic nitrogen (DON). The average effluent PON and DON concentrations ranged from 0.09 to 0.55mgN/L and from 0.91 to 1.88mgN/L, respectively. According to principal component analysis, org-N composition and characterization differed in PON and DON samples (n=20). Compared with DON, PON tended to be enriched in protein and nucleic acids, and showed a more proteinaceous character. Composition of org-N functional groups estimated from the X-ray photoelectron spectroscopy N 1s spectra indicate no significant differences in the molecular weight distribution of the protein-like materials between PON and DON. Moreover, PON exhibited a significantly higher bioavailability (61.0±13.3%) compared to DON (38.5±12.4%, p˂0.05, t-test) and a significantly higher NDMA yields (791.4±404.0ng/mg-N) compared to DON (374.8±62.5ng/mg-N, p˂0.05, t-test). Accordingly, PON contributed to approximately 12.3-41.7% of the total bioavailable org-N and 22.0-38.4% of the total NDMA precursors in wastewater effluents. Thus, the potential adverse effects of PON on wastewater discharge and reuse applications should not be overlooked, even though it only accounted for 7.4-26.8% of the total effluent org-N. PMID:27450243

  1. Effects of sludge retention times on reactivity of effluent dissolved organic matter for trihalomethane formation in hybrid powdered activated carbon membrane bioreactors.

    PubMed

    Ma, Defang; Gao, Baoyu; Xia, Chufan; Wang, Yan; Yue, Qinyan; Li, Qian

    2014-08-01

    In this study, real municipal wastewater intended for reuse was treated by two identical hybrid PAC/MBRs (membrane bioreactors with powdered activated carbon addition), which were operated at sludge retention times (SRTs) of 30 and 180 days, respectively. In order to investigate the effects of SRT on trihalomethane (THM) formation in chlorinated PAC/MBR effluents, characteristics and THM formation reactivity of effluent dissolved organic matter (EfOM) at different SRTs were examined. PAC/MBR-180 had higher level of EfOM, which contained less simple aromatic proteins and exhibited lower specific UV absorbance. EfOM with molecular weight <5 kDa from PAC/MBR-30 (23%) was lower than PAC/MBR-180 (26%). About 50% of EfOM from PAC/MBR-30 was hydrophobic acids, which was higher than that from PAC/MBR-180 (about 36%). EfOM at SRT 180 days exhibited higher hydrophilicity. Prolonging SRT greatly reduced THM formation reactivity of EfOM, but increased the formation of bromine-containing species during chlorination of PAC/MBR effluents. PMID:24929809

  2. Removal of dissolved organic matter by granular-activated carbon adsorption as a pretreatment to reverse osmosis of membrane bioreactor effluents.

    PubMed

    Gur-Reznik, Shirra; Katz, Ilan; Dosoretz, Carlos G

    2008-03-01

    The adsorption of dissolved organic matter (DOM) on granular-activated carbon (GAC) as a pretreatment to reverse osmosis (RO) desalination of membrane bioreactor (MBR) effluents was studied in lab- and pilot-scale columns. The pattern and efficiency of DOM adsorption and fate of the hydrophobic (HPO), transphilic (TPI) and hydrophilic (HPI) fractions were characterized, as well as their impact on organic fouling of the RO membranes. Relatively low DOM adsorption capacity and low intensity of adsorption were observed in batch studies. Continuous adsorption experiments performed within a range of hydraulic velocities of 0.9-12m/h depicted permissible values within the mass transfer zone up to 1.6m/h. The breakthrough curves within this range displayed a non-adsorbable fraction of 24+/-6% and a biodegradable fraction of 49+/-12%. Interestingly, the adsorbable fraction remained almost constant ( approximately 30%) in the entire hydraulic range studied. Comparative analysis by HPO interaction chromatography showed a steady removal (63-66%) of the HPO fraction. SUVA index and Fourier Transform Infrared (FTIR) spectra indicated that DOM changes during the adsorption phase were mainly due to elution of the more HPI components. GAC pretreatment in pilot-scale columns resulted in 80-90% DOM removal from MBR effluents, which in turn stabilized membrane permeability and increased permeate quality. FTIR analysis indicated that the residual DOM present in the RO permeate, regardless of the pretreatment, was mainly of HPI character (e.g., low-molecular-weight humics linked to polysaccharides and proteins). The DOM removed by GAC pretreatment is composed mainly of HPO and biodegradable components, which constitutes the fraction primarily causing organic fouling. PMID:17980400

  3. Molecular characterisation of the dissolved organic matter of wastewater effluents by MSSV pyrolysis GC-MS and search for source markers.

    PubMed

    Greenwood, P F; Berwick, L J; Croué, J-P

    2012-04-01

    Microscale sealed vessel pyrolysis (MSSVpy) was used to characterise the hydrophobic (HPO) and colloid (COL) fractions of dissolved organic matter (DOM) from the effluents (EFFs) of two waste water treatment plants (WWTPs) and several primary source waters (SWs). The EFFs showed a large range of anthropogenically sourced organics - including the metabolites of industrial chemicals (e.g., dioxanes, n- and sec-alkyl substituted benzenes and long chain alkyl phenols), pharmaceuticals (e.g., N- and S-heterocycles) and human waste (e.g., S- and N-organics, steranes/sterenes) - as well as high concentrations of alkyl aromatic and N-organic products (e.g., alkyl indoles, carbazoles and β-carbolines) attributed to the treatment biota. Some anthropogenic chemicals are potentially toxic at even trace levels, whilst the N-organics may be precursors for toxic N-disinfection by-products. Much lower concentrations of just a few of the anthropogenic and N-organic products were detected by more traditional flash pyrolysis (Flash-py) of the EFF samples, reflecting the higher sensitivity of MSSVpy to many chemical functionalities. Few of these products were detected in the corresponding MSSVpy analysis of the SWs, but these samples did show relatively high abundances of lignin (e.g., alkylphenols) and carbohydrate (e.g., furans) derived products. Their lower EFF abundances are consistent with efficient removal by the water treatment procedures applied. Conversely, the detection of the anthropogenics in the treated EFFs reflects their general resistance to treatment. Their occurrence in the HPO fractions isolated by XAD resin separation suggests a potential relationship with the structurally stable macromolecular fraction of the DOM. PMID:22261369

  4. Removal of dissolved organic matter in municipal effluent with ozonation, slow sand filtration and nanofiltration as high quality pre-treatment option for artificial groundwater recharge.

    PubMed

    Linlin, Wu; Xuan, Zhao; Meng, Zhang

    2011-04-01

    In the paper the combination process of ozonation, slow sand filtration (SSF) and nanofiltration (NF) was investigated with respect to dissolved organic matter (DOM) removal as high quality pre-treatment option for artificial groundwater recharge. With the help of ozonation leading to breakdown of the large organic molecules, SSF preferentially removes soluble microbial by-product-like substances and DOM with molecular weight (MW) less than 1.0 kDa. NF, however, removes aromatic, humic acid-like and fulvic acid-like substances efficiently and specially removes DOM with MW above 1.0 kDa. The residual DOM of the membrane permeate is dominated by small organics with MW 500 Da, which can be further reduced by the aquifer treatment, despite of the very low concentration. Consequently, the O(3)/SSF/NF system offers a complementary process in DOM removal. Dissolved organic carbon (DOC) and trihalomethane formation potential (THMFP) can be reduced from 6.5±1.1 to 0.7±0.3 mg L(-1) and from 267±24 to 52±6 μg L(-1), respectively. The very low DOC concentration of 0.6±0.2 mg L(-1) and THMFP of 44±4 μg L(-1) can be reached after the aquifer treatment. PMID:21382634

  5. Export of Dissolved Methane and Carbon Dioxide with Effluents from Municipal Wastewater Treatment Plants.

    PubMed

    Alshboul, Zeyad; Encinas-Fernández, Jorge; Hofmann, Hilmar; Lorke, Andreas

    2016-06-01

    Inland waters play an important role for regional and global scale carbon cycling and are significant sources of the atmospheric greenhouse gases methane (CH4) and carbon dioxide (CO2). Although most studies considered the input of terrestrially derived organic and inorganic carbon as the main sources for these emissions, anthropogenic sources have rarely been investigated. Municipal wastewater treatment plants (WWTPs) could be additional sources of carbon by discharging the treated wastewater into the surrounding aquatic ecosystems. Here we analyze seasonally resolved measurements of dissolved CH4 and CO2 concentrations in effluents and receiving streams at nine WWTPs in Germany. We found that effluent addition significantly altered the physicochemical properties of the streamwater. Downstream of the WWTPs, the concentrations of dissolved CH4 and CO2 were enhanced and the atmospheric fluxes of both gases increased by a factor of 1.2 and 8.6, respectively. The CH4 exported with discharged effluent, however, accounted for only a negligible fraction (0.02%) of the estimated total CH4 emissions during the treatment process. The CH4 concentration in the effluent water was linearly related to the organic load of the wastewater, which can provide an empirical basis for future attempts to add WWTPs inputs to regional-scale models for inland water-carbon fluxes. PMID:27160023

  6. Characteristics and transformations of dissolved organic nitrogen in municipal biological nitrogen removal wastewater treatment plants

    NASA Astrophysics Data System (ADS)

    Huo, Shouliang; Xi, Beidou; Yu, Honglei; Qin, Yanwen; Zan, Fengyu; Zhang, Jingtian

    2013-12-01

    Dissolved organic nitrogen (DON) represents most of the dissolved nitrogen in the effluent of biological nitrogen removal (BNR) wastewater treatment plants (WWTPs). The characteristics of wastewater-derived DON in two different WWTPs were investigated by several different methods. The major removals of DON and biodegradable dissolved organic nitrogen (BDON) along the treatment train were observed in the anaerobic process. Dissolved combined amino acids (DCAA) and dissolved free amino acids (DFAA) in the effluent accounted approximately for less than 4% and 1% of the effluent DON, respectively. Approximately half of wastewater-derived DON was capable of passing through a 1 kDa ultrafilter, and low MW DON cannot effectively be removed by BNR processes. More than 80% of effluent DON was composed of hydrophilic compounds, which stimulate algal growth. The study provided important information for future upgrading of WWTPs or the selection of DON removal systems to meet more demanding nitrogen discharge limits.

  7. Transient Dissolved Organic Carbon Through Soils

    NASA Astrophysics Data System (ADS)

    Mei, Y.; Hornberger, G. M.; Kaplan, L. A.; Newbold, J. D.; Aufdenkampe, A. K.; Tsang, Y.

    2009-12-01

    Dissolved organic carbon (DOC) is an important constituent of soil solution that plays a role in many chemical and biological processes in soils; it is also an important energy source for bacteria in the soil ecosystem. Hydrology has a significant control on the transport and fate of dissolved organic carbon in the soil but mechanisms that affect said transport are not well understood. In particular, dynamic information on DOC transport through forest soils on short time scales (one or two precipitation event) is lacking at present. DOC is a very complex mix of organic compounds. A key to quantifying DOC dynamics is to establish useful approximations for behavior of this complex mixture. Biodegradable dissolved organic carbon (BDOC) is an important part of DOC. It is reported that between 12 and 44% of DOC released from the forest floor can be decomposed in solutions by indigenous microbes. In our study, we considered how DOC, BDOC, and flow interact in soil columns. In-situ soil cores with two different lengths were installed under a mixed deciduous canopy. The effects of artificial rain on DOC and BDOC transport were examined by dripping nano pure water amended with bromide on the top of soil cores and sampling the water collected at the bottom of the cores for DOC and BDOC. We used plug-flow biofilm reactors to measure the BDOC concentration. It is likely that reduced rates of decomposition in dry soils will cause microbial products of DOC to accumulate; hence DOC concentration should be high at the first flush of rain and decline as the event proceeds. The experimental results show the expected pattern, that is, the first samples we collected always had the highest DOC and BDOC concentrations. The concentrations tend to decline through the simulated precipitation event. Application of a second “storm” forty minutes after the cessation of the first application of water resulted in effluent DOC concentration increasing a small amount initially and then

  8. Characterization of the dissolved phosphorus uptake kinetics for the effluents from advanced nutrient removal processes.

    PubMed

    Li, Bo; Brett, Michael T

    2015-11-01

    Given the importance of the watershed protection plans, direct determination of phosphorus (P) mineralization rates in advanced wastewater treatment facility effluents is crucial for developing the most protective strategies minimiz eutrophication in receiving surface waters. In this study, algal bioassays were used to determine the uptake rate of dissolved P in effluents from a broad range of advanced nutrient removal technologies (e.g., membrane biological reactor, traditional biological, tertiary membrane, Blue PRO™, etc.). Dissolved P uptake kinetics were fit to a gamma model and three first-order decay models. A traditional one-pool model correlated poorly with the experimental data (i.e., r(2) = 0.73 ± 0.09), whereas two-pool model and three-pool models performed much better (i.e., r(2) > 0.9). These models also provided strong evidence for the existence of recalcitrant P in the effluents from these tertiary facilities. The Gamma model showed the mineralization of organic P followed a reactive continuum and further suggested the partitioning of P loads with different bioavailability levels should be accounted for the future modeling practices. From a modeling perspective, the Gamma model should be considered to be the theoretically best model as it gave the most parsimonious fit to the data using the fewest terms. Our study suggested that the current Total Maximum Daily Load (TMDL) model could be easily modified with the updated mineralization kinetics, which should lead to both ecological and economic benefits. PMID:26233657

  9. Nature and transformation of dissolved organic matter in treatment wetlands

    USGS Publications Warehouse

    Barber, L.B.; Leenheer, J.A.; Noyes, T.I.; Stiles, E.A.

    2001-01-01

    This investigation into the occurrence, character, and transformation of dissolved organic matter (DOM) in treatment wetlands in the western United States shows that (i) the nature of DOM in the source water has a major influence on transformations that occur during treatment, (ii) the climate factors have a secondary effect on transformations, (iii) the wetlands receiving treated wastewater can produce a net increase in DOM, and (iv) the hierarchical analytical approach used in this study can measure the subtle DOM transformations that occur. As wastewater treatment plant effluent passes through treatment wetlands, the DOM undergoes transformation to become more aromatic and oxygenated. Autochthonous sources are contributed to the DOM, the nature of which is governed by the developmental stage of the wetland system as well as vegetation patterns. Concentrations of specific wastewaterderived organic contaminants such as linear alkylbenzene sulfonate, caffeine, and ethylenediaminetetraacetic acid were significantly attenuated by wetland treatment and were not contributed by internal loading.

  10. Dissolved organic carbon losses from tile drained agroecosystems.

    PubMed

    Ruark, Matthew D; Brouder, Sylvie M; Turco, Ronald F

    2009-01-01

    Artificial subsurface drainage is commonly used in midwestern agriculture and drainage losses of dissolved organic carbon (DOC) from such systems are an under-quantified portion of the terrestrial carbon (C) cycle. The objectives of this study were to determine the effect of common agricultural management practices on DOC losses from subsurface tile drains and to assess patterns of loss as a function of year, time of year, and drainflow. Daily drainflow was collected across six water years (1999-2004) from a restored prairie grass system and cropping systems which include continuous corn (Zea mays L.) and corn-soybean [Glycine max (L.) Merr.] rotations fertilized with urea-ammonium-nitrate (UAN) or swine (Sus scrofa) manure lagoon effluent. The DOC concentrations in tile drainflow were low, typically <2 mg L(-1). Yearly DOC losses, which ranged from 1.78 to 8.61 kg ha(-1), were not affected by management practices and were small compared to organic C inputs. Spring application of lagoon effluent increased yearly flow-weighted (FW)-DOC concentrations relative to other cropping systems in three of the years and increased monthly FW-DOC concentrations when drainflow occurred within 1 mo of application. Drainflow was significantly and positively correlated with DOC loss. Drainflow also affected DOC concentrations as greater 6-yr cumulative drainflow was associated with lower 6-yr FW-DOC concentrations and greater daily drainflow was associated with higher daily DOC concentrations. Our results indicate that lagoon effluent application and fertilizer N rates do not affect long-term losses of DOC from tile drains and that drainflow is the main driver of DOC losses. PMID:19398518

  11. Mathematical modeling of wastewater-derived biodegradable dissolved organic nitrogen.

    PubMed

    Simsek, Halis

    2016-11-01

    Wastewater-derived dissolved organic nitrogen (DON) typically constitutes the majority of total dissolved nitrogen (TDN) discharged to surface waters from advanced wastewater treatment plants (WWTPs). When considering the stringent regulations on nitrogen discharge limits in sensitive receiving waters, DON becomes problematic and needs to be reduced. Biodegradable DON (BDON) is a portion of DON that is biologically degradable by bacteria when the optimum environmental conditions are met. BDON in a two-stage trickling filter WWTP was estimated using artificial intelligence techniques, such as adaptive neuro-fuzzy inference systems, multilayer perceptron, radial basis neural networks (RBNN), and generalized regression neural networks. Nitrite, nitrate, ammonium, TDN, and DON data were used as input neurons. Wastewater samples were collected from four different locations in the plant. Model performances were evaluated using root mean square error, mean absolute error, mean bias error, and coefficient of determination statistics. Modeling results showed that the R(2) values were higher than 0.85 in all four models for all wastewater samples, except only R(2) in the final effluent sample for RBNN modeling was low (0.52). Overall, it was found that all four computing techniques could be employed successfully to predict BDON. PMID:27019968

  12. Isolation and chemical characterization of dissolved and colloidal organic matter

    USGS Publications Warehouse

    Aiken, G.; Leenheer, J.

    1993-01-01

    Commonly used techniques for the concentration and isolation of organic matter from water, such as preparative chromatography, ultrafiltration and reverse osmosis, and the methods used to analyze the organic matter obtained by these methods are reviewed. The development of methods to obtain organic matter that is associated with fractions of the dissolved organic carbon other than humic substances, such as organic bases, hydrophilic organic acids and colloidal organic matter are discussed. Methods specifically used to study dissolved organic nitrogen and dissolved organic phosphorous are also discussed. -from Authors

  13. Relating dissolved organic matter fluorescence to functional properties

    NASA Astrophysics Data System (ADS)

    Tipping, E.; Baker, A.; Thacker, S.; Gondar, D.

    2007-12-01

    The fluorescence excitation emission matrix properties of dissolved organic matter from three rivers and one lake in NW England are analysed. Sites are sampled in duplicate and for some sites seasonally to cover variations in dissolved organic matter composition, river flow, and carbon isotopic (13C, 14C) variability. Results are compared to the functional properties of the dissolved organic matter, the functional assays provide quantitative information on light absorption, fluorescence, photochemical fading, pH buffering, copper binding, benzo[a]pyrene binding, hydrophilicity and adsorption to alumina. Fluorescence characterization of the dissolved organic matter samples demonstrates that peak C fluorescence emission wavelength, the ratio of peak T to peak C fluorescence intensity, and the fluorescence : absorbance ratio best differentiate different dissolved organic matter samples. These parameters correspond to dissolved organic matter aromaticity, the ratio of labile to recalcitrant organic matter, and dissolved organic matter molecular weight. Peak C fluorescence emission wavelength, the ratio of peak T to peak C fluorescence intensity, and the fluorescence : absorbance ratio fluorescence parameters also have strong correlations with several of the functional assays, in particular the extinction coefficients, benzo(a)pyrene binding and alumina adsorption, and buffering capacity. In many cases, regression equations with a correlation coefficient >0.9 are obtained, suggesting that dissolved organic matter functional character can be predicted from DOM fluorescence properties. For one site, the relationship between dissolved organic matter source, fluorescence, function and carbon isotopic composition is discussed.

  14. Composition of dissolved organic matter in groundwater

    NASA Astrophysics Data System (ADS)

    Longnecker, Krista; Kujawinski, Elizabeth B.

    2011-05-01

    Groundwater constitutes a globally important source of freshwater for drinking water and other agricultural and industrial purposes, and is a prominent source of freshwater flowing into the coastal ocean. Therefore, understanding the chemical components of groundwater is relevant to both coastal and inland communities. We used electrospray ionization coupled with Fourier-transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) to examine dissolved organic compounds in groundwater prior to and after passage through a sediment-filled column containing microorganisms. The data revealed that an unexpectedly high proportion of organic compounds contained nitrogen and sulfur, possibly due to transport of surface waters from septic systems and rain events. We matched 292 chemical features, based on measured mass:charge ( m/z) values, to compounds stored in the Kyoto Encyclopedia of Genes and Genomes (KEGG). A subset of these compounds (88) had only one structural isomer in KEGG, thus supporting tentative identification. Most identified elemental formulas were linked with metabolic pathways that produce polyketides or with secondary metabolites produced by plants. The presence of polyketides in groundwater is notable because of their anti-bacterial and anti-cancer properties. However, their relative abundance must be quantified with appropriate analyses to assess any implications for public health.

  15. Temperature Dependence of Photodegradation of Dissolved Organic Matter to Dissolved Inorganic Carbon and Particulate Organic Carbon

    PubMed Central

    Porcal, Petr; Dillon, Peter J.; Molot, Lewis A.

    2015-01-01

    Photochemical transformation of dissolved organic matter (DOM) has been studied for more than two decades. Usually, laboratory or “in-situ” experiments are used to determine photodegradation variables. A common problem with these experiments is that the photodegradation experiments are done at higher than ambient temperature. Five laboratory experiments were done to determine the effect of temperature on photochemical degradation of DOM. Experimental results showed strong dependence of photodegradation on temperature. Mathematical modeling of processes revealed that two different pathways engaged in photochemical transformation of DOM to dissolved inorganic carbon (DIC) strongly depend on temperature. Direct oxidation of DOM to DIC dominated at low temperatures while conversion of DOM to intermediate particulate organic carbon (POC) prior to oxidation to DIC dominated at high temperatures. It is necessary to consider this strong dependence when the results of laboratory experiments are interpreted in regard to natural processes. Photodegradation experiments done at higher than ambient temperature will necessitate correction of rate constants. PMID:26106898

  16. Recovery and biological oxidation of dissolved methane in effluent from UASB treatment of municipal sewage using a two-stage closed downflow hanging sponge system.

    PubMed

    Matsuura, Norihisa; Hatamoto, Masashi; Sumino, Haruhiko; Syutsubo, Kazuaki; Yamaguchi, Takashi; Ohashi, Akiyoshi

    2015-03-15

    A two-stage closed downflow hanging sponge (DHS) reactor was used as a post-treatment to prevent methane being emitted from upflow anaerobic sludge blanket (UASB) effluents containing unrecovered dissolved methane. The performance of the closed DHS reactor was evaluated using real municipal sewage at ambient temperatures (10-28 °C) for one year. The first stage of the closed DHS reactor was intended to recover dissolved methane from the UASB effluent and produce a burnable gas with a methane concentration greater than 30%, and its recovery efficiency was 57-88%, although the amount of dissolved methane in the UASB effluent fluctuated in the range of 46-68 % of methane production greatly depending on the temperature. The residual methane was oxidized and the remaining organic carbon was removed in the second closed DHS reactor, and this reactor performed very well, removing more than 99% of the dissolved methane during the experimental period. The rate at which air was supplied to the DHS reactor was found to be one of the most important operating parameters. Microbial community analysis revealed that seasonal changes in the methane-oxidizing bacteria were key to preventing methane emissions. PMID:25576697

  17. Black Carbon in Estuarine and Coastal Ocean Dissolved Organic Matter

    NASA Technical Reports Server (NTRS)

    Mannino, Antonio; Harvey, H. Rodger

    2003-01-01

    Analysis of high-molecular-weight dissolved organic matter (DOM) from two estuaries in the northwest Atlantic Ocean reveals that black carbon (BC) is a significant component of previously uncharacterized DOM, suggesting that river-estuary systems are important exporters of recalcitrant dissolved organic carbon to the ocean.

  18. Dissolved organic carbon and chromophoric dissolved organic matter properties of rivers in the USA

    USGS Publications Warehouse

    Spencer, Robert G.M.; Butler, Kenna D.; Aiken, George R.

    2012-01-01

    Dissolved organic carbon (DOC) concentration and chromophoric dissolved organic matter (CDOM) parameters were measured over a range of discharge in 30 U.S. rivers, covering a diverse assortment of fluvial ecosystems in terms of watershed size and landscape drained. Relationships between CDOM absorption at a range of wavelengths (a254, a350, a440) and DOC in the 30 watersheds were found to correlate strongly and positively for the majority of U.S. rivers. However, four rivers (Colorado, Colombia, Rio Grande and St. Lawrence) exhibited statistically weak relationships between CDOM absorption and DOC. These four rivers are atypical, as they either drain from the Great Lakes or experience significant impoundment of water within their watersheds, and they exhibited values for dissolved organic matter (DOM) parameters indicative of autochthonous or anthropogenic sources or photochemically degraded allochthonous DOM and thus a decoupling between CDOM and DOC. CDOM quality parameters in the 30 rivers were found to be strongly correlated to DOM compositional metrics derived via XAD fractionation, highlighting the potential for examining DOM biochemical quality from CDOM measurements. This study establishes the ability to derive DOC concentration from CDOM absorption for the majority of U.S. rivers, describes characteristics of riverine systems where such an approach is not valid, and emphasizes the possibility of examining DOM composition and thus biogeochemical function via CDOM parameters. Therefore, the usefulness of CDOM measurements, both laboratory-based analyses and in situ instrumentation, for improving spatial and temporal resolution of DOC fluxes and DOM dynamics in future studies is considerable in a range of biogeochemical studies.

  19. Dissolved organic carbon and chromophoric dissolved organic matter properties of rivers in the USA

    NASA Astrophysics Data System (ADS)

    Spencer, Robert G. M.; Butler, Kenna D.; Aiken, George R.

    2012-09-01

    Dissolved organic carbon (DOC) concentration and chromophoric dissolved organic matter (CDOM) parameters were measured over a range of discharge in 30 U.S. rivers, covering a diverse assortment of fluvial ecosystems in terms of watershed size and landscape drained. Relationships between CDOM absorption at a range of wavelengths (a254, a350, a440) and DOC in the 30 watersheds were found to correlate strongly and positively for the majority of U.S. rivers. However, four rivers (Colorado, Colombia, Rio Grande and St. Lawrence) exhibited statistically weak relationships between CDOM absorption and DOC. These four rivers are atypical, as they either drain from the Great Lakes or experience significant impoundment of water within their watersheds, and they exhibited values for dissolved organic matter (DOM) parameters indicative of autochthonous or anthropogenic sources or photochemically degraded allochthonous DOM and thus a decoupling between CDOM and DOC. CDOM quality parameters in the 30 rivers were found to be strongly correlated to DOM compositional metrics derived via XAD fractionation, highlighting the potential for examining DOM biochemical quality from CDOM measurements. This study establishes the ability to derive DOC concentration from CDOM absorption for the majority of U.S. rivers, describes characteristics of riverine systems where such an approach is not valid, and emphasizes the possibility of examining DOM composition and thus biogeochemical function via CDOM parameters. Therefore, the usefulness of CDOM measurements, both laboratory-based analyses and in situ instrumentation, for improving spatial and temporal resolution of DOC fluxes and DOM dynamics in future studies is considerable in a range of biogeochemical studies.

  20. Kinetics of desorption of organic compounds from dissolved organic matter.

    PubMed

    Kopinke, Frank-Dieter; Ramus, Ksenia; Poerschmann, Juergen; Georgi, Anett

    2011-12-01

    This study presents a new experimental technique for measuring rates of desorption of organic compounds from dissolved organic matter (DOM) such as humic substances. The method is based on a fast solid-phase extraction of the freely dissolved fraction of a solute when the solution is flushed through a polymer-coated capillary. The extraction interferes with the solute-DOM sorption equilibrium and drives the desorption process. Solutes which remain sorbed to DOM pass through the extraction capillary and can be analyzed afterward. This technique allows a time resolution for the desorption kinetics from subseconds up to minutes. It is applicable to the study of interaction kinetics between a wide variety of hydrophobic solutes and polyelectrolytes. Due to its simplicity it is accessible for many environmental laboratories. The time-resolved in-tube solid-phase microextraction (TR-IT-SPME) was applied to two humic acids and a surfactant as sorbents together with pyrene, phenanthrene and 1,2-dimethylcyclohexane as solutes. The results give evidence for a two-phase desorption kinetics: a fast desorption step with a half-life of less than 1 s and a slow desorption step with a half-life of more than 1 min. For aliphatic solutes, the fast-desorbing fraction largely dominates, whereas for polycyclic aromatic hydrocarbons such as pyrene, the slowly desorbing, stronger-bound fraction is also important. PMID:22035249

  1. Lamella dissolved air flotation treatment of fish farming effluents as a part of an integrated farming and effluent treatment concept.

    PubMed

    Jokela, Petri; Lepistö, Raghida

    2014-01-01

    Nutrient emissions from fish farming can be reduced by a bag pen, i.e., a floating circular basin which serves simultaneously both as a fish cultivation tank and a swirl separation tank. Solid matter (excreta and uneaten feed) is collected at the bottom of the bag pen and pumped as an underflow to a dissolved air flotation (DAF) unit for nutrient removal. DAF equipped with lamella elements was studied in real conditions. Altogether 3000 rainbow trout females (2.0 kg each) were cultivated. Solid-water mixture was pumped from the bottom of the bag pen to an equalizing basin using a sequence of 2-min pumping followed by a 4-min pause. In some tests the influent was pumped directly and continuously from the bag pen to DAF. The influent quality changed substantially: average suspended solids (SS) and phosphorus (P) concentrations were 290 mg l⁻¹ ± 110 mg l⁻¹ and 3.2 mg l⁻¹ ± 1.2 mg l⁻¹, respectively. When the influent was fresh and P strongly associated with SS, DAF without precipitation chemicals produced up to 86% SS and 83% P removals. The influence of chemical doses was studied using 6.4-29.2 mg Fe l⁻¹ with hydraulic loadings (HLs) of 11.0-11.7 m h⁻¹. SS and P removal did not change substantially and the effluent concentration levelled at 30 mg SS l⁻¹ and 0.20-0.30 mg P l⁻¹, respectively. The lamella DAF, coupled with ferric precipitation, produced up to 90% P and 80% nitrogen reductions. HLs, excluding recycle water flow and lamella projection, up to 21 m h⁻¹ could be used. PMID:25176307

  2. Temperature and Hydrological Controls on Dissolved Organic Matter Mobilization and Transport within forest soils

    NASA Astrophysics Data System (ADS)

    Xu, N.; Saiers, J. E.

    2009-12-01

    Natural dissolved organic matter (DOM) influences nutrients cycling and contaminants mobility, provides an energy source for heterotrophic production, and regulates soil and water pH. The objectives of this laboratory study were (i) to investigate the relative influence of temperature and rainfall characteristics on the mobilization and transport of DOM (quantity and composition) in forest soils; (ii) to evaluate the possible difference between dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) dynamics; and (iii) to elucidate the importance of biotic and physico-chemical mechanisms that govern DOM mobilization and transport during rainfall events. We applied intermittent rainfalls to unsaturated topsoil columns. The experimental treatments were distinguished on the basis of rainfall intensity, rainfall frequency, temperature, soil biotic activity (i.e., sterile vs unsterile soil), and soil storage time before rainfall initiation. A mathematical model incorporating reversible linear kinetics expressions for DOC release at soil-water interfaces closely describes the DOC breakthrough-curve data. Our results show that temperature significantly affects the release rate and composition of leached DOM, while changes in rainfall intensity and frequency only affect the quantity of mobilized DOM. Effluent concentrations of DON showed broadly similar temporal patterns with DOC during rainfall events. Differences between the quantity of DOC and DON were reflected in the C:N ratios of effluent DOM. Our results also indicate the relative importance of physico-chemical mechanisms for the DOM export process.

  3. NONVOLATILE ORGANICS IN DISINFECTED WASTEWATER EFFLUENTS: CHEMICAL CHARACTERIZATION AND MUTAGENICITY

    EPA Science Inventory

    Principal objectives of this research program were to examine the effects of disinfection by chlorine, ozone, and ultraviolet light irradiation on nonvolatile organic constituents in secondary effluents relative to chemical effects and formation of mutagenic substances. In a comp...

  4. Dissolved Organic Matter and Emerging Contaminants in Urban Stream Ecosystems

    NASA Astrophysics Data System (ADS)

    Kaushal, S. S.; Findlay, S.; Groffman, P.; Belt, K.; Delaney, K.; Sides, A.; Walbridge, M.; Mayer, P.

    2009-05-01

    We investigated the effects of urbanization on the sources, bioavailability and forms of natural and anthropogenic organic matter found in streams located in Maryland, U.S.A. We found that the abundance, biaoavailability, and enzymatic breakdown of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and dissolved organic phosphorus (DOP) increased in streams with increasing watershed urbanization suggesting that organic nutrients may represent a growing form of nutrient loading to coastal waters associated with land use change. Organic carbon, nitrogen, and phosphorus in urban streams were elevated several-fold compared to forest and agricultural streams. Enzymatic activities of stream microbes in organic matter decomposition were also significantly altered across watershed land use. Chemical characterization suggested that organic matter in urban streams originated from a variety of sources including terrestrial, sewage, and in-stream transformation. In addition, a characterization of emerging organic contaminants (polyaromatic cyclic hydrocarbons, organochlorine pesticides, and polybrominated diphenyl ether flame retardents), showed that organic contaminants and dissolved organic matter increase with watershed urbanization and fluctuate substantially with changing climatic conditions. Elucidating the emerging influence of urbanization on sources, transport, and in-stream transformation of organic nutrients and contaminants will be critical in unraveling the changing role of organic matter in urban degraded and restored stream ecosystems.

  5. Composition, removal, redox, and metal complexation properties of dissolved organic nitrogen in composting leachates.

    PubMed

    He, Xiao-Song; Xi, Bei-Dou; Zhang, Zong-Yong; Gao, Ru-Tai; Tan, Wen-Bing; Cui, Dong-Yu; Yuan, Ying

    2015-01-01

    This study investigated the composition, removal, redox, and metal complexation characteristics of dissolved organic nitrogen (DON) in composting leachates. Results showed that the leachate-derived DON comprised proteinaceous compounds and amines, and most of them were integrated into the fulvic- and humic-like substances. Neutral, basic, acidic, hydroxylic, aromatic, and sulfuric amino acids all were detected in the influent leachates. However, most of them were removed by the biological and physical processes, and only neutral amino acids were detected in the effluent. The DON was not the main contributor to the redox capability of the leachate dissolved organic matter (DOM). However, it exhibited a strong capability for metal complexation. The amines formed strong complexes with the metals Mo, Co, Cr, and Ni, while the proteinaceous matter interacted with the metals Cr and Ni. PMID:25282175

  6. Comparison of dissolved-organic-carbon residuals from air- and pure-oxygen-activated-sludge sequencing-batch reactors.

    PubMed

    Esparza-Soto, Mario; Fox, Peter; Westerhoff, Paul

    2006-03-01

    Literature shows that full-scale pure-oxygen activated sludge (O2-AS) wastewater treatment plants (WWTPs) generate effluents with higher dissolved-organic carbon (DOC) concentrations and larger high-molecular-weight fractions compared to air-activated-sludge (Air-AS) WWTP effluents. The purpose of this paper was to evaluate how gas supplied (air vs. pure oxygen) to sequencing-batch reactors affected DOC transformations. The main conclusions of this paper are (a) O2-AS effluent DOC is more refractory than air-AS effluent DOC; and (b) O2-AS systems may have higher five-day biochemical oxygen demand removals than air-AS systems; however, in terms of COD and DOC removal, air-AS systems are better than O2-AS systems. Analysis of a database from side-by-side O2- and air-AS pilot tests from literature supported these observations. PMID:16629273

  7. Removal of dissolved organic matter by anion exchange: Effect of dissolved organic matter properties

    USGS Publications Warehouse

    Boyer, T.H.; Singer, P.C.; Aiken, G.R.

    2008-01-01

    Ten isolates of aquatic dissolved organic matter (DOM) were evaluated to determine the effect that chemical properties of the DOM, such as charge density, aromaticity, and molecular weight, have on DOM removal by anion exchange. The DOM isolates were characterized asterrestrial, microbial, or intermediate humic substances or transphilic acids. All anion exchange experiments were conducted using a magnetic ion exchange (MIEX) resin. The charge density of the DOM isolates, determined by direct potentiometric titration, was fundamental to quantifying the stoichiometry of the anion exchange mechanism. The results clearly show that all DOM isolates were removed by anion exchange; however, differences among the DOM isolates did influence their removal by MIEX resin. In particular, MIEX resin had the greatest affinity for DOM with high charge density and the least affinity for DOM with low charge density and low aromaticity. This work illustrates that the chemical characteristics of DOM and solution conditions must be considered when evaluating anion exchange treatment for the removal of DOM. ?? 2008 American Chemical Society.

  8. Do soils loose phosphorus with dissolved organic matter?

    NASA Astrophysics Data System (ADS)

    Kaiser, K.; Brödlin, D.; Hagedorn, F.

    2014-12-01

    During ecosystem development and soil formation, primary mineral sources of phosphorus are becoming increasingly depleted. Inorganic phosphorus forms tend to be bound strongly to or within secondary minerals, thus, are hardly available to plants and are not leached from soil. What about organic forms of phosphorus? Since rarely studied, little is known on the composition, mobility, and bioavailability of dissolved organic phosphorus. There is some evidence that plant-derived compounds, such as phytate, bind strongly to minerals as well, while microbial compounds, such as nucleotides and nucleic acids, may represent more mobile fractions of soil phosphorus. In some weakly developed, shallow soils, leaching losses of phosphorus seem to be governed by mobile organic forms. Consequently, much of the phosphorus losses observed during initial stages of ecosystem development may be due to the leaching of dissolved organic matter. However, the potentially mobile microbial compounds are enzymatically hydrolysable. Forest ecosystems on developed soils already depleted in easily available inorganic phosphorus are characterized by rapid recycling of organic phosphors. That can reduce the production of soluble forms of organic phosphorus as well as increase the enzymatic hydrolysis and subsequent plant uptake of phosphorus bound within dissolved organic matter. This work aims at giving an outlook to the potential role of dissolved organic matter in the cycling of phosphorus within developing forest ecosystems, based on literature evidence and first results of ongoing research.

  9. Differences in dissolved organic matter between reclaimed water source and drinking water source.

    PubMed

    Hu, Hong-Ying; Du, Ye; Wu, Qian-Yuan; Zhao, Xin; Tang, Xin; Chen, Zhuo

    2016-05-01

    Dissolved organic matter (DOM) significantly affects the quality of reclaimed water and drinking water. Reclaimed water potable reuse is an effective way to augment drinking water source and de facto reuse exists worldwide. Hence, when reclaimed water source (namely secondary effluent) is blended with drinking water source, understanding the difference in DOM between drinking water source (dDOM) and reclaimed water source (rDOM) is essential. In this study, composition, transformation, and potential risk of dDOM from drinking water source and rDOM from secondary effluent were compared. Generally, the DOC concentration of rDOM and dissolved organic nitrogen (DON) content in reclaimed water source were higher but rDOM exhibited a lower aromaticity. Besides, rDOM comprises a higher proportion of hydrophilic fractions and more low-molecular weight compounds, which are difficult to be removed during coagulation. Although dDOM exhibited higher specific disinfection byproducts formation potential (SDBPFP), rDOM formed more total disinfection byproducts (DBPs) during chlorination including halomethanes (THMs) and haloacetic acids (HAAs) due to high DOC concentration. Likewise, in consideration of DOC basis, rDOM contained more absolute assimilable organic carbon (AOC) despite showing a lower specific AOC (normalized AOC per unit of DOC). Besides, rDOM exhibited higher biotoxicity including genotoxicity and endocrine disruption. Therefore, rDOM presents a greater potential risk than dDOM does. Reclaimed water source needs to be treated carefully when it is blended with drinking water source. PMID:26874770

  10. IDENTIFICATION OF ORGANIC COMPOUNDS IN INDUSTRIAL EFFLUENT DISCHARGES

    EPA Science Inventory

    Samples of 63 effluent and 22 intake waters were collected from a wide range of chemical manufacturers in areas across the United States. The samples were analyzed for organic compounds in an effort to identify previously unknown and potentially hazardous organic pollutants. Each...

  11. Applications of Fluorescence Spectroscopy for dissolved organic matter characterization in wastewater treatment plants

    NASA Astrophysics Data System (ADS)

    Goffin, Angélique; Guérin, Sabrina; Rocher, Vincent; Varrault, Gilles

    2016-04-01

    Dissolved organic matter (DOM) influences wastewater treatment plants efficiency (WTTP): variations in its quality and quantity can induce a foaming phenomenon and a fouling event inside biofiltration processes. Moreover, in order to manage denitrification step (control and optimization of the nitrate recirculation), it is important to be able to estimate biodegradable organic matter quantity before biological treatment. But the current methods used to characterize organic matter quality, like biological oxygen demand are laborious, time consuming and sometimes not applicable to directly monitor organic matter in situ. In the context of MOCOPEE research program (www.mocopee.com), this study aims to assess the use of optical techniques, such as UV-Visible absorbance and more specifically fluorescence spectroscopy in order to monitor and to optimize process efficiency in WWTP. Fluorescence excitation-emission matrix (EEM) spectroscopy was employed to prospect the possibility of using this technology online and in real time to characterize dissolved organic matter in different effluents of the WWTP Seine Centre (240,000 m3/day) in Paris, France. 35 sewage water influent samples were collected on 10 days at different hours. Data treatment were performed by two methods: peak picking and parallel factor analysis (PARAFAC). An evolution of DOM quality (position of excitation - emission peaks) and quantity (intensity of fluorescence) was observed between the different treatment steps (influent, primary treatment, biological treatment, effluent). Correlations were found between fluorescence indicators and different water quality key parameters in the sewage influents. We developed different multivariate linear regression models in order to predict a variety of water quality parameters by fluorescence intensity at specific excitation-emission wavelengths. For example dissolved biological oxygen demand (r2=0,900; p<0,0001) and ammonium concentration (r2=0,898; p<0

  12. Effects of dissolved organic matter from a eutrophic lake on the freely dissolved concentrations of emerging organic contaminants.

    PubMed

    Xiao, Yi-Hua; Huang, Qing-Hui; Vähätalo, Anssi V; Li, Fei-Peng; Chen, Ling

    2014-08-01

    The authors studied the effects of dissolved organic matter (DOM) on the bioavailability of bisphenol A (BPA) and chloramphenicol by measuring the freely dissolved concentrations of the contaminants in solutions containing DOM that had been isolated from a mesocosm in a eutrophic lake. The abundance and aromaticity of the chromophoric DOM increased over the 25-d mesocosm experiment. The BPA freely dissolved concentration was 72.3% lower and the chloramphenicol freely dissolved concentration was 56.2% lower using DOM collected on day 25 than using DOM collected on day 1 of the mesocosm experiment. The freely dissolved concentrations negatively correlated with the ultraviolent absorption coefficient at 254 nm and positively correlated with the spectral slope of chromophoric DOM, suggesting that the bioavailability of these emerging organic contaminants depends on the characteristics of the DOM present. The DOM-water partition coefficients (log KOC ) for the emerging organic contaminants positively correlated with the aromaticity of the DOM, measured as humic acid-like fluorescent components C1 (excitation/emission=250[313]/412 nm) and C2 (excitation/emission=268[379]/456 nm). The authors conclude that the bioavailability of emerging organic contaminants in eutrophic lakes can be affected by changes in the DOM. PMID:24839192

  13. Unimodal response of fish yield to dissolved organic carbon.

    PubMed

    Finstad, Anders G; Helland, Ingeborg P; Ugedal, Ola; Hesthagen, Trygve; Hessen, Dag O

    2014-01-01

    Here, we demonstrate a contrasting effect of terrestrial coloured dissolved organic material on the secondary production of boreal nutrient poor lakes. Using fish yield from standardised brown trout gill-net catches as a proxy, we show a unimodal response of lake secondary productivity to dissolved organic carbon (DOC). This suggests a trade-off between positive and negative effects, where the initial increase may hinge upon several factors such as energy subsidising, screening of UV-radiation or P and N load being associated with organic carbon. The subsequent decline in production with further increase in DOC is likely associated with light limitations of primary production. We also show that shallow lakes switch from positive to negative effects at higher carbon loads than deeper lakes. These results underpin the major role of organic carbon for structuring productivity of boreal lake ecosystems. PMID:24165396

  14. Triplet photochemistry of effluent and natural organic matter in whole water and isolates from effluent-receiving rivers.

    PubMed

    Bodhipaksha, Laleen C; Sharpless, Charles M; Chin, Yu-Ping; Sander, Michael; Langston, William K; MacKay, Allison A

    2015-03-17

    Effluent organic matter (EfOM), contained in treated municipal wastewater, differs in composition from naturally occurring dissolved organic matter (DOM). The presence of EfOM may thus alter the photochemical production of reactive intermediates in rivers that receive measurable contributions of treated municipal wastewater. Quantum yield coefficients for excited triplet-state OM (3OM*) and apparent quantum yields for singlet oxygen (1O2) were measured for both whole water samples and OM isolated by solid phase extraction from whole water samples collected upstream and downstream of municipal wastewater treatment plant discharges in three rivers receiving differing effluent contributions: Hockanum R., CT (22% (v/v) effluent flow), E. Fork Little Miami R., OH (11%), and Pomperaug R., CT (6%). While only small differences in production of these reactive intermediates were observed between upstream and downstream whole water samples collected from the same river, yields of 3OM* and 1O2 varied by 30-50% between the rivers. Apparent quantum yields of 1O2 followed similar trends to those of 3OM*, consistent with 3OM* as a precursor to 1O2 formation. Higher 3OM* reactivity was observed for whole water samples than for OM isolates of the same water, suggesting differential recoveries of photoreactive moieties by solid phase extraction. 3OM* and 1O2 yields increased with increasing E2/E3 ratio (A254 nm divided by A365 nm) and decreased with increasing electron donating capacities of the samples, thus exhibiting trends also observed for reference humic and fulvic acid isolates. Mixing experiments with EfOM and DOM isolates showed evidence of quenching of triplet DOM by EfOM when measured yields were compared to theoretical yields. Together, the results suggest that effluent contributions of up to 25% (v/v) to river systems have a negligible influence on photochemical production of 3OM* and 1O2 apparently because of quenching of triplet DOM by EfOM. Furthermore, the results

  15. TECHNIQUE FOR REMOVAL OF DISSOLVED AND DISPERSED HYDROCARBONS FROM BIOASSAY EFFLUENTS

    EPA Science Inventory

    A method for the efficient removal of petroleum-derived hydrocarbons from the oil-contaminated effluent of a continuous flow-through oil bioassay system is described. The concentration of No. 2 fuel oil in the effluent, discharged at rates from 17 to 26 L/min, is reduced from an ...

  16. Tracing origins of sewage and organic matter using dissolved sterols in Masan and Haengam Bay, Korea

    NASA Astrophysics Data System (ADS)

    Lee, Hyo Jin; Hong, Sang Hee; Kim, Moonkoo; Ha, Sung Yong; An, Soon Mo; Shim, Won Joon

    2011-06-01

    Masan and Haengam Bays in Korea are highly polluted and semi-enclosed. Domestic and industrial effluents are directly or indirectly discharged into the bays through sewage treatment plants (STP) and creeks. In this study, 15 dissolved sterol compounds were determined in order to understand their sources and relative contribution. Freshwater samples were taken from 13 creeks and at two STP sites on a monthly basis. Total dissolved sterol concentrations ranged from 993 to 4158 ng/L. The concentrations of sterols in winter were higher than in summer. Among the sterols analyzed, cholesterol, β-sitosterol, coprostanol and cholestanone were major compounds in creek water. Seawater samples were concurrently collected at 21 stations in Masan Bay. Total sterol concentrations ranged 118-6,956 ng/L. Inner bay showed high concentrations of sterols in summer, while outer bay showed high sterol concentrations in winter. Among the sterols, cholesterol, β-sitosterol and brassicasterol were major compounds in seawater. In order to examine the contribution of urban sewage, the concentration of coprostanol and fecal sterol ratios were calculated. Most of the creek water, inner bay and near STP outlet samples were affected by sewage. Terrestrial organic matters accounted for a high proportion of dissolved organic matter origin. Fecal origins were relatively high in the inner bay areas and in the STP outlet, while sterols of marine origin were high in the outer bay areas.

  17. Impact of biological filtrations for organic micropollutants and polyfluoroalkyl substances removal from secondary effluent.

    PubMed

    Pramanik, Biplob Kumar; Pramanik, Sagor Kumar; Suja, Fatihah

    2016-08-01

    The impact of biological activated carbon (BAC), sand filtration (SF) and biological aerated filter (BAF) for removal of the selected organic micropollutants and polyfluoroalkyl substances (PFASs) from secondary effluent was studied. BAC led to greater removal of dissolved organic carbon (43%) than BAF (30%) which in turn was greater than SF (24%). All biological filtration systems could effectively remove most of the selected organic micropollutants, and there was a greater removal of these micropollutants by BAC (76-98%) than BAF (70-92%) or SF (68-90%). It was found that all treatment was effective for removal of the hydrophobic (log D > 3.2) and readily biodegradable organic micropollutants. The major mechanism for the removal of these molecules was biodegradation by the micro-organism and sorption by the biofilm. Compared to organic micropollutants removal, there was a lower removal of PFASs by all treatments, and BAF and SF had a considerably lower removal than BAC treatment. The better removal for all molecule types by BAC was due to additional adsorption capacity by the activated carbon. This study demonstrated that the BAC process was most effective in removing organic micropollutants present in the secondary effluent. PMID:26695189

  18. Assessment of sewage treatment plant effluents impact on river water quality using dissolved Rb/Sr ratio

    SciTech Connect

    Nirel, P.M.; Revaclier, R. )

    1999-06-15

    The authors present a new approach to elucidate and manage the impact of sewage effluents on river water quality using the dissolved Rb/Sr ratio. Rubidium is present in larger quantities than strontium in biological matrices (such as feces and urine), so that the ratio of these two elements represents an effective tracer. This is especially true in regions where the natural Rb/Sr ratio is low (calcareous regions). For a given water quality, the Rb/Sr ratio will remain constant, regardless of the river flow. Since both elements are easy to measure, this ratio has already been successfully used for pollution assessment in Geneva. The Rb/Sr ratio can also be used to model, for a given watershed, the capacity to withstand the effect of sewage effluent and to recover its natural quality.

  19. Iron traps terrestrially derived dissolved organic matter at redox interfaces

    PubMed Central

    Riedel, Thomas; Zak, Dominik; Biester, Harald; Dittmar, Thorsten

    2013-01-01

    Reactive iron and organic carbon are intimately associated in soils and sediments. However, to date, the organic compounds involved are uncharacterized on the molecular level. At redox interfaces in peatlands, where the biogeochemical cycles of iron and dissolved organic matter (DOM) are coupled, this issue can readily be studied. We found that precipitation of iron hydroxides at the oxic surface layer of two rewetted fens removed a large fraction of DOM via coagulation. On aeration of anoxic fen pore waters, >90% of dissolved iron and 27 ± 7% (mean ± SD) of dissolved organic carbon were rapidly (within 24 h) removed. Using ultra-high-resolution MS, we show that vascular plant-derived aromatic and pyrogenic compounds were preferentially retained, whereas the majority of carboxyl-rich aliphatic acids remained in solution. We propose that redox interfaces, which are ubiquitous in marine and terrestrial settings, are selective yet intermediate barriers that limit the flux of land-derived DOM to oceanic waters. PMID:23733946

  20. Photochemical flocculation of terrestrial dissolved organic matter and iron

    NASA Astrophysics Data System (ADS)

    Helms, John R.; Mao, Jingdong; Schmidt-Rohr, Klaus; Abdulla, Hussain; Mopper, Kenneth

    2013-11-01

    Dissolved organic matter (DOM) rich water samples (Great Dismal Swamp, Virginia) were 0.1-μm filtered and UV-irradiated in a solar simulator for 30 days. During the irradiation, pH increased, particulate organic matter (POM) and particulate iron formed. After 30 days, 7% of the dissolved organic carbon (DOC) was converted to POC while 75% was remineralized. Approximately 87% of the iron was removed from the dissolved phase after 30 days, but iron did not flocculate until a major fraction of DOM was removed by photochemical degradation and flocculation (>10 days); thus, during the initial 10 days, there were sufficient organic ligands present or the pH was low enough to keep iron in solution. Nuclear magnetic resonance and Fourier transform infrared spectroscopies indicated that photochemically flocculated POM was more aliphatic than the residual non-flocculated DOM. Photochemically flocculated POM was also enriched in amide functionality, while carbohydrate-like material was resistant to both photochemical degradation and flocculation. Abiotic photochemical flocculation likely removes a significant fraction of terrestrial DOM from the upper water column between headwaters and the ocean, but has previously been ignored. Preliminary evidence suggests that this process may significantly impact the transport of DOM and POM in ocean margin environments including estuaries.

  1. Iron traps terrestrially derived dissolved organic matter at redox interfaces.

    PubMed

    Riedel, Thomas; Zak, Dominik; Biester, Harald; Dittmar, Thorsten

    2013-06-18

    Reactive iron and organic carbon are intimately associated in soils and sediments. However, to date, the organic compounds involved are uncharacterized on the molecular level. At redox interfaces in peatlands, where the biogeochemical cycles of iron and dissolved organic matter (DOM) are coupled, this issue can readily be studied. We found that precipitation of iron hydroxides at the oxic surface layer of two rewetted fens removed a large fraction of DOM via coagulation. On aeration of anoxic fen pore waters, >90% of dissolved iron and 27 ± 7% (mean ± SD) of dissolved organic carbon were rapidly (within 24 h) removed. Using ultra-high-resolution MS, we show that vascular plant-derived aromatic and pyrogenic compounds were preferentially retained, whereas the majority of carboxyl-rich aliphatic acids remained in solution. We propose that redox interfaces, which are ubiquitous in marine and terrestrial settings, are selective yet intermediate barriers that limit the flux of land-derived DOM to oceanic waters. PMID:23733946

  2. Molecular weight of dissolved organic matter-napropamide complex transported through soil columns.

    PubMed

    Williams, C F; Letey, J; Farmer, W J

    2002-01-01

    Soil-derived dissolved organic matter (DOM) has been shown to form stable complexes with the herbicide napropamide [2-(alpha-naphthoxy-N,N-diethylpropionamide] capable of enhancing the transport of napropamide through soil columns. Two soils, one containing sewage sludge-derived organic matter (SS) and the other having only natural organic matter (NoSS) were treated with napropamide and allowed to dry to promote complex formation. Soil columns were prepared by packing a 10-cm layer of untreated, dry, sieved soil followed by an overlying 5-cm layer of napropamide-treated soil. Columns were irrigated and the effluent collected and placed in dialysis chambers. After equilibration napropamide concentrations were determined on both sides of the membrane and complex and quantified based on the amount of napropamide unable to cross the membrane. it was found that for the SS soil 7% and for the NoSS 2.4% of the applied napropamide underwent facilitated transport. In addition, most of the complex transported through the columns had a molecular weight between 500 and 1000 Daltons (Da). The solutions from the SS soil were also found to have formed at least two distinct complexes that were resolved after passing through the untreated soil layer. The results obtained were in agreement with other published results and the techniques used offer a way to separate and concentrate DOM complexes from column effluents for further characterization. PMID:11931454

  3. Influence of effluent organic matter on copper speciation and bioavailability in rivers under strong urban pressure.

    PubMed

    Matar, Z; Soares Pereira, C; Chebbo, G; Uher, E; Troupel, M; Boudahmane, L; Saad, M; Gourlay-France, C; Rocher, V; Varrault, Gilles

    2015-12-01

    This study focuses on spatiotemporal variations in the type of dissolved organic matter (DOM) and copper binding ability both upstream and downstream of Paris. It also compares the relative influence of both natural DOM upstream of Paris and effluent dissolved organic matter (EfDOM) output from a wastewater treatment plant (WWTP) on trace metal speciation and bioavailability in aquatic systems. In addition to the typical high- and low-affinity binding sites, a third family of very high-affinity binding sites has been highlighted for EfDOM. In receiving waters downstream of Paris during low-flow periods, the percentage of high- and very high-affinity sites originating from EfDOM reaches nearly 60 %. According to the speciation computation, the free copper concentration upstream of Paris exceeds the downstream Paris concentration by a factor of 2 to 4. As regards copper bioavailability, the highest EC50tot values were observed for EfDOM and downstream DOM, with a very low aromaticity and low UV absorbance. This finding suggests that specific ultraviolet absorbance (SUVA) is unlikely to be useful in assessing metal speciation and toxicity in aquatic systems subject to strong urban pressures. These results also highlight that the copper speciation computation for surface water exposed to considerable human pressures should include not only the humic and/or fulvic part of dissolved organic carbon but more hydrophilic fractions as well, originating for example from EfDOM. PMID:26257119

  4. Changes in the components and biotoxicity of dissolved organic matter in a municipal wastewater reclamation reverse osmosis system.

    PubMed

    Sun, Ying-Xue; Hu, Hong-Ying; Shi, Chun-Zhen; Yang, Zhe; Tang, Fang

    2016-09-01

    The characteristics of dissolved organic matter (DOM) and the biotoxicity of these components were investigated in a municipal wastewater reclamation reverse osmosis (mWRRO) system with a microfiltration (MF) pretreatment unit. The MF pretreatment step had little effect on the levels of dissolved organic carbon (DOC) in the secondary effluent, but the addition of chlorine before MF promoted the formation of organics with anti-estrogenic activity. The distribution of excitation emission matrix (EEM) fluorescence constituents exhibited obvious discrepancies between the secondary effluent and the reverse osmosis (RO) concentrate. Using size exclusion chromatography, DOM with low molecular weights of approximately 1.2 and 0.98 kDa was newly formed during the mWRRO. The normalized genotoxicity and anti-estrogenic activity of the RO concentrate were 32.1 ± 10.2 μg4-NQO/mgDOC and 0.36 ± 0.08 mgTAM/mgDOC, respectively, and these values were clearly higher than those of the secondary effluent and MF permeate. The florescence volume of Regions I and II in the EEM spectrum could be suggested as a surrogate for assessing the genotoxicity and anti-estrogenic activity of the RO concentrate. PMID:26803912

  5. Multi-pollutant treatment of crystalline cellulosic effluent: Function of dissolved oxygen on process control.

    PubMed

    Shanthi Sravan, J; Naresh Kumar, A; Venkata Mohan, S

    2016-10-01

    Treatment of crystalline cellulose based wastewater was carried out in periodic discontinuous batch reactor (PDBR). Specific influence of dissolved oxygen on treatment of crystalline cellulosic (CC) wastewater was evaluated in three different microenvironments such as aerobic, anoxic and anaerobic. PDBR-aerobic biosystem documented relatively higher substrate degradation [2.63kgCOD/m(3)-day (92%)] in comparison to PDBR-anoxic [2.12kgCOD/m(3)-day (71%)] and PDBR-anaerobic [1.81kgCOD/m(3)-day (63%)], which is in accordance with the observed DO levels. Similarly, multipollutants viz., phosphates and nitrates removal was observed to be higher in aerobic followed by anoxic and anaerobic operations. Higher nitrate removal in aerobic operation might be attributed to the efficient denitrification carried out by the biocatalyst, which utilizes both nitrates and oxygen as oxidizing agents. Multiscan spectral profiles depicted reduction in color intensity in all three microenvironments that correlated with the substrate degradation observed. Despite the high organic load, PDBR functioned well without exhibiting process inhibition. PMID:27005787

  6. The availability of dissolved organic phosphorus compounds to marine phytoplankton

    NASA Astrophysics Data System (ADS)

    Hua-Sheng, Hong; Hai-Li, Wang; Bang-Qin, Huang

    1995-06-01

    The availability of three dissolved organic phosphorus (DOP) compounds as nutrient sources for experimental culture of three algae was studied. Results indicated that these compounds could be utilized by algae, and that dissolved inorganic phosphorus (DIP) was first to be uptaken when various forms of phosphorus (DIP and DOP) co-existed. Dicrateria zhanjiangensis' uptake of sodium glycerophosphate was faster than that of D-ribose-5-phosphate. The increase of sodium glycerophosphate had little effect on the maximum uptake rate( V max) of Chlorella sp., but increased the semisaturation constant( K s) remarkably; the photosynthesis rates(PR) of Dicrateria zhanjiangensis and Chlorella sp. were rarely affected by using various forms of phosphorus in the culture experiments. The possible DOP pathways utilized by algae are discussed.

  7. Why dissolved organic matter (DOM) enhances photodegradation of methylmercury

    SciTech Connect

    Qian, Yun; Yin, Xiangping Lisa; Brooks, Scott C; Liang, Liyuan; Gu, Baohua

    2014-01-01

    Methylmercury (MeHg) is known to degrade photochemically, but it remains unclear what roles naturally dissolved organic matter (DOM) and complexing organic ligands play in MeHg photodegradation. Here we investigate the rates and mechanisms of MeHg photodegradation using DOM samples with varying oxidation states and origins as well as organic ligands with known molecular structures. All DOM and organic ligands increased MeHg photodegradation under solar irradiation, but the first-order rate constants varied depending on the oxidation state of DOM and the type and concentration of the ligands. Compounds containing both thiols and aromatics (e.g., thiosalicylate and reduced DOM) increased MeHg degradation rates far greater than those containing only aromatic or thiol functional groups (e.g., salicylate or glutathione). Our results suggest that, among other factors, the synergistic effects of thiolate and aromatic moieties in DOM greatly enhance MeHg photodegradation.

  8. Photochemical degradation of dissolved organic matter and dissolved lignin phenols from the Congo River

    NASA Astrophysics Data System (ADS)

    Spencer, Robert G. M.; Stubbins, Aron; Hernes, Peter J.; Baker, Andy; Mopper, Kenneth; Aufdenkampe, Anthony K.; Dyda, Rachael Y.; Mwamba, Vincent L.; Mangangu, Arthur M.; Wabakanghanzi, Jose N.; Six, Johan

    2009-09-01

    Photochemical degradation of Congo River dissolved organic matter (DOM) was investigated to examine the fate of terrigenous DOM derived from tropical ecosystems. Tropical riverine DOM receives greater exposure to solar radiation, particularly in large river plumes discharging directly into the open ocean. Initial Congo River DOM exhibited dissolved organic carbon (DOC) concentration and compositional characteristics typical of organic rich blackwater systems. During a 57 day irradiation experiment, Congo River DOM was shown to be highly photoreactive with a decrease in DOC, chromophoric DOM (CDOM), lignin phenol concentrations (Σ8) and carbon-normalized yields (Λ8), equivalent to losses of ˜45, 85-95, >95 and >95% of initial values, respectively, and a +3.1 ‰ enrichment of the δ13C-DOC signature. The loss of Λ8 and enrichment of δ13C-DOC during irradiation was strongly correlated (r = 0.99, p < 0.01) indicating tight coupling between these biomarkers. Furthermore, the loss of CDOM absorbance was correlated to the loss of Λ8 (e.g., a355 versus Λ8; r = 0.98, p < 0.01) and δ13C-DOC (e.g., a355 versus δ13C; r = 0.97, p < 0.01), highlighting the potential of CDOM absorbance measurements for delineating the photochemical degradation of lignin and thus terrigenous DOM. It is apparent that these commonly used measurements for examination of terrigenous DOM in the oceans have a higher rate of photochemical decay than the bulk DOC pool. Further process-based studies are required to determine the selective removal rates of these biomarkers for advancement of our understanding of the fate of this material in the ocean.

  9. Fluorescence Excitation-Emission Matrix Regional Integration to Quantify Spectra for Dissolved Organic Matter

    USGS Publications Warehouse

    Chen, W.; Westerhoff, P.; Leenheer, J.A.; Booksh, K.

    2003-01-01

    Excitation-emission matrix (EEM) fluorescence spectroscopy has been widely used to characterize dissolved organic matter (DOM) in water and soil. However, interpreting the >10,000 wavelength-dependent fluorescence intensity data points represented in EEMs has posed a significant challenge. Fluorescence regional integration, a quantitative technique that integrates the volume beneath an EEM, was developed to analyze EEMs. EEMs were delineated into five excitation-emission regions based on fluorescence of model compounds, DOM fractions, and marine waters or freshwaters. Volumetric integration under the EEM within each region, normalized to the projected excitation-emission area within that region and dissolved organic carbon concentration, resulted in a normalized region-specific EEM volume (??i,n). Solid-state carbon nuclear magnetic resonance (13C NMR), Fourier transform infrared (FTIR) analysis, ultraviolet-visible absorption spectra, and EEMs were obtained for standard Suwannee River fulvic acid and 15 hydrophobic or hydrophilic acid, neutral, and base DOM fractions plus nonfractionated DOM from wastewater effluents and rivers in the southwestern United States. DOM fractions fluoresced in one or more EEM regions. The highest cumulative EEM volume (??T,n = ????i,n) was observed for hydrophobic neutral DOM fractions, followed by lower ??T,n values for hydrophobic acid, base, and hydrophilic acid DOM fractions, respectively. An extracted wastewater biomass DOM sample contained aromatic protein- and humic-like material and was characteristic of bacterial-soluble microbial products. Aromatic carbon and the presence of specific aromatic compounds (as indicated by solid-state 13C NMR and FTIR data) resulted in EEMs that aided in differentiating wastewater effluent DOM from drinking water DOM.

  10. Dissolved oxygen as an indicator of bioavailable dissolved organic carbon in groundwater

    USGS Publications Warehouse

    Chapelle, Francis H.; Bradley, Paul M.; McMahon, Peter B.; Kaiser, Karl; Benner, Ron

    2012-01-01

    Concentrations of dissolved oxygen (DO) plotted vs. dissolved organic carbon (DOC) in groundwater samples taken from a coastal plain aquifer of South Carolina (SC) showed a statistically significant hyperbolic relationship. In contrast, DO-DOC plots of groundwater samples taken from the eastern San Joaquin Valley of California (CA) showed a random scatter. It was hypothesized that differences in the bioavailability of naturally occurring DOC might contribute to these observations. This hypothesis was examined by comparing nine different biochemical indicators of DOC bioavailability in groundwater sampled from these two systems. Concentrations of DOC, total hydrolysable neutral sugars (THNS), total hydrolysable amino acids (THAA), mole% glycine of THAA, initial bacterial cell counts, bacterial growth rates, and carbon dioxide production/consumption were greater in SC samples relative to CA samples. In contrast, the mole% glucose of THNS and the aromaticity (SUVA254) of DOC was greater in CA samples. Each of these indicator parameters were observed to change with depth in the SC system in a manner consistent with active biodegradation. These results are uniformly consistent with the hypothesis that the bioavailability of DOC is greater in SC relative to CA groundwater samples. This, in turn, suggests that the presence/absence of a hyperbolic DO-DOC relationship may be a qualitative indicator of relative DOC bioavailability in groundwater systems.

  11. Metabolomics confirms that dissolved organic carbon mitigates copper toxicity.

    PubMed

    Taylor, Nadine S; Kirwan, Jennifer A; Yan, Norman D; Viant, Mark R; Gunn, John M; McGeer, James C

    2016-03-01

    Reductions in atmospheric emissions from the metal smelters in Sudbury, Canada, produced major improvements in acid and metal contamination of local lakes and indirectly increased dissolved organic carbon (DOC) concentrations. Metal toxicity, however, has remained a persistent problem for aquatic biota. Integrating high-throughput, nontargeted mass spectrometry metabolomics with conventional toxicological measures elucidated the mediating effects of dissolved organic matter (DOM) on the toxicity of Cu to Daphnia pulex-pulicaria, a hybrid isolated from these soft water lakes. Two generations of daphniids were exposed to Cu (0-20 μg/L) at increasing levels of natural DOM (0-4 mg DOC/L). Added DOM reduced Cu toxicity monotonically with median lethal concentration values increasing from 2.3 μg/L Cu without DOM to 22.7 μg/L Cu at 4 mg DOC/L. Reproductive output similarly benefited, increasing with DOM, yet falling with increases in Cu. Second generation reproduction was more impaired than the first generation. Dissolved organic matter had a greater influence than Cu on the metabolic status of the daphniids. Putative identification of metabolite peaks indicated that DOM elevation increased the metabolic energy status of the first generation animals, but this benefit was reduced in the second generation, although evidence of increased oxidative stress was detected. These results indicate that Sudbury's terrestrial ecosystems should be managed to increase aquatic DOM supply to enable daphniid colonists to both survive and foster stable populations. Environ Toxicol Chem 2016;35:635-644. © 2015 SETAC. PMID:26274843

  12. Bacterial biomarkers thermally released from dissolved organic matter

    USGS Publications Warehouse

    Greenwood, P.F.; Leenheer, J.A.; McIntyre, C.; Berwick, L.; Franzmann, P.D.

    2006-01-01

    Hopane biomarker products were detected using microscale sealed vessel (MSSV) pyrolysis gas chromatography-mass spectrometry (GC-MS) analysis of dissolved organic matter from natural aquatic systems colonised by bacterial populations. MSSV pyrolysis can reduce the polyhydroxylated alkyl side chain of bacteriohopanepolyols, yielding saturated hopane products which are more amenable to GC-MS detection than their functionalised precursors. This example demonstrates how the thermal conditions of MSSV pyrolysis can reduce the biologically-inherited structural functionality of naturally occurring organic matter such that additional structural fragments can be detected using GC methods. This approach complements traditional analytical pyrolysis methods by providing additional speciation information useful for establishing the structures and source inputs of recent or extant organic material. ?? 2006.

  13. Utilizing Colored Dissolved Organic Matter to Derive Dissolved Black Carbon Export by Arctic Rivers

    NASA Astrophysics Data System (ADS)

    Stubbins, Aron; Spencer, Robert; Mann, Paul; Holmes, R.; McClelland, James; Niggemann, Jutta; Dittmar, Thorsten

    2015-10-01

    Wildfires have produced black carbon (BC) since land plants emerged. Condensed aromatic compounds, a form of BC, have accumulated to become a major component of the soil carbon pool. Condensed aromatics leach from soils into rivers, where they are termed dissolved black carbon (DBC). The transport of DBC by rivers to the sea is a major term in the global carbon and BC cycles. To estimate Arctic river DBC export, 25 samples collected from the six largest Arctic rivers (Kolyma, Lena, Mackenzie, Ob’, Yenisey and Yukon) were analyzed for dissolved organic carbon (DOC), colored dissolved organic matter (CDOM), and DBC. A simple, linear regression between DOC and DBC indicated that DBC accounted for 8.9 ± 0.3% DOC exported by Arctic rivers. To improve upon this estimate, an optical proxy for DBC was developed based upon the linear correlation between DBC concentrations and CDOM light absorption coefficients at 254 nm (a254). Relatively easy to measure a254 values were determined for 410 Arctic river samples between 2004 and 2010. Each of these a254 values was converted to a DBC concentration based upon the linear correlation, providing an extended record of DBC concentration. The extended DBC record was coupled with daily discharge data from the six rivers to estimate riverine DBC loads using the LOADEST modeling program. The six rivers studied cover 53% of the pan-Arctic watershed and exported 1.5 ± 0.1 million tons of DBC per year. Scaling up to the full area of the pan-Arctic watershed, we estimate that Arctic rivers carry 2.8 ± 0.3 million tons of DBC from land to the Arctic Ocean each year. This equates to ~8% of Arctic river DOC export, slightly less than indicated by the simpler DBC vs DOC correlation-based estimate. Riverine discharge is predicted to increase in a warmer Arctic. DBC export was positively correlated with river runoff, suggesting that the export of soil BC to the Arctic Ocean is likely to increase as the Arctic warms.

  14. Ocean metabolism and dissolved organic matter: How do small dissolved molecules persist in the ocean?

    NASA Astrophysics Data System (ADS)

    Benner, Ronald

    2010-05-01

    The ocean reservoir of dissolved organic matter (DOM) is among the largest global reservoirs (~700 Pg C) of reactive organic carbon. Marine primary production (~50 Pg C/yr) by photosynthetic microalgae and cyanobacteria is the major source of organic matter to the ocean and the principal substrate supporting marine food webs. The direct release of DOM from phytoplankton and other organisms as well as a variety of other processes, such as predation and viral lysis, contribute to the ocean DOM reservoir. Continental runoff and atmospheric deposition are relatively minor sources of DOM to the ocean, but some components of this material appear to be resistant to decomposition and to have a long residence time in the ocean. Concentrations of DOM are highest in surface waters and decrease with depth, a pattern that reflects the sources and diagenesis of DOM in the upper ocean. Most (70-80%) marine DOM exists as small molecules of low molecular weight (<1 kDalton). Surprisingly, high-molecular-weight (>1 kDalton) DOM is relatively enriched in major biochemicals, such as combined neutral sugars and amino acids, and is more bioavailable than low-molecular-weight DOM. The observed relationships among the size, composition, and reactivity of DOM have led to the size-reactivity continuum model, which postulates that diagenetic processes lead to the production of smaller molecules that are structurally altered and resistant to microbial degradation. The radiocarbon content of these small dissolved molecules also indicates these are the most highly aged components of DOM. Chemical signatures of bacteria are abundant in DOM and increase during diagenesis, indicating bacteria are an important source of slowly cycling biochemicals. Recent analyses of DOM isolates by ultrahigh-resolution mass spectrometry have revealed an incredibly diverse mixture of molecules. Carboxyl-rich alicyclic molecules are abundant in DOM, and they appear to be derived from diagenetically

  15. Seasonal variations in concentration and lability of dissolved organic carbon in Tokyo Bay

    NASA Astrophysics Data System (ADS)

    Kubo, A.; Yamamoto-Kawai, M.; Kanda, J.

    2015-01-01

    Concentrations of recalcitrant and bioavailable dissolved organic carbon (DOC) and their seasonal variations were investigated at three stations in Tokyo Bay, Japan, and in two freshwater sources flowing into the bay. On average, recalcitrant DOC (RDOC), as a remnant of DOC after 150 days of bottle incubation, accounted for 78% of the total DOC in Shibaura sewage treatment plant (STP) effluent, 67% in the upper Arakawa River water, 66% in the lower Arakawa River water, and 78% in surface bay water. Bioavailable DOC (BDOC) concentrations, defined as DOC minus RDOC, were lower than RDOC at all stations. In freshwater environments, RDOC concentrations were almost constant throughout the year. In the bay, RDOC was higher during spring and summer than in autumn and winter because of freshwater input and biological production. The relative concentration of RDOC in the bay derived from phytoplankton, terrestrial, and open-oceanic waters was estimated to be 8-10, 21-32, and 59-69%, respectively, based on multiple regression analysis of RDOC, salinity, and chl a. In addition, comparison with previous data from 1972 revealed that concentrations of RDOC and BDOC have decreased by 33 and 74% at freshwater sites and 39 and 76% in Tokyo Bay, while the ratio of RDOC to DOC has increased. The change in DOC concentration and composition was probably due to increased amounts of STP effluent entering the system. Tokyo Bay exported mostly RDOC to the open ocean because of the remineralization of BDOC.

  16. Seasonal variations in concentration and composition of dissolved organic carbon in Tokyo Bay

    NASA Astrophysics Data System (ADS)

    Kubo, A.; Yamamoto-Kawai, M.; Kanda, J.

    2014-07-01

    Concentrations of recalcitrant and bioavailable dissolved organic carbon (DOC) and their seasonal variations were investigated at three stations in Tokyo Bay, Japan, and in two freshwater sources flowing into the bay to evaluate the significance of DOC degradation for the carbon budget in coastal waters and carbon export to the open ocean. Recalcitrant DOC (RDOC) was differentiated from bioavailable DOC (BDOC) as a remnant of DOC after 150 days of bottle incubation. On average, RDOC accounted for 78% of the total DOC in Shibaura sewage treatment plant (STP) effluent, 67% in the upper Arakawa River water, 66% in the lower Arakawa River water, and 78% in surface bay water. RDOC concentrations were higher than BDOC at all stations. In freshwater environments, RDOC concentrations were almost constant throughout the year. In the bay, RDOC was higher during spring and summer than during autumn and winter. The relative abundance of RDOC in the bay derived from phytoplankton, terrestrial, and open oceanic waters was estimated to be 9%, 33%, and 58%, respectively, by multiple regression analysis of RDOC, salinity, and chl a. In addition, comparison with previous data from 1972 revealed that concentrations of RDOC and BDOC have decreased by 33% and 74% at freshwater sites and 39% and 76% at Tokyo Bay, while the ratio of RDOC to DOC has increased. The change in DOC concentration and composition was probably due to increased amounts of sewage treatment plant effluent entering the system. Tokyo Bay exported DOC, mostly RDOC, to the open ocean because of remineralization of BDOC.

  17. Effect of dissolved organic matter on Fe(II) oxidation in natural and engineered waters.

    PubMed

    Lee, Ying Ping; Fujii, Manabu; Terao, Koumei; Kikuchi, Tetsuro; Yoshimura, Chihiro

    2016-10-15

    Fe(II) oxidation was investigated in samples from the Sagami River basin (Japan) with particular emphasis on the effect of dissolved organic matter (DOM) in an urban river system. Collected samples consisted of main stream and tributary waters impacted to a moderate and minor extent by anthropogenic activities, respectively, and treated effluents from adjacent municipal wastewater treatment plants (MWWTPs: as representative anthropogenic point source). Nanomolar Fe(II) oxidation was measured in air-saturated waters using luminol chemiluminescence in the dark at 25 °C. Second-order rate constant for Fe(II) oxidation (with respect to Fe(II) and O2 concentrations) showed spatial and temporal variation. Annual average of the rate constant was highest for MWWTP effluents, followed by reservoir and river waters, with tributary waters showing the lowest oxidation rate. Manipulation experiments indicated that, in addition to pH (7.8-8.4), DOM characteristics are important explanatory variable for the Fe(II) oxidation. For example, the addition of MWWTP-derived humic-type DOM to anthropogenically less-influenced tributary water resulted in substantial increase in the oxidation rate. Significant negative correlation observed between the specific UV absorbance (SUVA254) and Fe(II) oxidation rate constant (pH 8.0) suggests a potential effect of humic-type DOM with low SUVA254 (high aliphatic content) on Fe(II) oxidation in natural and engineered waters. PMID:27450354

  18. The composition and degradability of upland dissolved organic matter

    NASA Astrophysics Data System (ADS)

    Moody, Catherine; Worrall, Fred; Clay, Gareth

    2016-04-01

    In order to assess controls on the degradability of DOM in stream water, samples of dissolved organic matter (DOM) and particulate organic matter (POM) were collected every month for a period of 24 months from an upland, peat-covered catchment in northern England. Each month the degradability of the DOM was assessed by exposing river water to light for up to 24 hours, and the change in the dissolved organic carbon (DOC) concentration in the water was measured. To provide context for the analysis of DOM and its degradability, samples of peat, vegetation, and litter were also taken from the same catchment and analysed. The organic matter samples were analysed by several methods including: elemental analysis (CHN and O), bomb calorimetry, thermogravimetric analysis, pyrolysis GC/MS, ICP-OES, stable isotope analysis (13C and 15N) and 13C solid state nuclear magnetic resonance (NMR). The water samples were analysed for pH, conductivity, absorbance at 400nm, anions, cations, particulate organic carbon (POC) and DOC concentrations. River flow conditions and meteorology were also recorded at the site and included in the analysis of the composition and degradability of DOM. The results of multiple regression models showed that the rates of DOC degradation were affected by the N-alkyl, O-alkyl, aldehyde and aromatic relative intensities, gross heat, OR and C:N. Of these, the N-alkyl relative intensity had the greatest influence, and this in turn was found to be dependent on the rainfall and soil temperature in the week before sampling.

  19. Global effects of agriculture on fluvial dissolved organic matter

    PubMed Central

    Graeber, Daniel; Boëchat, Iola G.; Encina-Montoya, Francisco; Esse, Carlos; Gelbrecht, Jörg; Goyenola, Guillermo; Gücker, Björn; Heinz, Marlen; Kronvang, Brian; Meerhoff, Mariana; Nimptsch, Jorge; Pusch, Martin T.; Silva, Ricky C. S.; von Schiller, Daniel; Zwirnmann, Elke

    2015-01-01

    Agricultural land covers approximately 40% of Earth’s land surface and affects hydromorphological, biogeochemical and ecological characteristics of fluvial networks. In the northern temperate region, agriculture also strongly affects the amount and molecular composition of dissolved organic matter (DOM), which constitutes the main vector of carbon transport from soils to fluvial networks and to the sea, and is involved in a large variety of biogeochemical processes. Here, we provide first evidence about the wider occurrence of agricultural impacts on the concentration and composition of fluvial DOM across climate zones of the northern and southern hemispheres. Both extensive and intensive farming altered fluvial DOM towards a more microbial and less plant-derived composition. Moreover, intensive farming significantly increased dissolved organic nitrogen (DON) concentrations. The DOM composition change and DON concentration increase differed among climate zones and could be related to the intensity of current and historical nitrogen fertilizer use. As a result of agriculture intensification, increased DON concentrations and a more microbial-like DOM composition likely will enhance the reactivity of catchment DOM emissions, thereby fuelling the biogeochemical processing in fluvial networks, and resulting in higher ecosystem productivity and CO2 outgassing. PMID:26541809

  20. Precipitates in landfill leachate mediated by dissolved organic matters.

    PubMed

    Li, Zhenze; Xue, Qiang; Liu, Lei; Li, Jiangshan

    2015-04-28

    Clogging of landfill leachate collection system is so ubiquitous that it causes problems to landfills. Although precipitations of calcite and other minerals have been widely observed, the mechanism of precipitation remains obscure. We examined the clog composition, dissolved organic matters, leachate chemical compositions and the correlation of these variables in view of the precipitation process. It is shown that Dissolved Organic Carbon (DOC) inhibits precipitation of landfill leachate. Using the advanced NICA-Donnan model, the analysis of aqueous chemical reactions between Mg-Ca-DOC-CO2 suggests a good agreement with experimental observations. Calcite and dolomite are both found to be oversaturated in most of the landfill leachate samples. DOC is found to preferentially bind with Mg than Ca, leading to more likely precipitation of Calcite than dolomite from landfill leachate. The NICA-Donnan model gives a reasonable estimation of dolomite saturation index in a wide range of DOC. Modeling confirms the major precipitation mechanism in terms of alkaline earth metal carbonate. Uncertainties in model parameters are discussed with particular focus on DOC composition, functional group types and density concentration and the influential factors. PMID:25661175

  1. Groundwater-transported dissolved organic nitrogen exports from coastal watersheds

    USGS Publications Warehouse

    Kroeger, K.D.; Cole, Marci L.; Valiela, I.

    2006-01-01

    We analyzed groundwater-transported nitrogen (N) exports from 41 watershed segments that comprised 10 Cape Cod, Massachusetts watersheds to test the hypotheses that chemical form of N exports is related to land use and to length of flow paths through watersheds. In the absence of human habitation, these glacial outwash-plain watersheds exported largely dissolved organic N (DON) but at relatively low annual rate. Addition of people to watersheds increased rates of both total dissolved N (TDN) and DON export through groundwater. Percent of TDN as DON in groundwater was negatively related to path length of groundwater through aquifers, but %DON was not significantly related to population density on the watersheds. DON was often the dominant form of N exported from the watersheds, even at high population densities. Our results suggest that natural sources are not entirely responsible for organic N exports from watersheds, but, instead, a substantial portion of anthropogenic N introduced to watersheds is exported as DON. This finding is in disagreement with previous results, which suggest that anthropogenic N is exported from watersheds largely as NO 3- and that DON exported from watersheds is from natural sources. ?? 2006, by the American Society of Limnology and Oceanography, Inc.

  2. Global effects of agriculture on fluvial dissolved organic matter

    NASA Astrophysics Data System (ADS)

    Graeber, Daniel; Boëchat, Iola G.; Encina-Montoya, Francisco; Esse, Carlos; Gelbrecht, Jörg; Goyenola, Guillermo; Gücker, Björn; Heinz, Marlen; Kronvang, Brian; Meerhoff, Mariana; Nimptsch, Jorge; Pusch, Martin T.; Silva, Ricky C. S.; von Schiller, Daniel; Zwirnmann, Elke

    2015-11-01

    Agricultural land covers approximately 40% of Earth’s land surface and affects hydromorphological, biogeochemical and ecological characteristics of fluvial networks. In the northern temperate region, agriculture also strongly affects the amount and molecular composition of dissolved organic matter (DOM), which constitutes the main vector of carbon transport from soils to fluvial networks and to the sea, and is involved in a large variety of biogeochemical processes. Here, we provide first evidence about the wider occurrence of agricultural impacts on the concentration and composition of fluvial DOM across climate zones of the northern and southern hemispheres. Both extensive and intensive farming altered fluvial DOM towards a more microbial and less plant-derived composition. Moreover, intensive farming significantly increased dissolved organic nitrogen (DON) concentrations. The DOM composition change and DON concentration increase differed among climate zones and could be related to the intensity of current and historical nitrogen fertilizer use. As a result of agriculture intensification, increased DON concentrations and a more microbial-like DOM composition likely will enhance the reactivity of catchment DOM emissions, thereby fuelling the biogeochemical processing in fluvial networks, and resulting in higher ecosystem productivity and CO2 outgassing.

  3. Photochemical and Nonphotochemical Transformations of Cysteine with Dissolved Organic Matter.

    PubMed

    Chu, Chiheng; Erickson, Paul R; Lundeen, Rachel A; Stamatelatos, Dimitrios; Alaimo, Peter J; Latch, Douglas E; McNeill, Kristopher

    2016-06-21

    Cysteine (Cys) plays numerous key roles in the biogeochemistry of natural waters. Despite its importance, a full assessment of Cys abiotic transformation kinetics, products and pathways under environmental conditions has not been conducted. This study is a mechanistic evaluation of the photochemical and nonphotochemical (dark) transformations of Cys in solutions containing chromophoric dissolved organic matter (CDOM). The results show that Cys underwent abiotic transformations under both dark and irradiated conditions. Under dark conditions, the transformation rates of Cys were moderate and were highly pH- and temperature-dependent. Under UVA or natural sunlight irradiations, Cys transformation rates were enhanced by up to two orders of magnitude compared to rates under dark conditions. Product analysis indicated cystine and cysteine sulfinic acid were the major photooxidation products. In addition, this study provides an assessment of the contributions of singlet oxygen, hydroxyl radical, hydrogen peroxide, and triplet dissolved organic matter to the CDOM-sensitized photochemical oxidation of Cys. The results suggest that another unknown pathway was dominant in the CDOM-sensitized photodegradation of Cys, which will require further study to identify. PMID:27172378

  4. Molecular-level dynamics of refractory dissolved organic matter

    NASA Astrophysics Data System (ADS)

    Niggemann, J.; Gerdts, G.; Dittmar, T.

    2012-04-01

    Refractory dissolved organic matter (DOM) accounts for most of the global oceanic organic carbon inventory. Processes leading to its formation and factors determining its stability are still largely unknown. We hypothesize that refractory DOM carries a universal molecular signature. Characterizing spatial and temporal variability in this universal signature is a key to understanding dynamics of refractory DOM. We present results from a long-term study of the DOM geo-metabolome in the open North Sea. Geo-metabolomics considers the entity of DOM as a population of compounds, each characterized by a specific function and reactivity in the cycling of energy and elements. Ten-thousands of molecular formulae were identified in DOM by ultrahigh resolution mass spectrometry analysis (FT-ICR-MS, Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry). The DOM pool in the North Sea was influenced by a complex interplay of processes that produced, transformed and degraded dissolved molecules. We identified a stable fraction in North Sea DOM with a molecular composition similar to deep ocean DOM. Molecular-level changes in this stable fraction provide novel information on dynamics and interactions of refractory DOM.

  5. Contaminant-mediated photobleaching of wetland chromophoric dissolved organic matter.

    PubMed

    Langlois, Maureen C; Weavers, Linda K; Chin, Yu-Ping

    2014-09-20

    Photolytic transformation of organic contaminants in wetlands can be mediated by chromophoric dissolved organic matter (CDOM), which in turn can lose its reactivity from photobleaching. We collected water from a small agricultural wetland (Ohio), Kawai Nui Marsh (Hawaii), the Everglades (Florida), and Okefenokee Swamp (Georgia) to assess the effect of photobleaching on the photofate of two herbicides, acetochlor and isoproturon. Analyte-spiked water samples were irradiated using a solar simulator and monitored for changes in CDOM light absorbance and dissolved oxygen. Photobleaching did not significantly impact the indirect photolysis rates of either herbicide over 24 hours of irradiation. Surprisingly, the opposite effect was observed with isoproturon, which accelerated DOM photobleaching. This phenomenon was more pronounced in higher-CDOM waters, and we believe that the redox pathway between triplet-state CDOM and isoproturon may be responsible for our observations. By contrast, acetochlor indirect photolysis was dependent on reaction with the hydroxyl radical and did not accelerate photobleaching of wetland water as much as isoproturon. Finally, herbicide indirect photolysis rate constants did not correlate strongly to any one chemical or optical property of the sampled waters. PMID:24828085

  6. Dissolved organic nitrogen in precipitation: Collection, analysis and atmospheric flux

    SciTech Connect

    Scudlark, J.R.; Church, T.M.; Russell, K.M.; Montag, J.A.; Maben, J.R.; Keene, W.C.; Galloway, J.N.

    1995-12-31

    Recent studies have documented the importance of atmosphere inorganic nitrogen deposition to coastal waters. However, due to the limited number of field measurements and concerns about the reliability of measurement techniques, the aeolian flux of organic N is very uncertain. Coordinated studies have been initiated at Lewes, DE and Charlottesville, VA to evaluate collection and analysis techniques for dissolved organic nitrogen (DON) in precipitation and to provide preliminary estimate of DON wet fluxes. Sampling was conducted both manually and employing an automated wet-only collector (ACM) on a daily basis. A total of 37 events were analyzed from October 1993 through December 1994. Side-by-side comparisons of standard white HDPE buckets and stainless steel and glass collection vessels indicate sampling artifacts associate with plastic buckets. DON in precipitation appears to be highly labile, with significant losses observed in some samples within 12 hours. Analytical methods evaluated include persulfate wet chemical oxidation, UV photo-oxidation and a modified high temperature instrumental (ANTEK 7000) technique. Based on preliminary results, the volume-weighted average concentration of DON in precipitation at the mid-Atlantic coast is 9.1 {micro}moles/1. On an annual basis, DON compromises 23% of the total dissolved nitrogen in precipitation, varying from 0--64% on an event basis. From an ecological perspective, DON wet flux represents a quantitatively important exogenous source of N to coastal waters such as Chesapeake Bay.

  7. Global effects of agriculture on fluvial dissolved organic matter.

    PubMed

    Graeber, Daniel; Boëchat, Iola G; Encina-Montoya, Francisco; Esse, Carlos; Gelbrecht, Jörg; Goyenola, Guillermo; Gücker, Björn; Heinz, Marlen; Kronvang, Brian; Meerhoff, Mariana; Nimptsch, Jorge; Pusch, Martin T; Silva, Ricky C S; von Schiller, Daniel; Zwirnmann, Elke

    2015-01-01

    Agricultural land covers approximately 40% of Earth's land surface and affects hydromorphological, biogeochemical and ecological characteristics of fluvial networks. In the northern temperate region, agriculture also strongly affects the amount and molecular composition of dissolved organic matter (DOM), which constitutes the main vector of carbon transport from soils to fluvial networks and to the sea, and is involved in a large variety of biogeochemical processes. Here, we provide first evidence about the wider occurrence of agricultural impacts on the concentration and composition of fluvial DOM across climate zones of the northern and southern hemispheres. Both extensive and intensive farming altered fluvial DOM towards a more microbial and less plant-derived composition. Moreover, intensive farming significantly increased dissolved organic nitrogen (DON) concentrations. The DOM composition change and DON concentration increase differed among climate zones and could be related to the intensity of current and historical nitrogen fertilizer use. As a result of agriculture intensification, increased DON concentrations and a more microbial-like DOM composition likely will enhance the reactivity of catchment DOM emissions, thereby fuelling the biogeochemical processing in fluvial networks, and resulting in higher ecosystem productivity and CO2 outgassing. PMID:26541809

  8. [Characteristics of dissolved organic matter in A/DAT-IAT system for municipal wastewater treatment based on ecological safety].

    PubMed

    Yang, Sai; Zhou, Qi-Xing; Hua, Tao

    2014-02-01

    To ensure the water-quality safety and harmlessness of effluent from municipal wastewater, based on the lab-scale improved SBR-A/DAT-IAT process, dissolved organic matter (DOM) in municipal wastewater, demand aeration tank (DAT) supernatant and final effluent were classified and separated by applying the ultrafiltration membranes, and indexes such as TOC, UV254, 3D-EEM and toxicity were measured, to find out the sources of the toxic substances. The results showed that the lab-scale A/DAT-IAT process performed well on each molecular-weight fraction of DOM. The main composition in the effluent was humic-like substance. Along the process, The DOM distribution presented a trend of shifting to high molecular weight. Meanwhile, the aromaticity of DOM in the fraction with relative molecular weight below 1 x 10(3) increased significantly, leading to the increase in the reactivity of effluent with chlorine, which then increased the risk of disinfection by-products. In the raw wastewater, the toxic effects were originated from the fraction with relative molecular weight below 1 x 10(3), although the toxic effects were still originated from the same fraction in the effluent, they came from the biological treatment itself instead of the raw wastewater. Based on the analysis of TOC, UV254, 3D-EEM and toxicity, the removal of low molecular-weight humic-like substance should be emphasized to achieve the effluent organic emissions standards and to control the risk of chlorination by-products and toxicity. Therefore, future studies should focus on the removal of this fraction of DOM by adjusting technological parameters or adding a targeted processing unit. PMID:24812958

  9. Release of biodegradable dissolved organic matter from ancient sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Schillawski, Sarah; Petsch, Steven

    2008-09-01

    Sedimentary rocks contain the largest mass of organic carbon on Earth, yet these reservoirs are not well integrated into modern carbon budgets. Here we describe the release of dissolved organic matter (DOM) from OM-rich sedimentary rocks under simulated weathering conditions. Results from column experiments demonstrate slow, sustained release of DOM from ancient sedimentary rocks under simulated weathering conditions. 1H-NMR analysis of shale-derived DOM reveals a highly aliphatic, carbohydrate-poor material distinct from other natural DOM pools. Shale-derived DOM is rapidly assimilated and biodegraded by aerobic heterotrophic bacteria. Consequently, no compositional signature of shale-derived DOM other than 14C-depletion is likely to persist in rivers or other surface reservoirs. Combined, these efforts show that dissolution provides a mechanism for the conversion of refractory kerogen into labile biomass, linking rock weathering with sedimentary OM oxidation and the delivery of aged OM to rivers and ocean margins.

  10. Dilution limits dissolved organic carbon utilization in the deep ocean

    NASA Astrophysics Data System (ADS)

    Arrieta, Jesús M.; Mayol, Eva; Hansman, Roberta L.; Herndl, Gerhard J.; Dittmar, Thorsten; Duarte, Carlos M.

    2015-04-01

    Oceanic dissolved organic carbon (DOC) is the second largest reservoir of organic carbon in the biosphere. About 72% of the global DOC inventory is stored in deep oceanic layers for years to centuries, supporting the current view that it consists of materials resistant to microbial degradation. An alternative hypothesis is that deep-water DOC consists of many different, intrinsically labile compounds at concentrations too low to compensate for the metabolic costs associated to their utilization. Here, we present experimental evidence showing that low concentrations rather than recalcitrance preclude consumption of a substantial fraction of DOC, leading to slow microbial growth in the deep ocean. These findings demonstrate an alternative mechanism for the long-term storage of labile DOC in the deep ocean, which has been hitherto largely ignored.

  11. Possible method for dissolved organic carbon speciation in forest soils

    NASA Astrophysics Data System (ADS)

    Drabek, O.; Tejnecký, V.; Ash, C.; Hubova, P.; Boruvka, L.

    2013-12-01

    Dissolved organic carbon (DOC) is a natural part of dissolved organic matter and it plays an important role in the biogeochemistry of soil processes. Low Molecular Mass Organic Acids (LMMOA) are an essential part of DOC. These acids play a key role in chemical processes that affect the entire soil environment. Knowing the amount of DOC and the speciation of LMMOA is required for realistic equilibrium modelling of soil chemical processes and transport mechanisms. There have been a number of proposed methods for the quantitative analysis of DOC and for speciation of LMMOA. The first aim of this contribution is to introduce and test a modified spectroscopic method for the determination of water-extractable organic carbon (WEOC) from forest soils. In general this method is based on the oxidization of WEOC by chromium-sulphuric acid. The presented method can be used as an economical alternative to the classical, more financially demanding elemental analysis. However, the main aim is to test the reliability of the method for LMMOA speciation. Ion exchange chromatography (IC) with hydroxide elution has proven to be a useful tool for the determination of LMMOA in many different water-based samples. However, the influence of multivalent cations (often present in environmental samples) on IC results has not yet been sufficiently studied. In order to assess the influence of Al, Fe, Mn, Mg and Ca on the amount of LMMOA determined by IC, an extensive set of model solutions was prepared and immediately analysed by means of IC. Moreover, the influence of pH on determined amounts of LMMOA in model solutions and representative soil aqueous extracts was investigated. These experimental results were compared to expected values and also to results provided by the chemical equilibrium model - PHREEQC. Based on the above listed research, some modifications to the common IC method for LMMOA speciation are presented.

  12. Fate of effluent organic matter during soil aquifer treatment: biodegradability, chlorine reactivity and genotoxicity.

    PubMed

    Quanrud, David M; Arnold, Robert G; Lansey, Kevin E; Begay, Carmen; Ela, Wendell; Gandolfi, A Jay

    2003-03-01

    Hydrophobic acid (HPO-A) and transphilic acid (TPI-A) fractions of dissolved organic matter (DOM) were isolated from a domestic secondary wastewater effluent that was polished via soil aquifer treatment (SAT). Fractions were isolated using XAD resin adsorption chromatography from samples obtained along the vadose zone flowpath at a full-scale basin recharge facility in Tucson, Arizona. Changes in isolate character during SAT were established via biodegradability (batch test), specific ultraviolet light absorbance (SUVA), trihalomethane formation potential (THMFP), and Ames mutagenicity assays. The dissolved organic carbon (DOC) concentration decreased by >90% during SAT. A significant fraction (up to 20%) of isolated post-SAT HPO-A was biodegradable. The (apparent) refractory nature of DOM that survives SAT may be a consequence of low DOC concentration in groundwater as well as the nature of the compounds themselves. Specific THMFP (microg THM per mg DOC) of HPO-A and TPI-A varied little as a consequence of SAT, averaging 52 and 49 microg THM per mg DOC, respectively. The nonbiodegradable fractions of HPO-A and TPI-A exhibited higher reactivities: 89 and 95 microg THM per mg DOC, respectively. Genotoxicity of HPO-A (on a per mass basis) increased after SAT, suggesting that responsible compounds are removed less efficiently than bulk organics during vadose zone transport. PMID:15384271

  13. Dissolved Organic Matter Transformations: Implications for Catchment-Scale Processes

    NASA Astrophysics Data System (ADS)

    Robinson, A.; Hernes, P.; Montanez, I.; Eustis, B.

    2006-12-01

    Particulate and dissolved phase lignin parameters are used to understand sources and dynamics of terrigenous organic matter (OM) in freshwater and marine systems. Impacts of catchment properties, such as soil type and mineralogy, vegetation distribution and hydrologic conditions on terrestrial dissolved and particulate biomarker compositions have not been addressed. Our experimental approach deciphers relative contributions of these parameters on bulk DOM compositions. Carbon-normalized lignin yields (Λ8) are one means to assess contributions of lignin phenols to bulk organic carbon. Ratios of syringyl (S), vanillyl (V) and cinnamyl (C) lignin phenols distinguish angiosperm and gymnosperm woody and nonwoody tissues. Ratios of acids:aldehydes (ad:ac) within vanillyl groups indicate diagenetic alteration of OM. Interpretation of these ratios relies on the fundamental assumption that each lignin compound behaves similarly, despite differences in solubility and sorption. Fractionation due to leaching impacts C:V, ac:al and (Λ8). C:V ranges from 1/2 to 4 times original plant compositions, increasing proportions of DOM ascribed to nonwoody tissues. Shifts in C:V and S:V due to leaching, suggest that source ratios from plant materials may not be appropriate endmembers for dissolved phases. An ~2-fold increase in ac:al ratios between litters and leachates suggest that dissolved phases are more diagenetically altered than litters, although this is simply due to solubilization. Λ8 values, tracking lignin and bulk carbon solubility differences, indicate greater loss of bulk OM relative to lignin for most plant litters. During sorption of leachates to mineral soils, lignin compositional trends are more variable compared to leaching data. Sorption of angiosperm leachates resulted in significant enrichment of S phenols on soils, which would increase the inferred contribution of angiosperms obtained for mixtures. C:V fractionation during sorption decreased in 3 of 4 plant

  14. Latitudinal Gradients in Degradation of Marine Dissolved Organic Carbon

    PubMed Central

    Arnosti, Carol; Steen, Andrew D.; Ziervogel, Kai; Ghobrial, Sherif; Jeffrey, Wade H.

    2011-01-01

    Heterotrophic microbial communities cycle nearly half of net primary productivity in the ocean, and play a particularly important role in transformations of dissolved organic carbon (DOC). The specific means by which these communities mediate the transformations of organic carbon are largely unknown, since the vast majority of marine bacteria have not been isolated in culture, and most measurements of DOC degradation rates have focused on uptake and metabolism of either bulk DOC or of simple model compounds (e.g. specific amino acids or sugars). Genomic investigations provide information about the potential capabilities of organisms and communities but not the extent to which such potential is expressed. We tested directly the capabilities of heterotrophic microbial communities in surface ocean waters at 32 stations spanning latitudes from 76°S to 79°N to hydrolyze a range of high molecular weight organic substrates and thereby initiate organic matter degradation. These data demonstrate the existence of a latitudinal gradient in the range of complex substrates available to heterotrophic microbial communities, paralleling the global gradient in bacterial species richness. As changing climate increasingly affects the marine environment, changes in the spectrum of substrates accessible by microbial communities may lead to shifts in the location and rate at which marine DOC is respired. Since the inventory of DOC in the ocean is comparable in magnitude to the atmospheric CO2 reservoir, such a change could profoundly affect the global carbon cycle. PMID:22216139

  15. Dynamics of dissolved organic matter in fjord ecosystems: Contributions of terrestrial dissolved organic matter in the deep layer

    NASA Astrophysics Data System (ADS)

    Yamashita, Youhei; McCallister, S. Leigh; Koch, Boris P.; Gonsior, Michael; Jaffé, Rudolf

    2015-06-01

    Annually, rivers and inland water systems deliver a significant amount of terrestrial organic matter (OM) to the adjacent coastal ocean in both particulate and dissolved forms; however, the metabolic and biogeochemical transformations of OM during its seaward transport remains one of the least understood components of the global carbon cycle. This transfer of terrestrial carbon to marine ecosystems is crucial in maintaining trophic dynamics in coastal areas and critical in global carbon cycling. Although coastal regions have been proposed as important sinks for exported terrestrial materials, most of the global carbon cycling data, have not included fjords in their budgets. Here we present distributional patterns on the quantity and quality of dissolved OM in Fiordland National Park, New Zealand. Specifically, we describe carbon dynamics under diverse environmental settings based on dissolved organic carbon (DOC) depth profiles, oxygen concentrations, optical properties (fluorescence) and stable carbon isotopes. We illustrate a distinct change in the character of DOC in deep waters compared to surface and mid-depth waters. Our results suggest that, both, microbial reworking of terrestrially derived plant detritus and subsequent desorption of DOC from its particulate counterpart (as verified in a desorption experiment) are the main sources of the humic-like enriched DOC in the deep basins of the studied fjords. While it has been suggested that short transit times and protection of OM by mineral sorption may ultimately result in significant terrestrial carbon burial and preservation in fjords, our data suggests the existence of an additional source of terrestrial OM in the form of DOC generated in deep, fjord water.

  16. Use of Passive Samplers to Measure Dissolved Organic Contaminants in a Temperate Estuary

    EPA Science Inventory

    Measuring dissolved concentrations of organic contaminants can be challenging given their low solubilities and high particle association. However, to perform accurate risk assessments of these chemicals, knowing the dissolved concentration is critical since it is considered to b...

  17. THE ROLE OF NITROGEN IN CHROMOPHORIC AND FLUORESCENT DISSOLVED ORGANIC MATTER FORMATION

    EPA Science Inventory

    Microbial and photochemical processes affect chromophoric dissolved organic matter (CDOM) dynamics in the ocean. Some evidence suggests that dissolved nitrogen plays a role in CDOM formation, although this has received little systematic attention in marine ecosystems. Coastal sea...

  18. Effects of ozonation and coagulation on effluent organic matter characteristics and ultrafiltration membrane fouling.

    PubMed

    Jeong, Kwon; Lee, Dae-Sung; Kim, Do-Gun; Ko, Seok-Oh

    2014-06-01

    Effluent organic matter (EfOM) is the major cause of fouling in the low pressure membranes process for wastewater reuse. Coagulation and oxidation of biological wastewater treatment effluent have been applied for the fouling control of microfiltration membranes. However, the change in EfOM structure by pre-treatments has not been clearly identified. The changes of EfOM characteristics induced by coagulation and ozonation were investigated through size exclusion chromatography, UV/Vis spectrophotometry, fluorescence spectrophotometry and titrimetric analysis to identify the mechanisms in the reduction of ultrafiltration (UF) membrane fouling. The results indicated that reduction of flux decline by coagulation was due to modified characteristics of dissolved organic carbon (DOC) content. Total concentration of DOC was not reduced by ozonation. However, the mass fraction of the molecules with molecular weight larger than 5 kDa, fluorescence intensity, aromaticity, highly condensed chromophores, average molecular weight and soluble microbial byproducts decreased greatly after ozonation. These results indicated that EfOM was partially oxidized by ozonation to low molecular weight, highly charged compounds with abundant electron-withdrawing functional groups, which are favourable for alleviating UF membrane flux decline. PMID:25079844

  19. GROUNDWATER TRANSPORT OF HYDROPHOBIC ORGANIC COMPOUNDS IN THE PRESENCE OF DISSOLVED ORGANIC MATTER

    EPA Science Inventory

    The effects of dissolved organic matter (DOM) on the transport of hydrophobic organic compounds in soil columns were investigated. Three compounds (naphthalene, phenanthrene and DDT) that spanned three orders of magnitude in water solubility were used. Instead of humic matter, mo...

  20. Catchment scale molecular composition of hydrologically mobilized dissolved organic matter

    NASA Astrophysics Data System (ADS)

    Raeke, Julia; Lechtenfeld, Oliver J.; Oosterwoud, Marieke R.; Bornmann, Katrin; Tittel, Jörg; Reemtsma, Thorsten

    2016-04-01

    Increasing concentrations of dissolved organic matter (DOM) in rivers of temperate catchments in Europe and North Amerika impose new technical challenges for drinking water production. The driving factors for this decadal increase in DOM concentration are not conclusive and changes in annual temperatures, precipitation and atmospheric deposition are intensely discussed. It is known that the majority of DOM is released by few but large hydrologic events, mobilizing DOM from riparian wetlands for export by rivers and streams. The mechanisms of this mobilization and the resulting molecular composition of the released DOM may be used to infer long-term changes in the biogeochemistry of the respective catchment. Event-based samples collected over two years from streams in three temperate catchments in the German mid-range mountains were analyzed after solid-phase extraction of DOM for their molecular composition by ultra-high resolution mass spectrometry (FT-ICR MS). Hydrologic conditions, land use and water chemistry parameters were used to complement the molecular analysis. The molecular composition of the riverine DOM was strongly dependent on the magnitude of the hydrologic events, with unsaturated, oxygen-enriched compounds being preferentially mobilized by large events. This pattern is consistent with an increase in dissolved iron and aluminum concentrations. In contrast, the relative proportions of nitrogen and sulfur bearing compounds increased with an increased agricultural land use but were less affected by the mobilization events. Co-precipitation experiments with colloidal aluminum showed that unsaturated and oxygen-rich compounds are preferentially removed from the dissolved phase. The precipitated compounds thus had similar chemical characteristics as compared to the mobilized DOM from heavy rain events. Radiocarbon analyses also indicated that this precipitated fraction of DOM was of comparably young radiocarbon age. DOM radiocarbon from field samples

  1. Fate of trace organics in a wastewater effluent dependent stream.

    PubMed

    Dong, Bingfeng; Kahl, Alandra; Cheng, Long; Vo, Hao; Ruehl, Stephanie; Zhang, Tianqi; Snyder, Shane; Sáez, A Eduardo; Quanrud, David; Arnold, Robert G

    2015-06-15

    Trace organic compounds (TOrCs) in municipal wastewater effluents that are discharged to streams are of potential concern to ecosystem and human health. This study examined the fate of a suite of TOrCs and estrogenic activity in water and sediments in an effluent-dependent stream in Tucson, Arizona. Sampling campaigns were performed during 2011 to 2013 along the Lower Santa Cruz River, where TOrCs and estrogenic activity were measured in aqueous (surface) and solid (riverbed sediment) phases. Some TOrCs, including contributors to estrogenic activity, were rapidly attenuated with distance of travel in the river. Those TOrCs that are not sufficiently attenuated and percolate to ground water have in common low biodegradation probabilities and low octanol-water distribution ratios. Independent experiments showed that attenuation of estrogenic compounds may be due in part to indirect photolysis caused by formation of organic radicals from sunlight absorption. Hydrophobic TOrCs may accumulate in riverbed sediments during dry weather periods, but riverbed sediment quality is periodically affected through storm-related scouring during periods of heavy rainfall and runoff. Taken together, evidence suggests that natural processes can attenuate at least some TOrCs, reducing potential impacts to ecosystem and human health. PMID:25777953

  2. Yucca Mountain Area Saturated Zone Dissolved Organic Carbon Isotopic Data

    SciTech Connect

    Thomas, James; Decker, David; Patterson, Gary; Peterman, Zell; Mihevc, Todd; Larsen, Jessica; Hershey, Ronald

    2007-06-25

    Groundwater samples in the Yucca Mountain area were collected for chemical and isotopic analyses and measurements of water temperature, pH, specific conductivity, and alkalinity were obtained at the well or spring at the time of sampling. For this project, groundwater samples were analyzed for major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC). The U.S. Geological Survey (USGS) performed all the fieldwork on this project including measurement of water chemistry field parameters and sample collection. The major ions dissolved in the groundwater, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) were analyzed by the USGS. All preparation and processing of samples for DOC carbon isotopic analyses and geochemical modeling were performed by the Desert Research Institute (DRI). Analysis of the DOC carbon dioxide gas produced at DRI to obtain carbon-13 and carbon-14 values was conducted at the University of Arizona Accelerator Facility (a NSHE Yucca Mountain project QA qualified contract facility). The major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of DIC were used in geochemical modeling (NETPATH) to determine groundwater sources, flow paths, mixing, and ages. The carbon isotopes of DOC were used to calculate groundwater ages that are independent of DIC model corrected carbon-14 ages. The DIC model corrected carbon-14 calculated ages were used to evaluate groundwater travel times for mixtures of water including water beneath Yucca Mountain. When possible, groundwater travel times were calculated for groundwater flow from beneath Yucca Mountain to down gradient sample sites. DOC carbon-14 groundwater ages were also calculated for groundwaters in the Yucca Mountain area. When possible, groundwater travel times were estimated for groundwater flow from beneath Yucca Mountain to down gradient groundwater sample sites using the DOC calculated

  3. Radiocarbon in dissolved organic carbon of the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Druffel, E. R. M.; Griffin, S.; Coppola, A. I.; Walker, B. D.

    2016-05-01

    Marine dissolved organic carbon (DOC) is produced in the surface ocean though its radiocarbon (14C) age in the deep ocean is thousands of years old. Here we show that ≥10% of the DOC in the deep North Atlantic is of postbomb origin and that the 14C age of the prebomb DOC is ≥4900 14C year, ~900 14C year older than previous estimates. We report 14C ages of DOC in the deep South Atlantic that are intermediate between values in the North Atlantic and the Southern Ocean. Finally, we conclude that prebomb DOC 14C ages are older and a portion of deep DOC is more dynamic than previously reported.

  4. Dissolved Organic Carbon in the North Atlantic Meridional Overturning Circulation.

    PubMed

    Fontela, Marcos; García-Ibáñez, Maribel I; Hansell, Dennis A; Mercier, Herlé; Pérez, Fiz F

    2016-01-01

    The quantitative role of the Atlantic Meridional Overturning Circulation (AMOC) in dissolved organic carbon (DOC) export is evaluated by combining DOC measurements with observed water mass transports. In the eastern subpolar North Atlantic, both upper and lower limbs of the AMOC transport high-DOC waters. Deep water formation that connects the two limbs of the AMOC results in a high downward export of non-refractory DOC (197 Tg-C·yr(-1)). Subsequent remineralization in the lower limb of the AMOC, between subpolar and subtropical latitudes, consumes 72% of the DOC exported by the whole Atlantic Ocean. The contribution of DOC to the carbon sequestration in the North Atlantic Ocean (62 Tg-C·yr(-1)) is considerable and represents almost a third of the atmospheric CO2 uptake in the region. PMID:27240625

  5. [Dissolved organic matter (DOM) dynamics in karst aquifer systems].

    PubMed

    Yao, Xin; Zou, Sheng-Zhang; Xia, Ri-Yuan; Xu, Dan-Dan; Yao, Min

    2014-05-01

    Dissolved organic matter (DOM) and nutrients have a unique way of producing, decomposing and storing in southwest karst water systems. To understand the biogeochemical cycle of DOM in karst aquifer systems, we investigated the behavioral changes of DOM fluorescence components in Zhaidi karst river system. Two humic-like components (C1 and C2), and one autochthonous tyrosine-like component (C4) were identified using the parallel factor analysis (PARAFAC) model. Compared with the traditional physical and chemical indicators, spatial heterogeneity of DOM was more obvious, which can reflect the subtle changes in groundwater system. Traditional indicators mainly reflect the regional characteristics of karst river system, while DOM fluorescence components reflect the attribute gaps of sampling types. PMID:25055664

  6. Dissolved Organic Carbon in the North Atlantic Meridional Overturning Circulation

    PubMed Central

    Fontela, Marcos; García-Ibáñez, Maribel I.; Hansell, Dennis A.; Mercier, Herlé; Pérez, Fiz F.

    2016-01-01

    The quantitative role of the Atlantic Meridional Overturning Circulation (AMOC) in dissolved organic carbon (DOC) export is evaluated by combining DOC measurements with observed water mass transports. In the eastern subpolar North Atlantic, both upper and lower limbs of the AMOC transport high-DOC waters. Deep water formation that connects the two limbs of the AMOC results in a high downward export of non-refractory DOC (197 Tg-C·yr−1). Subsequent remineralization in the lower limb of the AMOC, between subpolar and subtropical latitudes, consumes 72% of the DOC exported by the whole Atlantic Ocean. The contribution of DOC to the carbon sequestration in the North Atlantic Ocean (62 Tg-C·yr−1) is considerable and represents almost a third of the atmospheric CO2 uptake in the region. PMID:27240625

  7. Dissolved Organic Carbon in the North Atlantic Meridional Overturning Circulation

    NASA Astrophysics Data System (ADS)

    Fontela, Marcos; García-Ibáñez, Maribel I.; Hansell, Dennis A.; Mercier, Herlé; Pérez, Fiz F.

    2016-05-01

    The quantitative role of the Atlantic Meridional Overturning Circulation (AMOC) in dissolved organic carbon (DOC) export is evaluated by combining DOC measurements with observed water mass transports. In the eastern subpolar North Atlantic, both upper and lower limbs of the AMOC transport high-DOC waters. Deep water formation that connects the two limbs of the AMOC results in a high downward export of non-refractory DOC (197 Tg-C·yr‑1). Subsequent remineralization in the lower limb of the AMOC, between subpolar and subtropical latitudes, consumes 72% of the DOC exported by the whole Atlantic Ocean. The contribution of DOC to the carbon sequestration in the North Atlantic Ocean (62 Tg-C·yr‑1) is considerable and represents almost a third of the atmospheric CO2 uptake in the region.

  8. Dissolved organic carbon (DOC) in Arctic ground ice

    NASA Astrophysics Data System (ADS)

    Fritz, M.; Opel, T.; Tanski, G.; Herzschuh, U.; Meyer, H.; Eulenburg, A.; Lantuit, H.

    2015-01-01

    Thermal permafrost degradation and coastal erosion in the Arctic remobilize substantial amounts of organic carbon (OC) and nutrients which have been accumulated in late Pleistocene and Holocene unconsolidated deposits. Their vulnerability to thaw subsidence, collapsing coastlines and irreversible landscape change is largely due to the presence of large amounts of massive ground ice such as ice wedges. However, ground ice has not, until now, been considered to be a source of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC) and other elements, which are important for ecosystems and carbon cycling. Here we show, using geochemical data from a large number of different ice bodies throughout the Arctic, that ice wedges have the greatest potential for DOC storage with a maximum of 28.6 mg L-1 (mean: 9.6 mg L-1). Variation in DOC concentration is positively correlated with and explained by the concentrations and relative amounts of typically terrestrial cations such as Mg2+ and K+. DOC sequestration into ground ice was more effective during the late Pleistocene than during the Holocene, which can be explained by rapid sediment and OC accumulation, the prevalence of more easily degradable vegetation and immediate incorporation into permafrost. We assume that pristine snowmelt is able to leach considerable amounts of well-preserved and highly bioavailable DOC as well as other elements from surface sediments, which are rapidly stored in ground ice, especially in ice wedges, even before further degradation. In the Yedoma region ice wedges represent a significant DOC (45.2 Tg) and DIC (33.6 Tg) pool in permafrost areas and a fresh-water reservoir of 4172 km3. This study underlines the need to discriminate between particulate OC and DOC to assess the availability and vulnerability of the permafrost carbon pool for ecosystems and climate feedback upon mobilization.

  9. Dissolved organic carbon (DOC) in Arctic ground ice

    NASA Astrophysics Data System (ADS)

    Fritz, M.; Opel, T.; Tanski, G.; Herzschuh, U.; Meyer, H.; Eulenburg, A.; Lantuit, H.

    2015-04-01

    Thermal permafrost degradation and coastal erosion in the Arctic remobilize substantial amounts of organic carbon (OC) and nutrients which have accumulated in late Pleistocene and Holocene unconsolidated deposits. Permafrost vulnerability to thaw subsidence, collapsing coastlines and irreversible landscape change are largely due to the presence of large amounts of massive ground ice such as ice wedges. However, ground ice has not, until now, been considered to be a source of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC) and other elements which are important for ecosystems and carbon cycling. Here we show, using biogeochemical data from a large number of different ice bodies throughout the Arctic, that ice wedges have the greatest potential for DOC storage, with a maximum of 28.6 mg L-1 (mean: 9.6 mg L-1). Variation in DOC concentration is positively correlated with and explained by the concentrations and relative amounts of typically terrestrial cations such as Mg2+ and K+. DOC sequestration into ground ice was more effective during the late Pleistocene than during the Holocene, which can be explained by rapid sediment and OC accumulation, the prevalence of more easily degradable vegetation and immediate incorporation into permafrost. We assume that pristine snowmelt is able to leach considerable amounts of well-preserved and highly bioavailable DOC as well as other elements from surface sediments, which are rapidly frozen and stored in ground ice, especially in ice wedges, even before further degradation. We found that ice wedges in the Yedoma region represent a significant DOC (45.2 Tg) and DIC (33.6 Tg) pool in permafrost areas and a freshwater reservoir of 4200 km2. This study underlines the need to discriminate between particulate OC and DOC to assess the availability and vulnerability of the permafrost carbon pool for ecosystems and climate feedback upon mobilization.

  10. Estimating the Age Distribution of Oceanic Dissolved Organic Carbon

    NASA Astrophysics Data System (ADS)

    Follett, C. L.; Forney, D. C.; Repeta, D.; Rothman, D.

    2010-12-01

    Dissolved organic carbon (DOC) is a large, ubiquitous component of open ocean water at all depths and impacts atmospheric carbon dioxide levels at both short and long timescales. It is currently believed that oceanic DOC contains a multi-thousand-year-old refractory deep-water component which is mixed with a young labile component in surface waters. Unfortunately, the only evidence for this comes from a few isolated depth profiles of both DOC concentration and bulk radiocarbon. Although the profile data is consistent with a two-component mixing model, directly separating the two components has proven to be a challenge. We explore the validity of the two component mixing model by directly estimating the age distribution of oceanic DOC. The two-component model suggests that the age distribution is composed of two distinct peaks. In order to obtain an estimate of the age distribution we first record changes in both concentration and percent radiocarbon as a sample is oxidized under ultra-violet radiation [1]. We formulate a mathematical model relating the age distribution to these changes, assuming that they result from components of different radiocarbon age and UV-reactivity. This allows us to numerically invert the data and estimate the age distribution. We apply our procedure to DOC samples collected from three distinct depths (50, 500, and 2000 meters) in the north-central Pacific Ocean. [1] S.R. Beaupre, E.R.M. Druffel, and S. Griffin. A low-blank photochemical extraction system for concentration and isotopic analyses of marine dissolved organic carbon. Limnol. Oceanogr. Methods, 5:174-184, 2007.

  11. Molecular characterization of dissolved organic matter (DOM): a critical review.

    PubMed

    Nebbioso, Antonio; Piccolo, Alessandro

    2013-01-01

    Advances in water chemistry in the last decade have improved our knowledge about the genesis, composition, and structure of dissolved organic matter, and its effect on the environment. Improvements in analytical technology, for example Fourier-transform ion cyclotron (FT-ICR) mass spectrometry (MS), homo and hetero-correlated multidimensional nuclear magnetic resonance (NMR) spectroscopy, and excitation emission matrix fluorimetry (EEMF) with parallel factor (PARAFAC) analysis for UV-fluorescence spectroscopy have resulted in these advances. Improved purification methods, for example ultrafiltration and reverse osmosis, have enabled facile desalting and concentration of freshly collected DOM samples, thereby complementing the analytical process. Although its molecular weight (MW) remains undefined, DOM is described as a complex mixture of low-MW substances and larger-MW biomolecules, for example proteins, polysaccharides, and exocellular macromolecules. There is a general consensus that marine DOM originates from terrestrial and marine sources. A combination of diagenetic and microbial processes contributes to its origin, resulting in refractory organic matter which acts as carbon sink in the ocean. Ocean DOM is derived partially from humified products of plants decay dissolved in fresh water and transported to the ocean, and partially from proteinaceous and polysaccharide material from phytoplankton metabolism, which undergoes in-situ microbial processes, becoming refractory. Some of the DOM interacts with radiation and is, therefore, defined as chromophoric DOM (CDOM). CDOM is classified as terrestrial, marine, anthropogenic, or mixed, depending on its origin. Terrestrial CDOM reaches the oceans via estuaries, whereas autochthonous CDOM is formed in sea water by microbial activity; anthropogenic CDOM is a result of human activity. CDOM also affects the quality of water, by shielding it from solar radiation, and constitutes a carbon sink pool. Evidence in support

  12. Export Fluxes of Dissolved Organic Carbon From the Yukon River

    NASA Astrophysics Data System (ADS)

    Guo, L.; Cai, Y.; Belzile, C.; MacDonald, R.

    2005-12-01

    Quantitative determination of export fluxes of carbon species through Arctic rivers is required to constrain the carbon budget in the Arctic Ocean and to understand the biogeochemical consequence of climate change in Northern drainage basins. In order to quantify the annual riverine export flux from the Yukon River, monthly or bimonthly water samples were collected at Pilot Station from July 2004 to July 2005 and analyzed for concentrations of dissolved organic carbon (DOC), particulate organic carbon (POC) and dissolved inorganic carbon (DIC). Concentration of DOC varied from 182 to 1683 uM (average 441 uM), with the highest concentration during river ice opening and the lowest in April under the ice. In contrast, DIC concentration increased from ice opening in May (1178 uM) to winter frozen season (2128 uM), with an average of 1588 uM. In addition to the DOC maximum during ice opening, an elevated DOC concentration was observed during the early stage of river ice formation, suggesting the rejection of DOC from ice during its formation. There was a positive correlation of DOC with freshwater flow rate whereas DIC correlated negatively with flow, indicating a hydrological control on both components but different source terms and transport mechanisms. Integrated annual export flux during 2004/2005 was 2.78x1012 g-C/y for DOC and 4.53x1012 g-C/y for DIC. Within the annual fluxes, only 5% of DOC and 17% of DIC were exported during the winter period when the river was frozen over. Long-term observations of DOC and DIC together with their molecular and isotopic signatures are needed to understand how the Yukon River Basin responds to a changing climate.

  13. Dissolved organic carbon and its potential predictors in eutrophic lakes.

    PubMed

    Toming, Kaire; Kutser, Tiit; Tuvikene, Lea; Viik, Malle; Nõges, Tiina

    2016-10-01

    Understanding of the true role of lakes in the global carbon cycle requires reliable estimates of dissolved organic carbon (DOC) and there is a strong need to develop remote sensing methods for mapping lake carbon content at larger regional and global scales. Part of DOC is optically inactive. Therefore, lake DOC content cannot be mapped directly. The objectives of the current study were to estimate the relationships of DOC and other water and environmental variables in order to find the best proxy for remote sensing mapping of lake DOC. The Boosted Regression Trees approach was used to clarify in which relative proportions different water and environmental variables determine DOC. In a studied large and shallow eutrophic lake the concentrations of DOC and coloured dissolved organic matter (CDOM) were rather high while the seasonal and interannual variability of DOC concentrations was small. The relationships between DOC and other water and environmental variables varied seasonally and interannually and it was challenging to find proxies for describing seasonal cycle of DOC. Chlorophyll a (Chl a), total suspended matter and Secchi depth were correlated with DOC and therefore are possible proxies for remote sensing of seasonal changes of DOC in ice free period, while for long term interannual changes transparency-related variables are relevant as DOC proxies. CDOM did not appear to be a good predictor of the seasonality of DOC concentration in Lake Võrtsjärv since the CDOM-DOC coupling varied seasonally. However, combining the data from Võrtsjärv with the published data from six other eutrophic lakes in the world showed that CDOM was the most powerful predictor of DOC and can be used in remote sensing of DOC concentrations in eutrophic lakes. PMID:27318445

  14. Dissolved organic carbon transformations during laboratory-scale groundwater recharge using lagoon-treated wastewater

    SciTech Connect

    Westerhoff, P.; Pinney, M.

    2000-07-01

    Reuse of treated wastewater through groundwater recharge has emerged as an integral part of water and wastewater management in arid regions of the world. Aerated-lagoon wastewater treatment followed by surface infiltration offers a simple low-tech, low-cost treatment option for developing countries. This study investigated the fate of dissolved organic carbon (DOC) through laboratory-scale soil aquifer treatment (SAT) soil columns over a 64-week period. Aerated-lagoon wastewater (average DOE = 17 mg/l) and two soils were collected near the USA/Mexico border near Nogales, AZ. Laboratory-scale SAT columns exhibited three phases of aging where infiltration rates and DOC removals were delineated. DOC removal ranged from 39% to greater than 70% during the study, with DOC levels averaging 3.7 and 5.8 mg/l for the SAT columns packed with different soils. Soil with a higher fraction of organic carbon content had higher effluent DOC levels, presumably due to leaching of soil organic matter. UV absorbance data indicated preferential biodegradation removal of low molecular weight, low aromatic DOC. Overall, SAT reduced the potential towards forming trihalomethanes (THMs) during disinfection, although the reactivity ({mu}g THM/mg DOC) increased. SAT and groundwater recharge would provide a high degree of DOC removal in an integrated low-tech wastewater reuse management strategy, especially for developing countries in arid regions of the world.

  15. Elevated dissolved organic carbon biodegradability from thawing and collapsing permafrost

    NASA Astrophysics Data System (ADS)

    Abbott, Benjamin W.; Larouche, Julia R.; Jones, Jeremy B.; Bowden, William B.; Balser, Andrew W.

    2014-10-01

    As high latitudes warm, a portion of the large organic carbon pool stored in permafrost will become available for transport to aquatic ecosystems as dissolved organic carbon (DOC). If permafrost DOC is biodegradable, much will be mineralized to the atmosphere in freshwater systems before reaching the ocean, accelerating carbon transfer from permafrost to the atmosphere, whereas if recalcitrant, it will reach marine ecosystems where it may persist over long time periods. We measured biodegradable DOC (BDOC) in water flowing from collapsing permafrost (thermokarst) on the North Slope of Alaska and tested the role of DOC chemical composition and nutrient concentration in determining biodegradability. DOC from collapsing permafrost was some of the most biodegradable reported in natural systems. However, elevated BDOC only persisted during active permafrost degradation, with a return to predisturbance levels once thermokarst features stabilized. Biodegradability was correlated with background nutrient concentration, but nutrient addition did not increase overall BDOC, suggesting that chemical composition may be a more important control on DOC processing. Despite its high biodegradability, permafrost DOC showed evidence of substantial previous microbial processing, and we present four hypotheses explaining this incongruity. Because thermokarst features form preferentially on river banks and lake shores and can remain active for decades, thermokarst may be the dominant short-term mechanism delivering sediment, nutrients, and biodegradable organic matter to aquatic systems as the Arctic warms.

  16. Effects of Dissolved Organic Matter Source on Wetland Bacterial Metabolism

    NASA Astrophysics Data System (ADS)

    Ward, A. K.

    2005-05-01

    Wetlands are rich environments for organic matter production from a variety of wetland plant types. Investigations of the Talladega Wetland Ecosystem (TWE) in the southeastern U.S. show that bacterioplankton productivity is driven by dissolved organic carbon derived from wetland plants. The TWE is formed from a small coastal plain stream that has been dammed by beaver activity and resides in a forested catchment. In this study, bacterioplankton communities sampled from the wetland were amended with leachate from two different plants common in the TWE, the soft rush, Juncus effusus, and hazel alder, Alnus serrulata, and compared to unamended controls. The bacterioplankton response was examined by measuring bacterial carbon productivity and by an array of fluorescent microscope techniques used to distinguish metabolically active and non-active cells. Both plant leachates elicited rapid and significant increases in productivity and numbers of metabolically active bacterial cells. However, the timeframe of response, the magnitude of response, and the bacterial morphotypes varied depending on the leachate source. This study suggests that wetland bacterial communities contain different sub-component populations that may generally occur in low numbers, but that can adapt and respond rapidly to different sources of organic matter native to the wetland.

  17. Response of Dissolved Organic Matter to Warming and Nitrogen Addition

    NASA Astrophysics Data System (ADS)

    Choi, J. H.; Nguyen, H.

    2014-12-01

    Dissolved Organic Matter (DOM) is a ubiquitous mixture of soluble organic components. Since DOM is produced from the terrestrial leachate of various soil types, soil may influence the chemistry and biology of freshwater through the input of leachate and run-off. The increased temperature by climate change could dramatically change the DOM characteristics of soils through enhanced decomposition rate and losses of carbon from soil organic matter. In addition, the increase in the N-deposition affects DOM leaching from soils by changing the carbon cycling and decomposition rate of soil decay. In this study, we conducted growth chamber experiments using two types of soil (wetland and forest) under the conditions of temperature increase and N-deposition in order to investigate how warming and nitrogen addition influence the characteristics of the DOM leaching from different soil types. This leachate controls the quantity and quality of DOM in surface water systems. After 10 months of incubation, the dissolved organic carbon (DOC) concentrations decreased for almost samples in the range of 7.6 to 87.3% (ANOVA, p<0.05). The specific UV absorption (SUVA) values also decreased for almost samples after the first 3 months and then increased gradually afterward in range of 3.3 to 108.4%. Both time and the interaction between time and the temperature had the statistically significant effects on the SUVA values (MANOVA, p<0.05). Humification index (HIX) showed the significant increase trends during the duration of incubation and temperature for almost the samples (ANOVA, p<0.05). Higher decreases in the DOC values and increases in HIX were observed at higher temperatures, whereas the opposite trend was observed for samples with N-addition. The PARAFAC results showed that three fluorescence components: terrestrial humic (C1), microbial humic-like (C2), and protein-like (C3), constituted the fluorescence matrices of soil samples. During the experiment, labile DOM from the soils was

  18. Changes in dissolved organic matter during stream drying and rewetting

    NASA Astrophysics Data System (ADS)

    von Schiller, D.; Acuña, V.; Graeber, D.; Martí, E.; Ribot, M.; Sabater, S.; Timoner, X.; Tockner, K.

    2012-04-01

    Dissolved organic matter (DOM) is a complex mixture of organic compounds, which represents an essential source of carbon (C) and nutrients in aquatic ecosystems. In addition, DOM can play a key ecological role by modifying the optical properties of waters, mediating the availability of metals and influencing trophic food web structure. While the effects of drying and rewetting on DOM dynamics in terrestrial soils is a well studied subject, less is known about its effects in aquatic ecosystems, especially in streams. This is an important gap of knowledge since temporary streams that naturally cease to flow are found worldwide. Moreover, many streams with perennial flow are currently facing flow intermittency due to the effects of water extraction or changes in land-use and climate. The aim of this study was to evaluate the effects of stream flow intermittency on the spatial and temporal variability of DOM. The study was performed in a 300-m long reach of the Fuirosos stream (Catalonia, NE Spain) during the drying (June to July) and rewetting (October to November) phases. We sampled at several points along the study reach every 3 to 4 days. We assessed DOM amount by measuring the concentration of dissolved organic C and nitrogen (N). We characterized DOM composition using spectroscopic measurements, size-exclusion chromatography and C:N stoichiometry. Results showed two markedly distinct biogeochemical shifts between the drying and the rewetting phases. During the transition from continuous to fragmented flow we observed an increase in the magnitude and spatial variability of DOM concentrations and DOM was dominated by compounds from aquatic origin. After flow recovery, we also observed a pronounced increase in DOM concentration, but during this hydrologic phase DOM was dominated by compounds of terrestrial origin. Taken together, these results emphasize the relevance of flow intermittency in regulating stream DOM dynamics not only in terms of its availability but

  19. Annual Cycling of Dissolved Organic Matter in an Alpine Stream

    NASA Astrophysics Data System (ADS)

    Gabor, R. S.; McLoughlin, R.; McKnight, D. M.

    2009-12-01

    Boulder Creek, an alpine stream in the Colorado Front Range, runs through glacially-scoured landscapes and various alpine ecosystems from its headwaters at around 12,500 ft to the city of Boulder at around 6,000 ft. The flow in the lower potions of the creek is controlled by Barker Reservoir. As part of the Boulder Creek Critical Zone Observatory, water samples were collected from several sites along Boulder Creek at regular time intervals since May 2008. The concentration and quality of the Dissolved Organic Matter (DOM) in these samples was analyzed to understand the response to seasonal changes and variations in flow rates. Filtered samples were fractionated to isolate the humic material and both whole water and fulvic acid fractions were analyzed for dissolved organic carbon concentration as well as with fluorescence and UV-VIS spectroscopy. DOM concentration reached a maximum just before peak stream flow, likely due to dilution from the reservoir release. Near the end of summer, as flow slowed down and the dilution impact was minimized, the concentration began to rise again. In addition, the fluorescence index (FI), which can represent variations in DOM source, indicated a much higher microbial source during early snowmelt, likely due to microbial communities growing beneath the ice in the reservoir and lack of terrestrial runoff during the winter. The FI showed a slowly increasing terrestrial input throughout the summer as snowmelt and runoff from the watershed entered the stream. During late summer and fall the FI shifted back to a predominately microbial signal, indicative of less runoff and a greater percentage of DOM created in situ. In addition to stream measurements, surface soil samples along several transects were collected from a section of the watershed, as well as deeper samples from soil pits on both north-facing and south-facing slopes. DOM from these samples was leached with potassium sulfate and analyzed using the same techniques as the stream

  20. Optimized removal of dissolved organic carbon and trace organic contaminants during combined ozonation and artificial groundwater recharge.

    PubMed

    Hübner, U; Miehe, U; Jekel, M

    2012-11-15

    Pilot scale experiments using an 8 g/h ozonation unit and a 1.4 m(2) slow sand filter have demonstrated that the combination of ozonation and artificial groundwater recharge is suitable for efficient reduction of bulk and trace organics. The biodegradation of dissolved organic carbon (DOC) in the slow sand filter was enhanced from 22% without pre-treatment to 34% by pre-ozonation. In addition, realistic surface water concentrations of most investigated trace organic compounds (TrOCs) including carbamazepine, sulfamethoxazole, phenazone and metoprolol were reduced below the limits of quantification. Only a few TrOCs, e.g. primidone and benzotriazole, were not efficiently removed in both treatment steps and could be detected regularly in the filter effluent. For these compounds, enhanced treatment, such as advanced oxidation processes, needs to be considered. Testing for genotoxicity and cytotoxicity did not reveal any systematic adverse effects for human health. The formation of the by-product bromate from bromide was below the limit of the German drinking water directive of 10 μg/L. No removal of bromate was observed in the aerobic slow sand filter. Additional experiments with sand columns showed that operating a preceding bank filtration step to reduce DOC can reduce oxidant demand by approximately 20%. PMID:23014565

  1. Role of dissolved organic matter in ice photochemistry.

    PubMed

    Grannas, Amanda M; Pagano, Lisa P; Pierce, Brittany C; Bobby, Rachel; Fede, Alexis

    2014-09-16

    In this study, we provide evidence that dissolved organic matter (DOM) plays an important role in indirect photolysis processes in ice, producing reactive oxygen species (ROS) and leading to the efficient photodegradation of a probe hydrophobic organic pollutant, aldrin. Rates of DOM-mediated aldrin loss are between 2 and 56 times faster in ice than in liquid water (depending on DOM source and concentration), likely due to a freeze-concentration effect that occurs when the water freezes, providing a mechanism to concentrate reactive components into smaller, liquid-like regions within or on the ice. Rates of DOM-mediated aldrin loss are also temperature dependent, with higher rates of loss as temperature decreases. This also illustrates the importance of the freeze-concentration effect in altering reaction kinetics for processes occurring in environmental ices. All DOM source types studied were able to mediate aldrin loss, including commercially available fulvic and humic acids and an authentic Arctic snow DOM sample isolated by solid phase extraction, indicating the ubiquity of DOM in indirect photochemistry in environmental ices. PMID:25157605

  2. Quenching of excited triplet states by dissolved natural organic matter.

    PubMed

    Wenk, Jannis; Eustis, Soren N; McNeill, Kristopher; Canonica, Silvio

    2013-11-19

    Excited triplet states of aromatic ketones and quinones are used as proxies to assess the reactivity of excited triplet states of the dissolved organic matter ((3)DOM*) in natural waters. (3)DOM* are crucial transients in environmental photochemistry responsible for contaminant transformation, production of reactive oxygen species, and potentially photobleaching of DOM. In recent photochemical studies aimed at clarifying the role of DOM as an inhibitor of triplet-induced oxidations of organic contaminants, aromatic ketones have been used in the presence of DOM, and the question of a possible interaction between their excited triplet states and DOM has emerged. To clarify this issue, time-resolved laser spectroscopy was applied to measure the excited triplet state quenching of four different model triplet photosensitizers induced by a suite of DOM from various aquatic and terrestrial sources. While no quenching for the anionic triplet sensitizers 4-carboxybenzophenone (CBBP) and 9,10-anthraquinone-2,6-disulfonic acid (2,6-AQDS) was detected, second-order quenching rate constants with DOM for the triplets of 2-acetonaphthone (2AN) and 3-methoxyacetophenone (3MAP) in the range of 1.30-3.85 × 10(7) L mol(C)(-1) s(-1) were determined. On the basis of the average molecular weight of DOM molecules, the quenching for these uncharged excited triplet molecules is nearly diffusion-controlled, but significant quenching (>10%) in aerated water is not expected to occur below DOM concentrations of 22-72 mg(C) L(-1). PMID:24083647

  3. Benthic bacterial biomass supported by streamwater dissolved organic matter.

    PubMed

    Bott, T L; Kaplan, L A; Kuserk, F T

    1984-12-01

    Bacterial biomass in surface sediments of a headwater stream was measured as a function of dissolved organic carbon (DOC) flux and temperature. Bacterial biomass was estimated using epifluorescence microscopic counts (EMC) and ATP determinations during exposure to streamwater containing 1,788μg DOC/liter and after transfer to groundwater containing 693μg DOC/liter. Numbers of bacteria and ATP concentrations averaged 1.36×10(9) cells and 1,064 ng per gram dry sediment, respectively, under initial DOC exposure. After transfer to low DOC water, biomass estimates dropped by 53 and 55% from EMC and ATP, respectively. The decline to a new steady state occurred within 4 days from ATP assays and within 11 days from EMC measures. A 4°C difference during these exposures had little effect on generation times. The experiment indicated that 27.59 mg/hour of natural DOC supported a steady state bacterial biomass of approximately 10μg C/g dry weight of sediment (from EMC determinations). Steady state bacterial biomass estimates on sediments that were previously muffled to remove organic matter were approximately 20-fold lower. The ratio of GTP∶ATP indicated differences in physiological condition or community composition between natural and muffled sediments. PMID:24221176

  4. CHROMOPHORIC DISSOLVED ORGANIC MATTER (CDOM) DERIVED FROM DECOMPOSITION OF VARIOUS VASCULAR PLANT AND ALGAL SOURCES

    EPA Science Inventory

    Chromophoric dissolved organic (CDOM) in aquatic environments is derived from the microbial decomposition of terrestrial and microbial organic matter. Here we present results of studies of the spectral properties and photoreactivity of the CDOM derived from several organic matter...

  5. Tracing dissolved organic matter (DOM) from land-based aquaculture systems in North Patagonian streams.

    PubMed

    Nimptsch, Jorge; Woelfl, Stefan; Osorio, Sebastian; Valenzuela, Jose; Ebersbach, Paul; von Tuempling, Wolf; Palma, Rodrigo; Encina, Francisco; Figueroa, David; Kamjunke, Norbert; Graeber, Daniel

    2015-12-15

    Chile is the second largest producer of salmonids worldwide. The first step in the production of salmonids takes place in land-based aquacultures. However, the effects of the discharge from these aquacultures on stream dissolved organic matter (DOM) content, molecular composition and degradability are unknown. The aim of this study was thus to investigate the inputs of anthropogenic DOM from land-based aquaculture to the predominantly pristine river systems of North Patagonia. We hypothesized, that i) DOM exported from land-based aquaculture mainly consists of protein-like fluorescence (tyrosine and tryptophan) released from fish feces and food remains, and that ii) this DOM is highly degradable and therefore rapidly turned-over within the receiving streams. In the North Patagonian region we conducted a screening of ten land-based aquacultures and an intensive sampling campaign for one aquaculture. This was combined with longitudinal transects and a degradation experiment in order to couple the composition of DOM exported from land-based aquacultures to its degradability in streams. We measured dissolved organic carbon (DOC) concentration by high-temperature catalytic oxidation and DOM composition by fluorescence spectroscopy and parallel factor analysis. In the effluent of the ten screened aquacultures and in the repeated sampling of one aquaculture, we consistently found an increase of DOC concentrations and a dominance of protein-like fluorescence. The protein-like fluorescence rapidly disappeared downstream of the aquacultures, and in the degradation experiment. 21% of the DOC export from the repeatedly sampled aquaculture resulted from food addition and 76% from fish production. We conclude that large amounts of degradable DOM are exported from land-based aquacultures. This probably has strong effects on the ecological structure and function of North Patagonian streams, and similarly affected streams worldwide. PMID:26282747

  6. CHEMISTRY OF DISSOLVED ORGANIC CARBON AND ORGANIC ACIDS IN TWO STREAMS DRAINING FORESTED WATERSHEDS

    EPA Science Inventory

    The concentration, major fractions, and contribution of dissolved organic carbon (DOG) to stream chemistry were examined in two paired streams draining upland catchments in eastern Maine. oncentrations of DOC in East and West Bear Brooks were 183 +/- 73 and 169 +/- 70 umol CL-1 (...

  7. Estimating the removal efficiency of refractory dissolved organic matter in wastewater treatment plants using a fluorescence technique.

    PubMed

    Hur, Jin; Lee, Tae-Hwan; Lee, Bo-Mi

    2011-12-01

    The spectroscopic characteristics and relative distribution of refractory dissolved organic matter (R-DOM) in sewage have been investigated using the influent and the effluent samples collected from 15 large-scale biological wastewater treatment plants (WWTPs). Correlation between the characteristics of the influent and the final removal efficiency was also examined. Enhancement of specific ultraviolet absorbance (SUVA) and a higher R-DOM distribution ratio were observed for the effluent DOM compared with the influent DOM. However, the use of conventional rather than advanced biological treatments did not appear to affect either the effluent DOM or the removal efficiency, and there was no statistical significant difference between the two. No consistent trend was observed in the changes in the synchronous fluorescence spectra of the DOM after biological treatment. Irrespective of the treatment option, the removal efficiency of DOM was greater when the influent DOM had a lower SUVA, reduced DOC-normalized humic substance-like fluorescence, and a lower R-DOM distribution. These results suggest that selected characteristics of the influent may provide an indication of DOM removal efficiency in WWTPs. For R-DOM removal efficiency, however, similar characteristics of the influent did not show a negative relationship, and even exhibited a slight positive correlation, suggesting that the presence of refractory organic carbon structures in the influent sewage may stimulate microbial activity and inhibit the production of R-DOM during biological treatment. PMID:22439572

  8. Determination of dissolved organic matter removal efficiency in wastewater treatment works using fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Carstea, Elfrida M.; Bridgeman, John

    2015-04-01

    Fluorescence spectroscopy was used to investigate the removal efficiency of dissolved organic matter (DOM) in several wastewater treatment works, at different processing stages. The correlation between fluorescence values and biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total organic carbon (TOC) has been examined. Fluorescence was measured for unfiltered and filtered (0.45 and 0.20 μm) samples of crude, settled and secondary treated wastewater (activated sludge), and final effluent. Moreover, the potential of using portable fluorimeters has been explored in a laboratory scale activated sludge process. Good correlations were observed for filtered and unfiltered wastewater samples between protein-like fluorescence intensity (excitation 280 nm, emission 350 nm) and BOD (r = 0.78), COD (r = 0.90) and TOC (r = 0.79). BOD displayed a higher correlation at the 0.20 μm filtered samples compared to COD and TOC. Slightly better relation was seen between fluorescence and conventional parameters at the portable fluorimeters compared to laboratory-based instruments. The results indicated that fluorescence spectroscopy, in particular protein-like fluorescence, could be used for continuous, real-time assessment of DOM removal efficiency in wastewater treatment works.

  9. Interaction of bisphenol A with dissolved organic matter in extractive and adsorptive removal processes.

    PubMed

    Zhu, Fei-Die; Choo, Kwang-Ho; Chang, Hyun-Shik; Lee, Byunghwan

    2012-05-01

    The fate of endocrine disrupting chemicals (EDCs) in natural and engineered systems is complicated due to their interactions with various water constituents. This study investigated the interaction of bisphenol A (BPA) with dissolved organic matter (DOM) and colloids present in surface water and secondary effluent as well as its adsorptive removal by powdered activated carbons. The solid phase micro-extraction (SPME) method followed by thermal desorption and gas chromatography-mass spectrometry (GC-MS) was utilized for determining the distribution of BPA molecules in water. The BPA removal by SPME decreased with the increased DOM content, where the formation of BPA-DOM complexes in an aqueous matrix was responsible for the reduced extraction of BPA. Colloidal particles in water samples sorbed BPA leading to the marked reduction of liquid phase BPA. BPA-DOM complexes had a negative impact on the adsorptive removal of BPA by powered activated carbons. The complex formation was characterized based on Fourier transform infrared (FTIR) and ultraviolet-visible (UV-Vis) spectroscopy, along with the calculation of molecular interactions between BPA and functional groups in DOM. It was found that the hydrogen bonding between DOM and BPA would be preferred over aromatic interactions. A pseudo-equilibrium molecular coordination model for the complexation between a BPA molecule and a hydroxyl group of the DOM was developed, which enabled estimation of the maximum sorption site and complex formation constant as well as prediction of organic complexes at various DOM levels. PMID:22330311

  10. Formation and removal of dissolved organic nitrogen (DON) in membrane bioreactor and conventional activated sludge processes.

    PubMed

    Han, Xiaomeng; Wang, Zhiwei; Ma, Jinxing; Zheng, Junjian; Wang, Pan; Wu, Zhichao

    2015-08-01

    Dissolved organic nitrogen (DON) has become a growing concern due to its contribution to eutrophication and nitrogenous disinfection byproducts (N-DBPs) formation. However, information of DON in membrane bioreactors (MBRs) is very limited. In this study, occurrence, transformation and fate of DON in an MBR system were systematically investigated. MBR sludge showed a larger hydrolysis rate of particle organic nitrogen (PON) and also a higher transformation rate of DON to nitrate compared to conventional activated sludge (CAS). For long-term experiments, MBR achieved higher DON removal efficiency at low temperature than CAS; however, at high temperature, the effluent DON concentrations were almost the same in both systems. Batch tests on DON biodegradability showed that DON concentration increased and large molecular weight DON accumulated after 3-h aeration at low temperature, while DON concentration continuously decreased with the increase of aeration time at high temperature. The obtained results provide insights in DON removal in MBRs for meeting increasingly stringent regulations in terms of nitrogen removal. PMID:25911287

  11. Influence of dissolved organic matter on acute toxicity of zinc to larval fathead minnows (Pimephales promelas).

    PubMed

    Bringolf, Robert B; Morris, Brady A; Boese, Connie J; Santore, Robert C; Allen, Herbert E; Meyer, Joseph S

    2006-10-01

    We conducted laboratory toxicity tests in support of the development of a biotic ligand model (BLM) to predict acute toxicity of zinc (Zn) to fathead minnows (Pimephales promelas). To test the effect of dissolved organic matter (DOM) on Zn toxicity, we exposed larval fathead minnows to Zn in water containing elevated concentrations of dissolved organic carbon (DOC) in 96-h static-renewal toxicity tests. We tested DOM isolated from four surface waters: Cypress Swamp, Delaware; Edisto River, South Carolina; Suwannee River, Georgia; and Wilmington, Delaware, wastewater treatment effluent. The DOM isolates from the Edisto River and Wilmington wastewater treatment effluent contained elevated concentrations of NaCl (20-110x control NaCl) due to the use of a Na+-exchange resin to remove Ca2+ and Mg2+ during the DOM isolation process. Therefore, we also performed Zn toxicity tests in which we added up to 20 mM NaCl to exposure solutions containing Cypress Swamp and Suwannee River DOM. A threshold concentration of 11 mg DOC/L was needed to decrease Zn toxicity, after which the 96 h Zn LC50 was positively correlated with DOC concentration. Elevated NaCl concentrations did not alter Zn toxicity in the presence of DOM. In conjunction with data from other studies with fish and invertebrates, results of this study were used to calibrate Version 2.1.1 of the Zn BLM. BLM-predicted LC50s for our exposure waters containing elevated DOM concentrations were within the range of acceptable deviation relative to the observed LC50s (i.e., 0.5-2x observed LC50s); however, BLM-predicted LC50s for our exposure waters containing < 1 mg DOC/L were 2-3x lower than the observed LC50s (i.e., the BLM over-predicted the toxicity). Therefore, the current composite-species BLM for Zn could be improved for fathead minnows if that species were modeled separately from the other species used to calibrate Version 2.1.1. PMID:16788742

  12. The Impacts of Agricultural Land Use on Dissolved Organic Matter in a Dryland River System

    NASA Astrophysics Data System (ADS)

    Wise, J. L.; Bergamaschi, B. A.; Van Horn, D. J.; Diefendorf, A. F.

    2015-12-01

    Globally, expanding agriculture is significantly impacting aquatic nutrient cycles. In mesic systems, agriculture is a source of nitrogen and phosphorus and increases concentrations of structurally simple dissolved organic carbon (DOC). In contrast, recent studies suggest in dryland systems, where wastewater effluent is a primary nutrient source, agriculture is a nutrient sink—retaining nitrogen and phosphorous. Importantly, very little, is known about the influence of agriculture on DOC dynamics in dryland systems. To address this gap we used synoptic sampling, UV-absorbance, and fluorescence spectroscopy to elucidate source, character, and concentration of riverine and runoff DOC in a dryland agricultural system. Samples were collected along a 25 km stretch of the Rio Grande River in New Mexico (USA). The Rio Grande is an impoundment/irrigation-withdrawal controlled river that receives water from snowmelt, monsoonal storms, and wastewater effluent. During irrigation approximately 80% of the river's water is diverted into a manmade network where it waters crops and percolates through the soil before it enters a series of drains that return water to the river. Our preliminary characterization of the DOC reentering the river (DOCmean=3.23 mg/L, sd=0.81; SUVAmean=4.05, sd=1.37) indicates the agricultural pool is similar in concentration and aromaticity to riverine DOC (DOCmean= 3.10 mg/L, sd=1.17; SUVAmean= 4.64, sd=1.12). However, riverine organic matter is more terrestrially derived (FImean=1.68, sd=0.17) than organic matter in the drains (FImean=1.9, sd=0.24). Additionally, drains directly adjacent to actively irrigated fields show high concentrations (DOCmean=58.35; sd=0.91) of low aromaticity organic matter (SUVAmean=0.33; sd=0.11). We are continuing analysis throughout the irrigation season to further explore organic matter quality (traits such as bioavailability and freshness) and identify locations and processes of DOC transformation within the system

  13. Colored dissolved organic matter in Tampa Bay, Florida

    USGS Publications Warehouse

    Chen, Z.; Hu, C.; Conmy, R.N.; Muller-Karger, F.; Swarzenski, P.

    2007-01-01

    Absorption and fluorescence of colored dissolved organic matter (CDOM) and concentrations of dissolved organic carbon (DOC), chlorophyll and total suspended solids in Tampa Bay and its adjacent rivers were examined in June and October of 2004. Except in Old Tampa Bay (OTB), the spatial distribution of CDOM showed a conservative relationship with salinity in June, 2004 (aCDOM(400) = − 0.19 × salinity + 6.78, R2 = 0.98, n = 17, salinity range = 1.1–32.5) with little variations in absorption spectral slope and fluorescence efficiency. This indicates that CDOM distribution was dominated by mixing. In October, 2004, CDOM distribution was nonconservative with an average absorption coefficient (aCDOM(400), ∼ 7.76 m-1) about seven times higher than that in June (∼ 1.11 m-1). The nonconservative behavior was caused largely by CDOM removal at intermediate salinities (e.g., aCDOM(400) removal > 15% at salinity ∼ 13.0), which likely resulted from photobleaching due to stronger stratification. The spatial and seasonal distributions of CDOM in Tampa Bay showed that the two largest rivers, the Alafia River (AR) and Hillsborough River (HR) were dominant CDOM sources to most of the bay. In OTB, however, CDOM showed distinctive differences: lower absorption coefficient, higher absorption spectral slopes, and lower ratios of CDOM absorption to DOC and higher fluorescence efficiency. These differences may have stemmed from (1) changes in CDOM composition by more intensive photobleaching due to the longer residence time of water mass in OTB; (2) other sources of CDOM than the HR/AR inputs, such as local creeks, streams, groundwater, and/or bottom re-suspension. Average CDOM absorption in Tampa Bay at 443 nm, aCDOM(443), was about five times higher in June and about ten times higher in October than phytoplankton pigment absorption, aph(443), indicating that blue light attenuation in the water column was dominated by CDOM rather than by phytoplankton absorption throughout the

  14. Characterization Of Dissolved Organic Mattter In The Florida Keys Ecosystem

    NASA Astrophysics Data System (ADS)

    Adams, D. G.; Shank, G. C.

    2009-12-01

    Over the past few decades, Scleractinian coral populations in the Florida Keys have increasingly experienced mortality due to bleaching events as well as microbial mediated illnesses such as black band and white band disease. Such pathologies seem to be most correlated with elevated sea surface temperatures, increased UV exposures, and shifts in the microbial community living on the coral itself. Recent studies indicate that corals’ exposure to UV in the Florida Keys is primarily controlled by the concentration of CDOM (Chromophoric Dissolved Organic Matter) in the water column. Further, microbial community alterations may be linked to changes in concentration and chemical composition of the larger DOM (Dissolved Organic Matter) pool. Our research characterized the spatial and temporal properties of DOM in Florida Bay and along the Keys ecosystems using DOC analyses, in-situ water column optical measurements, and spectral analyses including absorbance and fluorescence measurements. We analyzed DOM characteristics along transects running from the mouth of the Shark River at the southwest base of the Everglades, through Florida Bay, and along near-shore Keys coastal waters. Two 12 hour time-series samplings were also performed at the Seven-Mile Bridge, the primary Florida Bay discharge channel to the lower Keys region. Photo-bleaching experiments showed that the chemical characteristics of the DOM pool are altered by exposure to solar radiation. Results also show that DOC (~0.8-5.8 mg C/L) and CDOM (~0.5-16.5 absorbance coefficient at 305nm) concentrations exhibit seasonal fluctuations in our study region. EEM analyses suggest seasonal transitions between primarily marine (summer) and terrestrial (winter) sources along the Keys. We are currently combining EEM-PARAFAC analysis with in-situ optical measurements to model changes in the spectral properties of DOM in the water column. Additionally, we are using stable δ13C isotopic analysis to further characterize DOM

  15. Photolytic processing of secondary organic aerosols dissolved in cloud droplets.

    PubMed

    Bateman, Adam P; Nizkorodov, Sergey A; Laskin, Julia; Laskin, Alexander

    2011-07-14

    The effect of UV irradiation on the molecular composition of aqueous extracts of secondary organic aerosol (SOA) was investigated. SOA was prepared by the dark reaction of ozone and d-limonene at 0.05-1 ppm precursor concentrations and collected with a particle-into-liquid sampler (PILS). The PILS extracts were photolyzed by 300-400 nm radiation for up to 24 h. Water-soluble SOA constituents were analyzed using high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) at different stages of photolysis for all SOA precursor concentrations. Exposure to UV radiation increased the average O/C ratio and decreased the average double bond equivalent (DBE) of the dissolved SOA compounds. Oligomeric compounds were significantly decreased by photolysis relative to the monomeric compounds. Direct pH measurements showed that acidic compounds increased in abundance upon photolysis. Methanol reactivity analysis revealed significant photodissociation of molecules containing carbonyl groups and the formation of carboxylic acids. Aldehydes, such as limononaldehyde, were almost completely removed. The removal of carbonyls was further confirmed by the UV/Vis absorption spectroscopy of the SOA extracts where the absorbance in the carbonyl n→π* band decreased significantly upon photolysis. The effective quantum yield (the number of carbonyls destroyed per photon absorbed) was estimated as ∼0.03. The total concentration of peroxides did not change significantly during photolysis as quantified with an iodometric test. Although organic peroxides were photolyzed, the likely end products of photolysis were smaller peroxides, including hydrogen peroxide, resulting in a no net change in the peroxide content. Photolysis of dry limonene SOA deposited on substrates was investigated in a separate set of experiments. The observed effects on the average O/C and DBE were similar to the aqueous photolysis, but the extent of chemical change was smaller in dry SOA. Our results suggest

  16. The soil organic carbon content of anthropogenically altered organic soils effects the dissolved organic matter quality, but not the dissolved organic carbon concentrations

    NASA Astrophysics Data System (ADS)

    Frank, Stefan; Tiemeyer, Bärbel; Bechtold, Michel; Lücke, Andreas; Bol, Roland

    2016-04-01

    Dissolved organic carbon (DOC) is an important link between terrestrial and aquatic ecosystems. This is especially true for peatlands which usually show high concentrations of DOC due to the high stocks of soil organic carbon (SOC). Most previous studies found that DOC concentrations in the soil solution depend on the SOC content. Thus, one would expect low DOC concentrations in peatlands which have anthropogenically been altered by mixing with sand. Here, we want to show the effect of SOC and groundwater level on the quantity and quality of the dissolved organic matter (DOM). Three sampling sites were installed in a strongly disturbed bog. Two sites differ in SOC (Site A: 48%, Site B: 9%) but show the same mean annual groundwater level of 15 and 18 cm below ground, respectively. The SOC content of site C (11%) is similar to Site B, but the groundwater level is much lower (-31 cm) than at the other two sites. All sites have a similar depth of the organic horizon (30 cm) and the same land-use (low-intensity sheep grazing). Over two years, the soil solution was sampled bi-weekly in three depths (15, 30 and 60 cm) and three replicates. All samples were analyzed for DOC and selected samples for dissolved organic nitrogen (DON) and delta-13C and delta-15N. Despite differences in SOC and groundwater level, DOC concentrations did not differ significantly (A: 192 ± 62 mg/L, B: 163 ± 55 mg/L and C: 191 ± 97 mg/L). At all sites, DOC concentrations exceed typical values for peatlands by far and emphasize the relevance even of strongly disturbed organic soils for DOC losses. Individual DOC concentrations were controlled by the temperature and the groundwater level over the preceding weeks. Differences in DOM quality were clearer. At site B with a low SOC content, the DOC:DON ratio of the soil solution equals the soil's C:N ratio, but the DOC:DON ratio is much higher than the C:N ratio at site A. In all cases, the DOC:DON ratio strongly correlates with delta-13C. There is no

  17. Molecular simulation of a model of dissolved organic matter

    SciTech Connect

    Sutton, Rebecca; Sposito, Garrison; Diallo, Mamadou S.; Schulten,Hans-Rolf

    2004-11-08

    A series of atomistic simulations was performed to assess the ability of the Schulten dissolved organic matter (DOM) molecule, a well-established model humic molecule, to reproduce the physical and chemical behavior of natural humic substances. The unhydrated DOM molecule had a bulk density value appropriate to humic matter, but its Hildebrand solubility parameter was lower than the range of current experimental estimates. Under hydrated conditions, the DOM molecule went through conformational adjustments that resulted in disruption of intramolecular hydrogen bonds (H-bonds), although few water molecules penetrated the organic interior. The radius of gyration of the hydrated DOM molecule was similar to those measured for aquatic humic substances. To simulate humic materials under aqueous conditions with varying pH levels, carboxyl groups were deprotonated, and hydrated Na{sup +} or Ca{sup 2+} were added to balance the resulting negative charge. Because of intrusion of the cation hydrates, the model metal- humic structures were more porous, had greater solvent-accessible surface areas, and formed more H-bonds with water than the protonated, hydrated DOM molecule. Relative to Na{sup +}, Ca{sup 2+} was both more strongly bound to carboxylate groups and more fully hydrated. This difference was attributed to the higher charge of the divalent cation. The Ca-DOM hydrate, however, featured fewer H-bonds than the Na-DOM hydrate, perhaps because of the reduced orientational freedom of organic moieties and water molecules imposed by Ca{sup 2+}. The present work is, to our knowledge, the first rigorous computational exploration regarding the behavior of a model humic molecule under a range of physical conditions typical of soil and water systems.

  18. Dissolved inorganic and organic selenium in the Orca Basin

    NASA Astrophysics Data System (ADS)

    Takayanagi, Kazufumi; Wong, George T. F.

    1985-02-01

    The vertical distributions of Se (IV), Se (VI) and dissolved organic Se have been determined in the oxic and non-sulfide-bearing anoxic zones of the Orca Basin. In the oxic waters, the concentration of Se (IV) increases with depth gradually from 0.25 nmole/kg at the surface to a maximum of 0.46 nmole/kg at 750 m and then decreases with depth to a relatively constant concentration of 0.39 nmole/ kg below 1,230 m. The concentration of Se (VI) is rather uniform in the top 250 m at about 0.24 nmole/ kg. Below 250 m it increases with depth to 0.50 nmole/kg at 1.230 m, and it stays relatively constant below this depth. The concentration of organic Se increases from 0.50 nmole/kg at the surface to 1.39 nmole/kg at 78 m. A pronounced broad maximum of organic Se exists between 78 and 250 m. The concentration decreases with depth below 250 m, dropping sharply between 250 and 380 m and more gradually at greater depths. It becomes undetectable at 1,230 m. Organic Se is the dominant species above 250 m. Se (IV) is the most abundant between 250 and 1,000 m while Se (VI) becomes the dominant species below 1,000 m. The distributions of these three species can be explained by the biological uptake of Se in the surface waters and the multi-step regeneration of Se from biogenic particles at greater depths. In suboxic waters at the oxic-anoxic interface, the concentration of Se (IV) increases while that of Se (VI) decreases reflecting a change in redox conditions in the environment. In the anoxic brine, the concentration of Se (IV) is around 0.25 nmole/kg while Se (VI) is undetectable. The concentration of organic Se increases sharply in the suboxic waters and reaches 2.6 nmole/kg in the anoxic brines probably as a result of the decomposition of organic matter and/or a diffusive flux from the underlying sediment.

  19. Dissolved Organic Carbon in the Yukon River Basin

    NASA Astrophysics Data System (ADS)

    Aiken, G.; Striegl, R.; Schuster, P.

    2003-12-01

    A critical question in carbon cycling is how climate change could alter the fate and chemical nature of dissolved organic carbon (DOC) released from watersheds and transported to rivers, lakes, estuaries and coastal waters. The spatial and temporal variability of DOC in surface waters associated with the Yukon River Basin is being studied to better define the processes controlling DOC in this system. The Yukon River Basin, a large and diverse ecosystem in northwestern Canada and central Alaska, is experiencing increasing temperatures, partial melting of permafrost, drying of upland soils and changing wetland environments. However, little is known about DOC transported in the system. Specific ultraviolet absorbance (SUVA) measurements, in combination with DOC and DOC fractionation analyses, were used to determine both the amount and nature of DOC in the Yukon River and major tributaries. DOC transported in the Yukon River and its tributaries was seasonally dependent. For example, DOC concentrations in the Yukon River at Steven's Village ranged from 2 to 17 mg C/L during 2003, and SUVA ranged from 2.0 to 3.5 L/mg C m, indicating a large variation in amount and nature of organic matter in the river. Lowest DOC concentrations and SUVA values were observed in winter under low flow conditions. Greatest DOC concentrations were measured on samples collected during the spring on the leading part of the hydrograph. These samples were also found to have the greatest SUVA values indicating that the organic matter transported during this period was more aromatic than DOC transported under low flow conditions. High SUVA values are indicative of greater amounts of organic material originating in soils and wetlands of the watershed. The amount and nature of organic matter transported by the tributaries appeared to be related to relief and wetland contribution to the watershed of the tributary. Based on DOC and SUVA data, the Yukon River tributaries can be classified as dark water

  20. Chemical composition of dissolved organic matter draining permafrost soils

    NASA Astrophysics Data System (ADS)

    Ward, Collin P.; Cory, Rose M.

    2015-10-01

    Northern circumpolar permafrost soils contain roughly twice the amount of carbon stored in the atmosphere today, but the majority of this soil organic carbon is perennially frozen. Climate warming in the arctic is thawing permafrost soils and mobilizing previously frozen dissolved organic matter (DOM) from deeper soil layers to nearby surface waters. Previous studies have reported that ancient DOM draining deeper layers of permafrost soils was more susceptible to degradation by aquatic bacteria compared to modern DOM draining the shallow active layer of permafrost soils, and have suggested that DOM chemical composition may be an important control for the lability of DOM to bacterial degradation. However, the compositional features that distinguish DOM drained from different depths in permafrost soils are poorly characterized. Thus, the objective of this study was to characterize the chemical composition of DOM drained from different depths in permafrost soils, and relate these compositional differences to its susceptibility to biological degradation. DOM was leached from the shallow organic mat and the deeper permafrost layer of soils within the Imnavait Creek watershed on the North Slope of Alaska. DOM draining both soil layers was characterized in triplicate by coupling ultra-high resolution mass spectrometry, 13C solid-state NMR, and optical spectroscopy methods with multi-variate statistical analyses. Reproducibility of replicate mass spectra was high, and compositional differences resulting from interfering species or isolation effects were significantly smaller than differences between DOM drained from each soil layer. All analyses indicated that DOM leached from the shallower organic mat contained higher molecular weight, more oxidized, and more unsaturated aromatic species compared to DOM leached from the deeper permafrost layer. Bacterial production rates and bacterial efficiencies were significantly higher for permafrost compared to organic mat DOM

  1. The Characterization of Dissolved Organic Nitrogen in Wetlands by Ultrahigh Resolution Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Podgorski, D. C.; Osborne, D.; Cooper, W. T.

    2009-12-01

    Dissolved Organic Nitrogen (DON) in agricultural runoff water can prove to be troublesome to wetland ecosystems. Therefore, Water Quality Treatment Areas (WQTAs) have been developed to reduce total nitrogen (TN) concentrations, specifically, organic nitrogen. At present the only parameter available for judging the effectiveness of WQTAs is total DON. However, total DON does not account for the biogeochemistry of individual organic nitrogen compounds. There are no doubt many organic-N species that are refractory and present no threat to receiving waters, but they are nevertheless counted as TN. Unfortunately, there is no general method for determining which DON molecules are biodegradable and which are refractory. The purpose of this research is to provide an analytical method that will drive the design of WTQAs that more effectively reduce organic nitrogen concentrations. We coupled Atmospheric Pressure Photo-ionization (APPI) with Fourier Transform-Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) to specifically focus on the characterization of DON compounds. Atmospheric pressure photoionization (APPI) represents an attractive alternative to the more conventional electrospray ionization (ESI) method. APPI has the ability to ionize both polar and nonpolar compounds, many of which are unobservable by ESI. APPI coupled with the ultrahigh resolution and mass accuracy provided by FT-ICR MS allowed us to unambiguously assign molecular formulas to the specific DON compounds. Therefore, we were able to determine the degree of oxidation and presence of other hetero-atoms, such as sulfur, in these DON compounds. Comparative analysis of the influent and effluent waters from the WTQAs provided valuable data about what types of molecules are successfully removed during the treatment process. This molecular level information was previously unavailable with other analytical techniques, and it may be used to design more effective WQTAs in the future.

  2. Dissolved organic matter reduces algal accumulation of methylmercury

    USGS Publications Warehouse

    Luengen, Allison C.; Fisher, Nicholas S.; Bergamaschi, Brian A.

    2012-01-01

    Dissolved organic matter (DOM) significantly decreased accumulation of methylmercury (MeHg) by the diatom Cyclotella meneghiniana in laboratory experiments. Live diatom cells accumulated two to four times more MeHg than dead cells, indicating that accumulation may be partially an energy-requiring process. Methylmercury enrichment in diatoms relative to ambient water was measured by a volume concentration factor (VCF). Without added DOM, the maximum VCF was 32 x 104, and the average VCF (from 10 to 72 h) over all experiments was 12.6 x 104. At very low (1.5 mg/L) added DOM, VCFs dropped by approximately half. At very high (20 mg/L) added DOM, VCFs dropped 10-fold. Presumably, MeHg was bound to a variety of reduced sulfur sites on the DOM, making it unavailable for uptake. Diatoms accumulated significantly more MeHg when exposed to transphilic DOM extracts than hydrophobic ones. However, algal lysate, a labile type of DOM created by resuspending a marine diatom in freshwater, behaved similarly to a refractory DOM isolate from San Francisco Bay. Addition of 67 μM L-cysteine resulted in the largest drop in VCFs, to 0.28 x 104. Although the DOM composition influenced the availability of MeHg to some extent, total DOM concentration was the most important factor in determining algal bioaccumulation of MeHg.

  3. [Effects of dissolved organic matter on copper absorption by ryegrass].

    PubMed

    Tang, Chao; Wang, Bin; Liu, Man-Qiang; Hu, Feng; Li, Hui-Xin; Jiao, Jia-Guo

    2012-08-01

    In this study, dissolved organic matter (DOM) was extracted from earthworm casts and from the cattle manure with which the earthworms were fed, and a water culture experiment was conducted to study the effects of the DOM on the copper (Cu2+) absorption by ryegrass in the presence of different concentration Cu2+ (0, 5 and 10 mg x L(-1)). With the increasing concentration of Cu2+ in the medium, there was a gradual decrease in the dry mass of ryegrass shoots and roots and in the root length, surface area, volume, and tip number. In the presence of medium Cu2+, DOM increased the biomass of shoots and roots and the root length, surface area, volume, and tip number significantly. DOM reduced the Cu2+ concentration in roots, promoted the Cu2+ translocation from roots to shoots, and significantly increased the Cu2+ accumulation in shoots. The DOM from earthworm casts had better effects than that from cattle manure, and high concentration DOM had better effects than low concentration DOM. PMID:23189712

  4. Variations in dissolved organic carbon concentrations across peatland hillslopes

    NASA Astrophysics Data System (ADS)

    Boothroyd, I. M.; Worrall, F.; Allott, T. E. H.

    2015-11-01

    Peatlands are important terrestrial carbon stores and dissolved organic carbon (DOC) is one of the most important contributors to carbon budgets in peatland systems. Many studies have investigated factors affecting DOC concentration in peatland systems, yet hillslope position has been thus far overlooked as a variable that could influence DOC cycling. This study investigates the importance of hillslope position with regard to DOC cycling. Two upland peat hillslopes were studied in the Peak District, UK, to determine what impact, if any, hillslope position had upon DOC concentration. Hillslope position was found to be a significant factor affecting variation in soil pore water DOC concentration, with bottom-slope positions having significantly lower DOC concentrations than up-slope because of dilution of DOC as water moves down-slope and is flushed out of the system via lateral throughflow. Water table drawdown on steeper mid-slopes increased DOC concentrations through increased DOC production and extended residence times allowing a build-up of humic-rich DOC compounds. Hillslope position did not significantly affect DOC concentrations in surface runoff water because of the dilution of near-surface soil pore water by precipitation inputs, while stream water had similar water chemistry properties to soil pore water under low-flow conditions.

  5. Black Carbon in Estuarine and Coastal Ocean Dissolved Organic Matter

    NASA Technical Reports Server (NTRS)

    Mannino, Antonio; Harvey, H. Rodger

    2003-01-01

    Black carbon (BC) in ultrafiltered high-molecular-weight DOM (UDOM) was measured in surface waters of Delaware Bay, Chesapeake Bay and the adjacent Atlantic Ocean (USA) to ascertain the importance of riverine and estuarine DOM as a source of BC to the ocean. BC comprised 5-72% of UDOM-C (27+/-l7%) and on average 8.9+/-6.5% of dissolved organic carbon (DOC) with higher values in the turbid region of the Delaware Estuary and lower yields in the river and coastal ocean. The spatial and seasonal distributions of BC along the salinity gradient of Delaware Bay suggest that the higher levels of BC in surface water UDOM originated from localized sources, possibly from atmospheric deposition or released from resuspended sediments. Black carbon comprised 4 to 7% of the DOC in the coastal Atlantic Ocean, revealing that river-estuary systems are important exporters of colloidal BC to the ocean. The annual flux of BC from Delaware Bay UDOM to the Atlantic Ocean was estimated at 2.4x10(exp 10) g BC yr(exp -1). The global river flux of BC through DOM to the ocean could be on the order of 5.5x1O(exp 12)g BC yr (exp -1). These results support the hypothesis that the DOC pool is the intermediate reservoir in which BC ages prior to sedimentary deposition.

  6. Hidden cycle of dissolved organic carbon in the deep ocean

    PubMed Central

    Follett, Christopher L.; Repeta, Daniel J.; Rothman, Daniel H.; Xu, Li; Santinelli, Chiara

    2014-01-01

    Marine dissolved organic carbon (DOC) is a large (660 Pg C) reactive carbon reservoir that mediates the oceanic microbial food web and interacts with climate on both short and long timescales. Carbon isotopic content provides information on the DOC source via δ13C and age via Δ14C. Bulk isotope measurements suggest a microbially sourced DOC reservoir with two distinct components of differing radiocarbon age. However, such measurements cannot determine internal dynamics and fluxes. Here we analyze serial oxidation experiments to quantify the isotopic diversity of DOC at an oligotrophic site in the central Pacific Ocean. Our results show diversity in both stable and radio isotopes at all depths, confirming DOC cycling hidden within bulk analyses. We confirm the presence of isotopically enriched, modern DOC cocycling with an isotopically depleted older fraction in the upper ocean. However, our results show that up to 30% of the deep DOC reservoir is modern and supported by a 1 Pg/y carbon flux, which is 10 times higher than inferred from bulk isotope measurements. Isotopically depleted material turns over at an apparent time scale of 30,000 y, which is far slower than indicated by bulk isotope measurements. These results are consistent with global DOC measurements and explain both the fluctuations in deep DOC concentration and the anomalous radiocarbon values of DOC in the Southern Ocean. Collectively these results provide an unprecedented view of the ways in which DOC moves through the marine carbon cycle. PMID:25385632

  7. Chemical Characterization of Dissolved Organic Matter in Hiroshima Bay, Japan

    NASA Astrophysics Data System (ADS)

    Fukushima, T.; Ishibashi, T.; Imai, A.

    2001-07-01

    The concentrations of dissolved organic carbon (DOC) and hydrophilic DOC (Hil-DOC) in Hiroshima Bay showed clear seasonal changes (high in summer and low in winter), suggesting the autochthonous production of Hil-DOC. The percentages of hydrophobic DOC (Hob-DOC) fractionated by XAD-8 resin were 33% for the bay waters and 41% for the river waters, whereas those of labile DOC (which decomposed during an incubation period of 100 days) were 20% and 24%, respectively. The increment of DOC to Chlorophyll a was calculated to be (0·014 mgl -1)/(μgl -1). The mixing experiments suggested a negligible deposition of DOC at the estuaries of inflowing rivers. The Hob-DOC went through the bay with negligible changes in concentration in both summer and winter, but its chemical characteristics, e.g. spectrophotometric properties and mean molecular weight, differed from those of riverine origin. In contrast, both labile and refractory components of Hil-DOC were produced mainly in the inner part of the bay during summer, and although a significant percentage of the labile component was subjected to biodegradation during transport to the outer part of the bay, its chemical characteristics did not change dramatically.

  8. Photochemical Degradation of Persistent Organic Pollutants: A Study of Ice Photochemistry Mediated by Dissolved Organic Matter

    NASA Astrophysics Data System (ADS)

    Bobby, R.; Pagano, L.; Grannas, A. M.

    2012-12-01

    It is well established that ice is a reactive medium in the environment and that active photochemistry occurs in frozen systems. Snow and ice contain a number of absorbing species including nitrate, peroxide and organic matter. Upon irradiation, they can generate a variety of reactive intermediates such as hydroxyl radical and singlet oxygen. It has been shown that dissolved organic matter is a ubiquitous component of snow and ice and plays an important role in overall light absorption properties of the sample. Additionally, the reactive intermediates produced can further react with contaminants present and alter their fate in the environment. Unfortunately, the role of dissolved organic matter in ice photochemistry has received little attention. Here we present results from laboratory-based studies aimed at elucidating the role of dissolved organic matter photochemistry on contaminant degradation in ice. Aqueous samples of our target pollutant, aldrin (20 μg/L), in liquid and frozen phases, were irradiated under Q-Panel 340 lamps to simulate the UV radiation profile of natural sunlight. Results indicated that frozen samples degraded more quickly than liquid samples and that the addition of dissolved organic matter increases the aldrin degradation rate significantly. Both terrestrial (Suwannee River, U.S.) and microbial sources (Pony Lake, Antarctica) of DOM were able to sensitize aldrin loss in ice. Scavengers of singlet oxygen, such as furfuryl alcohol and β-carotene, were also added to DOM solutions. Based on the type of organic matter present, the scavengers had different effects on the photochemical degradation of aldrin. Our results indicate that natural organic matter present in ice is an important component of ice photochemical processes.

  9. Ocean Warming–Acidification Synergism Undermines Dissolved Organic Matter Assembly

    PubMed Central

    Chen, Chi-Shuo; Anaya, Jesse M.; Chen, Eric Y-T; Farr, Erik; Chin, Wei-Chun

    2015-01-01

    Understanding the influence of synergisms on natural processes is a critical step toward determining the full-extent of anthropogenic stressors. As carbon emissions continue unabated, two major stressors—warming and acidification—threaten marine systems on several scales. Here, we report that a moderate temperature increase (from 30°C to 32°C) is sufficient to slow— even hinder—the ability of dissolved organic matter, a major carbon pool, to self-assemble to form marine microgels, which contribute to the particulate organic matter pool. Moreover, acidification lowers the temperature threshold at which we observe our results. These findings carry implications for the marine carbon cycle, as self-assembled marine microgels generate an estimated global seawater budget of ~1016 g C. We used laser scattering spectroscopy to test the influence of temperature and pH on spontaneous marine gel assembly. The results of independent experiments revealed that at a particular point, both pH and temperature block microgel formation (32°C, pH 8.2), and disperse existing gels (35°C). We then tested the hypothesis that temperature and pH have a synergistic influence on marine gel dispersion. We found that the dispersion temperature decreases concurrently with pH: from 32°C at pH 8.2, to 28°C at pH 7.5. If our laboratory observations can be extrapolated to complex marine environments, our results suggest that a warming–acidification synergism can decrease carbon and nutrient fluxes, disturbing marine trophic and trace element cycles, at rates faster than projected. PMID:25714090

  10. Dissolved Organic Carbon In Precipitation At A Coastal Rural Site

    NASA Astrophysics Data System (ADS)

    Liptzin, D.; Daley, M.; Sive, B. C.; Talbot, R. W.; McDowell, W. H.

    2013-12-01

    Dissolved organic carbon (DOC) is a ubiquitous component of precipitation. This DOC is a complex mixture of compounds from biogenic and anthropogenic sources. The amount and chemistry of the DOC in precipitation has been studied for a variety of reasons: as a source of acidity, as a source of C to marine and terrestrial ecosystems, or to track the fate of individual compounds or pollutants. In most cases, past studies have focused on particular compounds or a limited number of precipitation events. Very little is known about the temporal trends in DOC or the relationship between DOC and other constituents of precipitation. We collected precipitation events for more than five years at a rural coastal site in New Hampshire. We evaluated the seasonal patterns and compared the DOC concentrations to other typical measures of the wet atmospheric deposition (ammonium, nitrate, sulfate, and chloride). In addition, we compared the DOC in precipitation to the concentrations of various organic constituents of the atmosphere. The volume weighted mean C concentration was 0.75 mg C/L with concentrations in the summer significantly higher than in the other three seasons. The DOC concentration was most strongly associated with ammonium concentrations (r=0.81), but was also significantly related to nitrate (r=0.50) and sulfate (r=0.63) concentrations. There was no significant association between DOC and chloride concentrations. Preliminary regression tree analysis suggests that the DOC concentration in precipitation was best predicted by the atmospheric concentration of methyl vinyl ketone, an oxidation product of isoprene. These results suggest that both terrestrial biogenic and anthropogenic sources may be important precursors to the C removed from the atmosphere during precipitation events.

  11. Photolytic processing of secondary organic aerosols dissolved in cloud droplets

    SciTech Connect

    Bateman, Adam P; Nizkorodov, Serguei; Laskin, Julia; Laskin, Alexander

    2011-05-26

    The effect of UV irradiation on the molecular composition of aqueous extracts of secondary organic aerosol (SOA) was investigated. SOA was prepared by the dark reaction of ozone and d-limonene at 0.05 - 1 ppm precursor concentrations and collected with a particle-into-liquid sampler (PILS). The PILS extracts were photolyzed by 300 - 400 nm radiation for up to 24 hours. Water-soluble SOA constituents were analyzed using high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) at different stages of photolysis for all SOA precursor concentrations. Exposure to UV radiation increased the average O/C ratio and decreased the average double bond equivalent (DBE) of the dissolved SOA compounds. Oligomeric compounds were significantly reduced by photolysis relative to the monomeric compounds. Direct pH measurements showed that compounds containing carboxylic acids increased upon photolysis. Methanol reactivity analysis revealed significant photodissociation of molecules containing carbonyl groups and formation of carboxylic acids. Aldehydes, such as limononaldehyde, were almost completely removed. The removal of carbonylswas confirmed by the UV-Vis absorption spectroscopy of the SOA extracts where the absorbance in the carbonyl n→π* band decreased significantly upon photolysis. The effective quantum yield (the number of carbonyls destroyed per photon absorbed) was estimated as ~ 0.03. The concentration of peroxides did not change significantly during photolysis as quantified with an iodometric test. Although organic peroxides were photolyzed, the likely end products of photolysis were smaller peroxides, including hydrogen peroxide, resulting in a no net change in the peroxide content.

  12. Dissolved organic matter sources in large Arctic rivers

    NASA Astrophysics Data System (ADS)

    Amon, Rainer; Walker, Sally; Prokushkin, Anatoly; Guggenberger, Georg

    2013-04-01

    The composition of dissolved organic carbon (DOC) of the six largest Arctic rivers was studied between 2003 and 2007 as part of the PARTNERS Project. Samples were collected over seasonal cycles relatively close to the river mouths. Here we report the lignin phenol and p-hydroxybenzene composition along with optical properties of Arctic river DOC in order to identify major sources of carbon. Arctic river DOC represents an important carbon conduit linking the large pools of organic carbon in the Arctic/Subarctic watersheds to the Arctic Ocean. Most of the annual lignin discharge (>75%) occurs during the two month of spring freshet with extremely high lignin concentrations and a lignin phenol composition indicative of fresh vegetation from boreal forests. The three large Siberian rivers, Lena, Yenisei, and Ob, which also have the highest proportion of forests within their watersheds, contribute about 90% of the total lignin discharge to the Arctic Ocean. The composition of river DOC is also characterized by elevated levels of p-hydroxybenzenes, particularly during the low flow season, which indicates a larger contribution from mosses and peat bogs. The lignin composition was strongly related to the average 14C-age of DOC supporting the abundance of young, boreal-vegetation-derived leachates during spring flood, and older, soil-, peat-, and wetland-derived DOC during groundwater dominated low flow conditions, particularly in the Ob and Yukon Rivers. We observed significant differences in DOC concentration and composition between the rivers over the seasonal cycles with the Mackenzie River being the most unique, the Lena River being similar to the Yenisei, and the Yukon being most similar to the Ob. The observed relationship between the lignin phenol composition and watershed characteristics suggests that DOC discharge from these rivers could increase in a warmer climate under otherwise undisturbed conditions.

  13. Fluxes of dissolved organic carbon from Chesapeake Bay sediments

    SciTech Connect

    Burdige, D.J.; Homstead, J. )

    1994-08-01

    Benthic fluxes of dissolved organic carbon (DOC) were measured over an annual cycle at two contrasting sites in Chesapeake Bay. At an organic-rich, sulfidic site in the mesohaline portion of the Bay (site M) DOC fluxes from the sediments ranged from 1.4 to 2.9 mmol/m[sup 2]/d. Measured benthic DOC fluxes at site M corresponded to [approximately]3-13% of the depth-integrated benthic C remineralization rates ([Sigma]OCR), and agreed well with calculated diffusive DOC fluxes based on porewater DOC profiles. This agreement suggests that DOC fluxes from site M sediments were likely controlled by molecular diffusion. The second site that was studied is a heavily bioturbated site in the southern Bay (site S). The activity of macrobenthos did not appear to enhance DOC fluxes from these sediments, since measured benthic DOC fluxes (>0.5 mmol/m[sup 2]/d) were lower than those at site M. The ratios of benthic DOC fluxes to [Sigma]OCR values at site S were also slightly smaller than those observed at site M. Benthic DOC fluxes from Chesapeake Bay sediments do not appear to significantly affect the transport of DOC through this estuary, although uncertainties in the reactivity of DOC in estuaries makes this conclusion somewhat tentative at this time. However, when these results are used to make a lower limit estimate of the globally integrated benthic DOC flux from marine sediments, a value similar to that previously calculated by Burdige et al. is obtained. This observation further supports suggestions in this paper about the importance of benthic DOC fluxes in the oceanic C cycle.

  14. Dissolved Organic Carbon in Groundwater Overlain by Irrigated Sugarcane.

    PubMed

    Thayalakumaran, Thabo; Lenahan, Matthew J; Bristow, Keith L

    2015-01-01

    Elevated dissolved organic carbon (DOC) has been detected in groundwater beneath irrigated sugarcane on the Burdekin coastal plain of tropical northeast Australia. The maximum value of 82 mg/L is to our knowledge the highest DOC reported for groundwater beneath irrigated cropping systems. More than half of the groundwater sampled in January 2004 (n = 46) exhibited DOC concentrations greater than 30 mg/L. DOC was progressively lower in October 2004 and January 2005, with a total decrease greater than 90% indicating varying load(s) to the aquifer. It was hypothesized that the elevated DOC found in this groundwater system is sourced at or near the soil surface and supplied to the aquifer via vertical recharge following above average rainfall. Possible sources of DOC include organic-rich sugar mill by-products applied as fertilizer and/or sugarcane sap released during harvest. CFC-12 vertical flow rates supported the hypothesis that elevated DOC (>40 mg/L) in the groundwater results from recharge events in which annual precipitation exceeds 1500 mm/year (average = 960 mm/year). Occurrence of elevated DOC concentrations, absence of electron acceptors (O2 and NO3 (-) ) and both Fe(2+) and Mn(2+) greater than 1 mg/L in shallow groundwater suggest that the DOC compounds are chemically labile. The consequence of high concentrations of labile DOC may be positive (e.g., denitrification) or negative (e.g., enhanced metal mobility and biofouling), and highlights the need to account for a wider range of water quality parameters when considering the impacts of land use on the ecology of receiving waters and/or suitability of groundwater for irrigated agriculture. PMID:25213667

  15. Chemodiversity of dissolved organic matter in the Amazon Basin

    NASA Astrophysics Data System (ADS)

    Gonsior, Michael; Valle, Juliana; Schmitt-Kopplin, Philippe; Hertkorn, Norbert; Bastviken, David; Luek, Jenna; Harir, Mourad; Bastos, Wanderley; Enrich-Prast, Alex

    2016-07-01

    Regions in the Amazon Basin have been associated with specific biogeochemical processes, but a detailed chemical classification of the abundant and ubiquitous dissolved organic matter (DOM), beyond specific indicator compounds and bulk measurements, has not yet been established. We sampled water from different locations in the Negro, Madeira/Jamari and Tapajós River areas to characterize the molecular DOM composition and distribution. Ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) combined with excitation emission matrix (EEM) fluorescence spectroscopy and parallel factor analysis (PARAFAC) revealed a large proportion of ubiquitous DOM but also unique area-specific molecular signatures. Unique to the DOM of the Rio Negro area was the large abundance of high molecular weight, diverse hydrogen-deficient and highly oxidized molecular ions deviating from known lignin or tannin compositions, indicating substantial oxidative processing of these ultimately plant-derived polyphenols indicative of these black waters. In contrast, unique signatures in the Madeira/Jamari area were defined by presumably labile sulfur- and nitrogen-containing molecules in this white water river system. Waters from the Tapajós main stem did not show any substantial unique molecular signatures relative to those present in the Rio Madeira and Rio Negro, which implied a lower organic molecular complexity in this clear water tributary, even after mixing with the main stem of the Amazon River. Beside ubiquitous DOM at average H / C and O / C elemental ratios, a distinct and significant unique DOM pool prevailed in the black, white and clear water areas that were also highly correlated with EEM-PARAFAC components and define the frameworks for primary production and other aspects of aquatic life.

  16. Genotoxicity and cytotoxicity induced by municipal effluent in multiple organs of Wistar rats.

    PubMed

    da Silva, Victor Hugo Pereira; de Moura, Carolina Foot Gomes; Ribeiro, Flavia Andressa Pidone; Cesar, Augusto; Pereira, Camilo Dias Seabra; Silva, Marcelo Jose Dias; Vilegas, Wagner; Ribeiro, Daniel Araki

    2014-11-01

    The aim of this study was to evaluate cytotoxicity and genotoxicity in multiple organs of rats induced by municipal effluent released by submarine outfall in city of Santos. A total of 20 male Wistar rats were exposed to effluents by drinking water ad libitum at concentrations of 0, 10, 50, and 100 % for 30 days. Microscopic analysis revealed severe lesions such as necrosis and hemorrhagic areas in liver and kidney from animals exposed to effluent at 50 and 100 % concentration. DNA damage in peripheral blood, liver, and kidney cells were detected by comet assay at higher concentrations of effluent. Moreover, a decrease DNA repair capacity was detected in liver cells. Significant statistical differences (p<0.05) for micronucleated cells from liver were noticed at 50 % concentration of effluent. Taken together, our results demonstrate that municipal effluent is able to induce cytotoxicity and genotoxicity in multiple organs of Wistar rats. PMID:24996946

  17. Effect of bacteria and dissolved organics on mineral dissolution kinetics:

    NASA Astrophysics Data System (ADS)

    Pokrovsky, Oleg; Shirokova, Liudmila; Benezeth, Pascale; Zabelina, Svetlana

    2010-05-01

    Quantification of the effect of microorganisms and associated organic ligands on mineral dissolution rate is one among the last remaining challenges in modeling of water-rock interactions under earth surface and subsurface environments. This is especially true for deep underground settings within the context of CO2 capture, sequestration and storage. First, elevated CO2 pressures create numerous experimental difficulties for performing robust flow-through experiments at a given saturation state. Second, reactivity of main rock-forming minerals in abiotic systems at pCO2 >> 1 atm and circumneutral pH is still poorly constrained. And third, most of microbial habitats of the subsurface biosphere are not suitable for routine culturing in the laboratory, many of them are anaerobic and even strictly anaerobic, and many bacteria and archae cultures can live only in the consortium of microorganisms which is very hard to maintain at a controlled and stable biomass concentration. For experimental modeling of bio-mineral interactions in the laboratory, two other main conceptual challenges exist. Typical concentration of dissolved organic carbon that serves as a main nutrient for heterotrophic bacteria in underground waters rarely exceeds 3-5 mg/L. Typical concentration of DOC in nutrient media used for bacteria culturing is between 100 and 10,000 mg/L. Therefore, performing mineral-bacteria interactions in the laboratory under environmentally-sound conditions requires significant dilution of the nutrient media or the use of flow-through reactors. Concerning the effect of organic ligands and bacterial excudates on rock-forming mineral dissolution, at the present time, mostly empirical (phenomenological) approach can be used. Indeed, the pioneering studies of Stumm and co-workers have established a firm basis for modeling the catalyzing and inhibiting effects of ligands on metal oxide dissolution rate. This approach, very efficient for studying the interaction of organic and

  18. FACTORS INFLUENCING PHOTOREACTIONS OF DISSOLVED ORGANIC MATTER IN A COASTAL RIVER OF THE SOUTHEASTERN UNITED STATES

    EPA Science Inventory

    Photoreactions of dissolved organic matter can affect the oxidizing capacity, nutrient dynamics, trace gas exchange, and color of surface waters. This study focuses on factors that affect the photoreactions of the colored dissolved organic matter (CDOM) in the Satilla River, a co...

  19. DISSOLVED ORGANIC CARBON (DOC) CONCENTRATIONS IN SMALL STREAMS OF THE GEORGIA PIEDMONT

    EPA Science Inventory

    Dissolved organic matter (DOM) supports microbial activity and contributes to transport of N and P in streams. We have studied the impact of land uses on dissolved organic carbon (DOC) concentrations in 17 Georgia Piedmont headwater streams since January 2001. We classified the w...

  20. Bioavailable and biodegradable dissolved organic nitrogen in activated sludge and trickling filter wastewater treatment plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A study was carried out to understand the fate of biodegradable dissolved organic nitrogen (BDON) and bioavailable dissolved organic nitrogen (ABDON) along the treatment trains of a wastewater treatment facility (WWTF) equipped with an activated sludge (AS) system and a WWTF equipped with a two-stag...

  1. Contribution of root vs. leaf litter to dissolved organic carbon leaching through soil.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Very little is known about dissolved organic matter (DOM) originating from fine roots in forest soils in comparison to DOM originating from leaf litter. To compare the fate of root- versus leaf-derived dissolved organic carbon (DOC), we added 14C-labeled root litter at depths of 10 cm, a “shallow r...

  2. Removal of dissolved organic matter in water-hyacinth waste-water treatment lagoons

    SciTech Connect

    Victoria-Rueda, C.H.

    1991-01-01

    Secondary treatment of domestic wastewater in water hyacinth lagoons was evaluated under experimental conditions to assess the role of the roots' bacterial biofilm in the removal of dissolved organic matter (DOM). Research was conducted to (1) quantify removal rates by the biofilm as a function of bulk DOM concentration, (2) formulate an analytical model of DOM removal incorporating biofilm activity, and (3) test the model response to variable organic loads in a pilot-scale plant. Removal of DOM by the biofilm was quantified in continuous-flow water hyacinth tanks at ten concentrations ranging from 45 to 330 g COD m {sup {minus}3} . Total DOM removal in the denitrifying, acetate-based experimental system was measured and partitioned into two fractions associated with the activity of biofilm and suspended bacteria. Calculated DOM removal by the biofilm was adjusted for the release of organic compounds by debris decomposition. Values of DOM removal were used to calculate oxygen transfer rates from the water hyacinth roots. A model of DOM removal in water hyacinth lagoons was formulated. The model, composed of four differential equations, was solved at steady-state conditions and the validity of its simulation results was tested in pilot-scale tanks. Hydraulic detection times ranging from 2 to 28 days were evaluated using biofilm density and concentrations of DOM and particulate organics as monitoring parameters of the model response. The observed decrease of suspended bacterial biomass along the tank was correctly simulated by the model, but predictions of effluent concentrations were not always consistent. Predicted values of biofilm bacterial mass were similar to those measured in the tanks, except when large algal populations were present in the film.

  3. Soil dissolved organic matter export to coastal temperate rainforest streams

    NASA Astrophysics Data System (ADS)

    Edwards, R. T.; D'Amore, D. V.; Hood, E.; Johnson, A.

    2006-12-01

    The north coastal temperate rainforest is a dynamic area of biogeochemical exchange between terrestrial and aquatic ecosystems. Wetlands and poorly drained soils dominate the landscape, where wetlands alone comprise 30% of the watersheds. The region is experiencing warming with potentially profound impacts on soil processes, forest structure, stream productivity, and the large and valuable salmon fishery. There are few data on stream chemistry, biological productivity, or discharge among soils and streams in the region. To predict the impact of climate change, management practices or land use on streams we need better baseline data on soil-stream interactions in temperate rainforest watersheds. We measured weekly export of dissolved organic matter from 3 dominant soil vegetation communities (peat bogs, forested wetlands and mineral soil uplands) during spring through fall of 2006. Three replicate sites for each soil type were gauged with weirs and fluxes of major forms of carbon, nitrogen and phosphorus measured. Discharge dominated the seasonal flux dynamics but major differences in export and area-specific export emphasized differences in soil-specific transformations on nutrient export potential. Export per unit soil area varied from 0.01 to 25 kg C/ha/day. Peat bogs exported 2-5 times as much per unit area as the other two soils. Forested wetlands were intermediate between bogs and uplands in export per unit area. Mean daily carbon fluxes from gauged subcatchments ranged from 0.01 to 75 kg C/day. Because they are larger than bogs, forested wetlands exported the greatest amount of DOC at our study locations, with uplands exporting intermediate amounts during spring floods. Uplands and bogs exported far less than forested wetlands during normal flow conditions. Total nitrogen fluxes were dominated by organic forms and seasonal trends closely followed the patterns observed for DOC. Although wetlands of either type export more organic matter per unit area, the

  4. Selective Sorption of Dissolved Organic Carbon Compounds by Temperate Soils

    SciTech Connect

    Jagadamma, Sindhu; Mayes, Melanie; Phillips, Jana Randolph

    2012-01-01

    Physico-chemical sorption of dissolved organic carbon (DOC) on soil minerals is one of the major processes of organic carbon (OC) stabilization in soils, especially in deeper layers. The attachment of C on soil solids is related to the reactivity of the soil minerals and the chemistry of the sorbate functional groups, but the sorption studies conducted without controlling microbial activity may overestimate the sorption potential of soil. This study was conducted to examine the sorptive characteristics of a diverse functional groups of simple OC compounds (D-glucose, L-alanine, oxalic acid, salicylic acid, and sinapyl alcohol) on temperate climate soil orders (Mollisols, Ultisols and Alfisols) with and without biological degradative processes. Equilibrium batch experiments were conducted using 0-100 mg C L-1 at a solid-solution ratio of 1:60 for 48 hrs and the sorption parameters were calculated by Langmuir model fitting. The amount of added compounds that remained in the solution phase was detected by high performance liquid chromatography (HPLC) and total organic C (TOC) analysis. Soil sterilization was performed by -irradiation technique and experiments were repeated to determine the contribution of microbial degradation to apparent sorption. Overall, Ultisols did not show a marked preference for apparent sorption of any of the model compounds, as indicated by a narrower range of maximum sorption capacity (Smax) of 173-527 mg kg soil-1 across compounds. Mollisols exhibited a strong preference for apparent sorption of oxalic acid (Smax of 5290 mg kg soil-1) and sinapyl alcohol (Smax of 2031 mg kg soil-1) over the other compounds. The propensity for sorption of oxalic acid is mainly attributed to the precipitation of insoluble Ca-oxalate due to the calcareous nature of most Mollisol subsoils and its preference for sinapyl alcohol could be linked to the polymerization of this lignin monomer on 2:2 mineral dominated soils. The reactivity of Alfisols to DOC was in

  5. Transformation of dissolved organic matters in landfill leachate-bioelectrochemical system.

    PubMed

    Zhang, Guodong; Jiao, Yan; Lee, Duu-Jong

    2015-09-01

    A membraneless bioelectrochemical system (BES) reactor and an anoxic/oxic (A/O) reactor of identical configurations were applied to treat the landfill leachate (20,100 mg l(-1) chemical oxygen demand (COD) and 1330 mg l(-1) NH4(+)-N) at 24-h hydraulic retention time and 3 kg chemical oxygen demand m(-3) d(-1) volume loading. The BES with maximum power density of 2.77±0.26 W m(-3) and internal resistance of 47.5±1.4 Ω removed 84-89% COD and 94-98% NH4(+)-N, 11% and 47%, respectively, higher than the A/O reactor. The dissolved organic matters (DOM) in effluents from the BES and the A/O reactor were for the first time characterized and compared. The MFC preferentially degraded hydrophilic fraction (HPI) of the fed DOM and yielded excess humin with high aromaticity. The electric fields by bioelectrochemical reactions occurred at cathode stimulate the activities of COD degraders and nitrifiers in biofilms to enhance ammonium removals by BES reactor. PMID:26037237

  6. Molecular characterization of dissolved organic matter through a desalination process by high resolution mass spectrometry.

    PubMed

    Cortés-Francisco, Nuria; Caixach, Josep

    2013-09-01

    The effect of different water treatments such as ultrafiltration (UF) and reverse osmosis (RO) on dissolved organic matter (DOM) is still unknown. Electrospray ionization Fourier transform orbitrap mass spectrometry has been used to provide valuable information of marine DOM evolution through a desalination process on a molecular scale. In the present manuscript, the characterization of four real composite water samples from a desalination pilot plant installed in the coast of Barcelona (Spain) has been carried out. The sampling was performed on each point of the pilot plant: raw seawater (RSW), UF effluent, brine RO and permeate RO. The mass spectra of the different samples show several thousand peaks, however for the present screening study, only the mass range m/z 200-500 and the main signals in this mass range (relative intensities ≥1%) have been considered. The analysis of RSW and UF samples reveal that there is little effect on DOM by the UF pilot. However, when the water is treated on the RO an important change on DOM has been observed. The recurring periodical patterns found in RSW and UF are lost in Permeate RO sample. Compounds with more aliphatic character, with higher H/C ratio (H/Cav 1.72) are present in the Permeate and some of them have been tentatively identified as fatty acids. PMID:23879562

  7. Pb-binding to various dissolved organic matter in urban aquatic systems: Key role of the most hydrophilic fraction

    NASA Astrophysics Data System (ADS)

    Pernet-Coudrier, Benoît; Companys, Encarnació; Galceran, Josep; Morey, Margalida; Mouchel, Jean-Marie; Puy, Jaume; Ruiz, Núria; Varrault, Gilles

    2011-07-01

    Dissolved organic matter (DOM) from the treated effluent of a wastewater treatment plant and from the river Seine under high human pressure has been separated into three fractions: hydrophobic (containing humic and fulvic substances), transphilic and hydrophilic using a two column array of XAD-8 and XAD-4 resins. The acid base properties and the binding characteristics with respect to Pb ions (using the new electroanalytical technique AGNES, Absence of Gradients and Nernstian Equilibrium Stripping) have been studied and fitted to NICA (Non-Ideal Competitive Isotherm). We evaluated the binding potential of each DOM fraction in order to better predict the speciation of Pb and, later, its bioavailability in the river. The total binding capacity of the different fractions to Pb, as well as the total titratable charge, reaches its maximum value at the most hydrophilic fraction from the treated effluent. Specific properties of the distribution of the complexing sites within each DOM fraction have been exposed by plotting the conditional affinity spectrum (CAS). The addition of these distributions, weighted according to the respective abundance of each organic fraction, allows for a full description of the Pb binding properties of the whole DOM of a sampling site. Despite its weak aromaticity, the hydrophilic fraction from the wastewater treatment plant effluent exhibits a high lead binding affinity, so that at typical environmental pH and free Pb levels (0.1 μg L -1), Pb is mainly bound to the most hydrophilic fraction of the treated effluent (49% of bound Pb at pH 7). This feature may greatly enhance the transport of Pb and highlights that Pb speciation should also consider other fractions apart from humic and/or fulvic acids when studying surface waters under high human pressure.

  8. Determining Passive Sampler Partition Coefficients for Dissolved-phase Organic Contaminants

    EPA Science Inventory

    Passive samplers are used for environmental and analytical purposes to measure dissolved nonionic organic contaminants (NOCs) by absorption from a contaminated medium into a clean phase, usually in the form of a synthetic organic film. Recently developed passive sampler techniqu...

  9. Adsorption of dissolved natural organic matter by modified activated carbons.

    PubMed

    Cheng, Wei; Dastgheib, Seyed A; Karanfil, Tanju

    2005-06-01

    Adsorption of dissolved natural organic matter (DOM) by virgin and modified granular activated carbons (GACs) was studied. DOM samples were obtained from two water treatment plants before (i.e., raw water) and after coagulation/flocculation/sedimentation processes (i.e., treated water). A granular activated carbon (GAC) was modified by high temperature helium or ammonia treatment, or iron impregnation followed by high temperature ammonia treatment. Two activated carbon fibers (ACFs) were also used, with no modification, to examine the effect of carbon porosity on DOM adsorption. Size exclusion chromatography (SEC) and specific ultraviolet absorbance (SUVA(254)) were employed to characterize the DOMs before and after adsorption. Iron-impregnated (HDFe) and ammonia-treated (HDN) activated carbons showed significantly higher DOM uptakes than the virgin GAC. The enhanced DOM uptake by HDFe was due to the presence of iron species on the carbon surface. The higher uptake of HDN was attributed to the enlarged carbon pores and basic surface created during ammonia treatment. The SEC and SUVA(254) results showed no specific selectivity in the removal of different DOM components as a result of carbon modification. The removal of DOM from both raw and treated waters was negligible by ACF10, having 96% of its surface area in pores smaller than 1 nm. Small molecular weight (MW) DOM components were preferentially removed by ACF20H, having 33% of its surface area in 1--3 nm pores. DOM components with MWs larger than 1600, 2000, and 2700 Da of Charleston raw, Charleston-treated, and Spartanburg-treated waters, respectively, were excluded from the pores of ACF20H. In contrast to carbon fibers, DOM components from entire MW range were removed from waters by virgin and modified GACs. PMID:15927230

  10. Concurrent photolytic degradation of aqueous methylmercury and dissolved organic matter.

    PubMed

    Fleck, Jacob A; Gill, Gary; Bergamaschi, Brian A; Kraus, Tamara E C; Downing, Bryan D; Alpers, Charles N

    2014-06-15

    Monomethyl mercury (MeHg) is a potent neurotoxin that threatens ecosystem viability and human health. In aquatic systems, the photolytic degradation of MeHg (photodemethylation) is an important component of the MeHg cycle. Dissolved organic matter (DOM) is also affected by exposure to solar radiation (light exposure) leading to changes in DOM composition that can affect its role in overall mercury (Hg) cycling. This study investigated changes in MeHg concentration, DOM concentration, and the optical signature of DOM caused by light exposure in a controlled field-based experiment using water samples collected from wetlands and rice fields. Filtered water from all sites showed a marked loss in MeHg concentration after light exposure. The rate of photodemethylation was 7.5×10(-3)m(2)mol(-1) (s.d. 3.5×10(-3)) across all sites despite marked differences in DOM concentration and composition. Light exposure also caused changes in the optical signature of the DOM despite there being no change in DOM concentration, indicating specific structures within the DOM were affected by light exposure at different rates. MeHg concentrations were related to optical signatures of labile DOM whereas the percent loss of MeHg was related to optical signatures of less labile, humic DOM. Relationships between the loss of MeHg and specific areas of the DOM optical signature indicated that aromatic and quinoid structures within the DOM were the likely contributors to MeHg degradation, perhaps within the sphere of the Hg-DOM bond. Because MeHg photodegradation rates are relatively constant across freshwater habitats with natural Hg-DOM ratios, physical characteristics such as shading and hydrologic residence time largely determine the relative importance of photolytic processes on the MeHg budget in these mixed vegetated and open-water systems. PMID:23642571

  11. Microbial dissolved organic phosphorus utilization in the Hudson River Estuary

    SciTech Connect

    Ammerman, J.W. ); Angel, D.L. )

    1990-01-09

    The Hudson River Estuary has large inputs of phosphorus and other nutrients from sewage discharge. Concentrations of soluble reactive phosphorus (SRP) reach at least 4 uM during the summer low-flow period. Biological utilization of phosphorus and other nutrients is usually minimal because of the high turbidity and short residence time of the water. Therefore SRP is normally a conservative tracer of salinity, with maximum concentrations found off Manhattan and decreasing to the north. Despite this abundance of SRP, some components of the dissolved organic phosphorus (DOP) appear to be rapidly cycled by microbes. The objective of this study was to measure this DIP cycling during both the high- and low-flow periods. We measured the concentrations of SRP and DOP, the SRP turnover rate, algal and bacterial biomass, and the substrate turnover rates of two microbial cell-surface phosphatases, alkaline phosphatase (AP) and 5[prime] - nucleotidase (5PN). SRP concentrations ranged from about 0.5-4 uM, DOP was usually less than 1 uM. SRP and AP turnover were slow (generally < 5%/h), but 5PN substrate turnover was high with a median rate of 100%/h. Furthermore, over 30% of the phosphate hydrolyzed by 5PN was immediately taken up. If the nucleotide-P concentration is conservatively assumed to be 5 nM, than the rate of phosphate utilization from DOP is nearly equal to that from SRP. That is paradoxical considering the large SRP concentration, but suggests that much of this SRP may be biologically unavailable due to complexation with iron or other processes.

  12. Concurrent photolytic degradation of aqueous methylmercury and dissolved organic matter

    USGS Publications Warehouse

    Fleck, Jacob A.; Gill, Gary W.; Bergamaschi, Brian A.; Kraus, Tamara E.C.; Downing, Bryan D.; Alpers, Charles N.

    2014-01-01

    Monomethyl mercury (MeHg) is a potent neurotoxin that threatens ecosystem viability and human health. In aquatic systems, the photolytic degradation of MeHg (photodemethylation) is an important component of the MeHg cycle. Dissolved organic matter (DOM) is also affected by exposure to solar radiation (light exposure) leading to changes in DOM composition that can affect its role in overall mercury (Hg) cycling. This study investigated changes in MeHg concentration, DOM concentration, and the optical signature of DOM caused by light exposure in a controlled field-based experiment using water samples collected from wetlands and rice fields. Filtered water from all sites showed a marked loss in MeHg concentration after light exposure. The rate of photodemethylation was 7.5 × 10-3 m2 mol-1 (s.d. 3.5 × 10-3) across all sites despite marked differences in DOM concentration and composition. Light exposure also caused changes in the optical signature of the DOM despite there being no change in DOM concentration, indicating specific structures within the DOM were affected by light exposure at different rates. MeHg concentrations were related to optical signatures of labile DOM whereas the percent loss of MeHg was related to optical signatures of less labile, humic DOM. Relationships between the loss of MeHg and specific areas of the DOM optical signature indicated that aromatic and quinoid structures within the DOM were the likely contributors to MeHg degradation, perhaps within the sphere of the Hg-DOM bond. Because MeHg photodegradation rates are relatively constant across freshwater habitats with natural Hg–DOM ratios, physical characteristics such as shading and hydrologic residence time largely determine the relative importance of photolytic processes on the MeHg budget in these mixed vegetated and open-water systems.

  13. Biogeochemical Processes That Produce Dissolved Organic Matter From Wheat Straw

    USGS Publications Warehouse

    Wershaw, Robert L.; Rutherford, David W.; Leenheer, Jerry A.; Kennedy, Kay R.; Cox, Larry G.; Koci, Donald R.

    2003-01-01

    The chemical reactions that lead to the formation of dissolved organic matter (DOM) in natural waters are poorly understood. Studies on the formation of DOM generally are complicated because almost all DOM isolates have been derived from mixtures of plant species composed of a wide variety of different types of precursor compounds for DOM formation. This report describes a study of DOM derived mainly from bales of wheat straw that had been left in a field for several years. During this period of time, black water from the decomposing wheat straw accumulated in pools in the field. The nuclear magnetic resonance and infrared spectra of the black water DOM indicate that it is composed almost entirely of lignin and carbohydrate polymeric units. Analysis by high-performance size-exclusion chromatography with multi-angle laser-light scattering detection indicates that the number average molecular weight of the DOM is 124,000 daltons. The results presented in this report indicate that the black water DOM is composed of hemicellulose chains cross-linked to lignin oligomers. These types of structures have been shown to exist in the hemicellulose matrix of plant cell walls. The cross-linked lignin-hemicellulose complexes apparently were released from partially degraded wheat-straw cell walls with little alteration. In solution in the black water, these lignin-hemicellulose polymers fold into compact globular particles in which the nonpolar parts of the polymer form the interiors of the particles and the polar groups are on the exterior surfaces of the particles. The tightly folded, compact conformation of these particles probably renders them relatively resistant to microbial degradation. This should be especially the case for the aromatic lignin structures that will be buried in the interiors of the particles.

  14. Dissolved organic matter kinetically controls mercury bioavailability to bacteria.

    PubMed

    Chiasson-Gould, Sophie A; Blais, Jules M; Poulain, Alexandre J

    2014-03-18

    Predicting the bioavailability of inorganic mercury (Hg) to bacteria that produce the potent bioaccumulative neurotoxin monomethylmercury remains one of the greatest challenges in predicting the environmental fate and transport of Hg. Dissolved organic matter (DOM) affects mercury methylation due to its influence on cell physiology (as a potential nutrient) and its influence on Hg(II) speciation in solution (as a complexing agent), therefore controlling Hg bioavailability. We assessed the role of DOM on Hg(II) bioavailability to a gram-negative bacterium bioreporter under oxic pseudo- and nonequilibrium conditions, using defined media and field samples spanning a wide range of DOM levels. Our results showed that Hg(II) was considerably more bioavailable under nonequilibrium conditions than when DOM was absent or when Hg(II) and DOM had reached pseudoequilibrium (24 h) prior to cell exposure. Under these enhanced uptake conditions, Hg(II) bioavailability followed a bell shaped curve as DOM concentrations increased, both for defined media and natural water samples, consistent with bioaccumulation results in a companion paper (this issue) observed for amphipods. Experiments also suggest that DOM may not only provide shuttle molecules facilitating Hg uptake, but also alter cell wall properties to facilitate the first steps toward Hg(II) internalization. We propose the existence of a short-lived yet critical time window (<24 h) during which DOM facilitates the entry of newly deposited Hg(II) into aquatic food webs, suggesting that the bulk of mercury incorporation in aquatic food webs would occur within hours following its deposition from the atmosphere. PMID:24524696

  15. Selective Sorption of Dissolved Organic Carbon Compounds by Temperate Soils

    PubMed Central

    Jagadamma, Sindhu; Mayes, Melanie A.; Phillips, Jana R.

    2012-01-01

    Background Physico-chemical sorption onto soil minerals is one of the major processes of dissolved organic carbon (OC) stabilization in deeper soils. The interaction of DOC on soil solids is related to the reactivity of soil minerals, the chemistry of sorbate functional groups, and the stability of sorbate to microbial degradation. This study was conducted to examine the sorption of diverse OC compounds (D-glucose, L-alanine, oxalic acid, salicylic acid, and sinapyl alcohol) on temperate climate soil orders (Mollisols, Ultisols and Alfisols). Methodology Equilibrium batch experiments were conducted using 0–100 mg C L−1 at a solid-solution ratio of 1∶60 for 48 hrs on natural soils and on soils sterilized by γ-irradiation. The maximum sorption capacity, Qmax and binding coefficient, k were calculated by fitting to the Langmuir model. Results Ultisols appeared to sorb more glucose, alanine, and salicylic acid than did Alfisols or Mollisols and the isotherms followed a non-linear pattern (higher k). Sterile experiments revealed that glucose and alanine were both readily degraded and/or incorporated into microbial biomass because the observed Qmax under sterile conditions decreased by 22–46% for glucose and 17–77% for alanine as compared to non-sterile conditions. Mollisols, in contrast, more readily reacted with oxalic acid (Qmax of 886 mg kg−1) and sinapyl alcohol (Qmax of 2031 mg kg−1), and no degradation was observed. The reactivity of Alfisols to DOC was intermediate to that of Ultisols and Mollisols, and degradation followed similar patterns as for Ultisols. Conclusion This study demonstrated that three common temperate soil orders experienced differential sorption and degradation of simple OC compounds, indicating that sorbate chemistry plays a significant role in the sorptive stabilization of DOC. PMID:23209742

  16. Processing of particulate organic carbon associated with secondary-treated pulp and paper mill effluent in intertidal sediments: a 13C pulse-chase experiment.

    PubMed

    Oakes, Joanne M; Ross, Donald J; Eyre, Bradley D

    2013-01-01

    To determine the benthic transformation pathways and fate of carbon associated with secondary-treated pulp and paper mill (PPM) effluent, (13)C-labeled activated sludge biomass (ASB) and phytoplankton (PHY) were added, separately, to estuarine intertidal sediments. Over 28 days, (13)C was traced into sediment organic carbon, fauna, seagrass, bacteria, and microphytobenthos and into fluxes of dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) from inundated sediments, and carbon dioxide (CO2(g)) from exposed sediments. There was greater removal of PHY carbon from sediments (~85% over 28 days) compared to ASB (~75%). Although there was similar (13)C loss from PHY and ASB plots via DIC (58% and 56%, respectively) and CO2(g) fluxes (<1%), DOC fluxes were more important for PHY (41%) than ASB (12%). Faster downward transport and loss suggest that fauna prefer PHY, due to its lability and/or toxins associated with ASB; this may account for different carbon pathways. Secondary-treated PPM effluent has lower oxygen demand than primary-treated effluent, but ASB accumulation may contribute to sediment anoxia, and respiration of ASB and PHY-derived DOC may make the water column more heterotrophic. This highlights the need to optimize secondary-treatment processes to control the quality and quantity of organic carbon associated with PPM effluent. PMID:24261917

  17. Comparative Toxicity of Chlorinated Saline and Freshwater Wastewater Effluents to Marine Organisms.

    PubMed

    Yang, Mengting; Liu, Jiaqi; Zhang, Xiangru; Richardson, Susan D

    2015-12-15

    Toilet flushing with seawater results in saline wastewater, which may contain approximately 33-50% seawater. Halogenated disinfection byproducts (DBPs), especially brominated and iodinated DBPs, have recently been found in chlorinated saline wastewater effluents. With the occurrence of brominated and iodinated DBPs, the adverse effects of chlorinated saline wastewater effluents to marine ecology have been uncertain. By evaluating the developmental effects in the marine polychaete Platynereis dumerilii directly exposed to chlorinated saline/freshwater wastewater effluents, we found surprisingly that chlorinated saline wastewater effluents were less toxic than a chlorinated freshwater wastewater effluent. This was also witnessed by the marine alga Tetraselmis marina. The toxicity of a chlorinated wastewater effluent to the marine species was dominated by its relatively low salinity compared to the salinity in seawater. The organic matter content in a chlorinated wastewater effluent might be partially responsible for the toxicity. The adverse effects of halogenated DBPs on the marine species were observed pronouncedly only in the "concentrated" chlorinated wastewater effluents. pH and ammonia content in a wastewater effluent caused no adverse effects on the marine species. The results suggest that using seawater to replace freshwater for toilet flushing might mitigate the "direct" acute detrimental effect of wastewater to the marine organisms. PMID:26505276

  18. Dissolved organic carbon reduces the toxicity of aluminum to three tropical freshwater organisms.

    PubMed

    Trenfield, Melanie A; Markich, Scott J; Ng, Jack C; Noller, Barry; van Dam, Rick A

    2012-02-01

    The influence of dissolved organic carbon (DOC) on the toxicity of aluminum (Al) at pH 5 (relevant to acid mine drainage conditions), to the tropical green hydra (Hydra viridissima), green alga (Chlorella sp.), and cladoceran (Moinodaphnia macleayi) was assessed. Two DOC sources, a natural in situ DOC in soft billabong water (SBW) and Suwannee River fulvic acid (SRFA) standard, were compared. The order of sensitivity of the test organisms to dissolved Al (0.1 µm fraction) was Hydra viridissima > Moinodaphnia macleayi > Chlorella sp. with DOC reducing dissolved Al toxicity most for Hydra viridissima. However, colloidal or precipitated Al may contribute indirectly to the toxicity for M. macleayi and Chlorella sp. The toxicity of dissolved Al was up to six times lower in test waters containing 10 mg L(-1) DOC (in the form of SRFA), relative to toxicity observed at 1 mg L(-1) DOC. In contrast, the toxicity of Al was up to two times lower in SBW containing 10 mg L(-1) DOC, relative to water containing 1 mg L(-1) DOC. The increased ability of SRFA in reducing Al toxicity was linked to its greater affinity for complexing Al compared with the in situ DOC. This has important implications for studies that use commercial standards of humic substances to predict Al toxicity in local environments. Speciation modeling demonstrated that Al(3+) and AlOH(2+) provided a strong relationship with toxicity. An empirical relationship is provided for each organism that can be used to predict Al toxicity at a given Al and DOC concentration. PMID:22105345

  19. Dissolved organic carbon pools and export from the coastal ocean

    NASA Astrophysics Data System (ADS)

    Barrón, Cristina; Duarte, Carlos M.

    2015-10-01

    The distribution of dissolved organic carbon (DOC) concentration across coastal waters was characterized based on the compilation of 3510 individual estimates of DOC in coastal waters worldwide. We estimated the DOC concentration in the coastal waters that directly exchange with open ocean waters in two different ways, as the DOC concentration at the edge of the shelf break and as the DOC concentration in coastal waters with salinity close to the average salinity in the open ocean. Using these estimates of DOC concentration in the coastal waters that directly exchange with open ocean waters, the mean DOC concentration in the open ocean and the estimated volume of water annually exchanged between coastal and open ocean, we estimated a median ± SE (and average ± SE) global DOC export from coastal to open ocean waters ranging from 4.4 ± 1.0 Pg C yr-1 to 27.0 ± 1.8 Pg C yr-1 (7.0 ± 5.8 Pg C yr-1 to 29.0 ± 8.0 Pg C yr-1) depending on the global hydrological exchange. These values correspond to a median and mean median (and average) range between 14.7 ± 3.3 to 90.0 ± 6.0 (23.3 ± 19.3 to 96.7 ± 26.7) Gg C yr-1 per km of shelf break, which is consistent with the range between 1.4 to 66.1 Gg C yr-1 per km of shelf break of available regional estimates of DOC export. The estimated global DOC export from coastal to open ocean waters is also consistent with independent estimates of the net metabolic balance of the coastal ocean. The DOC export from the coastal to the open ocean is likely to be a sizeable flux and is likely to be an important term in the carbon budget of the open ocean, potentially providing an important subsidy to support heterotrophic activity in the open ocean.

  20. Composition of dissolved organic nitrogen in rivers associated with wetlands.

    PubMed

    Watanabe, Akira; Tsutsuki, Kiyoshi; Inoue, Yudzuru; Maie, Nagamitsu; Melling, Lulie; Jaffé, Rudolf

    2014-09-15

    As basic information for assessing reactivity and functionality of wetland-associated dissolved organic matter (DOM) based on their composition and structural properties, chemical characteristics of N in ultrafiltered DOM (UDON; >1 kD) isolated from wetland-associated rivers in three climates (cool-temperate, Hokkaido, Japan; sub-tropical, Florida, USA; tropical, Sarawak, Malaysia) were investigated. The UDON was isolated during dry and wet seasons, or during spring, summer, and autumn. The proportion of UDON present as humic substances, which was estimated as the DAX-8 adsorbed fraction, ranged from 47 to 91%, with larger values in the Sarawak than at the other sites. The yield of hydrolyzable amino acid N ranged 1.24 to 7.01 mg g(-1), which correlated positively to the total N content of UDOM and tended to be larger in the order of Florida>Hokkaido>Sarawak samples. X-ray photoelectron N1s spectra of UDON showed a strong negative correlation between the relative abundances of amide/peptide N and primary amine N. The relative abundances of amide/peptide N and primary amine N in the Sarawak samples were smaller (70-76%) and larger (20-23%) respectively compared to those (80-88% and 4-9%) in the Florida and Hokkaido samples. Assuming terminal amino groups and amide N of peptides as major constituents of primary amine N and amide/peptide N, respectively, the average molecular weight of peptides was smaller in the Sarawak samples than that in the Florida and Hokkaido samples. Seasonal variations in UDON composition were scarce in the Sarawak and Florida samples, whereas the distribution of humic substance-N and nonhumic substance-N and compositions of amino acids and N functional groups showed a clear seasonality in the Hokkaido samples. While aromatic N increased from spring to autumn, contributions from fresh proteinaceous materials were also enhanced during autumn, resulting in the highest N content of UDOM for this season. PMID:24946034

  1. Analytical Determinations of the Phenolic Content of Dissolved Organic Matter

    NASA Astrophysics Data System (ADS)

    Pagano, T.; Kenny, J. E.

    2010-12-01

    Indicators suggest that the amount of dissolved organic matter (DOM) in natural waters is increasing. Climate Change has been proposed as a potential contributor to the trend, and under this mechanism, the phenolic content of DOM may also be increasing. We have explored the possibility of assessing the phenolic character of DOM using fluorescence spectroscopy as a more convenient alternative to wet chemistry methods. In this work, parallel factor analysis (PARAFAC) was applied to fluorescence excitation emission matrices (EEMs) of humic samples in an attempt to analyze their phenolic content. The PARAFAC results were correlated with phenol concentrations derived from the Folin-Ciocalteau reagent-based method. The reagent-based method showed that the phenolic content of five International Humic Substance Society (IHSS) DOM samples vary from approximately 5 to 22 ppm Tannic Acid Equivalents (TAE) in phenol concentration. A five-component PARAFAC fit was applied to the EEMs of the IHSS sample dataset and it was determined by PARAFAC score correlations with phenol concentrations from the reagent-based method that components C1 (R2=0.78), C4 (R2=0.82), and C5 (R2=0.88) have the highest probability of containing phenolic groups. Furthermore, when the scores of components C4 and C5 were summed, the correlation improved (R2=0.99). Likewise, when the scores of C1, C4, and C5 were summed, their correlations were stronger than their individual parts (R2=0.89). Since the reagent-based method is providing an indicator of “total phenol” amount, regardless of the exact molecular structure of C1, C4, and C5, it seems reasonable that each of these components individually contributes a portion to the summed “total phenol” profile, and that the sum of their phenol-related spectral parts represents a larger portion of the “total phenol” index. However, when the sum of all five components were plotted against the reagent-based phenol concentrations, due to the considerable

  2. Geochemistry and Reactivity of Exported Congo Riverine Dissolved Organic Matter

    NASA Astrophysics Data System (ADS)

    Spencer, R. G.; Stubbins, A. P.; Hernes, P. J.; Aufdenkampe, A. K.; Gulliver, P.; Mopper, K.; Baker, A.; Dyda, R. Y.; Six, J. W.

    2008-12-01

    The Congo River basin drains the second largest area of rainforest in the world and is also the second largest river in terms of catchment size (3,680,000 km2) and freshwater discharge (42,000 m3 s- 1). Congo riverine dissolved organic carbon (DOC) export is estimated at 12.4 Tg DOC yr -1 or approximately 5 % of global riverine DOC export to the ocean. The sheer scale of this export makes further study of this system imperative for increased quantification and understanding of the terrestrial-ocean linkages in the global C cycle. Samples were collected in January and February 2008 from the Congo river- system and analyzed for a suite of compositional and degradation related measurements and its reactivity investigated. Our initial analyses of Congo riverine DOM yielded 14C ages of modern origin (fraction modern of 14C = 107.14 ± 0.50)) as expected for a large tropical river with a highly productive basin. Lignin phenol concentrations (Σ8 = 76.6 μgL-1) and compositions (Λ8 = 0.72 mg (100 mg OC)-1) are also indicative of fresh vascular plant derived DOM inputs, as are the 13C- DOC values (approximately -28.9), UV-vis spectral slope and slope ratio values and the fluorescence EEM data. Congo riverine DOM was shown to be highly photoreactive with fractional losses of DOC, colored DOM (CDOM) and lignin phenols equivalent to approximately 45 %, 95 % and 95 % respectively during the course of a 57 day irradiation experiment. CDOM spectral slope ratio values trended towards open ocean values during the irradiation (S275-295:S350-400 changed from 0.81 to 1.38). These spectral shifts have previously been shown to be indicative of a reduction in DOM aromaticity and average molecular weight. Lignin phenol data also trends towards typical carbon-normalized yield values of those observed previously in surface marine waters upon irradiation from 0.72 mg (100 mg OC)-1) at the start of the irradiation to 0.03 mg (100 mg OC)-1) after 57 days. Lignin phenols also showed increases

  3. Influence of dissolved organic substances in groundwater on sorption behavior of americium and neptunium

    SciTech Connect

    Boggs, S. Jr.; Seitz, M.G.

    1984-01-01

    Groundwaters typically contain dissolved organic carbon consisting largely of high molecular weight compounds of humic and fulvic acids. To evaluate whether these dissolved organic substances can enhance the tranport of radionuclides through the groundwater system, experiments were conducted to examine the sorption of americium and neptunium onto crushed basalt in the presence of dissolved humic- and fulvic-acid organic carbon introduced into synthetic groundwater. The partitioning experiments with synthetic groundwater show that increasing the concentration of either humic or fulvic acid in the water has a significant inhibiting effect on sorption of both americium and neptunium. At 22/sup 0/C, adsorption of these radionuclides, as measured by distribution ratios (the ratio of nuclide sorbed onto the solid to nuclide in solution at the end of the experiment), decreased by 25% to 50% by addition of as little as 1 mg/L dissolved organic carbon and by one to two orders of magnitude by addition of 100 to 200 mg/L dissolved organic carbon. Distribution ratios measured in solutions reacted at 90/sup 0/C similarly decreased with the addition of dissolved organic carbon but generally ranged from one to two orders of magnitude higher than those determined in the 22/sup 0/C experiment. These results suggest that organic carbon dissolved in deep groundwaters may significantly enhance the mobility of radionuclides of americium and neptunium. 23 references, 5 figures, 11 tables.

  4. Natural versus wastewater derived dissolved organic carbon: implications for the environmental fate of organic micropollutants.

    PubMed

    Neale, Peta A; Antony, Alice; Gernjak, Wolfgang; Leslie, Greg; Escher, Beate I

    2011-08-01

    The interaction of organic micropollutants with dissolved organic carbon (DOC) can influence their transport, degradation and bioavailability. While this has been well established for natural organic carbon, very little is known regarding the influence of DOC on the fate of micropollutants during wastewater treatment and water recycling. Dissolved organic carbon-water partition coefficients (K(DOC)) for wastewater derived and reference DOC were measured for a range of micropollutants using a depletion method with polydimethylsiloxane disks. For micropollutants with an octanol-water partition coefficient (log K(OW)) greater than 4 there was a significant difference in K(DOC) between reference and wastewater derived DOC, with partitioning to wastewater derived DOC over 1000 times lower for the most hydrophobic micropollutants. The interaction of nonylphenol with wastewater derived DOC from different stages of a wastewater and advanced water treatment train was studied, but little difference in K(DOC) was observed. Organic carbon characterisation revealed that reference and wastewater derived DOC had very different properties due to their different origins. Consequently, the reduced sorption capacity of wastewater derived DOC may be related to their microbial origin which led to reduced aromaticity and lower molecular weight. This study suggests that for hydrophobic micropollutants (log K(OW) > 4) a higher concentration of freely dissolved and thus bioavailable micropollutants is expected in the presence of wastewater derived DOC than predicted using K(DOC) values quantified using reference DOC. The implication is that naturally derived DOC may not be an appropriate surrogate for wastewater derived DOC as a matrix for assessing the fate of micropollutants in engineered systems. PMID:21703657

  5. Sources and fate of bioavailable dissolved organic nitrogen in the Neuse River Estuary, North Carolina

    NASA Astrophysics Data System (ADS)

    Paerl, H. W.; Peierls, B. L.; Hounshell, A.; Osburn, C. L.

    2015-12-01

    Eutrophication is a widespread problem affecting the structure and function of estuaries and is often linked to anthropogenic nitrogen (N) enrichment, since N is the primary nutrient limiting algal production. Watershed management actions typically have ignored dissolved organic nitrogen (DON) loading because of its perceived refractory nature and instead focused on inorganic N as targets for loading reductions. A fluorescence-based model indicated that anthropogenic sources of DON near the head of the microtidal Neuse River Estuary (NRE), NC were dominated by septic systems and poultry waste. A series of bioassays were used to determine the bioavailability of river DON and DON-rich sources to primary producers and whether those additions promoted the growth of certain phytoplankton taxa, particularly harmful species. Overall, at time scales up to two to three weeks, estuarine phytoplankton and bacteria only showed limited responses to additions of high molecular weight (HMW, >1 kDa) river DON. When increases in productivity and biomass did occur, they were quite small compared with the response to inorganic N. Low molecular weight (LMW) river DON, waste water treatment plant effluent, and poultry litter extract did have a positive effect on phytoplankton and bacterial production, indicating a bioavailable fraction. High variability of bulk DON concentration suggested that bioavailable compounds added in the experimental treatments were low in concentration and turned over quite rapidly. Some phytoplankton taxa, as measured by diagnostic photopigments, appeared to be selectively enhanced by the HMW and specific source DON additions, although the taxa could not be positively identified as harmful species. Preliminary tests show that labile autochthonous organic matter may act as a primer for the mineralization of the HMW DON. These and other, longer-term bioavailability studies will be needed to adequately address the fate of watershed DON in estuarine ecosystems.

  6. Changes and characteristics of dissolved organic matter in a constructed wetland system using fluorescence spectroscopy.

    PubMed

    Yao, Yuan; Li, Yun-Zhen; Guo, Xu-Jing; Huang, Tao; Gao, Ping-Ping; Zhang, Ying-Pei; Yuan, Feng

    2016-06-01

    Domestic wastewater was treated by five constructed wetland beds in series. Dissolved organic matter (DOM) collected from influent and effluent samples from the constructed wetland was investigated using fluorescence spectroscopy combined with fluorescence regional integration (FRI), parallel factor (PARAFAC) analysis, and two-dimensional correlation spectroscopy (2D-COS). This study evaluates the capability of these methods in detecting the spectral characteristics of fluorescent DOM fractions and their changes in constructed wetlands. Fluorescence excitation-emission matrix (EEM) combined with FRI analysis showed that protein-like materials displayed a higher removal ratio compared to humic-like substances. The PARAFAC analysis of wastewater DOM indicated that six fluorescent components, i.e., two protein-like substances (C1 and C6), three humic-like substances (C2, C3 and C5), and one non-humic component (C4), could be identified. Tryptophan-like C1 was the dominant component in the influent DOM. The removal ratios of six fluorescent components (C1-C6) were 56.21, 32.05, 49.19, 39.90, 29.60, and 45.87 %, respectively, after the constructed wetland treatment. Furthermore, 2D-COS demonstrated that the sequencing of spectral changes for fluorescent DOM followed the order 298 nm → 403 nm → 283 nm (310-360 nm) in the constructed wetland, suggesting that the peak at 298 nm is associated with preferential tryptophan fluorescence removal. Variation of the fluorescence index (FI) and the ratio of fluorescence components indicated that the constructed wetland treatment resulted in the decrease of fluorescent organic pollutant with increasing the humification and chemical stability of the DOM. PMID:26976008

  7. Influence of dissolved organic materials on turbid water optical properties and remote-sensing reflectance

    NASA Technical Reports Server (NTRS)

    Witte, W. G.; Whitlock, C. H.; Harriss, R. C.; Usry, J. W.; Poole, L. R.; Houghton, W. M.; Morris, W. D.; Gurganus, E. A.

    1982-01-01

    The effects of dissolved organic materials on turbid-water optical properties are assessed, by means of field measurements and laboratory simulations in which upwelled reflectance, attenuation, absorption, and backscatter spectral properties at wavelengths from 450 to 800 nm are examined in relation to water chemistry. The data show that dissolved organic materials decrease upwelled reflectance from turbid waters, and that the decrease in reflectance is a nonlinear function of concentration with the largest gradients at low carbon concentrations, depending on wavelength. Upwelled reflectance is found to be highly correlated with two backscatter-absorption parameters used in some optical models, which are nonlinear with dissolved organic material concentration change.

  8. Trophic complexity in aqueous systems: bacterial species richness and protistan predation regulate dissolved organic carbon and dissolved total nitrogen removal.

    PubMed

    Saleem, Muhammad; Fetzer, Ingo; Harms, Hauke; Chatzinotas, Antonis

    2016-02-24

    Loading of water bodies with dissolved organic carbon (DOC) and dissolved total nitrogen (DTN) affects their integrity and functioning. Microbial interactions mitigate the negative effects of high nutrient loads in these ecosystems. Despite numerous studies on how biodiversity mediates ecosystem functions, whether and how diversity and complexity of microbial food webs (horizontal, vertical) and the underlying ecological mechanisms influence nutrient removal has barely been investigated. Using microbial microcosms accommodating systematic combinations of prey (bacteria) and predator (protists) species, we showed that increasing bacterial richness improved the extent and reliability of DOC and DTN removal. Bacterial diversity drove nutrient removal either due to species foraging physiology or functional redundancy, whereas protistan diversity affected nutrient removal through bacterial prey resource partitioning and changing nutrient balance in the system. Our results demonstrate that prey-predator diversity and trophic interactions interactively determine nutrient contents, thus implying the vital role of microbial trophic complexity as a biological buffer against DOC and DTN. PMID:26888033

  9. Removal of organic contaminants from secondary effluent by anodic oxidation with a boron-doped diamond anode as tertiary treatment.

    PubMed

    Garcia-Segura, Sergi; Keller, Jürg; Brillas, Enric; Radjenovic, Jelena

    2015-01-01

    Electrochemical advanced oxidation processes (EAOPs) have been widely investigated as promising technologies to remove trace organic contaminants from water, but have rarely been used for the treatment of real waste streams. Anodic oxidation with a boron-doped diamond (BDD) anode was applied for the treatment of secondary effluent from a municipal sewage treatment plant containing 29 target pharmaceuticals and pesticides. The effectiveness of the treatment was assessed from the contaminants decay, dissolved organic carbon and chemical oxygen demand removal. The effect of applied current and pH was evaluated. Almost complete mineralization of effluent organic matter and trace contaminants can be obtained by this EAOP primarily due to the action of hydroxyl radicals formed at the BDD surface. The oxidation of Cl(-) ions present in the wastewater at the BDD anode gave rise to active chlorine species (Cl2/HClO/ClO(-)), which are competitive oxidizing agents yielding chloramines and organohalogen byproducts, quantified as adsorbable organic halogen. However, further anodic oxidation of HClO/ClO(-) species led to the production of ClO3(-) and ClO4(-) ions. The formation of these species hampers the application as a single-stage tertiary treatment, but posterior cathodic reduction of chlorate and perchlorate species may reduce the risks associated to their presence in the environment. PMID:25464295

  10. Influence of dissolved organic matter on dissolved vanadium speciation in the Churchill River estuary (Manitoba, Canada).

    PubMed

    Shi, Yong Xiang; Mangal, Vaughn; Guéguen, Céline

    2016-07-01

    Diffusive gradients in thin films (DGT) devices were used to investigate the temporal and spatial changes in vanadium (V) speciation in the Churchill estuary system (Manitoba). Thirty-six DGT sets and 95 discrete water samples were collected at 8 river and 3 estuary sites during spring freshet and summer base flow. Dissolved V concentration in the Churchill River at summer base flow was approximately 5 times higher than those during the spring high flow (27.3 ± 18.9 nM vs 4.8 ± 3.5 nM). DGT-labile V showed an opposite trend with greater values found during the spring high flow (2.6 ± 1.8 nM vs 1.4 ± 0.3 nM). Parallel factor analysis (PARAFAC) conducted on 95 excitation-emission matrix spectra validated four humic-like (C1C4) and one protein-like (C5) fluorescent components. Significant positive relationship was found between protein-like DOM and DGT-labile V (r = 0.53, p < 0.05), indicating that protein-like DOM possibly affected the DGT-labile V concentration in Churchill River. Sediment leachates were enriched in DGT-labile V and protein-like DOM, which can be readily released when river sediment began to thaw during spring freshet. PMID:27065459

  11. [Spectroscopy properties of dissolved organic matter in landfill leachate during corrosion cell-Fenton post-treatment].

    PubMed

    Zhao, Qing-Liang; Bu, Lin; Yang, Jun-Chen; Wang, Kun

    2011-08-01

    To differentiate the transformation of dissolved organic matter (DOM) during corrosion cell-Fenton (CCF) post-treatment, the leachate was separated into five fractions by XAD-8 and XAD-4 resins (hydrophilic fraction, HPI; hydrophobic acid, HPO-A; transphilic acid, TPI-A; hydrophobic neutral, HPO-N; transphilic neutral, TPI-N). UV-Vis spectroscopy and fluorescence spectroscopy were used for the degradation analysis. Experimental results showed that DOM in landfill leachate reduced 61.8% of dissolved organic carbon (DOC). Especially for HPO-A and HPO-N, with the removal ratios were up to 74.9% and 66.5%, respectively. The predominant portion in the effluent was HPI (comprising 60.1% of DOC). Spectral analyses showed that the leachate DOM was composed of abundant condensed ring aromatic compounds and humic substances, with the HPO-A was the highest aromatic fraction. The ratio of absorbance at 253 nm and 203 nm (E253/E203) was decreased in the order of HPO-A > HPO-N > TPI-A > TPI-N > HPI. The unsaturated conjugated structures were efficiently destroyed after the CCF treatment, and the functional groups such as carbonyl, amine were also eliminated. The main fluorophores in leachate fractions were in the region of aromatic protein-like and visible fulvic-like. The fluorescence intensity of peaks in each fraction decreased after CCF treatment, especially for the fulvic-like fluorescent substances. The results indicated that the CCF treatment was efficient to remove the hydrophobic fractions and reduce the complicacy of leachate effluent. PMID:22619966

  12. Methane hydrate-bearing seeps as a source of aged dissolved organic carbon to the oceans

    USGS Publications Warehouse

    Pohlman, J.W.; Bauer, J.E.; Waite, W.F.; Osburn, C.L.; Chapman, N.R.

    2011-01-01

    Marine sediments contain about 500-10,000 Gt of methane carbon, primarily in gas hydrate. This reservoir is comparable in size to the amount of organic carbon in land biota, terrestrial soils, the atmosphere and sea water combined, but it releases relatively little methane to the ocean and atmosphere. Sedimentary microbes convert most of the dissolved methane to carbon dioxide. Here we show that a significant additional product associated with microbial methane consumption is methane-derived dissolved organic carbon. We use ??14 C and ??13 C measurements and isotopic mass-balance calculations to evaluate the contribution of methane-derived carbon to seawater dissolved organic carbon overlying gas hydrate-bearing seeps in the northeastern Pacific Ocean. We show that carbon derived from fossil methane accounts for up to 28% of the dissolved organic carbon. This methane-derived material is much older, and more depleted in 13 C, than background dissolved organic carbon. We suggest that fossil methane-derived carbon may contribute significantly to the estimated 4,000-6,000 year age of dissolved organic carbon in the deep ocean, and provide reduced organic matter and energy to deep-ocean microbial communities. ?? 2011 Macmillan Publishers Limited. All rights reserved.

  13. Evaluation of screening procedures for bioconcentratable organic chemicals in effluents and sediments

    SciTech Connect

    Burkhard, L.P.; Sheedy, B.R.

    1995-04-01

    Screening procedures have been developed by the US Environmental Protection Agency (EPA) to isolate and tentatively identify nonpolar organic chemicals in effluent and sediment samples with high potential to form chemical residues in aquatic organisms. The objective of this study was to determine if the sample components tentatively identified by the effluent- and sediment-screening procedures actually form chemical residues in aquatic organisms. This evaluation consisted of analyzing effluent and sediment samples from a field site with discharges from two coke-manufacturing facilities using the screening procedures. Effluent, sediment, crayfish (Decapoda), and sunfish (Lepomis sp.) samples from the field site were also prepared using conventional sample preparation procedures and analyzed for the tentatively identified chemicals (TIDs) reported by the screening procedures. Results of the screening procedures were then compared to the results of the analyses on the samples prepared using the conventional sample preparation procedures. For the effluent-screening procedure, 182 of 183 TIDs in Coke Plant 1 effluent and all of the 7 TIDs in Coke Plant 2 effluent were found in the crayfish, sunfish, and/or sediment samples downstream of the discharges. For the sediment-screening procedure, 92 of 93 TIDs and all of 47 TIDs in sediment samples from two sampling stations downstream of the discharges were found in the crayfish and/or sunfish samples.

  14. Investigating the relationship between toxicity and organic sum-parameters in kraft mill effluents.

    PubMed

    Raptis, Catherine E; Juraske, Ronnie; Hellweg, Stefanie

    2014-12-01

    Elaborate toxicity diagnostics, such as toxicity identification evaluation (TIE) and effects-directed analysis (EDA) have helped in identifying the causative agents of effluent wastewater toxicity. However, simpler means of relating ecotoxicological effects to effluent composition could be useful for effluent management practices when there is no scope for more complex procedures. The aim of this work was to investigate and isolate the relationship between biological responses and commonly measured organic sum-parameters, such as chemical- and biochemical oxygen demand (COD and BOD, respectively) in kraft mill effluents. In a top-down approach, the whole effluent toxicity (WET) of effluent samples was first determined from Pseudokirchneriella subcapitata and Ceriodaphnia dubia bioassays. The theoretical toxicity that could be attributed to the metal content was then estimated, via a combination of equilibrium chemical speciation- and metal toxicity modelling. By assuming concentration addition, the metal toxicity was subtracted from the WET, isolating the toxicity thought to be caused by the organics. Strong and significant correlations between the 'corrected' toxicity and organic sum-parameters were found for both species. The growth of P. subcapitata was negatively associated with increasing COD concentrations, whereas reproduction of C. dubia was negatively associated with increasing BOD concentrations. The linear relationships, along with robust estimations of their uncertainty bounds, can provide valuable, albeit rough, guidance for kraft mill effluent management practices. PMID:25213683

  15. Sources and Fates of Dissolved Organic Matter in the Mid-Atlantic Bight

    SciTech Connect

    Hopkinson, C. S.

    2000-08-16

    The objectives of the research program were to identify and determine the relative importance of various sources of dissolved organic matter to the continental shelf, and to estimate the net carbon balance for the Middle Atlantic Bight.

  16. Impact of solids retention time on dissolved organic nitrogen and its biodegradability in treated wastewater

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dissolved organic nitrogen (DON) and its biodegradability in treated wastewater have recently gained attention because DON potentially causes oxygen depletion and/or eutrophication in receiving waters. Laboratory scale chemostat experiments were conducted at 9 different solids retention times (SRTs)...

  17. CHANGES IN SPECTRAL AND PHOTOCHEMICAL PROPERTIES OF COLORED DISSOLVED ORGANIC MATTER IN A COASTAL ESTUARY

    EPA Science Inventory

    Colored dissolved organic matter (CDOM) is the primary determinant of UV penetration and exposure in freshwater and coastal environments. CDOM is photochemically reactive and its photoreactions can lead to reductions in UV absorbance and increased UV exposure in aquatic ecosystem...

  18. Influence of carbonization methods on the aromaticity of pyrogenic dissolved organic carbon

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dissolved organic carbon (DOC) components of soil amendments such as biochar will influence the fundamental soil chemistry including the metal speciation, nutrient availability, and microbial activity. Quantitative correlation is necessary between (i) pyrogenic DOC components of varying aromaticity...

  19. CHROMOPHORIC DISSOLVED ORGANIC MATTER (CDOM) SOURCE CHARACTERIZATION IN THE LOUISIANA BIGHT

    EPA Science Inventory

    Chromophoric dissolved organic matter (CDOM) in the Mississippi plume region may have several distinct sources: riverine (terrestrial soils), wetland (terrestrial plants), biological production (phytoplankton, zooplankton, microbial), and sediments. Complex mixing, photodegradati...

  20. DISSOLVED ORGANIC CARBON TRENDS RESULTING FROM CHANGES IN ATMOSPHERIC DEPOSITION CHEMISTRY

    EPA Science Inventory

    Several hypotheses have been proposed to explain recent, widespread increases in concentrations of dissolved organic carbon (DOC) in the surface waters of glaciated landscapes across eastern North America and northern and central Europe. Some invoke anthropogenic forcing through ...

  1. Sulfamethazine sorption to soil: vegetative management, pH, and dissolved organic matter effects

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Elucidating veterinary antibiotic (VA) interactions with soil is important for assessing and mitigating possible environmental hazards. Objectives of this study were to investigate the effects of vegetative management, soil physical and chemical properties, and manure-derived dissolved organic matte...

  2. Photobleaching Kinetics of Chromophoric Dissolved Organic Matter Derived from Mangrove Leaf Litter and Floating Sargassum Colonies

    EPA Science Inventory

    We examined the photoreactivity of chromophoric dissolved organic matter (CDOM) derived from Rhizophora mangle (red mangrove) leaf litter and floating Sargassum colonies as these marine plants can be important contributors to coastal and open ocean CDOM pools, respectively. Mangr...

  3. PHOTOCHEMICALLY-INDUCED TRANSFORMATIONS OF DISSOLVED ORGANIC MATTER IN RIVERINE WATERS

    EPA Science Inventory

    We demonstrated that exposure of riverine water to natural sunlight initiated degradation and corresponding alteration to the stable carbon isotope ratio and biochemical composition of the associated dissolved organic carbon (DOC). Water samples were collected from two distinct ...

  4. Northern Gulf of Mexico estuarine coloured dissolved organic matter derived from MODIS data

    EPA Science Inventory

    Coloured dissolved organic matter (CDOM) is relevant for water quality management and may become an important measure to complement future water quality assessment programmes. An approach to derive CDOM using the Moderate Resolution Imaging Spectroradiometer (MODIS) was developed...

  5. Chromatographic methods for the isolation, separation and characterisation of dissolved organic matter.

    PubMed

    Sandron, Sara; Rojas, Alfonso; Wilson, Richard; Davies, Noel W; Haddad, Paul R; Shellie, Robert A; Nesterenko, Pavel N; Kelleher, Brian P; Paull, Brett

    2015-09-01

    This review presents an overview of the separation techniques applied to the complex challenge of dissolved organic matter characterisation. The review discusses methods for isolation of dissolved organic matter from natural waters, and the range of separation techniques used to further fractionate this complex material. The review covers both liquid and gas chromatographic techniques, in their various modes, and electrophoretic based approaches. For each, the challenges that the separation and fractionation of such an immensely complex sample poses is critically reviewed. PMID:26290053

  6. Mechanisms of dissolved organic carbon cycling in an ocean margin. Final technical report

    SciTech Connect

    Benner, R.

    1997-11-24

    Dissolved organic carbon (DOC) is the largest reservoir of organic carbon in the ocean, and the objectives of this project were to investigate the mechanisms and pathways of DOC formation and consumption in seawater. Carbohydrates are the most abundant form of DOC, and this project included measurements of dissolved carbohydrates as well as DOC to help delineate the cycling of DOC. Many of the methods and approaches for investigating DOC production were developed as part of this project.

  7. PHOTOCHEMICAL ALTERATION OF DISSOLVED ORGANIC MATTER: EFFECTS ON THE CONCENTRATION AND ACIDITIES OF IONIZABLE SITES IN DISSOLVED ORGANIC MATTER IN THE SATILLA RIVER OF GEORGIA, USA

    EPA Science Inventory

    The acid-base properties of humic substances, the major component of dissolved organic matter (DOM), area major control on the alkalinity, or acid neutralizing capacity of freshwater systems. Alkalinity is one of the fundamental parameters measured in aquatic sciences, and is an ...

  8. Utilizing chromophoric dissolved organic matter measurements to derive export and reactivity of dissolved organic carbon exported to the Arctic Ocean: A case study of the Yukon River, Alaska

    USGS Publications Warehouse

    Spencer, R.G.M.; Aiken, G.R.; Butler, K.D.; Dornblaser, M.M.; Striegl, R.G.; Hernes, P.J.

    2009-01-01

    The quality and quantity of dissolved organic matter (DOM) exported by Arctic rivers is known to vary with hydrology and this exported material plays a fundamental role in the biogeochemical cycling of carbon at high latitudes. We highlight the potential of optical measurements to examine DOM quality across the hydrograph in Arctic rivers. Furthermore, we establish chromophoric DOM (CDOM) relationships to dissolved organic carbon (DOC) and lignin phenols in the Yukon River and model DOC and lignin loads from CDOM measurements, the former in excellent agreement with long-term DOC monitoring data. Intensive sampling across the historically under-sampled spring flush period highlights the importance of this time for total export of DOC and particularly lignin. Calculated riverine DOC loads to the Arctic Ocean show an increase from previous estimates, especially when new higher discharge data are incorporated. Increased DOC loads indicate decreased residence times for terrigenous DOM in the Arctic Ocean with important implications for the reactivity and export of this material to the Atlantic Ocean. Citation: Spencer, R. G. M., G. R. Aiken, K. D. Butler, M. M. Dornblaser, R. G. Striegl, and P. J. Hernes (2009), Utilizing chromophoric dissolved organic matter measurements to derive export and reactivity of dissolved organic carbon exported to the Arctic Ocean: A case study of the Yukon River, Alaska, Geophys. Res. Lett., 36, L06401, doi:10.1029/ 2008GL036831. Copyright 2009 by the American Geophysical Union.

  9. Dissolved organic matter in anoxic pore waters from Mangrove Lake, Bermuda

    USGS Publications Warehouse

    Orem, W.H.; Hatcher, P.G.; Spiker, E. C.; Szeverenyi, N.M.; Maciel, G.E.

    1986-01-01

    Dissolved organic matter and dissolved inorganic chemical species in anoxic pore water from Mangrove Lake, Bermuda sediments were studied to evaluate the role of pore water in the early diagenesis of organic matter. Dissolved sulphate, titration alkalinity, phosphate, and ammonia concentration versus depth profiles were typical of many nearshore clastic sediments and indicated sulphate reduction in the upper 100 cm of sediment. The dissolved organic matter in the pore water was made up predominantly of large molecules, was concentrated from large quantities of pore water by using ultrafiltration and was extensively tudied by using elemental and stable carbon isotope analysis and high-resolution, solid state 13C nuclear magnetic resonance and infrared spectroscopy. The results indicate that this material has a predominantly polysaccharide-like structure and in addition contains a large amount of oxygen-containing functional groups (e.g., carboxyl groups). The 13C nulcear magnetic resonance spectra of the high-molecular-weight dissolved organic matter resemble those of the organic matter in the surface sediments of Mangrove Lake. We propose that this high-molecular-weight organic matter in pore waters represents the partially degraded, labile organic components of the sedimentary organic matter and that pore waters serve as a conduit for removal of these labile organic components from the sediments. The more refractory components are, thus, selectively preserved in the sediments as humic substances (primarily humin). ?? 1986.

  10. Chemical characterization of dissolved organic compounds from coastal sea surface microlayers (Baltic Sea, Germany).

    PubMed

    van Pinxteren, Manuela; Müller, Conny; Iinuma, Yoshiteru; Stolle, Christian; Herrmann, Hartmut

    2012-10-01

    The physicochemical properties of the sea surface microlayer (SML), i.e. the boundary layer between the air and the sea, and its impact on air-sea exchange processes have been investigated for decades. However, a detailed description about these processes remains incomplete. In order to obtain a better chemical characterization of the SML, in a case study three pairs of SML and corresponding bulk water samples were taken in the southern Baltic Sea. The samples were analyzed for dissolved organic carbon and dissolved total nitrogen, as well as for several organic nitrogen containing compounds and carbohydrates, namely aliphatic amines, dissolved free amino acids, dissolved free monosaccharides, sugar alcohols, and monosaccharide anhydrates. Therefore, reasonable analytical procedures with respect to desalting and enrichment were established. All aliphatic amines and the majority of the investigated amino acids (11 out of 18) were found in the samples with average concentrations between 53 ng L(-1) and 1574 ng L(-1). The concentrations of carbohydrates were slightly higher, averaging 2900 ng L(-1). Calculation of the enrichment factor (EF) between the sea surface microlayer and the bulk water showed that dissolved total nitrogen was more enriched (EF: 1.1 and 1.2) in the SML than dissolved organic carbon (EF: 1.0 and 1.1). The nitrogen containing organic compounds were generally found to be enriched in the SML (EF: 1.9-9.2), whereas dissolved carbohydrates were not enriched or even depleted (EF: 0.7-1.2). Although the investigated compounds contributed on average only 0.3% to the dissolved organic carbon and 0.4% to the total dissolved nitrogen fraction, these results underline the importance of single compound analysis to determine SML structure, function, and its potential for a transfer of compounds into the atmosphere. PMID:22475414

  11. Seqestration of dissolved organic carbon in the deep sea

    SciTech Connect

    Daniel J. Repeta

    2006-03-01

    There are 600 GT of dissolved organic carbon (DOC) sequestered in seawater. The marine inventory of DOC is set by its concentration in the deep sea, which is nearly constant at 35+2µM C, irrespective of sample location or depth. Isotopic measurements show deep sea DOC to be depleted in radiocarbon, with an apparent radiocarbon age of between 4000ybp (Atlantic) and 6000ybp (Pacific). From the radiocarbon data, we can infer that deep sea DOC is inert and does not cycle on less than millennial time scales. However, high precision DOC measurements show deep sea concentrations are variable at the + 1-2µM DOC level, suggesting a fraction of deep sea DOC, equivalent to 15-30Gt C, is cycling on short time scales, acting as a sink for new, atmospheric carbon. This project is designed to identify and quantify the biological and physical processes that sequester DOM in the deep sea by making compound specific radiocarbon measurements on sugars and proteins extracted from deep sea DOC. Our Hawaii surface seawater sample has a DIC Δ14C value of 72 + 7 ‰ and shows the influence of bomb radiocarbon on surface water DIC values. HMWDOC Δ14C is 10 ‰, significantly depleted in radiocarbon relative to DIC. Purification of HMWDOC by reverse phase HPLC yields seven neutral sugars with radiocarbon values of 47 – 67‰. Assuming the radiocarbon determinations of individual sugars in HMWDOC serve as replicates, then the average Δ14C for neutral sugars in HMWDOC is 57 + 6 ‰(1 SD, n=11), only slightly depleted in 14C relative to DIC. There has been a sharp decrease in radiocarbon values for DIC in the North Pacific Ocean over the past few decades. If neutral sugars cycle more slowly than DIC, we would expect them to have correspondingly higher radiocarbon values. Previous studies have modeled upper ocean DOC as a two component mixture of newly synthesized DOC with a radiocarbon value equal to DIC, and an old component with a radiocarbon value equal to deep sea DO14C. In order to

  12. Effects of effluent organic matter characteristics on the removal of bulk organic matter and selected pharmaceutically active compounds during managed aquifer recharge: Column study

    NASA Astrophysics Data System (ADS)

    Maeng, Sung Kyu; Sharma, Saroj K.; Abel, Chol D. T.; Magic-Knezev, Aleksandra; Song, Kyung-Guen; Amy, Gary L.

    2012-10-01

    Soil column experiments were conducted to investigate the effects of effluent organic matter (EfOM) characteristics on the removal of bulk organic matter (OM) and pharmaceutically active compounds (PhACs) during managed aquifer recharge (MAR) treatment processes. The fate of bulk OM and PhACs during an MAR is important to assess post-treatment requirements. Biodegradable OM from EfOM, originating from biological wastewater treatment, was effectively removed during soil passage. Based on a fluorescence excitation-emission matrix (F-EEM) analysis of wastewater effluent-dominated (WWE-dom) surface water (SW), protein-like substances, i.e., biopolymers, were removed more favorably than fluorescent humic-like substances under oxic compared to anoxic conditions. However, there was no preferential removal of biopolymers or humic substances, determined as dissolved organic carbon (DOC) observed via liquid chromatography with online organic carbon detection (LC-OCD) analysis. Most of the selected PhACs exhibited removal efficiencies of greater than 90% in both SW and WWE-dom SW. However, the removal efficiencies of bezafibrate, diclofenac and gemfibrozil were relatively low in WWE-dom SW, which contained more biodegradable OM than did SW (copiotrophic metabolism). Based on this study, low biodegradable fractions such as humic substances in MR may have enhanced the degradation of diclofenac, gemfibrozil and bezafibrate by inducing an oligotrophic microbial community via long term starvation. Both carbamazepine and clofibric acid showed persistent behaviors and were not influenced by EfOM.

  13. Assessing estrogenic activity and reproductive toxicity of organic extracts in WWTP effluents.

    PubMed

    Li, Bo; Cao, Jun; Xing, Chuanhong; Wang, Zhijin; Cui, Liuxin

    2015-03-01

    Trace level organic contaminants might not be completely removed from the municipal wastewater and the safety incurred by them had become a concern. These organic pollutants were extracted from water samples and detected by GC-MS. The estrogenic activity of the organic was tested using Yeast Estrogen Screen to detect the transcriptional activation of the estrogen receptor (ER) and immature mouse uterotrophic bioassays to study reproductive toxicity. The results of GC-MS demonstrated the organic extracts in the municipal wastewater and the WWTP effluents Included two major categories, benzenes and Phthalates. The estrogenic activity of organic extracts from the secondary effluent (SE) and tertiary effluent (TE) was below that of the raw wastewater (RW). Results of uterotrophic bioassay demonstrated that SE would bring some potential hazards on animals while TE was relatively safe. PMID:25818108

  14. Effluent, nutrient and organic matter export from shrimp and fish ponds causing eutrophication in coastal and back-reef waters of NE Hainan, tropical China

    NASA Astrophysics Data System (ADS)

    Herbeck, Lucia S.; Unger, Daniela; Wu, Ying; Jennerjahn, Tim C.

    2013-04-01

    Global aquaculture has grown at a rate of 8.7% per year since 1970. Particularly along the coasts of tropical Asia, aquaculture ponds have expanded rapidly at the expense of natural wetlands. The objectives of this study were (i) to characterize the extent and production process of brackish-water pond aquaculture at the NE coast of Hainan, tropical China, (ii) to quantify effluent and organic carbon, nitrogen and phosphorus export from shrimp and fish ponds and (iii) to trace their effect on the water quality in adjacent estuarine and nearshore coastal waters harboring seagrass meadows and coral reefs. During two expeditions in 2008 and 2009, we determined dissolved inorganic nutrients, dissolved organic carbon (DOC) and dissolved organic nitrogen (DON), chlorophyll a (chl a) and particulate organic matter (POM) in aquaculture ponds, drainage channels and coastal waters in three areas varying in extent of aquaculture ponds. From the analysis of satellite images we calculated a total of 39.6 km² covered by shrimp and fish ponds in the study area. According to pond owners, there is no standardized production pattern for feeding management and water exchange. Nutrient and suspended matter concentrations were high in aquaculture ponds and drainage channels, but varied considerably. The calculated annual export of total dissolved nitrogen (TDN) and particulate nitrogen (PN) from pond aquaculture into coastal waters was 612 and 680 t yr-1, respectively. High concentrations of dissolved inorganic nitrogen (DIN), phosphate and chl a at the majority of the coastal stations point at eutrophication of coastal waters, especially close to shore. Coastal eutrophication driven by the introduction of untreated aquaculture effluents may be especially harmful in back-reef areas, where estuarine retention and mixing with open ocean water is restricted thus threatening seagrasses and corals.

  15. Watershed scale spatial variability in dissolved and total organic and inorganic carbon in contrasting UK catchments

    NASA Astrophysics Data System (ADS)

    Cumberland, S.; Baker, A.; Hudson, N. J.

    2006-12-01

    Approximately 800 organic and inorganic carbon analyses have been undertaken from watershed scale and regional scale spatial surveys in various British catchments. These include (1) a small (<100 sq-km) urban catchment (Ouseburn, N England); (2) a headwater, lowland agricultural catchment (River Tern, C England) (3) a large UK catchment (River Tyne, ~3000 sq-km) and (4) a spatial survey of ~300 analyses from rivers from SW England (~1700 sq-km). Results demonstrate that: (1) the majority of organic and inorganic carbon is in the dissolved (DOC and DIC) fractions; (2) that with the exception of peat rich headwaters, DIC concentration is always greater than DOC; (3) In the rural River Tern, riverine DOC and DIC are shown to follow a simple end- member mixing between DIC (DOC) rich (poor) ground waters and DOC (DIC) rich (poor) riparian wetlands for all sample sites. (4) In the urbanized Ouseburn catchment, although many sample sites also show this same mixing trend, some tributaries follow a pollutant trend of simultaneous increases in both DOC and DIC. The Ouseburn is part of the larger Tyne catchment: this larger catchment follows the simple groundwater DIC- soil water DOC end member mixing model, with the exception of the urban catchments which exhibit an elevated DIC compared to rural sites. (5) Urbanization is demonstrated to increase DIC compared to equivalent rural catchments; this DIC has potential sources including diffuse source inputs from the dissolution of concrete, point sources such as trade effluents and landfill leachates, and bedrock derived carbonates relocated to the soil dissolution zone by urban development. (6) DIC in rural SW England demonstrates that spatial variability in DIC can be attributed to variations in geology; but that DIC concentrations in the SW England rivers dataset are typically lower than the urbanized Tyne catchments despite the presence of carbonate bedrock in many of the sample catchments in the SW England dataset. (7

  16. Reactivity and chemical characterization of effluent organic nitrogen from wastewater treatment plants determined by Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Mesfioui, Rajaa; Love, Nancy G; Bronk, Deborah A; Mulholland, Margaret R; Hatcher, Patrick G

    2012-03-01

    In advanced wastewater treatment plants that achieve high levels of nitrogen (N) removal, up to one-third of the N in effluent is organic, herein referred to as effluent organic N (EON). While we know that inorganic N is highly labile, it is unclear what fraction of EON is bioavailable. In this study, we demonstrate the utility of a method that can be used to examine the reactivity of EON in natural receiving waters to better understand both the ecosystem response and the potential bioavailability of EON. The technique is suitable for analyzing polar organic matter in natural waters; electrospray ionization coupled with Fourier transform mass spectrometry. Bioassays were performed on samples collected at the end of the biological process from two wastewater treatment plants achieving advanced N removal. The samples were concentrated, and then added to natural water samples collected from the oligohaline James River, a major tributary of the Chesapeake Bay. Our results demonstrate that while the lignin-like fraction of the effluent dissolved organic matter (some of which contains N) was conserved, a large portion of aliphatic and aromatic compounds containing N was removed (79-100%) during incubations, while other compounds were produced. Furthermore, the two effluents exhibited differences in the degree of degradation and type of degradation, which can be related both to the various processes employed in the two WWTPs and the dramatic differences in the type of influent they received. These findings suggest that EON is highly reactive in the natural environment and that simple assays examining net consumption or production of bulk dissolved organic N pools are inadequate for assessing the bioavailability of EON. PMID:22172558

  17. THERMODYNAMIC MODELING OF LIQUID AEROSOLS CONTAINING DISSOLVED ORGANICS AND ELECTROLYTES

    EPA Science Inventory

    Many tropospheric aerosols contain large fractions of soluble organic material, believed to derive from the oxidation of precursors such alpha-pinene. The chemical composition of aerosol organic matter is complex and not yet fully understood.

    The key properties of solu...

  18. Leaching of Particulate and Dissolved Organic Carbon from Compost Applied to Bioretention Systems

    NASA Astrophysics Data System (ADS)

    Iqbal, Hamid; Flury, Markus; Mullane, Jessica; Baig, Muhammad

    2015-04-01

    Compost is used in bioretention systems to improve soil quality, to promote plant growth, and to remove metal contaminants from stormwater. However, compost itself, particularly when applied freshly, can be a source of contamination of the stormwater. To test the potential contamination caused by compost when applied to bioretention systems, we continuously leached a compost column with water under unsaturated conditions and characterized dissolved and particulate organic matter in the leachate. Freshly applied, mature compost leached up to 400 mg/L of dissolved organic carbon and 2,000 mg/L of suspended particulate organic carbon. It required a cumulative water flux of 4,000 mm until concentrations of dissolved and particulate organic carbon declined to levels typical for surface waters. Although, dissolved and particulate organic carbon are not contaminants per se, they can facilitate the movement of metals, thereby enhancing the mobility of toxic metals present in stormwater. Therefore, we recommended that compost is washed before it is applied to bioretention systems. Keywords compost; leachate; alkali extract; dissolved organic carbon; flux

  19. Effects of sulfate deposition on pore water dissolved organic carbon, nutrients, and microbial enzyme activities in a northern peatland

    EPA Science Inventory

    Export of dissolved organic carbon from lakes and streams has increased throughout Europe and North America over the past several decades. One possible cause is altered deposition chemistry; specifically, decreasing sulfate inputs leading to changes in ionic strength and dissolve...

  20. DISTRIBUTION AND COMPOSITION OF DISSOLVED AND PARTICULATE ORGANIC CARBON IN NORTHERN SAN FRANCISCO BAY DURING LOW FRESHWATER FLOW CONDITIONS

    EPA Science Inventory

    The distribution of organic matter was studied in northern San Francisco Bay monthly through spring and summer 1996 along the salinity gradient from the Sacramento River to Central Bay. Dissolved constituents included monosaccharides (MONO), total carbohydrates (TCHO), dissolved ...

  1. Wastewater effluent, combined sewer overflows, and other sources of organic compounds to Lake Champlain

    USGS Publications Warehouse

    Phillips, P.; Chalmers, A.

    2009-01-01

    Some sources of organic wastewater compounds (OWCs) to streams, lakes, and estuaries, including wastewater-treatment-plant effluent, have been well documented, but other sources, particularly wet-weather discharges from combined-sewer-overflow (CSO) and urban runoff, may also be major sources of OWCs. Samples of wastewater-treatment-plant (WWTP) effluent, CSO effluent, urban streams, large rivers, a reference (undeveloped) stream, and Lake Champlain were collected from March to August 2006. The highest concentrations of many OWCs associated with wastewater were in WWTP-effluent samples, but high concentrations of some OWCs in samples of CSO effluent and storm runoff from urban streams subject to leaky sewer pipes or CSOs were also detected. Total concentrations and numbers of compounds detected differed substantially among sampling sites. The highest total OWC concentrations (10-100 ??g/l) were in samples of WWTP and CSO effluent. Total OWC concentrations in samples from urban streams ranged from 0.1 to 10 ??g/l, and urban stream-stormflow samples had higher concentrations than baseflow samples because of contributions of OWCs from CSOs and leaking sewer pipes. The relations between OWC concentrations in WWTP-effluent and those in CSO effluent and urban streams varied with the degree to which the compound is removed through normal wastewater treatment. Concentrations of compounds that are highly removed during normal wastewater treatment [including caffeine, Tris(2-butoxyethyl)phosphate, and cholesterol] were generally similar to or higher in CSO effluent than in WWTP effluent (and ranged from around 1 to over 10 ??g/l) because CSO effluent is untreated, and were higher in urban-stream stormflow samples than in baseflow samples as a result of CSO discharge and leakage from near-surface sources during storms. Concentrations of compounds that are poorly removed during treatment, by contrast, are higher in WWTP effluent than in CSO, due to dilution. Results indicate

  2. Dissolved organic carbon in rainwater: Glassware decontamination and sample preservation and volatile organic carbon

    NASA Astrophysics Data System (ADS)

    Campos, M. L. A. M.; Nogueira, R. F. P.; Dametto, P. R.; Francisco, J. G.; Coelho, C. H.

    The efficiency of different methods for the decontamination of glassware used for the analysis of dissolved organic carbon (DOC) was tested using reported procedures as well as new ones proposed in this work. A Fenton solution bath (1.0 mmol L -1 Fe 2+ and 100 mmol L -1 H 2O 2) for 1 h or for 30 min employing UV irradiation showed to combine simplicity, low cost and high efficiency. Using the optimized cleaning procedure, the DOC for stored UV-irradiated ultra-pure water reached concentrations below the limit of detection (0.19 μmol C L -1). Filtered (0.7 μm) rain samples maintained the DOC integrity for at least 7 days when stored at 4 °C. The volatile organic carbon (VOC) fraction in the rain samples collected at two sites in São Paulo state (Brazil) ranged from 0% to 56% of their total DOC content. Although these high-VOC concentrations may be derived from the large use of ethanol fuel in Brazil, our results showed that when using the high-temperature catalytic oxidation technique, it is essential to measure DOC rather than non-purgeble organic carbon to estimate organic carbon, since rainwater composition can be quite variable, both geographically and temporally.

  3. Improved automation of dissolved organic carbon sampling for organic-rich surface waters.

    PubMed

    Grayson, Richard P; Holden, Joseph

    2016-02-01

    In-situ UV-Vis spectrophotometers offer the potential for improved estimates of dissolved organic carbon (DOC) fluxes for organic-rich systems such as peatlands because they are able to sample and log DOC proxies automatically through time at low cost. In turn, this could enable improved total carbon budget estimates for peatlands. The ability of such instruments to accurately measure DOC depends on a number of factors, not least of which is how absorbance measurements relate to DOC and the environmental conditions. Here we test the ability of a S::can Spectro::lyser™ for measuring DOC in peatland streams with routinely high DOC concentrations. Through analysis of the spectral response data collected by the instrument we have been able to accurately measure DOC up to 66 mg L(-1), which is more than double the original upper calibration limit for this particular instrument. A linear regression modelling approach resulted in an accuracy >95%. The greatest accuracy was achieved when absorbance values for several different wavelengths were used at the same time in the model. However, an accuracy >90% was achieved using absorbance values for a single wavelength to predict DOC concentration. Our calculations indicated that, for organic-rich systems, in-situ measurement with a scanning spectrophotometer can improve fluvial DOC flux estimates by 6 to 8% compared with traditional sampling methods. Thus, our techniques pave the way for improved long-term carbon budget calculations from organic-rich systems such as peatlands. PMID:26580726

  4. Treatment of biorefractory organic compounds in wool scour effluent by hydroxyl radical oxidation.

    PubMed

    Poole, Andrew J

    2004-01-01

    Wool scouring effluent that had been treated with chemical flocculation and aerobic biological treatment (Sirolan CFB effluent) was tertiary treated by hydroxyl radical oxidation to remove residual organic compounds. These compounds impart a high chemical oxygen demand of 500-3000 mg/L and dark colour. However, a H2O2/UV process was found to effectively treat the majority of residual compounds, with up to 75% COD, 85% total organic carbon, and 100% removal of colour (T(480 nm)) achieved. This was despite the effluent being strongly absorbing in the UV region, with a film thickness of 0.21 mm reducing T(254 nm) by 50%. Treatment was unaffected by pH over the range 3-9. H2O2/UV treatment increased the biodegradability of the effluent (5-day biochemical oxygen demand increased from < 10 to 86 mg/L), but a combined chemical and biological process did not increase maximum COD removal or overall process efficiency. The tertiary treated effluent had a final COD in the range 125-750 mg/L, equating to a total COD removal from raw wool scour effluent of approximately 97.5%. This degree of treatment is sufficient for discharge in many, but not all, circumstances. PMID:15276763

  5. When dissolved is not truly dissolved--the importance of colloids in studies of metal sorption on organic matter.

    PubMed

    Schijf, Johan; Zoll, Alison M

    2011-09-01

    In controlled metal sorption experiments, the equilibrium distribution coefficient is a key variable quantifying sorbate partitioning across the solid-solution interface. Separation of metals into 'dissolved' and 'particulate' fractions is commonly achieved with syringe filtration, where the boundary is somewhat arbitrarily dictated by the limited selection of available pore sizes. Investigations involving natural organic matter, such as bacterial cells or plant tissues, are especially prone to experimental artifacts if the substrate releases abundant colloidal compounds that contribute to sorption by binding free metal cations in a pH-dependent fashion yet pass through conventional filters, causing the truly dissolved fraction to be grossly overestimated. We observed this phenomenon during a study of lanthanide sorption on a marine macroalga, Ulva lactuca, as a function of pH. At low ionic strength, distribution coefficients calculated for a 0.22-μm size cutoff falsely imply that metal sorption reverses to gradual release above pH 4.6, instead of continuing to increase. Centrifuging the filtrates in Amicon® Ultra units (30 and 3 kDa molecular weight cutoff) revealed a mounting proportion of colloid-bound metal, constituting up to 95% of the 'dissolved' (<0.22 μm) fraction near pH 8. Measurements of DOC concentrations suggest this being due to pH-dependent binding of free metal cations to a fixed pool of organic colloids. The process is well described with a simple 2-site Langmuir isotherm in 0.05, 0.5, and 5.0M NaCl. Using this model to correct the original distribution coefficients not only removed the spurious reversal at low ionic strength, but also uncovered a prominent suppressive effect on the intermediate and high ionic strength data that had initially gone undetected. Ultra-filtration may thus be an essential analytical tool for proper characterization and interpretation of metal sorption on organic matter over a wide range of experimental conditions

  6. Dissolved Organic Matter Dynamics in a Suburbanizing Watershed: The Importance of Wetlands, People, and Flowpaths

    NASA Astrophysics Data System (ADS)

    Koenig, L.; Daley, M. L.; Potter, J.; McDowell, W. H.

    2013-12-01

    Human development of a watershed often yields fundamental and quantifiable changes in water quality and inorganic nutrient cycling. The effects of suburban development on the cycling of dissolved organic matter (DOM), however, have received relatively less attention, and the understanding of local dissolved organic matter dynamics is rarely a stated goal of watershed management. In this study, we examine the effects of suburbanization on concentrations of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) as well as the optical properties of DOM using 17 study sites in the Lamprey River watershed, NH that integrate varying levels of human development and population density. We show that concentration of DOC and DON is related to wetland cover but is not correlated with population density. Further, we observed no response in DOC concentration with increased flow at the mainstem site, while DON concentration is diluted. The optical properties of dissolved organic matter, however, showed different trends. Fluorescence Index (FI) decreases with increasing wetland cover and lower population density. We show that in a coastal watershed, while DOM quantity is driven by the presence of wetlands, DOM quality changes with both wetland cover and human development. The decoupling of DOM quantity and quality in this suburbanizing watershed indicate that DOM quality may be an important yet overlooked control on watershed-scale biogeochemical cycling and nutrient export.

  7. EFFECT OF ACID TREATMENT ON DISSOLVED ORGANIC CARBON RETENTION BY A SPODIC HORIZON

    EPA Science Inventory

    Processes involving the movement of organic substances in forest soils are not well understood. This study was conducted to examine the role of acidic inputs on dissolved organic carbon (DOC) mobility, processes affecting the retention of DOV by a B horizon, and SO2-4 adsorption....

  8. FACTORS AFFECTING COLORED DISSOLVED ORGANIC MATTER IN AQUATIC ENVIRONMENTS OF THE SOUTHEASTERN UNITED STATES

    EPA Science Inventory

    The sunlight-absorbing (colored) component of dissolved organic matter (CDOM) in aquatic environments is widely distributed in freshwaters and coastal regions where it influences the fate and transport of toxic organic substances and biologically-important metals such as mercury,...

  9. Characterization of Plant-derived Dissolved Organic Matter by Multiple Spectroscopic Techniques

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dissolved organic matter (DOM) derived from fresh or early-stage decomposing soil amendment materials may play an important role in the process of organic matter accumulation. In this study, eight DOM samples from alfalfa, corn, crimson clover, hairy vetch, lupin, soybean, wheat and dairy manure wer...

  10. Effects of Low Dissolved Oxygen on Organisms Used in Freshwater Sediment Toxicity Tests

    EPA Science Inventory

    This manuscript describes the results of tests to determine the tolerance of three benthic organisms to reduced dissolved oxygen (DO). These three organisms are those recommended by EPA for use in toxicity testing of contaminated sediments. The results of the exposures indicate ...

  11. Transport of organic contaminants in subsoil horizons and effects of dissolved organic matter related to organic waste recycling practices.

    PubMed

    Chabauty, Florian; Pot, Valérie; Bourdat-Deschamps, Marjolaine; Bernet, Nathalie; Labat, Christophe; Benoit, Pierre

    2016-04-01

    Compost amendment on agricultural soil is a current practice to compensate the loss of organic matter. As a consequence, dissolved organic carbon concentration in soil leachates can be increased and potentially modify the transport of other solutes. This study aims to characterize the processes controlling the mobility of dissolved organic matter (DOM) in deep soil layers and their potential impacts on the leaching of organic contaminants (pesticides and pharmaceutical compounds) potentially present in cultivated soils receiving organic waste composts. We sampled undisturbed soil cores in the illuviated horizon (60-90 cm depth) of an Albeluvisol. Percolation experiments were made in presence and absence of DOM with two different pesticides, isoproturon and epoxiconazole, and two pharmaceutical compounds, ibuprofen and sulfamethoxazole. Two types of DOM were extracted from two different soil surface horizons: one sampled in a plot receiving a co-compost of green wastes and sewage sludge applied once every 2 years since 1998 and one sampled in an unamended plot. Results show that DOM behaved as a highly reactive solute, which was continuously generated within the soil columns during flow and increased after flow interruption. DOM significantly increased the mobility of bromide and all pollutants, but the effects differed according the hydrophobic and the ionic character of the molecules. However, no clear effects of the origin of DOM on the mobility of the different contaminants were observed. PMID:26676540

  12. Transformation of molecular weight distributions of dissolved organic carbon and UV-absorbing compounds at full-scale wastewater-treatment plants.

    PubMed

    Esparza-Soto, Mario; Fox, Peter; Westerhoff, Paul

    2006-03-01

    The molecular-weight distribution (MWD) of wastewater dissolved-organic carbon (DOC) was determined in samples from seven full-scale wastewater-treatment plants (WWTPs) that use different biological treatments (air activated sludge [air-AS], pure-oxygen AS [O2-AS], and trickling filters). The research objective was to determine how different biological treatments influenced the MWD of wastewater DOC. Primary sedimentation effluent DOC from most of the WWTPs exhibited a skewed distribution toward the low-molecular-weight fraction (MWF) (40 to 50%, < 0.5 K Daltons [KDa]). The Air-AS effluent DOC exhibited a centrally clustered distribution, with the majority of DOC in the intermediate MWF (0.5 to 3 KDa). The O2-AS effluent DOC exhibited a skewed distribution toward the high MWF (> 3 KDa). The removal of DOC by air- and O2-AS bacteria followed trends predicted by a macromolecule degradation model. Trickling-filter effluent DOC exhibited a skewed distribution toward the high MWF (50% DOC, > 3 KDa). PMID:16629265

  13. Predicting dissolved organic nitrogen export from a drained loblolly pine plantation

    NASA Astrophysics Data System (ADS)

    Tian, Shiying; Youssef, Mohamed A.; Skaggs, R. Wayne; Chescheir, G. M.; Amatya, Devendra M.

    2013-04-01

    Dissolved organic nitrogen (DON) export from terrestrial ecosystems influences the ecology of receiving surface waters. The soil carbon (C) and nitrogen (N) model, DRAINMOD-N II, was modified to simulate key processes associated with DON transformations and transport in the soil profile. DON production is modeled by tracking dynamic C:N ratios of dissolved organic matter originating from various organic matter pools. The Langmuir isotherm was used to quantify the assumed instantaneous equilibrium between potentially soluble organic N in solid and aqueous phases. DON transport with soil water was simulated using a numerical solution to the advection-dispersion reaction equation. The modified model was used for simulating temporal variations of DON export from three loblolly pine (Pinus taeda L.) plantations located in eastern North Carolina. Results showed that the model can accurately predict DON export dynamics during storm events with Nash-Sutcliffe efficiency (E) of 0.5, seasonal DON losses with E above 0.6, and annual DON losses with E above 0.7. In addition to the well-recognized role of hydrological processes, reasonable quantifications of the seasonal changes in the potentially soluble soil organic matter, the DON sorption to soil particles, and the dynamic C:N ratios of dissolved organic matter were found to be essential for mechanistic representation of DON export dynamics. Specifically, adapting the dynamic C:N ratios enabled the model to reasonably describe the temporal variations of correlations between DON and dissolved organic carbon in drainage water.

  14. Degradation of terrigenous dissolved organic carbon in the western Arctic Ocean.

    PubMed

    Hansell, Dennis A; Kadko, David; Bates, Nicholas R

    2004-05-01

    The largest flux of terrigenous organic carbon into the ocean occurs in dissolved form by way of rivers. The fate of this material is enigmatic; there are numerous reports of conservative behavior over continental shelves, but the only knowledge we have about removal is that it occurs on long unknown time scales in the deep ocean. To investigate the removal process, we evaluated terrigenous dissolved organic carbon concentration gradients in the Beaufort Gyre of the western Arctic Ocean, which allowed us to observe the carbon's slow degradation. Using isotopic tracers of water-mass age, we determined that terrigenous dissolved organic carbon is mineralized with a half-life of 7.1 +/- 3.0 years, thus allowing only 21 to 32% of it to be exported to the North Atlantic Ocean. PMID:15131302

  15. Meridional fluxes of dissolved organic matter in the North Atlantic Ocean

    NASA Technical Reports Server (NTRS)

    Walsh, John J.; Carder, Kendall L.; Mueller-Karger, Frank E.

    1992-01-01

    Biooptical estimates of gelbstoff and a few platinum measurements of dissolved organic carbon (DOCpt) are used to construct a budget of the meridional flux of DOC and dissolved organic nitrogen (DON) across 36 deg 25 min N in the North Atlantic from previous inverse models of water and element transport. Distinct southward subsurface fluxes of dissolved organic matter within subducted shelf water, cabelled slope water, and overturned basin water are inferred. Within two cases of a positive gradient of DOCpt between terrestrial/shelf and offshore stocks, the net equatorward exports of O2 and DOCpt from the northern North Atlantic yield molar ratios of 2.1 to 9.1, compared to the expected Redfield O2/C ratio of 1.3. It is concluded that some shelf export of DOC, with a positive gradient between coastal and oceanic stocks, as well as falling particles, are required to balance carbon, nitrogen, and oxygen budgets of the North Atlantic.

  16. Spatial and temporal variation of dissolved organic matter in the Changjiang: Fluvial transport and flux estimation

    NASA Astrophysics Data System (ADS)

    Bao, Hongyan; Wu, Ying; Zhang, Jing

    2015-09-01

    The Changjiang is the most important source of freshwater and dissolved organic matter (DOM) for the East China Sea. However, knowledge regarding the sources, seasonal fluxes, and fluvial transport of terrigenous DOM (tDOM) in the Changjiang is lacking. To fill this knowledge gap, we measured dissolved organic carbon (DOC) and dissolved lignin in water samples collected in the middle and lower Changjiang under different hydrological conditions. Additional samples were collected biweekly in the lower Changjiang. Through comparisons with other rivers, we found that the DOC in the Changjiang is mainly from soil organic matter and has a higher fraction of tDOM during flood. Mass balance model results indicate that approximately 33% of the dissolved lignin discharged into the middle and lower Changjiang is removed during its transport to the lower reach during both low-discharge and flood periods. Based on a comparison of the removal rates under these two contrasting hydrological conditions and considering the lower organic carbon content and fine grain size of the Changjiang's suspended particles, we speculate that the major process for the removal of dissolved lignin is sorption, and potentially flocculation by suspended particles. Changjiang discharges 1.4 ± 0.10 Tg yr-1 and 8.6 ± 0.30 Gg yr-1 DOC and dissolved lignin to the estuary during the period of July 2010 to June 2011, respectively. Seasonal distributions of DOC and dissolved lignin fluxes are controlled by water discharge, which will be affected by future climate change and the Three Gorges Dam.

  17. Qualitative changes of riverine dissolved organic matter at low salinities due to flocculation

    NASA Astrophysics Data System (ADS)

    Asmala, Eero; Bowers, David G.; Autio, Riitta; Kaartokallio, Hermanni; Thomas, David N.

    2014-10-01

    The flocculation of dissolved organic matter (DOM) was studied along transects through three boreal estuaries. Besides the bulk concentration parameters, a suite of DOM quality parameters were investigated, including colored DOM (CDOM), fluorescent DOM, and the molecular weight of DOM as well as associated dissolved iron concentrations. We observed significant deviations from conservative mixing at low salinities (<2) in the estuarine samples of dissolved organic carbon (DOC), UV absorption (a(CDOM254)), and humic-like fluorescence. The maximum deviation from conservative mixing for DOC concentration was -16%, at salinities between 1 and 2. An associated laboratory experiment was conducted where an artificial salinity gradient between 0 and 6 was created. The experiment confirmed the findings from the estuarine transects, since part of the DOC and dissolved iron pools were transformed to particulate fraction (>0.2 µm) and thereby removing them from the dissolved phase. We also measured flocculation of CDOM, especially in the UV region of the absorption spectrum. Protein-like fluorescence of DOM decreased, while humic-like fluorescence increased because of salt-induced flocculation. Additionally, there was a decrease in molecular weight of DOM. Consequently, the quantity and quality of the remaining DOM pool was significantly changed after influenced to flocculation. Based on these results, we constructed a mechanistic, two-component flocculation model. Our findings underline the importance of the coastal filter, where riverine organic matter is flocculated and exported to the sediments.

  18. Seasonal losses of dissolved organic carbon and total dissolved solids from rice production systems in northern California.

    PubMed

    Ruark, Matthew D; Linquist, Bruce A; Six, Johan; van Kessel, Chris; Greer, Chris A; Mutters, Randall G; Hill, James E

    2010-01-01

    Water quality concerns have arisen related to rice (Oryza sativa L.) field drain water, which has the potential to contribute large amounts of dissolved organic carbon (DOC) and total dissolved solids (TDS) to the Sacramento River. Field-scale losses of DOC or TDS have yet to be quantified. The objectives of this study were to evaluate the seasonal concentrations of DOC and TDS in rice field drain water and irrigation canals, quantify seasonal fluxes and flow-weighted (FW) concentrations of DOC and TDS, and determine the main drivers of DOC and TDS fluxes. Two rice fields with different straw management practices (incorporation vs. burning) were monitored at each of four locations in the Sacramento Valley. Fluxes of DOC ranged from 3.7 to 34.6 kg ha(-1) during the growing season (GS) and from 0 to 202 kg ha(-1) during the winter season (WS). Straw management had a significant interaction effect with season, as the greatest DOC concentrations were observed during winter flooding of straw incorporated fields. Fluxes and concentrations of TDS were not significantly affected by either straw management or season. Total seasonal water flux accounted for 90 and 88% of the variability in DOC flux during the GS and WS, respectively. Peak DOC concentrations occurred at the onset of drainflow; therefore, changes in irrigation management may reduce peak DOC concentrations and thereby DOC losses. However, the timing of peak DOC concentrations from rice fields suggest that rice field drainage water is not the cause of peak DOC concentrations in the Sacramento River. PMID:20048318

  19. Changes in dissolved organic carbon and total dissolved nitrogen fluxes across subtropical forest ecosystems at different successional stages

    NASA Astrophysics Data System (ADS)

    Yan, Junhua; Li, Kun; Wang, Wantong; Zhang, Deqiang; Zhou, Guoyi

    2015-05-01

    Lateral transports of carbon and nitrogen are important processes linking terrestrial ecosystems and aquatic systems. Most previous studies made in temperate forests found that fluxes of carbon and nitrogen by runoff water varied in different forests, but few studies have been made in subtropical forests. This study was to investigate dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) fluxes at the catchment scale along a subtropical forest succession gradient from pine forest (pioneer) to coniferous and broadleaved mixed forest (transitional) to broadleaved forest (mature). Our results showed that DOC concentration significantly decreased (p<0.001) while TDN concentration significantly increased (p<0.001) in runoff water from pioneer to mature forests, which in turn resulted in a decrease in DOC flux and an increase in TDN flux, as mean annual runoff did not vary significantly among three succession forest catchments. The mean (±standard deviation) annual DOC flux was 118.1±43.6, 88.3±16.7 and 77.2±11.7 kg ha-1 yr-1for pioneer, transitional and mature forest catchments, respectively; and the mean annual TDN flux was 9.9 ±2.7, 18.2±3.0 and 21.2 ±4.5 kg ha-1 yr-1for pioneer, transitional and mature forest catchments, respectively. The mature forest reduced DOC flux by increased soil chemical adsorption and physical protection. An increase in TDN flux from pioneer to mature forests was consistent with the previous finding that mature forest was nitrogen saturated while pioneer forest was nitrogen limited. Therefore large-scale conversion of pioneer forests to transitional or mature forests in subtropical China will reduce DOC concentration and increase TDN concentration in the down-stream water, which may have significant impact on its water quality and aquatic biological activities.

  20. The Fluorescent Properties of Dissolved Organic Matter and Assessment of Total Nitrogen in Overlying Water with Different Dissolved Oxygen Conditions.

    PubMed

    Zhang Hua; Kuan, Wang; Song, Jian; Zhang, Yong; Huang, Ming; Huang, Jian; Zhu, Jing; Huang, Shan; Wang, Meng

    2016-03-01

    This paper used excitation-emission matrix spectroscopy (EEMs) to probe the fluorescence properties of dissolved organic matter (DOM) in the overlying water with different dissolved oxygen (DO) conditions, investigating the relationship between protein-like fluorescence intensity and total nitrogen concentration. The resulting fluorescence spectra revealed three protein-like components (high-excitation wavelength tyrosine, low-excitation wavelength tyrosine, low-excitation wavelength tryptophan) and two fulvic-like components (ultraviolet fulvic-like components, visible fulvic-like components) in the overlying water. Moreover, the protein-like components were dominant in the overlying water's DOM. The fluorescence intensity of the protein-like components decreased significantly after aeration. Two of the protein-like components--the low-excitation wavelength tyrosine and the low-excitation wavelength tryptophan--were more susceptible to degradation by microorganisms within the degradable organic matter with respect to the high-excitation wavelength tyrosine. In contrast, the ultraviolet and visible fulvic-like fluorescence intensity increased along with increasing DO concentration, indicating that the fulvic-like components were part of the refractory organics. The fluorescence indices of the DOM in the overlying water were between 1.65-1.80, suggesting that the sources of the DOM were related to terrigenous sediments and microbial metabolic processes, with the primary source being the contribution from microbial metabolism. The fluorescence indices increased along with DO growth, which showed that microbial biomass and microbial activity gradually increased with increasing DO while microbial metabolism also improved, which also increased the biogenic components in the overlying water. The fluorescence intensity of the high-excitation wavelength tyrosine peak A showed a good linear relationship with the total nitrogen concentration at higher DO concentrations of 2

  1. Dissolved organic matter export from a forested watershed during Hurricane Irene

    NASA Astrophysics Data System (ADS)

    Yoon, Byungman; Raymond, Peter A.

    2012-09-01

    We incorporate high-resolution time-series data to calculate the total amount of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) transported during Hurricane Irene in Esopus Creek in New York (August 2011). During this 200-yr event the Esopus Creek experienced a 330-fold discharge increase and a 4-fold increase in concentration, resulting in the export of roughly 43% and 31% of its average annual DOC and DON fluxes, respectively, in just 5 days. The source of this large dissolved organic matter (DOM) flux also shifted during its course and showed an increased contribution of aromatic organic matter. We conclude that more frequent large events due to climate change will increase the export of terrigenous dissolved organic matter, and potentially impact the water quality and biogeochemistry of lakes and coastal systems. In addition, we show that the use of conventional models for extreme events lead to erroneous flux calculations, unless supported by high resolution data collected during the events.

  2. 40 CFR Table 2 to Part 455 - Organic Pesticide Active Ingredient Effluent Limitations Best Available Technology Economically...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 30 2011-07-01 2011-07-01 false Organic Pesticide Active Ingredient... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS PESTICIDE CHEMICALS Pt. 455, Table 2 Table 2 to Part 455—Organic Pesticide Active Ingredient Effluent Limitations Best Available Technology Economically...

  3. 40 CFR Table 2 to Part 455 - Organic Pesticide Active Ingredient Effluent Limitations Best Available Technology Economically...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 30 2014-07-01 2014-07-01 false Organic Pesticide Active Ingredient... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) PESTICIDE CHEMICALS Pt. 455, Table 2 Table 2 to Part 455—Organic Pesticide Active Ingredient Effluent Limitations Best Available...

  4. 40 CFR Table 2 to Part 455 - Organic Pesticide Active Ingredient Effluent Limitations Best Available Technology Economically...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 31 2013-07-01 2013-07-01 false Organic Pesticide Active Ingredient... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) PESTICIDE CHEMICALS Pt. 455, Table 2 Table 2 to Part 455—Organic Pesticide Active Ingredient Effluent Limitations Best Available...

  5. 40 CFR Table 2 to Part 455 - Organic Pesticide Active Ingredient Effluent Limitations Best Available Technology Economically...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 31 2012-07-01 2012-07-01 false Organic Pesticide Active Ingredient... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) PESTICIDE CHEMICALS Pt. 455, Table 2 Table 2 to Part 455—Organic Pesticide Active Ingredient Effluent Limitations Best Available...

  6. 40 CFR Table 2 to Part 455 - Organic Pesticide Active Ingredient Effluent Limitations Best Available Technology Economically...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Organic Pesticide Active Ingredient... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS PESTICIDE CHEMICALS Pt. 455, Table 2 Table 2 to Part 455—Organic Pesticide Active Ingredient Effluent Limitations Best Available Technology Economically...

  7. Dissolving efficacy of some organic solvents on gutta-percha.

    PubMed

    Magalhães, Bianca Silva; Johann, Julia Elis; Lund, Rafael Guerra; Martos, Josué; Del Pino, Francisco Augusto Burkert

    2007-01-01

    The aim of this study was to evaluate the solubility of gutta-percha in four organic solvents used in endodontics. The solubility of gutta-percha (Dentsply) was assessed in xylol, orange oil, eucalyptol, chloroform and distilled water. A hundred and fifty samples of gutta-percha were prepared using a standardized stainless steel mould and divided into five groups for immersion in the different solvents tested and in distilled water (control group) for 2, 5 and 10 minutes. The means of gutta-percha dissolution in the solvents were obtained by the difference between the pre-immersion original weight and the post-immersion weight in a digital analytical scale (Gehaka-AG2000). Data were statistically analyzed by Analysis of Variance (ANOVA) and multiple comparisons with Scheffes test (p<0.05). The best solvency capacity was obtained with xylol. Chloroform, orange oil and eucalyptol presented similar results, and distilled water did not promote alterations in the gutta-percha. PMID:18060255

  8. Results of the 2008 dissolved organic matter fluorescence intercalibration study

    NASA Astrophysics Data System (ADS)

    Murphy, K. R.; Butler, K.; Spencer, R. G.; Boehme, J.; Aiken, G.

    2009-12-01

    In 2008, 20 laboratories around the world participated in an intercalibration study of organic matter fluorescence measurements via Excitation-Emission Matrix Spectroscopy (EEMS). The goal was to assess the variability of fluorescence measurements obtained for identical samples (n = 5 natural samples, Suwanee River Fulvic Acid, quinine sulphate and four Starna Fluorescence Reference cells) by different laboratories, and to examine potential sources of this variability. Operator error was found to be a significant source of variability, with 6 laboratories submitting erroneous EEMs in an initial round. Uncorrected EEMs were significantly different from corrected EEMs, particularly at relatively low and relatively high excitation (λex) and emission (λem) wavelengths. When data from each lab were corrected according to a standard set of algorithms, the variability between EEMs for the same sample measured by different labs was wavelength dependent, with EEMs normalized to raman areas more similar at low λex and λem, and EEMs normalized to quinine sulphate equivalents more similar at higher wavelengths. The results confirm the importance of (1) applying spectral corrections prior to comparing fluorescence data acquired on different instruments, (2) full reporting of correction procedures and implementation according to an agreed standard protocol, and (3) strict implementation of quality assurance protocols prior to reporting EEMs.

  9. Aqueous leaching of organic acids and dissolved organic carbon from various biochars prepared at different temperatures.

    PubMed

    Liu, Peng; Ptacek, Carol J; Blowes, David W; Berti, William R; Landis, Richard C

    2015-03-01

    Biochar has been used as a soil amendment, as a water treatment material, and for carbon (C) sequestration. Thirty-six biochars, produced from wood, agricultural residue, and manure feedstocks at different temperatures, were evaluated for the aqueous leaching of different forms of soluble C. The release of inorganic C (alkalinity), organic acids (OAs), and total dissolved organic C (DOC) was highly variable and dependent on the feedstock and pyrolysis temperature. The pH and alkalinity increased for the majority of samples. Higher pH values were associated with high-temperature (high-T) (600 and 700°C) biochars. Statistically significant differences in alkalinity were not observed between low-temperature (low-T) (300°C) and high-T biochars, whereas alkalinity released from wood-based biochar was significantly lower than from others. Concentrations of OAs and DOC released from low-T biochars were greater than from high-T biochars. The C in the OAs represented 1 to 60% of the total DOC released, indicating the presence of other DOC forms. The C released as DOC represented up to 3% (majority <0.1%) of the total C in the biochar. Scanning electron microscopy with energy dispersive X-ray spectroscopy showed the high-T biochars had a greater proportion of micropores. Fourier transform infrared spectroscopy showed that hydroxyl, aliphatic, and quinone were the predominant functional groups of all biochars and that the abundance of other functional groups was dependent on the feedstock. The release of DOC, especially bioavailable forms such as OAs, may promote growth of organisms and heavy metal complexation and diminish the potential effectiveness of various biochars for C sequestration. PMID:26023986

  10. Complexation of trace organic contaminants with fractionated dissolved organic matter: implications for mass spectrometric quantification.

    PubMed

    Ruiz, Selene Hernandez; Wickramasekara, Samanthi; Abrell, Leif; Gao, Xiaodong; Chefetz, Benny; Chorover, Jon

    2013-04-01

    Interaction with aqueous phase dissolved organic matter (DOM) can alter the fate of trace organic contaminants of emerging concern once they enter the water cycle. In order to probe possible DOM binding mechanisms and their consequences for contaminant detection and quantification in natural waters, a set of laboratory experiments was conducted with aqueous solutions containing various operationally-defined "hydrophilic" and "hydrophobic" freshwater DOM fractions isolated by resin adsorption techniques from reference Suwannee River natural organic matter (SROM). Per unit mass of SROM carbon, hydrophobic acids (HoA) comprised the largest C fraction (0.63±0.029), followed by hydrophilic-neutrals (HiN, 0.11±0.01) and acids (HiA, 0.09±0.017). Aqueous solutions comprising 8mgL(-1) DOC of each SROM fraction were spiked with a concentration range (10-1000μgL(-1)) of bisphenol A (BPA), carbamazepine (CBZ), or ibuprofen (IBU) as model target compounds in 24mM NH4HCO3 background electrolyte at pH 7.4. Contaminant interaction with the SROM fractions was probed using fluorescence spectroscopy, and effects on quantitative analysis of the target compounds were measured using direct aqueous-injection liquid chromatography tandem mass spectrometry (LC-MS/MS). Total quenching was greater for the hydrophilic fractions of SROM and associations were principally with protein-like and fulvic acid-like constituents. Whereas LC-MS/MS recoveries indicated relatively weak interactions with most SROM factions, an important exception was the HiA fraction, which diminished recovery of CBZ and IBU by ca. 30% and 70%, respectively, indicating relatively strong molecular interactions. PMID:23276460

  11. Fluorescence spectroscopy: considerations for highly absorbing dissolved organic matter samples

    NASA Astrophysics Data System (ADS)

    Simone, B. E.; Miller, M.; McKnight, D. M.

    2009-12-01

    Fluorescence spectroscopy is a robust method for characterizing organic matter (OM). However, proper collection and correction of spectra are necessary to provide useful data. One important correction is the inner-filter correction, which primarily accounts for the inner-filter effect by adjusting for the wavelength dependent attenuation of emitted light by the solution prior to detection by the fluorometer. The most commonly used correction is based on an assumption that light is emitted at the center of the pathlength. Thus, the inner-filter effect is more pronounced in highly absorbing samples, and has the potential to skew the fluorescence spectra. For this study, the terrestrially derived Suwannee River fulvic acid (SRFA) and microbially derived Pony Lake fulvic acid (PLFA), from the International Humic Substances Society (IHSS), were diluted to incremental absorbances at a wavelength of 254 nm from 0.05 to 1.0 at pH 4 and 7. Three dimensional fluorescence spectra were measured and modeled with the Cory and McKnight (2005) parallel factor analysis (PARAFAC) model which resolves the fluorescence spectra into 13 components, including quinone-like and protein-like components. In the absence of inner-filter effects, plots of absorbance vs. loadings should be linear. Using the data from absorbance of 0.05 to 0.3, where the inner-filter affect is least pronounced, a linear regression was created and used as a baseline to predict component loadings at higher absorbance values in the absence of inner-filter effects. Results indicate that at absorbance values greater than 0.3, the commonly-used inner-filter correction is not able to remove the inner-filter effect. Therefore, in order to obtain reliable component loadings and correctly interpret the spectra, samples should be diluted to absorbance values less than 0.3 at 254 nm prior to collection of three dimensional fluorescence scans. The recommendation of a maximum absorbance of 0.3 agrees with the results of a

  12. ISOLATION OF DISSOLVED ORGANIC MATTER FROM THE SUWANNEE RIVER USING REVERSE OSMOSIS

    EPA Science Inventory

    A portable reverse osmosis (RO) system was constructed and used to concentrate dissolved organic matter (DOM) from the Suwannee River in southeastern Georgia. sing this RO system, 150-180 1/h of river water could be processed with 90% recovery of DOM. fter further cation exchange...

  13. Influence of Dissolved Organic Matter and Fe (II) on the Abiotic Reduction of Pentachloronitrobenzene

    EPA Science Inventory

    Nitroaromatic pesticides (NAPs) are hydrophobic contaminants that can accumulate in sediments by the deposition of suspended solids from surface waters. Fe(II) and dissolved organic matter (DOM), present in suboxic and anoxic zones of freshwater sediments, can transform NAPs in n...

  14. Response to Comment on “Dilution limits dissolved organic carbon utilization in the deep ocean”

    NASA Astrophysics Data System (ADS)

    Arrieta, Jesús M.; Mayol, Eva; Hansman, Roberta L.; Herndl, Gerhard J.; Dittmar, Thorsten; Duarte, Carlos M.

    2015-12-01

    Our recent finding that dilution limits dissolved organic carbon (DOC) utilization in the deep ocean has been criticized based on the common misconception that lability equates to rapid and complete utilization. Even when considering the redefinition of recalcitrant DOC recently proposed by Jiao et al., the dilution hypothesis best explains our experimental observations.

  15. Organic carbon and dissolved oxygen budgets for a commerical-size, in-pond raceway system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Intensive production of Ictalurid catfish in the United States has increased over the past several years and a better understanding of the amount of organic carbon (OC) and dissolved oxygen (DO) in these culture environments is needed. Budgets for OC and DO were estimated over a production season (M...

  16. PHOTOCHEICAL PRODUCTION OF HYDROXYL RADICAL IN NATURAL WATER - THE ROLE OF IRON AND DISSOLVED ORGANIC MATTER

    EPA Science Inventory

    Photochemical hydroxyl radical (OH) production was measured in several natural waters to investigate the importance of colored dissolved organic matter (CDOM) and iron-CDOM complexes as sources of OH. High rates of OH photoproduction in highly colored, iron-rich, acidic waters a...

  17. INFLUENCE OF DISSOLVED ORGANIC MATTER ON AGROCHEMICAL PHOTOREACTIONS IN AQUATIC ENVIRONMENTS

    EPA Science Inventory

    Pioneering studies by Don Crosby and co-workers demonstrated that the sunlight-induced dissipation of agrochemicals in water often is strongly affected by natural constituents in the water such as nitrate and dissolved organic matter. In this presentation, the focus is on the rol...

  18. Production of Chromophoric Dissolved Organic Matter from Mangrove Leaf Litter and Floating Sargassum Colonies

    EPA Science Inventory

    Chromophoric dissolved organic matter (CDOM) strongly absorbs solar radiation in the blue-green and serves as the primary attenuator of water column ultraviolet radiation (UV-R). CDOM interferes with remote sensing of ocean chlorophyll and can control UV-R-induced damage to light...

  19. ESTIMATING THE POTENTIAL FOR FACILITATED TRANSPORT OF NAPROPAMIDE BY DISSOLVED ORGANIC MATTER

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dissolved organic matter (DOM) has been found to significantly affect the soil sorption/desorption of napropamide [2-(a-naphthoxy-N, N-diethylpropionamide] and to enhance its transport through soil columns. A method to qualitatively predict if DOM will enhance the transport of napropamide based on e...

  20. PHOTOCHEMICAL MINERALIZATION OF DISSOLVED ORGANIC NITROGEN TO AMMONIUM IN THE BALTIC SEA

    EPA Science Inventory

    Solar radiation-induced photochemistry can be considered as a new source of nutrients when photochemical reactions release bioavailable nitrogen from biologically non-reactive dissolved organic nitrogen (DON). Pretreatments of Baltic Sea waters in the dark indicated that >72% of ...

  1. Importance of Dissolved Organic Nitrogen to Water Quality in Narragansett Bay

    EPA Science Inventory

    This preliminary analysis of the importance of the dissolved organic nitrogen (DON) pool in Narragansett Bay is being conducted as part of a five-year study of Narragansett Bay and its watershed. This larger study includes water quality and ecological modeling components that foc...

  2. CONSTANTS FOR MERCURY BINDING BY DISSOLVED ORGANIC MATTER ISOLATES FROM THE FLORIDA EVERGLADES. (R827653)

    EPA Science Inventory

    Dissolved organic matter (DOM) has been implicated as an important complexing agent for Hg that can affect its mobility and bioavailability in aquatic ecosystems. However, binding constants for natural Hg-DOM complexes are not well known. We employed a competitive ligand appro...

  3. Comment on “Dilution limits dissolved organic carbon utilization in the deep ocean”

    NASA Astrophysics Data System (ADS)

    Jiao, Nianzhi; Legendre, Louis; Robinson, Carol; Thomas, Helmuth; Luo, Ya-Wei; Dang, Hongyue; Liu, Jihua; Zhang, Rui; Tang, Kai; Luo, Tingwei; Li, Chao; Wang, Xiaoxue; Zhang, Chuanlun

    2015-12-01

    Arrieta et al. (Reports, 17 April 2015, p. 331) propose that low concentrations of labile dissolved organic carbon (DOC) preclude prokaryotic consumption of a substantial fraction of DOC in the deep ocean and that this dilution acts as an alternative mechanism to recalcitrance for long-term DOC storage. Here, we show that the authors’ data do not support their claims.

  4. Chemical compositions of dissolved organic matter from various sources as characterized by solid-state NMR

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dissolved organic matter (DOM) in surface waters plays an important role in biogeochemical and ecological processes. This study used solid-state NMR techniques to explore the molecular signatures of riverine DOM in relation to its point and nonpoint sources. DOM samples were isolated from (1) two st...

  5. Pyrolysis temperature-dependent release of dissolved organic carbon from plant, manure, and biorefinery wastes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Limited information is available to understand the chemical structure of biochar’s labile dissolved organic carbon (DOC) fraction that will change amended soil’s DOC composition. This study utilized the high sensitivity of fluorescence excitation-emission (EEM) spectrophotometry to understand the s...

  6. TREATMENT OF URBAN STORMWATER FOR DISSOLVED POLLUTANTS: A COMPARATIVE STUDY OF THREE NATURAL ORGANIC MEDIA

    EPA Science Inventory

    The feasibility of using hard and soft wood tree mulch and processed jute fiber, as filter media, for treating mixtures of dissolved pollutants (toxic organic compounds and heavy metals) in urban stormwater (SW) runoff was evaluated. Copper (Cu), cadmium (Cd), chromium (Cr+6), l...

  7. ISOTOPIC BIOGEOCHEMISTRY OF DISSOLVED ORGANIC NITROGEN: A NEW TECHNIQUE AND APPLICATION. (R825151)

    EPA Science Inventory

    We present a new technique for isolating and isotopically characterizing dissolved organic nitrogen (DON) for non-marine waters, 15N values for DON from lacustrine samples and data suggesting that this technique will be a...

  8. PRODUCTION OF HYDRATED ELECTRONS FROM PHOTOIONIZATION OF DISSOLVED ORGANIC MATTER IN NATURAL WATERS

    EPA Science Inventory

    Under UV irradiation, an important primary photochemical reaction of colored dissolved organic matter (CDOM) is electron ejection, producing hydrated electrons (e-aq). The efficiency of this process has been studied in both fresh and seawater samples with both steady-state scave...

  9. [Temporal and Spatial Distribution Characteristics of Dissolved Organic Matter and Influencing Factors in Lake Chaohu].

    PubMed

    Ye, Lin-lin; Wu, Xiao-dong; Liu, Bo; Yan, De-zhi; Zhang, Mei-qi; Zhou, Yang

    2015-09-01

    To study the temporal and spatial distribution of dissolved organic matter (DOM) and the related influencing factors of Lake Chaohu, surface water samples were collected at seventeen sites in three different regions of the Lake from April 2013 to April 2014. The concentration of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) were then analyzed. A significance difference in DON concentration was observed among the sampling sites (P <0. 01, n = 13), which was caused by the terrestrial input from the western rivers and the bioavailability of DON. The ratio of total nitrogen to total phosphorus, total dissolved nitrogen to total dissolved phosphorus, and dissolved inorganic nitrogen to soluble reactive phosphorus (DIN/SRP) declined gradually during the phytoplankton bloom period, especially the ratio of DIN/SRP dropped to 5 ± 7 in August 2013, indicating the nitrogen was limited in lake water. Moreover, the concentration of DON was decreased and a significant negative correlation was observed between DON and Chl-a (r = - 0. 265, P < 0. 05, n = 91), suggesting that DON is bioavailable, and can be utilized by phytoplankton directly or indirectly during nitrogen limitation. No significant difference in DOC concentration was observed and water temperature was the major factor related to the variation of DOC. Chl-a and nitrate concentrations can also affect the dynamics of DOC. In addition, the ratio of DOC/DON was considerably varied, the concentration of DON contributed to the variation of DOC/DON, and DON was the major component contributed to the bioavailability of DOM. PMID:26717677

  10. The effect of feed water dissolved organic carbon concentration and composition on organic micropollutant removal and microbial diversity in soil columns simulating river bank filtration.

    PubMed

    Bertelkamp, C; van der Hoek, J P; Schoutteten, K; Hulpiau, L; Vanhaecke, L; Vanden Bussche, J; Cabo, A J; Callewaert, C; Boon, N; Löwenberg, J; Singhal, N; Verliefde, A R D

    2016-02-01

    This study investigated organic micropollutant (OMP) biodegradation rates in laboratory-scale soil columns simulating river bank filtration (RBF) processes. The dosed OMP mixture consisted of 11 pharmaceuticals, 6 herbicides, 2 insecticides and 1 solvent. Columns were filled with soil from a RBF site and were fed with four different organic carbon fractions (hydrophilic, hydrophobic, transphilic and river water organic matter (RWOM)). Additionally, the effect of a short-term OMP/dissolved organic carbon (DOC) shock-load (e.g. quadrupling the OMP concentrations and doubling the DOC concentration) on OMP biodegradation rates was investigated to assess the resilience of RBF systems. The results obtained in this study imply that - in contrast to what is observed for managed aquifer recharge systems operating on wastewater effluent - OMP biodegradation rates are not affected by the type of organic carbon fraction fed to the soil column, in case of stable operation. No effect of a short-term DOC shock-load on OMP biodegradation rates between the different organic carbon fractions was observed. This means that the RBF site simulated in this study is resilient towards transient higher DOC concentrations in the river water. However, a temporary OMP shock-load affected OMP biodegradation rates observed for the columns fed with the river water organic matter (RWOM) and the hydrophilic fraction of the river water organic matter. These different biodegradation rates did not correlate with any of the parameters investigated in this study (cellular adenosine triphosphate (cATP), DOC removal, specific ultraviolet absorbance (SUVA), richness/evenness of the soil microbial population or OMP category (hydrophobicity/charge). PMID:26432535

  11. Investigation of organic carbon transformation in soils of dominant dissolved organic carbon source zones

    NASA Astrophysics Data System (ADS)

    Pissarello, Anna; Miltner, Anja; Oosterwoud, Marieke; Fleckenstein, Jan; Kästner, Matthias

    2014-05-01

    Over the past 20 years both a decrease in soil organic matter (SOM) and an increase in the dissolved organic carbon (DOC) concentrations in surface water bodies, including drinking water reservoirs, have been recorded in the northern hemisphere. This development has severe consequences for soil fertility and for drinking water purification. As both processes occur simultaneously, we assume that microbial SOM degradation, which transforms SOM into CO2 and DOC, is a possible source of the additional DOC in the surface water. In addition we speculate that both processes are initially triggered by physical mechanisms, resulting in a modification of the organic matter solubility equilibria and thus in higher SOM availability and DOC mobilization. The general hypothesis of the study is therefore that SOM loss and DOC increase are combined consequences of enhanced microbial degradation of SOM and that this is a result of climate variations and global change, e.g. the increase of the temperature, the alteration of the water regime (i.e. increase of the frequency of drying and rewetting cycles and a higher number of heavy rain events), but also the decrease of the atmospheric acid deposition resulting in an increase of soil pH values. The general goal of the study is the identification of the dominant processes and controlling factors involved in soil microbial carbon turnover and mobilization of DOC in soils from catchment areas that contribute DOC to the receiving waters and the downstream Rappbode reservoir, which showed a pronounced increase in DOC concentration in recent years. This reservoir is the source of drinking water for about one million people in northern Germany. Preliminary screening experiments, consisting of 65-day soil batch incubation experiments, have been conducted in order to select the parameters (and the parameter ranges) of relevance for further in-depth experiments. During the experiments, different soil systems were exposed to different

  12. Chloro-Organics in Papermill Effluent: Identification and Removal by Sequencing Batch Biofilm Reactor

    NASA Astrophysics Data System (ADS)

    Abd. Rahman, Rakmi; Zahrim, A. Y.; Abu Bakar, Azizah

    Effluents from paper mills are among major sources of aquatic pollution and may be toxic since they contain chlorinated phenolic compounds which are measured as adsorbable organic halides (AOX). In this work, removal of chlorophenol was investigated using a Sequencing Batch Biofilm Reactor (SBBR) with Granular Activated Carbon (GAC) as a growth media. Wastewater for this study was obtained from treated effluent outlet of a papermill in Selangor. Treatment of the papermill secondary effluent shows that SBBR process, with a combination of adsorption and biodegradation, gave a good removal of pentachlorophenol (PCP), on average, about 70%. The growth kinetic parameters obtained were: YH = 0.6504 mg biomass/mg PCP, dH = 6.50x10-5 h-1, μh = 0.00315 h-1 and Ks = 5.82 mg PCP L-1. These show that the SBBR system is suitable to be operated at long SRTs.

  13. Effects of industrial effluents, heavy metals, and organic solvents on mallard embryo development

    USGS Publications Warehouse

    Hoffman, D.J.; Eastin, W.C., Jr.

    1981-01-01

    Mallard eggs were externally exposed at 3 and 8 days of incubation to 7 different industrial effluents and to 7 different heavy metal, organic solvent, and petroleum solutions to screen for potential embryo-toxic effects. This route of exposure was chosen in order to simulate the transfer of pollutant from the plumage of aquatic birds to their eggs. Five of the effluents including mineral pigment, scouring effluent, sludge, and tannery effluent resulted in small but significant reductions in embryonic growth. Treatment with methyl mercury chloride solution of 50 ppm (Hg) impaired embryonic growth but much higher concentrations were required to affect survival and cause teratogenic effects. Oil used to suppress road dust was the most toxic of the pollutants tested and only 0.5 microliter/egg caused 60% mortality by 18 days of development. These findings, in combination with other studies suggest that petroleum pollutants, or effluents in combination with petroleum, may pose a hazard to birds' eggs when exposure is by this route.

  14. A Comparison of Dissolved and Particulate Organic Material in Two Southwestern Desert River Systems

    NASA Astrophysics Data System (ADS)

    Haas, P. A.; Brooks, P.

    2001-12-01

    Desert river systems of the southwestern U.S. acquire a substantial fraction of their dissolved organic matter (DOM) from the terrestrial environment during episodic rain events. This DOM provides carbon for stream metabolism and nitrogen, which is limiting in lower order streams in this environment. The San Pedro and Rio Grande Rivers represent two endpoints of catchment scale, discharge, and land use in the southwest. The San Pedro is a protected riparian corridor (San Pedro Riparian National Conservation Area), while the middle Rio Grande is a large river with extensive agriculture, irrigation, and reservoirs. Relative abundance and spectral properties of fulvic acids isolated from filtered samples were used to determine the source of dissolved organic carbon (DOC). Total DOC and particulate organic carbon (POC) changes with respect to episodic flooding events were compared for the two river systems. The San Pedro River DOC concentrations remain low approximately 2.2 to 3.3 ppm unless a relatively large storm event occurs when concentrations may go above 5.5 ppm (1000cfs flow). In contrast typical concentrations for the Rio Grande were approximately 5 ppm during the monsoon season. Particulate organic matter (POM) appears to be a more significant source of organic matter to the San Pedro than DOM. The relative importance of terrestrial vs. aquatic and dissolved vs. particulate organic matter with respect to aquatic ecosystems will be discussed.

  15. Enhanced dissolution of cinnabar (mercuric sulfide) by dissolved organic matter isolated from the Florida Everglades

    SciTech Connect

    Ravichandran, M.; Ryan, J.N.; Aiken, G.R.; Reddy, M.M.

    1998-11-01

    Organic matter isolated from the Florida Everglades caused a dramatic increase in mercury release from cinnabar (HgS), a solid with limited solubility. Hydrophobic (a mixture of both humic and fulvic) acids dissolved more mercury than hydrophilic acids and other nonacid fractions of dissolved organic matter (DOM). Cinnabar dissolution by isolated organic matter and natural water samples was inhibited by cations such as Ca{sup 2+}. Dissolution was independent of oxygen content in experimental solutions. Dissolution experiments conducted in Dl water had no detectable dissolved mercury. The presence of various inorganic (chloride, sulfate, or sulfide) and organic ligands (salicylic acid, acetic acid, EDTA, or cysteine) did not enhance the dissolution of mercury from the mineral. Aromatic carbon content in the isolates correlated positively with enhanced cinnabar dissolution. {zeta}-potential measurements indicated sorption of negatively charged organic matter to the negatively charged cinnabar at pH 6.0. Possible mechanisms of dissolution include surface complexation of mercury and oxidation of surface sulfur species by the organic matter.

  16. The Relationship Between Dissolved Organic Matter Composition and Organic Matter Optical Properties in Freshwaters

    NASA Astrophysics Data System (ADS)

    Aiken, G.; Spencer, R. G.; Butler, K.

    2010-12-01

    Dissolved organic matter (DOM) chemistry and flux are potentially useful, albeit, underutilized, indicators of watershed characteristics, climate influences on watershed hydrology and soils, and changes associated with resource management. Source materials, watershed geochemistry, oxidative processes and hydrology exert strong influences on the nature and reactivity of DOM in aquatic systems. The molecules that comprise DOM, in turn, control a number of environmental processes important for ecosystem function including light penetration and photochemistry, microbial activity, mineral dissolution/precipitation, and the transport and reactivity of hydrophobic compounds and metals (e.g. Hg). In particular, aromatic molecules derived from higher plants exert strong controls on aquatic photochemistry, and on the transport and biogeochemistry of metals. Assessment of DOM composition and transport, therefore, can provide a basis for understanding watershed processes and biogeochemistry of rivers and streams. Here we present results of multi-year studies designed to assess the seasonal and spatial variability of DOM quantity and quality for 57 North American Rivers. DOM concentrations and composition, based on DOM fractionation on XAD resins, ultraviolet (UV)/visible absorption and fluorescence spectroscopic analyses, and specific compound analyses, varied greatly both between sites and seasonally within a given site. DOM in these rivers exhibited a wide range of concentration (<80 to >4000 µM C* L-1) and specific ultra-violet absorbance at 254 nm (SUVA254) (0.6 to 5 L *mg C-1 *m-1), an optical measurement that is an indicator of aromatic carbon content. In almost all systems, UV absorbance measured at specific wavelengths (e.g. 254 nm) correlated strongly with DOM and hydrophobic organic acid (HPOA) content (aquatic humic substances). The relationships between dissolved organic carbon (DOC) concentration and absorbance for the range of systems were quite variable due to

  17. Dissolved total hydrolyzable enantiomeric amino acids in precipitation: Implications on bacterial contributions to atmospheric organic matter

    NASA Astrophysics Data System (ADS)

    Yan, Ge; Kim, Guebuem; Kim, Jeonghyun; Jeong, Yu-Sik; Kim, Young Il

    2015-03-01

    We analyzed dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and dissolved enantiomeric amino acids in precipitation samples collected at two sites in Korea over a one-year period. The average concentrations of DOC, DON, and total hydrolyzable amino acids at Seoul (an inland urban area) were lower than those at Uljin (a coastal rural area). The different bulk compositions of dissolved organic matter (DOM) at these two sites (reflected by qualitative indicators) were mainly attributed to differences in contributing sources. The D-enantiomers of four individual amino acids (aspartic acid, glutamic acid, serine, and alanine) were ubiquitously present, with average enantiomeric (D/L) ratios of 0.34, 0.26, 0.21, and 0.61 for Seoul, and 0.18, 0.11, 0.09, and 0.31 for Uljin, respectively. The much higher D/L ratios observed at Seoul than at Uljin might result from more advanced diagenetic stages as well as higher contributions from bacteria inhabiting terrestrial environments. The C- and N-normalized yields of D-alanine in DOM of our samples were found to be comparable to literature values reported for aquatic systems, where a significant portion of DOM was suggested to be of bacterial origin. Our study suggests that bacteria and their remnants might constitute an important fraction of OM in the atmosphere, contributing significantly to the quality of atmospheric OM and its post-depositional bioavailability in the surface ecosystems.

  18. Importance of within-lake processes in affecting the dynamics of dissolved organic carbon and dissolved organic and inorganic nitrogen in an Adirondack forested lake/watershed

    NASA Astrophysics Data System (ADS)

    Kang, P.-G.; Mitchell, M. J.; McHale, P. J.; Driscoll, C. T.; McHale, M. R.; Inamdar, S.; Park, J.-H.

    2015-10-01

    Lakes nested in forested watersheds play important roles in mediating the concentrations and fluxes of dissolved organic matter. We compared long-term patterns of concentrations and fluxes of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and dissolved inorganic nitrogen (DIN) in the Arbutus Lake Watershed to evaluate how a lake nested in a forested watershed affects the dynamics of DOC and DON in the Adirondack Mountains of New York State, USA. We observed no significant long-term changes of concentrations and fluxes of DOC and DON in the Lake outlet since 1983 and 1994, respectively. However, the temporal patterns of DOC and DON concentrations in the Lake inlet showed significant seasonality such as increases during the vegetation-growing season along with notable decreases in the dormant season. A comparison of mass-balances between inlet and outlet for the period from 2000 to 2009 suggested that the Lake was a sink of DOC (mean of influx minus outflux: +1140 mol C ha-1 yr-1). In contrast, the difference of discharge-weighted DON concentrations (mean of inlet minus outlet: -1.0 μmol N L-1) between inlet and outlet was much smaller than the discharge-weighted DOC concentrations (average of inlet minus outlet: +87 μmol C L-1). DON fluxes showed considerable variation among years (mean of influx minus outflux: +8 mol N ha-1 yr-1; range of differences: -15 to 27 mol N ha-1 yr-1). DON exhibited low % retention ((influx - outflux) / influx) (mean: 6.9 %, range: -34.8 to +31.2) compared to DOC (mean: 30.1 %, range: +9.2 to +44.1). The resultant increase of DON within the lake was closely linked with a net decrease of DIN through monthly Pearson correlation analysis, suggesting the importance of biotic factors in mediating a lake DON dynamics. Our results show different relative retentions of DOC compared with DON, along with a larger retention of DIN than DON, suggesting that DOC and DON might display substantially different biogeochemical

  19. Organic amendments' dissolved organic carbon influences bioavailability of agricultural soil DOC

    NASA Astrophysics Data System (ADS)

    Straathof, Angela L.; Chincarini, Riccardo; Hoffland, Ellis; Comans, Rob N. J.

    2013-04-01

    Agricultural soils benefit from additions of organic amendments because they improve soil structure, are a source of plant nutrients, and increase concentrations of soil organic carbon (SOC). The latter fuels microbial processes important for plant growth, including nutrient mineralization and the suppression of plant diseases. However, these amendment additions range in quality and quantity of C and little is known about how their properties interact with native soil C and affect turnover. The dissolved pool of SOC (DOC) may be the most important C source for these processes as it is more biologically available and thus relatively easily turned over by the soil microbial biomass. Using a rapid-batch DOC fractionation procedure, we studied the composition of different organic amendments' DOC pools and measured how their additions change the quantity and turnover of soil DOC. Fractions isolated and quantified with this procedure include humic and fulvic acids, hydrophobic neutral and hydrophilic compounds. We hypothesized that these range from biologically recalcitrant to readily available, respectively. Amendments analysed included composts of different source materials and maturation stages collected from two different compost facilities in the Netherlands. Both total DOC concentrations and proportions of the aforementioned fractions ranged highly between composts. Composts cured for >10 days had a lower proportion of hydrophilic C compounds, suggesting that these are the most bioavailable and released as CO2 via microbial activity during maturation. To measure the effects of compost DOC on soil DOC, we extracted the former and added it to a sandy soil in an incubation experiment. The amendment increased soil total DOC, CO2 production from the soil, and the pools of humic and fulvic acids as a proportion of total DOC. Turnover of C from the incubated soil was measured by substrate-induced CO2 production (an indicator of microbial activity) from a 96-well

  20. Tracing the long-term microbial production of recalcitrant fluorescent dissolved organic matter in seawater

    NASA Astrophysics Data System (ADS)

    Jørgensen, Linda; Stedmon, Colin A.; Granskog, Mats A.; Middelboe, Mathias

    2014-04-01

    The majority of dissolved organic matter (DOM) in the ocean is resistant to microbial degradation, yet its formation remains poorly understood. The fluorescent fraction of DOM can be used to trace the formation of recalcitrant DOM (RDOM). A long-term (> 1 year) experiment revealed 27-52% removal of dissolved organic carbon and a nonlinear increase in RDOM fluorescence associated with microbial turnover of semilabile DOM. This fluorescence was also produced using glucose as the only initial carbon source, suggesting that degradation of prokaryote remnants contributes to RDOM. Our results indicate that the formation of a fluorescent RDOM component depends on the bioavailability of the substrate: the less labile, the larger the production of fluorescent RDOM relative to organic carbon remineralized. The anticipated increase in microbial carbon demand due to ocean warming can potentially force microbes to degrade less labile substrates, thereby increasing RDOM production and stimulating ocean carbon storage.

  1. Complexation of Cu with dissolved organic carbon in municipal solid waste incinerator bottom ash leachates

    SciTech Connect

    Meima, J.A.; Van Zomeren, A.; Comans, R.N.J.

    1999-05-01

    The complexation of Cu with dissolved organic carbon (DOC) in leachates from fresh and 1.5-year old municipal solid waste incinerator (MSWI) bottom ash was studied using a competitive ligands-exchange solvent extraction procedure. At least two different ligands appear to be involved in the complexation of copper with DOC. The dissolved Cu appears to be 95--100% organically bound in leachates from both the fresh and the weathered bottom ash, and geochemical modeling indicates that the leaching of Cu from these ashes is primarily controlled by the availability of the organic ligands in the bottom ash. The mechanism that binds Cu to the solid phase is likely to be tenorite in the fresh bottom ash, and sorption to amorphous Fe/Al-(hydr)-oxides in the weathered bottom ash.

  2. Coupled ocean-atmosphere loss of marine refractory dissolved organic carbon

    NASA Astrophysics Data System (ADS)

    Kieber, David J.; Keene, William C.; Frossard, Amanda A.; Long, Michael S.; Maben, John R.; Russell, Lynn M.; Kinsey, Joanna D.; Tyssebotn, Inger Marie B.; Quinn, Patricia K.; Bates, Timothy S.

    2016-03-01

    The oceans hold a massive quantity of organic carbon, nearly all of which is dissolved and more than 95% is refractory, cycling through the oceans several times before complete removal. The vast reservoir of refractory dissolved organic carbon (RDOC) is a critical component of the global carbon cycle that is relevant to our understanding of fundamental marine biogeochemical processes and the role of the oceans in climate change with respect to long-term storage and sequestration of atmospheric carbon dioxide. Here we show that RDOC includes surface-active organic matter that can be incorporated into primary marine aerosol produced by bursting bubbles at the sea surface. We propose that this process will deliver RDOC from the sea surface to the atmosphere wherein its photochemical oxidation corresponds to a potentially important and hitherto unknown removal mechanism for marine RDOC.

  3. Biogeochemical characteristics of dissolved and particulate organic matter in Russian rivers entering the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Lobbes, Jörg M.; Fitznar, Hans Peter; Kattner, Gerhard

    2000-09-01

    The biogeochemical signature of riverine matter in the Russian Arctic was investigated to establish a background for tracing terrestrial organic material in the Arctic Ocean. Elemental and lignin compositions of particulate and dissolved organic matter (POM, DOM), stable carbon isotope ratios of POM and nutrient concentrations are reported for 12 Russian rivers along 4000 km of coastline. The 12 rivers account for about 43% of the freshwater supply to the Arctic Ocean. Nine rivers drain both tundra and taiga areas and three rivers only tundra. Concentrations of nitrogenous nutrients and phosphate were low, whereas silicate values were generally high with only few exceptions. The concentrations of particulate organic carbon (POC) varied between 25.5 and 291 μmol/L C, contributing 0.4-2.1% to the total suspended sediment (TSS). Dissolved organic carbon (DOC) ranging from 230 to 1006 μmol/L C was on average eight times higher than POC. The concentrations of particulate and dissolved organic nitrogen were similar (ca. 11 μmol/L N) resulting in four times higher C/N ratios in the dissolved fraction (48) compared to the particulate fraction (11). The δ 13C ratios were uniform (-25.6 to -27.4‰) and similar in taiga and tundra draining rivers. The exclusively terrestrial component lignin, determined as lignin phenols after cupric oxide oxidation, ranged from 5.6 to 37.6 nmol/L in the particulate fraction and from 34 to 319 nmol/L in the dissolved fraction. The syringyl/vanillyl (S/V) and cinnamyl/vanillyl (C/V) ratios of the particulate and dissolved lignin phenols were significantly correlated with the proportion of tundra and taiga in the drainage areas. This is true despite different formation processes and diagenetic degree of POM and DOM, as evident from acid/aldehyde ratios of vanillyl phenols [(Ad/Al)v]. Export rates were calculated from the carbon and lignin data. The 12 rivers studied transport about 10 × 10 12 g of total organic carbon per year into the

  4. CARBON LOSS AND OPTICAL PROPERTY CHANGES DURING LONG-TERM PHOTOCHEMICAL AND BIOLOGICAL DEGRADATION OF ESTUARINE DISSOLVED ORGANIC MATTER

    EPA Science Inventory

    Terrestrially derived dissolved organic matter (DOM) impacts the optical properties of coastal seawater and affects carbon cycling on a global scale. We studied sequential long-term photochemical and biological degradation of estuarine dissolved organic matter from the
    Satilla...

  5. Optical signatures of dissolved organic matter from the Endeavour and Axial vent fields

    NASA Astrophysics Data System (ADS)

    Stubbins, A.; Butterfield, D.; Rossel, P. E.; Dittmar, T.

    2011-12-01

    Recent studies have revealed that hydrothermal systems in the deep ocean are both sources and processors of dissolved organic matter (DOM). Sub-floor stores of fossil organic carbon may be exported to the deep ocean directly adding fossil C to the deep ocean dissolved organic carbon (DOC) pool and altering its apparent age. Fossil methane and carbon dioxide are also exported from vents. These C sources can then be utilized by chemotrophs and later enter the DOM pool as fossil DOC. Finally, when deep ocean waters are entrained into vent systems, the resultant heating may alter the chemical and optical properties of the DOM in these deep ocean waters. Dissolved organic matter (DOM) samples were collected from vents ranging in temperature from 10 to over 300 degrees centigrade across the Endeavour and Axial fields along the Juan de Fuca ridge. Elevated DOC and protein-like fluorescence reveal the vents to fuel the chemotrophic production of organic matter either in the adjacent water column or local sediments. High DOC and increased humic-like fluorescence in the hottest vent fluids, suggests the thermal degradation of DOM either from buried fossil sources or the entrainment of local waters enriched in DOC due to chemotrophic productivity. Natural and radio-carbon analyses are underway and will provide further insight into the ultimate source of this colored, fluorescent hydrothermal DOM.

  6. Copper-binding ability of dissolved organic matter derived from anaerobically digested biosolids

    SciTech Connect

    Han, N.; Thompson, M.L.

    1999-05-01

    The fate of metals in soils where soluble organic compound are present may be strongly influenced by the degree to which they are complexed by organic ligands. The authors undertook this study to determine the combined effect of molecular weight (MW) and hydrophobicity on the Cu-binding ability of dissolved organic compounds in biosolids (i.e., sewage sludge). Dissolved organic matter (DOM) from anaerobically digested sewage biosolids was fractionated by using a combination of MW fractionation and XAD-8 resin chromatography. The Cu-binding abilities of the DOM fractions were obtained by using a Cu{sup 2+}-ion-selective electrode (Cu-ISE) technique. The Cu-binding ability of fractionated DOM decreased significantly with increasing molecular weight, indicating that low-MW DOM had more metal-binding sites than high-MW DOM. Within each MW fraction, the hydrophilic and the hydrophobic components also exhibited differences in Cu-binding ability. For the DOM with MW 500--3,500 Da, the hydrophilic fraction showed a greater Cu-binding capacity than did the hydrophobic fraction, whereas the hydrophobic acid components were most important in binding Cu for DOM with MW > 3,500 Da. The maximum Cu-binding capacities of different biosolids-derived DOM fractions, estimated by employing a Langmuir model, ranged from 1.85 to 14.3 mmol Cu mol{sup {minus}1} dissolved organic C (DOC), which is the same order of magnitude as similar measurements of DOM from other sources.

  7. A major biopolymeric component to dissolved organic carbon in surface sea water

    NASA Astrophysics Data System (ADS)

    Aluwihare, Lihini I.; Repeta, Daniel J.; Chen, Robert F.

    1997-05-01

    Organic carbon dissolved in sea water is an important component of the global carbon cycle1. Concentrations of dissolved organic carbon (DOC) in the ocean's surface mixed layer are at least twice those in the deep sea2,3, because of the production of soluble carbon compounds by marine algae in the euphotic zone4,5. But very little is known about the chemical composition of DOC, and the connection between photosynthetic production and DOC accumulation is not well understood6,7. Here we report the chemical characterization of macromolecular DOC at several sites in the Atlantic and Pacific oceans. Neutral sugars, acetate and lipids show similar distributions, suggesting that these constituents are linked together in a common macromolecular structure. Chemical linkage patterns between the oligosaccharide portions of dissolved organic matter subjected to ultrafiltration are highly specific, with little variation between ocean basins. We show that laboratory culture experiments on the decomposition of algal exudate produce macromolecular organic matter with similar compositions and linkage characteristics. We propose that a significant fraction of DOC in sea surface water consists of structurally related and biosynthetically derived acyl oligosaccharides that persist after more labile organic matter has been degraded.

  8. INFLUENCE OF METHOD FOR REMOVAL OF SESTON ON THE DISSOLVED ORGANIC MATTER(1).

    PubMed

    Parker, B C

    1967-12-01

    Comparisons of various methods and method modifications for treating water samples to render them free of seston prior to analysis of dissolved organic matter have corroborated a number of suspected sources of error. Among the more important points arising from this study arc: 1. All cellulose ester filters must be washed to remove elutable carbon. 2. In some instances filtration to dryness may produce artifacts resulting from cell injury. 3. A significant difference in filter retention can result between 0.45 and 0.22 μ membranes. 4. Among the methods most satisfactory are wet filtration through 0.22 μ pre-washed Millipore membranes and continuous-flow centrifugation at ca. 10,000 x g and 100 cc/min flow rate, both of which have their inherent weaknesses and limitations. 5. Regular centrifugation does not remove some planktonic organisms which have considerable buoyancy, or organic substances may somehow be released by cells without producing morphological damage. The newly developed bio dialysis technique for dissolved organic matter collection consistently yielded lower values than continuous-flow centrifugation. In contrast, biodialysis yielded lower values for pond water and higher values for Scenedesmus cultures than the best filtration method. Evidence suggests that biodialysis will be useful as both a supplementary and, in some zuays, more accurate method in studies of dissolved organic matter. PMID:27065026

  9. Characterization of dissolved organic matter in landfill leachate during the combined treatment process of air stripping, Fenton, SBR and coagulation

    SciTech Connect

    Liu, ZhiPing; Wu, WenHui; Shi, Ping; Guo, JinSong; Cheng, Jin

    2015-07-15

    Highlights: • DOM fractions spectra analysis during the whole treatment process. • Efficient method was achieved to remove organic matters in landfill leachate. • Molecular weight distribution and fractions were discussed. - Abstract: A combined treatment process of air stripping + Fenton + sequencing batch reactor (SBR)+ coagulation was performed to remove the pollutants in landfill leachate. Molecular weight (MW) distribution and fractions of dissolved organic matter (DOM) were discussed to study the characteristics. The experiment showed that the removal rate of chemical oxygen demand (COD), five day biological oxygen demand (BOD{sub 5}) and ammonia nitrogen (NH{sub 3}−N) by the combined process were 92.8%, 87.8% and 98.0%, respectively. Humic acid (HA) and fulvic acid (FA) were the main fractions in raw leachate with 81.8% of the total COD concentration, while hydrophilic organic matter (HyI) was the dominant fraction in the final effluent of the combined process with 63.5% of the total COD concentration. After the combined treatment process, the removal rate of DOM and fractions HA, FA, HyI were 91.9%, 97.1%, 95.8% and 71.7%, respectively. Organic matters of MW < 2 k and MW > 100 k were removed with 90.5% and 97.9% COD concentration after the treatment. The ultraviolet–visible spectra (UV–vis), Fourier transform infrared spectra (FTIR) and three-dimensional excitation-emission matrices spectra (EEMs) indicated that benzene materials and phenol compounds were preferentially removed in air stripping. High MW matters, aromatic rings, conjugated moieties and some functional groups were mainly removed by Fenton. While small MW fractions, carboxylic acids, alcohols and protein-like materials were preferentially biodegraded via SBR. Fulvic-like and humic-like materials were mainly destroyed via Fenton oxidation and coagulation.

  10. Exchanges and photo-biogeochemical transformation of dissolved organic compounds in Eastern US tidal marsh ecosystems.

    NASA Astrophysics Data System (ADS)

    Tzortziou, Maria; Neale, Patrick; Megonigal, Patrick; Butterworth, Megan; Jaffe, Rudolf

    2010-05-01

    The role of tidal marshes as sources, sinks and/or transformers of biologically important nutrients, carbon and pollutants has been studied in various marsh-estuarine environments and geomorphological settings. Although there is no consensus on the magnitude and direction of marsh-estuary net (particulate and dissolved) organic fluxes, most previous studies suggest that salt marshes export dissolved organic carbon (DOC) to the surrounding estuarine waters. There has been less attention, however, to the influence of transformations on marsh-exported organic carbon composition or "quality". Yet, carbon composition affects a wide variety of estuarine processes, including microbial respiration and photochemistry. Our objectives in this study were to quantify the photo-reactivity and bio-availability of dissolved organic carbon compounds exported from tidal wetlands of the Chesapeake Bay and determine their effects on the optical properties of colored organic matter (CDOM). We quantified DOC bioavailability with two assays of microbial mineralization: the traditional batch incubation approach in which a suspension of DOM and microbial cells (1 µm filtrate) was incubated in bottles for 7 d, and a continuous-flow bioreactor approach in which DOC (0.2 µm filtrate) was passed through a microbial community that had been pre-established on glass beads from the same source water. Photochemical degradation was measured after a 10h exposure to filtered xenon irradiance simulating midday surface exposure. We measured decreases in CDOM absorption and fluorescence spectra, DOC concentrations, changes in molecular weight distribution, and increases in dissolved inorganic carbon (DIC) and CO2. Results provide important insights on the transformation, fate and cycling of marsh-exported organic compounds, and the role of tidal marsh systems as major regulators of short-scale biological, optical and biogeochemical variability in highly dynamic coastal margins and catchment areas.

  11. The characterization and bioavailability of dissolved organic carbon in deep subsurface and surface waters

    SciTech Connect

    Palumbo, A.V.; Jardine, P.M.; McCarthy, J.F. ); Zaidi, B.R. . Dept. of Marine Sciences)

    1990-01-01

    We characterized and compared the bioavailability of chemical fractions of dissolved organic carbon (DOC) from deep wells at the US Department of Energy Savannah River Plant (SRP) site with that from South Carolina surface waters. Experiments with three bacterial cultures (Corynebacterium sp., Pseudomonas sp., and a bacteria included isolated from the surface water) indicated that the bioavailability of the carbon in the near surface water may be limited by inorganic nutrients. Associated with well-defined organic compounds. The purpose of this preliminary investigation was to improve our understanding of the organic matter in groundwater by characterizing the natural organic matter in water recovered from different formations in the Deep Probe Subsurface Microbiology program and by determining if the natural organic carbon can support growth of bacterial populations. The characterization was directed at elucidating the properties of of dissolved or colloidal organic matter that are relevant to the transport and mobility of the organic matter (and contaminants sorbed to the organic matter) and that may also be relevant to the potential role of organic matter in groundwater as a nutrient source supporting microbial productivity in the deep subsurface. A secondary objective of this study was to determine the factors limiting microbial growth in surface waters and near surface groundwaters and to determine the response of the microbial community to a mixing of these waters.

  12. Molecular characterization of low molecular weight dissolved organic matter in water reclamation processes using Orbitrap mass spectrometry.

    PubMed

    Phungsai, Phanwatt; Kurisu, Futoshi; Kasuga, Ikuro; Furumai, Hiroaki

    2016-09-01

    Reclaimed water has recently become an important water source for urban use, but the composition of dissolved organic matter (DOM) in reclaimed water has rarely been characterized at the compound level because of its complexity. In this study, the transformation and changes in composition of low molecular weight DOM in water reclamation processes, where secondary effluent of the municipal wastewater treatment plant was further treated by biofiltration, ozonation and chlorination, were investigated by "unknown" screening analysis using Orbitrap mass spectrometry (Orbitrap MS). The intense ions were detected over an m/z range from 100 to 450. In total, 2412 formulae with various heteroatoms were assigned, and formulae with carbon (C), hydrogen (H) and oxygen (O) only and C, H, O and sulfur (S) were the most abundant species. During biofiltration, CHO-only compounds with relatively high hydrogen to carbon (H/C) ratio or with saturated structure were preferentially removed, while CHOS compounds were mostly removed. Ozonation induced the greatest changes in DOM composition. CHOS compounds were mostly decreased after ozonation while ozone selectively removed CHO compounds with relatively unsaturated structure and produced compounds that were more saturated and with a higher degree of oxidation. After chlorination, 168 chlorine-containing formulae, chlorinated disinfection by-products (DBPs), were additionally detected. Candidate DBP precursors were determined by tracking chlorinated DBPs formed via electrophilic substitution, half of which were generated during the ozonation. PMID:27235773

  13. Modeling organic matter stabilization during windrow composting of livestock effluents.

    PubMed

    Oudart, D; Paul, E; Robin, P; Paillat, J M

    2012-01-01

    Composting is a complex bioprocess, requiring a lot of empirical experiments to optimize the process. A dynamical mathematical model for the biodegradation of the organic matter during the composting process has been developed. The initial organic matter expressed by chemical oxygen demand (COD) is decomposed into rapidly and slowly degraded compartments and an inert one. The biodegradable COD is hydrolysed and consumed by microorganisms and produces metabolic water and carbon dioxide. This model links a biochemical characterization of the organic matter by Van Soest fractionating with COD. The comparison of experimental and simulation results for carbon dioxide emission, dry matter and carbon content balance showed good correlation. The initial sizes of the biodegradable COD compartments are explained by the soluble, hemicellulose-like and lignin fraction. Their sizes influence the amplitude of the carbon dioxide emission peak. The initial biomass is a sensitive variable too, influencing the time at which the emission peak occurs. PMID:23393964

  14. High fluvial export of dissolved organic nitrogen from a peatland catchment with elevated inorganic nitrogen deposition.

    PubMed

    Edokpa, D A; Evans, M G; Rothwell, J J

    2015-11-01

    This study investigates seasonal concentrations and fluxes of nitrogen (N) species under stormflow and baseflow conditions in the peat dominated Kinder River catchment, south Pennines, UK. This upland region has experienced decades of high atmospheric inorganic N deposition. Water samples were collected fortnightly over one year, in combination with high resolution stormflow sampling and discharge monitoring. The results reveal that dissolved organic nitrogen (DON) constitutes ~54% of the estimated annual total dissolved nitrogen (TDN) flux (14.3 kg N ha(-1) yr(-1)). DON cycling in the catchment is influenced by hydrological and biological controls, with greater concentrations under summer stormflow conditions. Dissolved organic carbon (DOC) and DON are closely coupled, with positive correlations observed during spring, summer and autumn stormflow conditions. A low annual mean DOC:DON ratio (<25) and elevated dissolved inorganic N concentrations (up to 63μmoll(-1) in summer) suggest that the Kinder catchment is at an advanced stage of N saturation. This study reveals that DON is a significant component of TDN in peatland fluvial systems that receive high atmospheric inputs of inorganic N. PMID:26119385

  15. PHOTOREACTIVITY OF CHROMOPHORIC DISSOLVED ORGANIC MATTER (CDOM) DERIVED FROM DECOMPOSITION OF VARIOUS VASCULAR PLANT AND ALGAL SOURCES

    EPA Science Inventory

    Chromophoric dissolved organic matter (CDOM) in aquatic environments is derived from the microbial decomposition of terrestrial and microbial organic matter. Here we present results of studies of the spectral properties and photoreactivity of the CDOM derived from several organi...

  16. PATTERNS AND CONTROLS OF DISSOLVED ORGANIC MATTER EXPORT BY MAJOR RIVERS: A NEW SEASONAL, SPATIALLY EXPLICIT, GLOBAL MODEL

    EPA Science Inventory

    River-derived dissolved organic matter (DOM) influences metabolism, light attenuation, and bioavailability of metals and nutrients in coastal ecosystems. Recent work suggests that DOM concentrations in surface waters vary seasonally because different organic matter pools are mobi...

  17. Application of passive sampling for measuring dissolved concentrations of organic contaminants in the water column at three marine superfund sites

    EPA Science Inventory

    At contaminated sediment sites, including U.S. EPA Superfund sites, it is critical to measure water column concentrations of freely dissolved contaminants to understand the complete exposure of aquatic organisms to hydrophobic organic contaminants (HOCs). However, historically a...

  18. Three-dimensional excitation-emission matrix fluorescence spectroscopy and fractions of dissolved organic matter change in landfill leachate by biological treatment.

    PubMed

    Cui, Yanrui; Wu, Qing; Yang, Mengsi; Cui, Fengling

    2016-01-01

    The water quality improvement of landfill leachate after sequencing batch reactor (SBR) activated sludge process were evaluated by chemical oxygen demand (COD), dissolved organic matter (DOM) fractions, and three-dimensional excitation-emission matrix (EEM), from which the new understanding was obtained. The results indicated that less than 14% COD was removed by SBR. The EEM of leachate and SBR effluent showed that HPO-A and TPI-A were appeared in the peak C, while the HPI, HPO-N, and TPI-N could not be found due to dilution. Although humic acid appeared in peak C, not all the organic materials in peak C are humic acid. And because landfill leachate is a kind of complicated wastewater, therefore, only EEM cannot efficiently reflect the water quality. PMID:26341332

  19. Recalcitrant organic compounds (chemical oxygen demand sources) in biologically treated pulp and paper mill effluents: Their fate and environmental impact in receiving waters

    SciTech Connect

    Archibald, F.; Roy-Arcand, L.; Methot, M.; Valeanu, L.

    1998-11-01

    Most North American pulp and paper mills now biologically treat (biotreat) their liquid effluent. However, treated water still contains effluent-derived recalcitrant organic material (EROM), measured as chemical oxygen demand (COD), for which emission limits exist in Europe and are being considered in the US. Production of microbially resistant, dissolved natural organic material (NOM) typically found in Canadian stream and lake waters occurs slowly under gentle conditions, while mill EROM is generated from lignocellulosics by faster and harsher processes. Similarity of the environmental effects of NOM and pulp and paper mill EROM are examined. Changes occurring over 4 months in biologically treated effluent from two modern Canadian mills and lake NOM when sealed in gas- and light-permeable bags and placed in a pristine Quebec lake are reported. Addition of microbial co-metabolites significantly improved the dark mineralization of organochlorines surviving mill biological treatment. Mill EROM was light sensitive, nonacutely toxic in the Microtox assay, and similar to NOM in the surrounding lake in most bulk properties. There was no evidence to suggest that placing specific limits on mill EROM (COD) emissions would be environmentally beneficial.

  20. Study of fouling and scaling in capacitive deionisation by using dissolved organic and inorganic salts.

    PubMed

    Mossad, Mohamed; Zou, Linda

    2013-01-15

    In this work, fouling, scaling and cleaning of the capacitive deionisation (CDI) with activated carbon electrodes were systematically investigated for the first time. Electrode fouling caused by dissolved organic matter using sodium salt of humic acid as a model foulant (measured by total organic carbon concentration, TOC) and inorganic salt (NaCl, MgCl(2), CaCl(2) and FeCl(3)) in the CDI feed solutions was investigated in a series of controlled fouling experiments. After each CDI experiment, a series of cleaning steps was performed to understand the reversibility of fouling accumulated on the electrode surface by analysing the cleaning solutions. The higher the TOC concentration in the CDI feed solution, the more the reduction of salt removal efficiency, declination in the production rate and energy consumption. Dissolved organic matter is the main cause of electrode fouling, as it blocks the activated carbon pores and reduces their electrosorption capacitance. Ca and Mg have no noticeable effect on the CDI treatment performance. However, Fe seemed to have a greater effect on CDI electrode fouling. Alkaline and acid cleaning solutions were able to restore the recovery of the CDI performance from fouling. Pre-treatment to reduce the dissolved organic matter levels is recommended to achieve sustainable treatment performance. PMID:23274796

  1. Molecular weight distribution of phosphorus fraction of aquatic dissolved organic matter.

    PubMed

    Ged, Evan C; Boyer, Treavor H

    2013-05-01

    This study characterized dissolved organic phosphorus (DOP) that is discharged from the Everglades Agricultural Area as part of the larger pool of aquatic dissolved organic matter (DOM). Whole water samples collected at the Everglades stormwater treat area 1 West (STA-1 W) were fractionated using a batch ultrafiltration method to separate organic compounds based on apparent molecular weight (AMW). Each AMW fraction of DOM was characterized for phosphorus, carbon, nitrogen, UV absorbance, and fluorescence. The DOP content of the Everglades water matrix was characteristically variable constituting 4-56% of total phosphorus (TP) and demonstrated no correlation with dissolved organic carbon (DOC). Measured values for DOP exceeded 14μgL(-1) in four out of five sampling dates making phosphorus load reductions problematic for the stormwater treatment areas (STAs), which target inorganic phosphorus and have a goal of 10μgL(-1) as TP. The molecular weight distributions revealed 40% of DOP is high molecular weight, aromatic-rich DOM. The results of this research are expected to be of interest to environmental chemists, environmental engineers, and water resources managers because DOP presents a major obstacle to achieving TP levels <10μgL(-1). PMID:23466281

  2. Cellulase activity and dissolved organic carbon release from lignocellulose macrophyte-derived in four trophic conditions.

    PubMed

    Bottino, Flávia; Cunha-Santino, Marcela Bianchessi; Bianchini, Irineu

    2016-01-01

    Considering the importance of lignocellulose macrophyte-derived for the energy flux in aquatic ecosystems and the nutrient concentrations as a function of force which influences the decomposition process, this study aims to relate the enzymatic activity and lignocellulose hydrolysis in different trophic statuses. Water samples and two macrophyte species were collected from the littoral zone of a subtropical Brazilian Reservoir. A lignocellulosic matrix was obtained using aqueous extraction of dried plant material (≈40°C). Incubations for decomposition of the lignocellulosic matrix were prepared using lignocelluloses, inoculums and filtered water simulating different trophic statuses with the same N:P ratio. The particulate organic carbon and dissolved organic carbon (POC and DOC, respectively) were quantified, the cellulase enzymatic activity was measured by releasing reducing sugars and immobilized carbon was analyzed by filtration. During the cellulose degradation indicated by the cellulase activity, the dissolved organic carbon daily rate and enzyme activity increased. It was related to a fast hydrolysable fraction of cellulose that contributed to short-term carbon immobilization (ca. 10 days). After approximately 20 days, the dissolved organic carbon and enzyme activity were inversely correlated suggesting that the respiration of microorganisms was responsible for carbon mineralization. Cellulose was an important resource in low nutrient conditions (oligotrophic). However, the detritus quality played a major role in the lignocelluloses degradation (i.e., enzyme activity) and carbon release. PMID:26991278

  3. Dynamics of Dissolved Organic Matter in Amazon Basin: Insights into Negro River Contribution

    NASA Astrophysics Data System (ADS)

    Moreira-Turcq, P.; Perez, M. P.; Benedetti, M.; Oliveira, M. A.; Lagane, C.; Seyler, P.; Oliveira, E.

    2006-12-01

    The study of global carbon cycle requires a precise knowledge of spatial and temporal distributions and exportation from continents to oceans. Organic carbon fluxes represent approximately half of the total carbon budget carried by rivers. Tropical rivers transport two third of the total organic carbon discharged into the world oceans but important gaps still exist in the knowledge of the tropical river carbon biochemistry. The Amazon River is responsible for 10% of the annual amount of organic carbon transported from rivers to oceans. The most important portion of total organic matter transported in the Amazon Basin is the dissolved fraction (between 80% and 95%). Amazonian annual flux of dissolved organic matter is directly related to hydrological variations. All rivers in the Amazon basin are characterized by monomodal hydrograms, with a low water period in october/november and a high water period in may/june. Temporal variations in Amazon dissolved organic carbon (3.0 to 9.1 mg l^{- 1}) are mainly controled by Negro River inputs. DOC and DON contributions from the Negro River can vary between 120 kgC s-1 and 520 kg C s-1, and between 5 kgN s--1 and 15 kgN s-1, during low and high water period, respectivelly. In the Negro River, during high water stages, while DOC concentrations are stable from the upstream stations to the downstream ones (about 11 mg l-1), discharge increases from 16000 to 46000 m3 s-1 and NOD can quintuple from upstream (0.071 mg l-1) to downstream (0.341 mg l-1). Then the nature of dissolved organic matter is variable (C/N ratio varied from 33 to 120 from upstream to downstream). During low water stages DOC concentrations are lower (mean DOC of 8.1 mg l-1) while DON is in the same range, discharge is about 10000 m3 s-1 at downstream stations of Negro River and the C/N ratio is lower and steadier along the River. Finaly, despite a low basin surface (12%) compared with the two other main Amazon tributaries, Solimões and Madeira Rivers, and a

  4. Elevated atmospheric CO2 fuels leaching of old dissolved organic matter at the alpine treeline

    NASA Astrophysics Data System (ADS)

    Hagedorn, Frank; van Hees, Patrick A. W.; Handa, I. Tanya; HäTtenschwiler, Stephan

    2008-06-01

    Dissolved organic matter (DOM), the mobile form of soil organic matter (SOM), plays an important role in soil C cycling and in nutrient transport. We investigated the effects of 5 years of CO2 enrichment (370 versus 570 μmol CO2 mol-1) on DOM dynamics at the alpine treeline, including the analysis of fast-cycling components such as low molecular weight organic acids (LMWOAs), dissolved organic carbon (DOC) biodegradability, and the decomposition of 14C-labeled oxalate. Concentrations of DOC in canopy throughfall were 20% higher at elevated CO2, probably driven by higher carbohydrate concentrations in leaves. In the organic soil layer, 5 years of CO2 enrichment increased water-extractable organic C by 17% and soil solution DOC at 5 cm depth by 20%. The 13C tracing of recently assimilated CO2 revealed that the input of recent plant-derived C (<15% of total DOC) was smaller than the CO2-induced increase in DOC. This strongly suggests that CO2 enrichment enhanced the mobilization of native DOC, which is supported by significant increases in dissolved organic nitrogen (DON). We mainly attribute these increases to a stimulated microbial activity as indicated by higher basal and soil respiration rates (+27%). The 14C-labeled oxalate was more rapidly mineralized from high CO2 soils. The concentrations of LMWOAs, but also those of "hydrophilic" DOC and biodegradable DOC (6% of total DOC), were, however, not affected by elevated CO2, suggesting that production and consumption of "labile" DOC were in balance. In summary, our data suggest that 5 years of CO2 enrichment speeded up the cycling of "labile" DOM and SOM in a late successional treeline ecosystem and increased the mobilization of older DOM through a stimulated microbial activity. Such a "priming effect" implies that elevated CO2 can accelerate the turnover of native SOM, and thus, it may induce increasing losses of old C from thick organic layers.

  5. Adsorption of dissolved organics in lake water by aluminum oxide. Effect of molecular weight

    USGS Publications Warehouse

    Davis, J.A.; Gloor, R.

    1981-01-01

    Dissolved organic compounds in a Swiss lake were fractionated into three molecular size classes by gel exclusion chromatography, and adsorption of each fraction on colloidal alumina was studied as a function of pH. Organic compounds with molecular weight (Mr) greater than 1000 formed strong complexes with the alumina surface, but low molecular weight compounds were weakly adsorbed. Electrophoretic mobility measurements indicated that alumina particles suspended in the original lake water were highly negatively charged because of adsorbed organic matter. Most of the adsorbed organic compounds were in the Mr range 1000 < Mr < 3000. Adsorption of these compounds during the treatment of drinking water by alum coagulation may be responsible for the preferential removal of trihalomethane precursors. Adsorption may also influence the molecular-weight distribution of dissolved organic material in lakes. surface, the present work will focus on the influence of molecular size and pH on the adsorption behavior of dissolved organic material of a Swiss lake. From a geochemical point of view, it is important to know the molecular-weight distribution of adsorbed organic matter so that we may better assess its reactivity with trace elements. The study also serves as a first step in quantifying the role of adsorption in the geochemical cycle of organic carbon in lacustrine environments. For water-treatment practice, we need to determine whether molecular weight fractionation occurs during adsorption by aluminum oxide. Such a fractionation could be significant in the light of recent reports that chloroform and other organochlorine compounds are preferentially produced by particular molecular-weight fractions (25-27). ?? 1981 American Chemical Society.

  6. Identification and chemical characterization of specific organic constituents of petrochemical effluents.

    PubMed

    Botalova, Oxana; Schwarzbauer, Jan; Frauenrath, Tom; Dsikowitzky, Larissa

    2009-08-01

    Based on extensive GC/MS screening analyses, the molecular diversity of petrochemical effluents discharged to a river in North Rhine-Westphalia was characterised. Within a wide spectrum of organic wastewater constituents, specific compounds that might act as source indicators have been determined. This differentiation was based on (i) the individual molecular structures, (ii) the quantitative appearance of organic compounds in treated effluents and (iii) the information on their general occurrence in the technosphere and hydrosphere. Principally, site-specific indicators have been distinguished from candidates to act as general petrochemical indicators. Further on, monitoring the environmental behaviour of target organic contaminants in an aquatic system shortly after their release into the river allowed a first evaluation of the impact of the petrogenic emission in terms of the quantity and spatial distribution. The identification of petrogenic contaminants was not restricted to constituents of the effluents only, but comprised the compounds circulating in the wastewater systems within a petrochemical plant. A number of environmentally relevant and structurally specific substances that are normally eliminated by wastewater treatment facilities were identified. Insufficient wastewater treatment, careless waste handling or accidents at industrial complexes are potential sources for a single release of the pollutants. This study demonstrates the relevance of source specific organic indicators to be an important tool for comprehensive assessment of the potential impact of petrochemical activities to the contamination of an aquatic environment. PMID:19577787

  7. Efficient Filtration of Effluent Organic Matter by Polycation-Clay Composite Sorbents: Effect of Polycation Configuration on Pharmaceutical Removal.

    PubMed

    Shabtai, Itamar A; Mishael, Yael G

    2016-08-01

    Hybrid polycation-clay composites, based on methylated poly vinylpyridinium, were optimized as sorbents for secondary effluent organic matter (EfOM) including emerging micropollutants. Composite structure was tuned by solution ionic strength and characterized by zeta potential, FTIR, X-ray diffraction, and thermal gravimetric analyses. An increase in ionic strength induced a transition from a train to a loops and tails configuration, accompanied by greater polycation adsorption. Composite charge reversal (zeta potential -18 to 45 mV) increased the adsorption of EfOM and humic acid (HA), moderately and sharply, respectively, suggesting electrostatic and also nonspecific interactions with EfOM. Filtration of EfOM by columns of positively charged composites was superior to that of granular activated carbon (GAC). The overall removal of EfOM was most efficient by the composite with a train configuration. Whereas a composite with a loops and tails configuration was beneficial for the removal of the anionic micropollutants diclofenac, gemfibrozil and ibuprofen from EfOM. These new findings suggest that the loops and tails may offer unique binding sites for small micropollutants which are overseen by the bulk EfOM. Furthermore, they may explain our previous observations that in the presence of dissolved organic matter, micropollutant filtration by GAC columns was reduced, while their filtration by composite columns remained high. PMID:27397603

  8. Increased Fluvial Dissolved Organic Carbon Fluxes over 130 Years of Land-Use Change in the Thames Basin

    NASA Astrophysics Data System (ADS)

    Noacco, V.; Howden, N. J. K.; Wagener, T.; Worrall, F.

    2014-12-01

    This study investigates drivers of changing dissolved organic carbon (DOC) export in the UK's River Thames basin between 1881 and 2011. Specifically, we consider how impacts of land-use change drive increases in DOC concentrations and fluxes at the basin outlet. First, we estimate soil organic carbon (SOC) stocks in the Thames basin for the period. Second, SOC losses due to land-use change are partitioned into DOC lost to surface waters through runoff, DOC leached into deeper soils and groundwater, and losses to the atmosphere as CO2. SOC stocks for each year are calculated from a large database of typical SOC levels for land-uses present in the Thames basin and are combined with literature values of transition times for SOC to adjust to a new level following land-use change. We also account for climate change effects on SOC stock due to temperature increases, which reduces SOC stocks as soil organic matter turnover rates increase. Soil carbon fluxes are calculated as the inter-annual change in SOC. We use a 130 year record of DOC concentration in the Thames, and parameters from previous long-term nitrate modeling, to constrain estimates of fluvial DOC rises caused by SOC losses. We developed a sewage model to evaluate the relative contribution of point and diffuse sources to the total DOC flux. The results show that sewage effluent point sources do not contribute to DOC concentration at the monitoring point, except for isolated periods of exceptionally low flow. Our work shows for the majority of years, diffuse sources are the main contributor to annual DOC loads. Moreover even though there are many small inter-annual variations in DOC concentration, the major change in both estimated SOC storage and fluvial DOC export occurred during WWII due to substantial changes in land-use, the legacy of which continues to date.

  9. Characterization of dissolved organic matter in landfill leachate during the combined treatment process of air stripping, Fenton, SBR and coagulation.

    PubMed

    Liu, ZhiPing; Wu, WenHui; Shi, Ping; Guo, JinSong; Cheng, Jin

    2015-07-01

    A combined treatment process of air stripping+Fenton+sequencing batch reactor (SBR)+ coagulation was performed to remove the pollutants in landfill leachate. Molecular weight (MW) distribution and fractions of dissolved organic matter (DOM) were discussed to study the characteristics. The experiment showed that the removal rate of chemical oxygen demand (COD), five day biological oxygen demand (BOD5) and ammonia nitrogen (NH3N) by the combined process were 92.8%, 87.8% and 98.0%, respectively. Humic acid (HA) and fulvic acid (FA) were the main fractions in raw leachate with 81.8% of the total COD concentration, while hydrophilic organic matter (HyI) was the dominant fraction in the final effluent of the combined process with 63.5% of the total COD concentration. After the combined treatment process, the removal rate of DOM and fractions HA, FA, HyI were 91.9%, 97.1%, 95.8% and 71.7%, respectively. Organic matters of MW<2k and MW>100k were removed with 90.5% and 97.9% COD concentration after the treatment. The ultraviolet-visible spectra (UV-vis), Fourier transform infrared spectra (FTIR) and three-dimensional excitation-emission matrices spectra (EEMs) indicated that benzene materials and phenol compounds were preferentially removed in air stripping. High MW matters, aromatic rings, conjugated moieties and some functional groups were mainly removed by Fenton. While smallMW fractions, carboxylic acids, alcohols and protein-like materials were preferentially biodegraded via SBR. Fulvic-like and humic-like materials were mainly destroyed via Fenton oxidation and coagulation. PMID:25899801

  10. Dissolved organic nitrogen removal during water treatment by aluminum sulfate and cationic polymer coagulation.

    PubMed

    Lee, Wontae; Westerhoff, Paul

    2006-12-01

    Coagulation of three surface waters was conducted with aluminum salt and/or cationic polymer to assess dissolved organic nitrogen (DON) removal. Coagulation with aluminum sulfate removed equal or slightly lower amounts of DON as compared to dissolved organic carbon (DOC). At aluminum sulfate dosages up to 5mg per mg DOC, the cationic polymer improved DON removal by an additional 15% to 20% over aluminum sulfate alone. At very high aluminum sulfate dosages (>8 mg aluminum sulfate per mg DOC), however, the cationic polymer addition negligibly increased DON removal. Molecular weight fractionation before and after coagulation experiments indicated that cationic polymer addition can increase the removal of all molecular weight fractions of DON with the highest molecular weight fraction (>10,000 Da) being preferentially removed. Results indicated that the DON added as part of the cationic polymer was almost completely removed at optimum aluminum sulfate and polymer doses. PMID:17023020

  11. Importance of within-lake processes in affecting the dynamics of dissolved organic carbon and dissolved organic and inorganic nitrogen in an Adirondack forested lake/watershed

    NASA Astrophysics Data System (ADS)

    Kang, Phil-Goo; Mitchell, Myron J.; McHale, Patrick J.; Driscoll, Charles T.; Inamdar, Shreeram; Park, Ji-Hyung

    2016-05-01

    Lakes nested in forested watersheds play an important role in mediating the concentrations and fluxes of dissolved organic matter. We compared long-term patterns of concentrations and fluxes of dissolved organic carbon (DOC) and dissolved organic (DON) and inorganic nitrogen (DIN) in aquatic ecosystems of the Arbutus Lake watershed to evaluate how a lake nested in a forested watershed affects the sources (e.g., production) and sinks (e.g., retention) of DOC and DON in the Adirondack Mountains of New York, USA. We observed no significant long-term changes of DOC and DON in the lake outlet since 1983 and 1994, respectively. However, the temporal patterns of DOC and DON concentrations in the lake inlet showed significant seasonality such as increases during the vegetation-growing season along with notable decreases in the dormant season. A comparison of mass balances between inlet and outlet for the period from 2000 to 2009 suggested that the lake was a sink of DOC (mean of influx minus outflux: +1140 mol C ha-1 yr-1). In contrast, the difference of discharge-weighted DON concentrations (mean of inlet minus outlet: -1.0 µmol N L-1) between inlet and outlet was much smaller than the discharge-weighted DOC concentrations (average of inlet minus outlet: + 87 µmol C L-1). DON fluxes showed considerable variation among years (mean of influx minus outflux: +8 mol N ha-1 yr-1; range of differences: -15 to 27 mol N ha-1 yr-1). DON exhibited low percent retention ((influx-outflux)/influx) (mean: 6.9 %, range: -34.8 to +31.2) compared to DOC (mean: 30.1 %, range: +9.2 to +44.1). The resultant increase of DON within the lake was closely linked with a net decrease of DIN through monthly Pearson correlation analysis, suggesting the importance of biotic factors in mediating lake DON dynamics. Our results show different relative retentions of DOC compared with DON, along with a larger retention of DIN than DON, suggesting that DOC and DON might display substantially different

  12. Relationships between Nitrate and Dissolved Organic Nitrogen and Watershed Characteristics in a Rural Temperate Basin

    NASA Astrophysics Data System (ADS)

    Daley, M. L.; McDowell, W. H.

    2002-05-01

    Global models have been developed to predict nitrate export, a main component of dissolved inorganic nitrogen (DIN) export, based on human population density and human activity. Controls on dissolved organic nitrogen (DON) export are largely unknown. We tested several global nitrate models and examined potential sources of riverine DON in the Lamprey River basin (479 km2) located in rural southeastern New Hampshire, and 11 of its sub-catchments. Dissolved organic nitrogen dominated total N export. Export of nitrate and DON from the Lamprey was 0.53 and 1.28 kg/ha/yr respectively. Mean annual nitrate and DON concentration in the Lamprey was 0.11 and 0.30 mg/L respectively. The global nitrate models over predicted (>200% difference) nitrate export for the Lamprey and all its sub-catchments except for the smallest most populated catchment. Population density (R2>0.89, p<0.00001) and riparian percentage agriculture (R2>0.90, p<0.00001) showed strong positive relationships with nitrate concentration and export. Dissolved organic nitrogen was not related to factors that control inorganic nitrogen (human population density or percentage agriculture). Non-purgeable organic carbon (NPOC) concentration and export (R2>0.84, p<0.0001), percentage wetland (R2=0.79, p<0.001) and riparian carbon storage (R2=0.84, p<0.0001) all showed strong positive relationships with DON. We conclude from the results of this study that human population density and activity are the main factors controlling DIN export and that wetlands and riparian soils are main sources of DON.

  13. Phase partitioning of trace metals in a contaminated estuary influenced by industrial effluent discharge.

    PubMed

    Wang, Wenhao; Wang, Wen-Xiong

    2016-07-01

    Severe trace metal pollution due to industrial effluents releases was found in Jiulong River Estuary, Southern China. In this study, water samples were collected during effluent release events to study the dynamic changes of environmental conditions and metal partitioning among dissolved, particulate and colloidal phases controlled by estuarine mixing. Intermittent effluent discharges during low tide caused decreasing pH and dissolved oxygen, and induced numerous suspended particulate materials and dissolved organic carbon to the estuary. Different behaviors of Cu, Zn, Ni, Cr and Pb in the dissolved fraction against the conservative index salinity indicated different sources, e.g., dissolved Ni from the intermittent effluent. Although total metal concentrations increased markedly following effluent discharges, Cu, Zn, Cr, Pb were predominated by the particulate fraction. Enhanced adsorption onto particulates in the mixing process resulted in elevated partitioning coefficient (Kd) values for Cu and Zn, and the particle concentration effect was not obvious under such anthropogenic impacts. Colloidal proportion of these metals (especially Cu and Zn) showed positive correlations with dissolved or colloidal organic carbon, suggesting the metal-organic complexation. However, the calculated colloidal partitioning coefficients were relatively constant, indicating the excess binding capacity. Overall, the intermittent effluent discharge altered the particulate/dissolved and colloidal/soluble phase partitioning process and may further influence the bioavailability and potential toxicity to aquatic organisms. PMID:27061473

  14. Dissolved Gases and Ice Fracturing During the Freezing of a Multicellular Organism: Lessons from Tardigrades

    PubMed Central

    Kletetschka, Gunther; Hruba, Jolana

    2015-01-01

    Abstract Three issues are critical for successful cryopreservation of multicellular material: gases dissolved in liquid, thermal conductivity of the tissue, and localization of microstructures. Here we show that heat distribution is controlled by the gas amount dissolved in liquids and that when changing the liquid into solid, the dissolved gases either form bubbles due to the absence of space in the lattice of solids and/or are migrated toward the concentrated salt and sugar solution at the cost of amount of heat required to be removed to complete a solid-state transition. These factors affect the heat distribution in the organs to be cryopreserved. We show that the gas concentration issue controls fracturing of ice when freezing. There are volumetric changes not only when changing the liquid into solid (volume increases) but also reduction of the volume when reaching lower temperatures (volume decreases). We discuss these issues parallel with observations of the cryosurvivability of multicellular organisms, tardigrades, and discuss their analogy for cryopreservation of large organs. PMID:26309797

  15. Dissolved Gases and Ice Fracturing During the Freezing of a Multicellular Organism: Lessons from Tardigrades.

    PubMed

    Kletetschka, Gunther; Hruba, Jolana

    2015-01-01

    Three issues are critical for successful cryopreservation of multicellular material: gases dissolved in liquid, thermal conductivity of the tissue, and localization of microstructures. Here we show that heat distribution is controlled by the gas amount dissolved in liquids and that when changing the liquid into solid, the dissolved gases either form bubbles due to the absence of space in the lattice of solids and/or are migrated toward the concentrated salt and sugar solution at the cost of amount of heat required to be removed to complete a solid-state transition. These factors affect the heat distribution in the organs to be cryopreserved. We show that the gas concentration issue controls fracturing of ice when freezing. There are volumetric changes not only when changing the liquid into solid (volume increases) but also reduction of the volume when reaching lower temperatures (volume decreases). We discuss these issues parallel with observations of the cryosurvivability of multicellular organisms, tardigrades, and discuss their analogy for cryopreservation of large organs. PMID:26309797

  16. Riverine Dissolved Organic Matter Degradation Modeled Through Microbial Incubations of Vascular Plant Leachates

    NASA Astrophysics Data System (ADS)

    Harfmann, J.; Hernes, P.; Chuang, C. Y.

    2015-12-01

    Dissolved organic matter (DOM) contains as much carbon as is in the atmosphere, provides the main link between terrestrial and marine carbon reservoirs, and fuels the microbial food web. The fate and removal of DOM is a result of several complex conditions and processes, including photodegradation, sorption/desorption, dominant vascular plant sources, and microbial abundance. In order to better constrain factors affecting microbial degradation, laboratory incubations were performed using Sacramento River water for microbial inoculums and vascular plant leachates. Four vascular plant sources were chosen based on their dominance in the Sacramento River Valley: gymnosperm needles from Pinus sabiniana (foothill pine), angiosperm dicot leaves from Quercus douglassi (blue oak), angiosperm monocot mixed annual grasses, and angiosperm monocot mixed Schoenoplectus acutus (tule) and Typha spp. (cattails). Three concentrations of microbial inoculum were used for each plant material, ranging from 0.2% to 10%. Degradation was monitored as a function of time using dissolved organic carbon (DOC), UV-Vis absorbance, and fluorescent dissolved organic matter (fDOM), and was compared across vascular plant type and inoculum concentration.

  17. Chemical characterization of high molecular weight dissolved organic matter in fresh and marine waters

    NASA Astrophysics Data System (ADS)

    Repeta, Daniel J.; Quan, Tracy M.; Aluwihare, Lihini I.; Accardi, AmyMarie

    2002-03-01

    The high molecular weight fraction of dissolved organic matter in a suite of lakes, rivers, seawater, and marine sediment interstitial water samples was collected by ultrafiltration and characterized by molecular level and spectroscopic techniques. Proton nuclear magnetic resonance spectra of all samples show a high degree of similarity, with major contributions from carbohydrates, bound acetate, and lipids. Molecular level analyses of neutral sugars show seven monosaccharides, rhamnose, fucose, arabinose, xylose, mannose, glucose, and galactose, to be abundant, and to occur in comparable relative amounts in each sample. Previous studies have emphasized the distinctive composition of dissolved humic substances in fresh and marine waters, and have attributed these differences to sources and transformations of organic matter unique to each environment. In contrast we find a large fraction of freshwater high molecular weight dissolved organic matter (HMWDOM; > 1kD) to be indistinguishable from marine HMWDOM in bulk and molecular-level chemical properties. Aquatic HMWDOM is similar in chemical composition to biologically derived acylated heteropolysaccharides isolated from marine algal cultures, suggesting a biological source for some fraction of persistent HMWDOM. High molecular weight DOC contributes 51 ± 26% of the total DOC, and monosaccharides 18 ± 8% of the total HMWDOC in our freshwater samples. These contributions are on average higher and more variable, but not significantly different than for surface seawater (30% and 16% respectively). Biogeochemical processes that produce, accumulate, and recycle DOM may therefore share important similarities and be broadly comparable across a range of environmental settings.

  18. Sorption of hydrophobic pesticides on a Mediterranean soil affected by wastewater, dissolved organic matter and salts.

    PubMed

    Rodríguez-Liébana, José A; Mingorance, Ma Dolores; Peña, Aránzazu

    2011-03-01

    Irrigation with treated wastewaters as an alternative in countries with severe water shortage may influence the sorption of pesticides and their environmental effects, as wastewater contains higher concentrations of suspended and dissolved organic matter and inorganic compounds than freshwater. We have examined the sorption behaviour of three highly hydrophobic pesticides (the herbicide pendimethalin and the insecticides α-cypermethrin and deltamethrin) on a Mediterranean agricultural soil using the batch equilibration method. We considered wastewater, extracts from urban sewage sludge with different dissolved organic carbon contents, and inorganic salt solutions, using Milli Q water as a control. All pesticides were strongly retained by soil although some sorption occurred on the walls of the laboratory containers, especially when wastewater and inorganic salt solutions were used. The calculation of distribution constants by measuring pesticide concentrations in soil and solution indicated that pendimethalin sorption was not affected whereas α-cypermethrin and deltamethrin retention were significantly enhanced (ca. 5 and 2 times, respectively) when wastewater or salt solutions were employed. We therefore conclude that the increased sorption of the two pesticides caused by wastewater cannot be only the result of its dissolved organic carbon content, but also of the simultaneous presence of inorganic salts in the solution. PMID:20980092

  19. Biogeochemistry of dissolved organic matter in an anoxic intertidal creek bank

    NASA Astrophysics Data System (ADS)

    Seidel, Michael; Beck, Melanie; Riedel, Thomas; Waska, Hannelore; Suryaputra, I. G. N. A.; Schnetger, Bernhard; Niggemann, Jutta; Simon, Meinhard; Dittmar, Thorsten

    2014-09-01

    Seawater circulation in permeable coastal sediments is driven by tidal changes in hydraulic gradients. The resulting submarine groundwater discharge is a source of nutrients and dissolved organic matter (DOM) to the water column. Yet, little is known about the cycling of DOM within tidal sediments, because the molecular DOM characterization remains analytically challenging. One technique that can dissect the multitude of molecules in DOM is ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). To aim at a high resolution DOM analysis we study the seasonal turnover and marine and terrestrial sources of DOM in an intertidal creek bank of the southern North Sea down to 3 m depth and link the biogeochemical processes to FT-ICR-MS data and the analyses of inorganic porewater chemistry, δ13C of solid-phase extracted dissolved organic carbon (SPE-DOC), dissolved black carbon (DBC) and dissolved carbohydrates (DCHO). Increasing concentrations of dissolved Fe, Mn, P, total alkalinity, dissolved nitrogen, DOC and a concomitant decrease of sulfate along the seawater circulation path from the upper tidal flat to the tidal flat margin indicate continuous microbial activity. The relative increase of Si concentrations, unsaturated aliphatics, peptide molecular formulae and isotopically more 13C-enriched SPE-DOC towards the tidal flat margin suggests that remineralization processes mobilize DOM from buried algal (diatoms) and microbial biomass. Porewater in sediments <100 cm depth contains 13C-depleted SPE-DOC and highly unsaturated compounds which are probably derived from eroded peats, suggesting rapid removal of bioavailable marine DOM such as DCHO from the water column and selective enrichment of terrestrial DOM. DBC concentrations are highest in the discharging porewater close to the tidal creek suggesting that the intertidal flat is an important DBC source to the coastal ocean. Porewater DOM accumulating at the low water line is

  20. Dissolved Organic Matter Quality in a Shallow Aquifer of Bangladesh: Implications for Arsenic Mobility.

    PubMed

    Mladenov, Natalie; Zheng, Yan; Simone, Bailey; Bilinski, Theresa M; McKnight, Diane M; Nemergut, Diana; Radloff, Kathleen A; Rahman, M Moshiur; Ahmed, Kazi Matin

    2015-09-15

    In some high arsenic (As) groundwater systems, correlations are observed between dissolved organic matter (DOM) and As concentrations, but in other systems, such relationships are absent. The role of labile DOM as the main driver of microbial reductive dissolution is not sufficient to explain the variation in DOM-As relationships. Other processes that may also influence As mobility include complexation of As by dissolved humic substances, and competitive sorption and electron shuttling reactions mediated by humics. To evaluate such humic DOM influences, we characterized the optical properties of filtered surface water (n = 10) and groundwater (n = 24) samples spanning an age gradient in Araihazar, Bangladesh. Further, we analyzed large volume fulvic acid (FA) isolates (n = 6) for optical properties, C and N content, and (13)C NMR spectroscopic distribution. Old groundwater (>30 years old) contained primarily sediment-derived DOM and had significantly higher (p < 0.001) dissolved As concentration than groundwater that was younger than 5 years old. Younger groundwater had DOM spectroscopic signatures similar to surface water DOM and characteristic of a sewage pollution influence. Associations between dissolved As, iron (Fe), and FA concentration and fluorescence properties of isolated FA in this field study suggest that aromatic, terrestrially derived FAs promote As-Fe-FA complexation reactions that may enhance As mobility. PMID:26192081

  1. Decolorization of dark brown colored coffee effluent using zinc oxide particles: the role of dissolved oxygen in degradation of colored compounds.

    PubMed

    Satori, Hirotaka; Kawase, Yoshinori

    2014-06-15

    The degradation of model dark brown colored coffee effluent using photocatalyst zinc oxide (ZnO) has been systematically studied by varying ZnO dosage from 0 to 4000 mg L(-1), coffee loading from 0 to 90 mg L(-1) and intensity of UV light having the radiation peak at 352 nm from 0 to 18 W(m-lamp length)(-1). Almost complete decolorization was achieved after 180 min for the initial coffee concentration of 50 mg L(-1) with ZnO dosage of 3000 mg L(-1) and three UV lamps. The dissolved oxygen (DO) largely affected the photodecolorization process. Without air sparging or with oxygen supply only through the free-surface, the DO concentration significantly decreased during the initial decolorization process and then increased to the saturated DO concentration after about 80% decolorization was achieved. Under the anoxic condition with nitrogen gas sparging, the efficient color removal was not obtained unlike the decolorization without air sparging or under the oxic condition with air sparging. These findings suggest that the change in DO concentration was controlled by the oxygen consumption for the formation of oxygen adduct intermediates such as organoperoxy radicals. The mineralization rate of model coffee effluent was rather slow as compared with the decolorization rate and it was insignificantly affected by anoxic and oxic conditions. The present results indicate that ZnO photocatalyst has potential for treatment of coffee processing wastewaters. PMID:24698992

  2. Microbial metabolism mediates interactions between dissolved organic matter and clay minerals in streamwater.

    PubMed

    Hunter, W R; Battin, T J

    2016-01-01

    Sorption of organic molecules to mineral surfaces is an important control upon the aquatic carbon (C) cycle. Organo-mineral interactions are known to regulate the transport and burial of C within inland waters, yet the mechanisms that underlie these processes are poorly constrained. Streamwater contains a complex and dynamic mix of dissolved organic compounds that coexists with a range of organic and inorganic particles and microorganisms. To test how microbial metabolism and organo-mineral complexation alter amino acid and organic carbon fluxes we experimented with (13)C-labelled amino acids and two common clay minerals (kaolinite and montmorillonite). The addition of (13)C-labelled amino acids stimulated increased microbial activity. Amino acids were preferentially mineralized by the microbial community, concomitant with the leaching of other (non-labelled) dissolved organic molecules that were removed from solution by clay-mediated processes. We propose that microbial processes mediate the formation of organo-mineral particles in streamwater, with potential implications for the biochemical composition of organic matter transported through and buried within fluvial environments. PMID:27481013

  3. Microbial metabolism mediates interactions between dissolved organic matter and clay minerals in streamwater

    PubMed Central

    Hunter, W. R.; Battin, T. J.

    2016-01-01

    Sorption of organic molecules to mineral surfaces is an important control upon the aquatic carbon (C) cycle. Organo-mineral interactions are known to regulate the transport and burial of C within inland waters, yet the mechanisms that underlie these processes are poorly constrained. Streamwater contains a complex and dynamic mix of dissolved organic compounds that coexists with a range of organic and inorganic particles and microorganisms. To test how microbial metabolism and organo-mineral complexation alter amino acid and organic carbon fluxes we experimented with 13C-labelled amino acids and two common clay minerals (kaolinite and montmorillonite). The addition of 13C-labelled amino acids stimulated increased microbial activity. Amino acids were preferentially mineralized by the microbial community, concomitant with the leaching of other (non-labelled) dissolved organic molecules that were removed from solution by clay-mediated processes. We propose that microbial processes mediate the formation of organo-mineral particles in streamwater, with potential implications for the biochemical composition of organic matter transported through and buried within fluvial environments. PMID:27481013

  4. Effect of biomass adaptation to biodegradation of dissolved organic carbon in water.

    PubMed

    Tihomirova, K; Briedis, A; Rubulis, J; Juhna, T

    2012-04-01

    In the present study the time of adaptation of fixed biomass for biodegradation of natural organic matter was investigated. The experiments were done in columns that are usually used for rapid determination of biodegradable dissolved organic carbon (BDOC). The biomass was adapted to samples with different concentrations of organic substances before measurements by pumping water to be investigated through the columns for several days. The time of adaptation was dependent on the initial concentration of the organic matter in the water sample. The adaptation time increased from 6 to 24 h with increase of concentration of acetate solution from 2 to 10 mg/l, thus adaptation rate decreased simultaneously from 0.28 to 0.11 min(-1). In natural water samples with the initial concentration in the range from 4.61-10.82 mg/l of dissolved organic carbon (DOC) the maximal adaptation time was less than 24 h. During the adaptation period the increase in reproducibility and decrease in the standard deviation was observed. The study showed that adaptation of column to the different concentration of organic matter in water sample is necessary in order to decrease the bias in BDOC measurements when using columns tests. PMID:21892664

  5. Microbial metabolism mediates interactions between dissolved organic matter and clay minerals in streamwater

    NASA Astrophysics Data System (ADS)

    Hunter, W. R.; Battin, T. J.

    2016-08-01

    Sorption of organic molecules to mineral surfaces is an important control upon the aquatic carbon (C) cycle. Organo-mineral interactions are known to regulate the transport and burial of C within inland waters, yet the mechanisms that underlie these processes are poorly constrained. Streamwater contains a complex and dynamic mix of dissolved organic compounds that coexists with a range of organic and inorganic particles and microorganisms. To test how microbial metabolism and organo-mineral complexation alter amino acid and organic carbon fluxes we experimented with 13C-labelled amino acids and two common clay minerals (kaolinite and montmorillonite). The addition of 13C-labelled amino acids stimulated increased microbial activity. Amino acids were preferentially mineralized by the microbial community, concomitant with the leaching of other (non-labelled) dissolved organic molecules that were removed from solution by clay-mediated processes. We propose that microbial processes mediate the formation of organo-mineral particles in streamwater, with potential implications for the biochemical composition of organic matter transported through and buried within fluvial environments.

  6. Association of dissolved mercury with dissolved organic carbon in U.S. rivers and streams: The role of watershed soil organic carbon

    NASA Astrophysics Data System (ADS)

    Stoken, Olivia M.; Riscassi, Ami L.; Scanlon, Todd M.

    2016-04-01

    Streams and rivers are important pathways for the export of atmospherically deposited mercury (Hg) from watersheds. Dissolved Hg (HgD) is strongly associated with dissolved organic carbon (DOC) in stream water, but the ratio of HgD to DOC is highly variable between watersheds. In this study, the HgD:DOC ratios from 19 watersheds were evaluated with respect to Hg wet deposition and watershed soil organic carbon (SOC) content. On a subset of sites where data were available, DOC quality measured by specific ultra violet absorbance at 254 nm, was considered as an additional factor that may influence HgD:DOC . No significant relationship was found between Hg wet deposition and HgD:DOC, but SOC content (g m-2) was able to explain 81% of the variance in the HgD:DOC ratio (ng mg-1) following the form: HgD:DOC=17.8*SOC-0.41. The inclusion of DOC quality as a secondary predictor variable explained only an additional 1% of the variance. A mathematical framework to interpret the observed power-law relationship between HgD:DOC and SOC suggests Hg supply limitation for adsorption to soils with relatively large carbon pools. With SOC as a primary factor controlling the association of HgD with DOC, SOC data sets may be utilized to predict stream HgD:DOC ratios on a more geographically widespread basis. In watersheds where DOC data are available, estimates of HgD may be readily obtained. Future Hg emissions policies must consider soil-mediated processes that affect the transport of Hg and DOC from terrestrial watersheds to streams for accurate predictions of water quality impacts.

  7. Sources, behaviors and degradation of dissolved organic matter in the East China Sea

    NASA Astrophysics Data System (ADS)

    Chen, Yan; Yang, Gui-Peng; Liu, Li; Zhang, Peng-Yan; Leng, Wei-Song

    2016-03-01

    Concentrations of dissolved organic carbon (DOC), dissolved inorganic nitrogen (DIN), dissolved organic nitrogen (DON) and its major compound classes-total hydrolysable amino acids (THAA) were measured at 4 cross-shelf transects of the East China Sea in July 2011. Surface concentrations of DOC, DIN, DON and THAA at the nearshore stations were mostly in excess of those found at the offshore sites, indicating either substantial autochthonous production or allochthonous inputs from the Changjiang River. The vertical distributions of DOC, DON and THAA showed similar trends with higher values in the surface layer, whereas the elevated concentrations of DIN were observed in the bottom layer. Major constituents of THAA presented in the study area were glycine, serine, alanine, glutamic acid, aspartic acid and valine. The mole percentages of neutral amino acids increased from surface water to bottom water, whereas acidic and hydroxy amino acids decreased with the water depth. Concentrations of DOC and THAA were negatively correlated to the ΔDIN values (the difference between the real concentration and theoretical concentration), respectively, indicating the coupling relation between dissolved organic matter (DOM) remineralization and nutrient regeneration in the water column. The C/N ratios in the water column exhibited different characteristics with elevated values appearing in the surface and bottom layers. Box and whisker plots showed that both degradation index (DI) values and THAA yields displayed a decreasing trend from the surface layer to the bottom layer, implying increasing degradation with the water depth. Our data revealed that glycine and alanine increased in relative abundance with decreasing DI, while tyrosine, valine, phenylalanine and isoleucine increased with increasing DI.

  8. Abundance and Characterization of Dissolved Organic Carbon in Suburban Streams of Baltimore, Maryland, USA

    NASA Astrophysics Data System (ADS)

    Mora, G.; Fazekas, M.

    2014-12-01

    The contribution of streams and rivers to the carbon cycle is significant, transporting to the oceans ~1.4 Pg C/yr, with dissolved carbon corresponding to as much as 0.7 Pg C/yr. Changes in land use have the potential effect of modifying this flux, particularly in urban areas where impervious areas are common. To investigate the effect of urbanization on riverine carbon transport, we studied four first-order streams in Towson, a suburb of Baltimore, Maryland, USA. The watersheds from the studied streams exhibit different levels of urbanization as measured by the percentage of impervious areas. Samples from these four streams were taken weekly, and several chemical constituents were measured either in the field or in the laboratory. These constituents included nitrate, dissolved organic nitrogen, pH, dissolved organic carbon (DOC), total carbon, dissolved inorganic carbon (DIC), phosphate, the carbon isotopic compositions of DOC and DIC, and fluorescence intensity of the DOC. Results show that DOC concentrations were consistently below 5 mg C/L regardless of the level of imperviousness of the watershed. Similarly, carbon isotope ratios were consistent across the studied streams, with values centered around -26.4 per mil, thus suggesting a significant influx of soil-derived organic carbon originated from C3 plants that are common in the watersheds. Confirming this interpretation, fluorescence spectroscopy data suggest a humic-like origin for the DOC of the streams, thus pointing to the heterotrophic nature of the streams. The combined results suggest that the studied streams exhibit similar DOC concentrations, carbon isotopic values, and fluorescence spectra, despite their level of impervious surfaces in their watersheds.

  9. Storm event exports of dissolved organic nitrogen (DON) across multiple catchments in a glaciated forested watershed

    NASA Astrophysics Data System (ADS)

    Inamdar, Shreeram P.; Mitchell, Myron J.

    2007-06-01

    Storm event patterns of dissolved organic nitrogen (DON) were studied for multiple events across four catchments (1.6-696 ha) in a forested, glaciated watershed in western New York State. Highest concentrations of DON in the watershed were recorded for litter leachate followed by throughfall. Storm event concentrations of DON consistently peaked at or before peak discharge while dissolved organic carbon (DOC) concentrations peaked on the hydrograph recession limbs. Concentrations of DON in stream water were derived from throughfall and litter layer while the DOC expression was attributed to throughfall, litter, and the flushing of the mineral soil by a rising water table. Temporal patterns of ammonium (NH4+) concentrations during events consistently matched those of DON indicating similar sources and flow paths. A previously validated end-member mixing analysis (EMMA) for NO3- failed to predict the DON concentrations observed in streamflow. DON concentrations and DON as % of total dissolved nitrogen (TDN) differed considerably between baseflow (% DON: 6 to 19%) and storm events (% DON: 6 to 64%). DON concentrations and % DON of TDN increased with catchment size and amount of saturated/wetland areas. A wetland catchment that consistently yielded high storm-event DOC concentrations produced variable amounts of DON, indicating a decoupling of DOC and DON dynamics in the wetland. Our study suggests that storm events and watershed characteristics, especially the proportion of saturated and wetland areas, may have a greater influence on DON exports than atmospheric N deposition.

  10. Molecular evidence for a terrestrial component of organic matter dissolved in ocean water

    NASA Astrophysics Data System (ADS)

    Meyers-Schulte, Kathleen J.; Hedges, John I.

    1986-05-01

    Dissolved organic matter (DOM) in seawater represents one of the largest active carbon reservoirs on Earth1. Although mass-balance calculations suggest a substantial riverine input to the marine DOM pool2, a terrestrial organic component has not been positively identified in open-ocean water. By using lignin-derived phenols as molecular-level probes of DOM (analogous to previous studies in sediments3-5), we report here the first unambiguous evidence for the presence of terrestrially derived DOM in open ocean water. Dissolved humic substances, isolated by resin adsorption from near-surface water of the eastern equatorial Pacific, yield lignin-derived phenols in compositional patterns which resemble those obtained from Amazon River water6,7. Total phenol yields from these open-ocean humic isolates are, on average, ~10% of those from Amazon humic substances, indicating that ~10% of dissolved marine humic material (and at least 0.5% of the bulk marine DOM) is terrestrially derived.

  11. Low contribution of litter derived carbon to dissolved organic matter in soils

    NASA Astrophysics Data System (ADS)

    Scheibe, A.; Krantz, L.; Gleixner, G.

    2010-12-01

    This study investigates the contribution of litter derived carbon to dissolved organic matter (DOM) pool because our knowledge on sources of dissolved organic carbon (DOC) is still very controversial. Here, a labeled litter exchange experiment was started in the National Park Hainich, Germany, in November 2008. In this experiment the native litter was exchanged with 13C and 15N labeled litter of ash (Fraxinus excelsior) and beech (Fagus sylvatica). Soil water was collected biweekly with glass suction plates (1 µm pore size, UMS, Munich, Germany), installed in a depth of 5 cm. The amount and isotopic content of the DOC in natural samples was measured using a newly developed method: a high pressure liquid chromatography which was on-line coupled to isotope ratio mass spectrometry (HPLC-IRMS) via wet chemical combustion. Reference measurements proved the excellent performance of the method. Unexpected was the very low contribution of litter 13C into the dissolved carbon pool. The highest contribution with up to 5% DOC labeled by ash litter derived carbon was found in the first month of application. Furthermore we found that only 1.1% and 2.8% (mean values) of DOC was labeled by carbon of the beech and ash litter, respectively. These results suggest that litter derived carbon is of low importance for DOM formation and consequently root / rhizosphere and soil derived carbon drives the DOM loss.

  12. Linking CDOM spectral absorption to dissolved organic carbon concentrations and loadings in boreal estuaries

    NASA Astrophysics Data System (ADS)

    Asmala, Eero; Stedmon, Colin A.; Thomas, David N.

    2012-10-01

    The quantity of chromophoric dissolved organic matter (CDOM) and dissolved organic carbon (DOC) in three Finnish estuaries (Karjaanjoki, Kyrönjoki and Kiiminkijoki) was investigated, with respect to predicting DOC concentrations and loadings from spectral CDOM absorption measurements. Altogether 87 samples were collected from three estuarine transects which were studied in three seasons, covering a salinity range between 0 and 6.8, and DOC concentrations from 1572 μmol l-1 in freshwater to 222 μmol l-1 in coastal waters. CDOM absorption coefficient, aCDOM(375) values followed the trend in DOC concentrations across the salinity gradient and ranged from 1.67 to 33.4 m-1. The link between DOC and CDOM was studied using a range of wavelengths and algorithms. Wavelengths between 250 and 270 nm gave the best predictions with single linear regression. Total dissolved iron was found to influence the prediction in wavelengths above 520 nm. Despite significant seasonal and spatial differences in DOC-CDOM models, a universal relationship was tested with an independent data set and found to be robust. DOC and CDOM yields (loading/catchment area) from the catchments ranged from 1.98 to 5.44 g C m-2 yr-1, and 1.67 to 11.5 aCDOM(375) yr-1, respectively.

  13. Lipid composition in particulate and dissolved organic matter in the Delaware Estuary: Sources and diagenetic patterns

    SciTech Connect

    Mannino, A.; Harvey, H.R.

    1999-08-01

    Dissolved organic matter (DOM) was isolated from surface waters of Delaware Bay along a transect from freshwater to the coastal ocean and fractionated by tangential flow ultrafiltration into high (1--30 kDa; HDOM) and very high (30 kDa--0.2 {micro}m; VHDOM) nominal molecular mass fractions. Carbon content, stable carbon isotopes, and lipid composition were measured for each DOM fraction, and particles collected in parallel. Lipids, excluding hydrocarbons, comprised up to 0.33% of HDOM organic carbon, 1.6% of VHDOM carbon, and 10% of POC, the majority of which were fatty acids. Although lipids comprised a small fraction of HDOM, fatty acids and sterols provided valuable information on the origins of DOM. Molecular composition of particulate and dissolved lipids and bulk stable carbon isotopes demonstrated differences in organic sources along the estuarine gradient with distinct terrestrial signals in the river and turbid middle estuary and an algal signal in the lower estuary and coastal ocean. Both particulate organic matter and VHDOM samples were enriched in lipids on a carbon basis compared to the HDOM fraction, which suggests that the HDOM fraction was less labile than particulate organic matter or VHDOM. Selective degradation of labile lipids by the microbial community can account for the depletions of unsaturated fatty acids, sterols, and phytol within HDOM relative to particles.

  14. Variable C : N : P stoichiometry of dissolved organic matter cycling in the Community Earth System Model

    DOE PAGESBeta

    Letscher, R. T.; Moore, J. K.; Teng, Y. -C.; Primeau, F.

    2015-01-12

    Dissolved organic matter (DOM) plays an important role in the ocean's biological carbon pump by providing an advective/mixing pathway for ~ 20% of export production. DOM is known to have a stoichiometry depleted in nitrogen (N) and phosphorus (P) compared to the particulate organic matter pool, a fact that is often omitted from biogeochemical ocean general circulation models. However the variable C : N : P stoichiometry of DOM becomes important when quantifying carbon export from the upper ocean and linking the nutrient cycles of N and P with that of carbon. Here we utilize recent advances in DOM observationalmore » data coverage and offline tracer-modeling techniques to objectively constrain the variable production and remineralization rates of the DOM C : N : P pools in a simple biogeochemical-ocean model of DOM cycling. The optimized DOM cycling parameters are then incorporated within the Biogeochemical Elemental Cycling (BEC) component of the Community Earth System Model (CESM) and validated against the compilation of marine DOM observations. The optimized BEC simulation including variable DOM C : N : P cycling was found to better reproduce the observed DOM spatial gradients than simulations that used the canonical Redfield ratio. Global annual average export of dissolved organic C, N, and P below 100 m was found to be 2.28 Pg C yr-1 (143 Tmol C yr-1, 16.4 Tmol N yr-1, and 1 Tmol P yr-1, respectively, with an average export C : N : P stoichiometry of 225 : 19 : 1 for the semilabile (degradable) DOM pool. Dissolved organic carbon (DOC) export contributed ~ 25% of the combined organic C export to depths greater than 100 m.« less

  15. Molecular insights into the microbial formation of marine dissolved organic matter: recalcitrant or labile?

    NASA Astrophysics Data System (ADS)

    Koch, B. P.; Kattner, G.; Witt, M.; Passow, U.

    2014-02-01

    The degradation of marine dissolved organic matter (DOM) is an important control variable in the global carbon cycle and dependent on the DOM composition. For our understanding of the kinetics of organic matter cycling in the ocean, it is therefore crucial to achieve a mechanistic and molecular understanding of its transformation processes. A long-term microbial experiment was performed to follow the production of non-labile DOM by marine bacteria. Two different glucose concentrations and dissolved algal exudates were used as substrates. We monitored the bacterial abundance, concentrations of dissolved and particulate organic carbon (DOC, POC), nutrients, amino acids, and transparent exopolymer particles (TEP) for two years. Ultrahigh resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) allowed the molecular characterization of extracted DOM after 70 days and after ∼2 years of incubation. Although glucose was quickly degraded, a DOC background was generated in glucose incubations. Only 20% of the organic carbon from algal exudate was degraded within the 2 years of incubation. TEP, which are released by micro-organisms, were produced during glucose degradation but decreased within less than three weeks back to half of the maximum concentration and were below detection in all treatments after 2 years. The molecular analysis demonstrated that DOM generated during glucose degradation differed appreciably from DOM produced during the degradation of the algal exudates. Our results led to several conclusions: (i) Higher substrate levels result in a higher level of non-labile DOC which is an important prerequisite for carbon sequestration in the ocean; (ii) TEP are generated by bacteria but are also degraded rapidly, thus limiting their potential contribution to carbon sequestration; (iii) The molecular signatures of DOM derived from algal exudates or glucose after 70 days of incubation differed strongly from refractory DOM. After 2 years

  16. Multidimensional spectrofluorometry characterization of dissolved organic matter in arsenic-contaminated shallow groundwater.

    PubMed

    Huang, Shuangbing; Wang, Yanxin; Cao, Ling; Pi, Kunfu; Yu, Mei; Even, Emilie

    2012-01-01

    Multidimensional spectrofluorometry was employed to characterize dissolved organic matter (DOM) in arsenic-contaminated shallow aquifers at Jianghan Plain (JHP), central China, to better understand the effect of biogeochemical processes on arsenic mobilization. The microbial humic quinone and amino acid components identified indicate the importance of microbially mediated processes in the reduction of iron oxyhydroxides. The relationship of quinone and amino acid-like components with Fe(2+) and S(2-) helps us understand the sequential redox transformation (SRT) in the high arsenic aquifer system and the origin of bicarbonate in groundwater. Correlation between DOM components and dissolved arsenic and Fe suggests that arsenic mobilization could be linked to the microbial reduction of iron oxyhydroxides with liable DOM as electron donors as well as to the electron shuttling function served by humic quinones. PMID:22571533

  17. Noncrystalline Condensation of Densely Dissolved Optically Nonlinear Organic Compound in Polymer Matrices

    NASA Astrophysics Data System (ADS)

    Hiraga, Takashi; Tanaka, Norio; Hayamizu, Kikuko; Mito, Akihiro; Takarada, Shigeru; Yamasaki, Yuuichi; Nakamura, Michie; Hoshino, Nobuo; Moriya, Tetsuo

    1993-04-01

    Optical properties and condensed states of the densely dissolved optically nonlinear organic compound in polymer matrices were investigated by means of optical measurements, structural analysis and pressure tuning spectroscopy. In the investigation of the absorption peak wavelength, 2-methyl-4-nitroaniline (MNA) in poly(methyl methacrylate) (PMMA) exhibited characteristics intermediate between the crystal and the MNA dissolved in solvents, i.e., noncrystalline condensation. This result was consistent with those of X-ray diffraction analysis, second- and third-harmonics generation, IR absorption and 13C-NMR spectroscopies. It has also been revealed that such a system provides the most suitable measuring method of the third optical nonlinear constant for a variety of compounds.

  18. Characterization of organic membrane foulants in a forward osmosis membrane bioreactor treating anaerobic membrane bioreactor effluent.

    PubMed

    Ding, Yi; Tian, Yu; Li, Zhipeng; Liu, Feng; You, Hong

    2014-09-01

    In this study, two aerobic forward osmosis (FO) membrane bioreactors (MBR) were utilized to treat the effluent of mesophilic (35°C) and atmospheric (25°C) anaerobic MBRs, respectively. The results showed that the FO membrane process could significantly improve the removal efficiencies of N and P. Meanwhile, the flux decline of the FOMBR treating effluent of mesophilic AnMBR (M-FOMBR) was higher than that treating effluent of atmospheric AnMBR (P-FOMBR). The organic membrane foulants in the two FOMBRs were analyzed to understand the membrane fouling behavior in FO processes. It was found that the slightly increased accumulation of protein-like substances into external foulants did not cause faster flux decline in P-FOMBR than that in M-FOMBR. However, the quantity of organic matter tended to deposit or adsorb into FO membrane pores in P-FOMBR was less than that in M-FOMBR, which was accordance with the tendency of membrane fouling indicated by flux decline. PMID:24976492

  19. Bacterial Contribution to Dissolved Organic Matter in Eutrophic Lake Kasumigaura, Japan

    PubMed Central

    Komatsu, Kazuhiro; Kohzu, Ayato; Tomioka, Noriko; Shinohara, Ryuichiro; Satou, Takayuki; Watanabe, Fumiko Nara; Tada, Yuya; Hamasaki, Koji; Kushairi, M. R. M.; Imai, Akio

    2013-01-01

    Incubation experiments using filtered waters from Lake Kasumigaura were conducted to examine bacterial contribution to a dissolved organic carbon (DOC) pool. Bacterial abundance, bacterial production, concentrations of DOC, total dissolved amino acids (TDAA), and total dissolved neutral sugars (TDNS) were monitored during the experiments. Bacterial production during the first few days was very high (20 to 35 μg C liter−1 day−1), accounting for 40 to 70% of primary production. The total bacterial production accounted for 34 to 55% of the DOC loss during the experiment, indicating high bacterial activities in Lake Kasumigaura. The DOC degradation was only 12 to 15%, whereas the degradation of TDAA and TDNS ranged from 30 to 50%, suggesting the preferential usage of TDAA and TDNS. The contribution of bacterially derived carbon to a DOC pool in Lake Kasumigaura was estimated using d-amino acids as bacterial biomarkers and accounted for 30 to 50% of the lake DOC. These values were much higher than those estimated for the open ocean (20 to 30%). The ratio of bacterially derived carbon to bulk carbon increased slightly with time, suggesting that the bacterially derived carbon is more resistant to microbial degradation than bulk carbon. This is the first study to estimate the bacterial contribution to a DOC pool in freshwater environments. These results indicate that bacteria play even more important roles in carbon cycles in freshwater environments than in open oceans and also suggests that recent increases in recalcitrant DOC in various lakes could be attributed to bacterially derived carbon. The potential differences in bacterial contributions to dissolved organic matter (DOM) between freshwater and marine environments are discussed. PMID:24038686

  20. Carbon dynamics and their link to dissolved organic matter quality across contrasting stream ecosystems.

    PubMed

    Bodmer, Pascal; Heinz, Marlen; Pusch, Martin; Singer, Gabriel; Premke, Katrin

    2016-05-15

    Streams represent active components of the carbon cycle as emitters of carbon dioxide (CO2) and methane to the atmosphere at a global scale. However, the mechanisms and governing factors of these emissions are still largely unknown, especially concerning the effect of land use. We compared dissolved and gaseous carbon dynamics in streams bordered by contrasting types of land use, specifically agriculture and forest. Carbon dioxide and methane partial pressures (pCO2 and pCH4, respectively) in the water body and carbon emissions via both gases were studied for 24h during four field expeditions. pCH4 did not differ between the two system types. pCO2 was constantly oversaturated in all streams and significantly higher in agricultural streams (annual mean 4282ppm) compared to forest streams (annual mean 2189ppm) during all seasons. However, emissions of CO2 were not significantly different between the stream types due to significantly higher gas transfer velocity in forest compared to agricultural streams. pCO2 was significantly positively correlated to the concentrations of dissolved organic carbon, dissolved nitrogen and soluble reactive phosphorus in the water. Furthermore, pCO2 was correlated to optical parameters of dissolved organic matter (DOM) quality, e.g., it increased with indicators of molecular size and an allochthonous fluorescent component identified by Parallel Factor Analysis (PARAFAC). This study demonstrates that different forms of land use may trigger a cascade of effects on the carbon production and emission of streams linked to changes in DOM quality. PMID:26938320

  1. [Spectral characteristics of dissolved organic matter released during the metabolic process of small medusa].

    PubMed

    Guo, Dong-Hui; Yi, Yue-Yuan; Zhao, Lei; Guo, Wei-Dong

    2012-06-01

    The metabolic processes of jellyfish can produce dissolved organic matter (DOM) which will influence the functioning of the aquatic ecosystems, yet the optical properties of DOM released by jellyfish are unknown. Here we report the absorption and fluorescence properties of DOM released by a medusa species Black fordia virginica during a 24 h incubation experiment. Compared with the control group, an obvious increase in the concentrations of dissolved organic carbon (DOC), absorption coefficient (a280) and total dissolved nitrogen (TDN) was observed in incubation group. This clearly demonstrated the release of DOM, chromophoric DOM (CDOM) and dissolved nutrients by B. virginica which feed on enough of Artemia sp. before the experiment. The increase in spectral slope ratio (SR) and decrease in humification index (HIX) indicated that the released DOM was less-humified and had relatively lower molecular weight. Parallel factor analysis (PARAFAC) decomposed the fluorescence matrices of DOM into three humic-like components (C1-C3) and one protein-like component (C4). The Fmax of two components (C2: < 250, 295/386 nm; C4: 275/334 nm) with the emission wavelength < 400 nm increased significantly during the metabolic process of B. virginica. However, the Fmax of the other two components with the emission wavelength > 400 nm showed little changes. Thus, we suggested a zooplankton index (ZIX) to trace and characterize the DOM excreted by metabolic activity of zooplankton, which is calculated as the ratio of the sum of Fmax of all fluorescence components with the emission wavelength < 400 nm to the sum of Fmax of the other components with the emission wavelength > 400 nm. PMID:22870644

  2. EU-wide monitoring survey on emerging polar organic contaminants in wastewater treatment plant effluents.

    PubMed

    Loos, Robert; Carvalho, Raquel; António, Diana C; Comero, Sara; Locoro, Giovanni; Tavazzi, Simona; Paracchini, Bruno; Ghiani, Michela; Lettieri, Teresa; Blaha, Ludek; Jarosova, Barbora; Voorspoels, Stefan; Servaes, Kelly; Haglund, Peter; Fick, Jerker; Lindberg, Richard H; Schwesig, David; Gawlik, Bernd M

    2013-11-01

    In the year 2010, effluents from 90 European wastewater treatment plants (WWTPs) were analyzed for 156 polar organic chemical contaminants. The analyses were complemented by effect-based monitoring approaches aiming at estrogenicity and dioxin-like toxicity analyzed by in vitro reporter gene bioassays, and yeast and diatom culture acute toxicity optical bioassays. Analyses of organic substances were performed by solid-phase extraction (SPE) or liquid-liquid extraction (LLE) followed by liquid chromatography tandem mass spectrometry (LC-MS-MS) or gas chromatography high-resolution mass spectrometry (GC-HRMS). Target microcontaminants were pharmaceuticals and personal care products (PPCPs), veterinary (antibiotic) drugs, perfluoroalkyl substances (PFASs), organophosphate ester flame retardants, pesticides (and some metabolites), industrial chemicals such as benzotriazoles (corrosion inhibitors), iodinated x-ray contrast agents, and gadolinium magnetic resonance imaging agents; in addition biological endpoints were measured. The obtained results show the presence of 125 substances (80% of the target compounds) in European wastewater effluents, in concentrations ranging from low nanograms to milligrams per liter. These results allow for an estimation to be made of a European median level for the chemicals investigated in WWTP effluents. The most relevant compounds in the effluent waters with the highest median concentration levels were the artificial sweeteners acesulfame and sucralose, benzotriazoles (corrosion inhibitors), several organophosphate ester flame retardants and plasticizers (e.g. tris(2-chloroisopropyl)phosphate; TCPP), pharmaceutical compounds such as carbamazepine, tramadol, telmisartan, venlafaxine, irbesartan, fluconazole, oxazepam, fexofenadine, diclofenac, citalopram, codeine, bisoprolol, eprosartan, the antibiotics trimethoprim, ciprofloxacine, sulfamethoxazole, and clindamycine, the insect repellent N,N'-diethyltoluamide (DEET), the pesticides

  3. Fluorescence characterization of cross flow ultrafiltration derived freshwater colloidal and dissolved organic matter.

    PubMed

    Liu, Ruixia; Lead, Jamie R; Baker, Andy

    2007-07-01

    3-D fluorescence excitation-emission matrix (EEM) spectrophotometry was applied to investigate the fluorescence characterization of colloidal organic matter (COM) and truly dissolved organic matter (DOM) from an urban lake and a rural river fractionated by the cross flow ultrafiltration (CFUF) process with a 1kDa membrane. Relatively high tryptophan-like fluorescence intensity is found in the urban water, although the fluorescence of both water samples is mainly dominated by humic/fulvic-like fluorophores. During CFUF processing, the fluorescence intensities of humic/fulvic-like materials in the retentate increased rapidly, but a slight increase is also observed in the permeate fluorescence intensity. Very different ultrafiltration behaviour occurred with respect to the tryptophan-like fluorophore, where both permeate and retentate fluorescence intensities increase substantially at the beginning of the CFUF process, then tend to remain constant at high concentration factor (cf) values. Comparison with tryptophan standards demonstrates that freshwater tryptophan-like fluorescence is not dissolved and 'free', but is, in part, colloidal and related to the ultrafiltration behaviour of fulvic/humic-like matter. A good linear relationship between the retentate humic/fulvic-like fluorescence intensity and organic carbon concentration further reveals that fluorescent humic/fulvic-like substances are the dominant contributors to colloidal organic carbon, mainly in the colloidal fraction. PMID:17350076

  4. Dissolved Organic Carbon Mobilisation in a Groundwater System Stressed by Pumping

    NASA Astrophysics Data System (ADS)

    Graham, P. W.; Baker, A.; Andersen, M. S.

    2015-12-01

    The concentration and flux of organic carbon in aquifers is influenced by recharge and abstraction, and surface and subsurface processing. In this study groundwater was abstracted from a shallow fractured rock aquifer and dissolved organic carbon (DOC) was measured in observation bores at different distances from the abstraction bore. Groundwater abstraction at rates exceeding the aquifers yield resulted in increased DOC concentration up to 3,500 percent of initial concentrations. Potential sources of this increased DOC were determined using optical fluorescence and absorbance analysis. Groundwater fluorescent dissolved organic material (FDOM) were found to be a combination of terrestrial-derived humic material and microbial or protein sourced material. Relative molecular weight of FDOM within four metres of the abstraction well increased during the experiment, while the relative molecular weight of FDOM between four and ten metres from the abstraction well decreased. When the aquifer is not being pumped, DOC mobilisation in the aquifer is low. We hypothesise that the physical shear stress on aquifer materials caused by intense abstraction significantly increases the temporary release of DOC from sloughing of biofilms and release of otherwise bound colloidal and sedimentary organic carbon (SOC).

  5. Dissolved Organic Carbon Mobilisation in a Groundwater System Stressed by Pumping

    PubMed Central

    Graham, P. W.; Baker, A.; Andersen, M. S.

    2015-01-01

    The concentration and flux of organic carbon in aquifers is influenced by recharge and abstraction, and surface and subsurface processing. In this study groundwater was abstracted from a shallow fractured rock aquifer and dissolved organic carbon (DOC) was measured in observation bores at different distances from the abstraction bore. Groundwater abstraction at rates exceeding the aquifers yield resulted in increased DOC concentration up to 3,500 percent of initial concentrations. Potential sources of this increased DOC were determined using optical fluorescence and absorbance analysis. Groundwater fluorescent dissolved organic material (FDOM) were found to be a combination of terrestrial-derived humic material and microbial or protein sourced material. Relative molecular weight of FDOM within four metres of the abstraction well increased during the experiment, while the relative molecular weight of FDOM between four and ten metres from the abstraction well decreased. When the aquifer is not being pumped, DOC mobilisation in the aquifer is low. We hypothesise that the physical shear stress on aquifer materials caused by intense abstraction significantly increases the temporary release of DOC from sloughing of biofilms and release of otherwise bound colloidal and sedimentary organic carbon (SOC). PMID:26691238

  6. Dissolved Organic Carbon Mobilisation in a Groundwater System Stressed by Pumping.

    PubMed

    Graham, P W; Baker, A; Andersen, M S

    2015-01-01

    The concentration and flux of organic carbon in aquifers is influenced by recharge and abstraction, and surface and subsurface processing. In this study groundwater was abstracted from a shallow fractured rock aquifer and dissolved organic carbon (DOC) was measured in observation bores at different distances from the abstraction bore. Groundwater abstraction at rates exceeding the aquifers yield resulted in increased DOC concentration up to 3,500 percent of initial concentrations. Potential sources of this increased DOC were determined using optical fluorescence and absorbance analysis. Groundwater fluorescent dissolved organic material (FDOM) were found to be a combination of terrestrial-derived humic material and microbial or protein sourced material. Relative molecular weight of FDOM within four metres of the abstraction well increased during the experiment, while the relative molecular weight of FDOM between four and ten metres from the abstraction well decreased. When the aquifer is not being pumped, DOC mobilisation in the aquifer is low. We hypothesise that the physical shear stress on aquifer materials caused by intense abstraction significantly increases the temporary release of DOC from sloughing of biofilms and release of otherwise bound colloidal and sedimentary organic carbon (SOC). PMID:26691238

  7. Water solubility enhancement of some organic pollutants and pesticides by dissolved humic and fulvic acids

    USGS Publications Warehouse

    Chiou, C.T.; Malcolm, R.L.; Brinton, T.I.; Kile, D.E.

    1986-01-01

    Water solubility enhancements by dissolved humic and fulvic acids from soil and aquatic origins and by synthetic organic polymers have been determined for selected organic pollutants and pesticides (p,p???-DDT, 2,4,5,2???,5???-PCB, 2,4,4???-PCB, 1,2,3-trichlorobenzene, and lindane). Significant solubility enhancements of relatively water-insoluble solutes by dissolved organic matter (DOM) of soil and aquatic origins may be described in terms of a partition-like interaction of the the solutes with the microscopic organic environment of the high-molecular-weight DOM species; the apparent solute solubilities increase linearly with DOM concentration and show no competitive effect between solutes. With a given DOM sample, the solute partition coefficient (Kdom) increases with a decrease of solute solubility (Sw) or with an increase of the solute's octanol-water partition coefficient (Kow). The Kdom values of solutes with soil-derived humic acid are approximately 4 times greater than with soil fulvic acid and 5-7 times greater than with aquatic humic and fulvic acids. The effectiveness of DOM in enhancing solute solubility appears to be largely controlled by the DOM molecular size and polarity. The relative inability of high-molecular-weight poly(acrylic acids) to enhance solute solubility is attributed to their high polarities and extended chain structures that do not permit the formation of a sizable intramolecular nonpolar environment.

  8. Reduction of dissolved organic matter in terms of DOC, UV-254, SUVA and THMFP in industrial estate wastewater treated by stabilization ponds.

    PubMed

    Musikavong, Charongpun; Wattanachira, Suraphong

    2007-11-01

    The aim of this research was to monitor the influent and effluent water quality of the aeration, facultative and oxidation water treatment ponds of an industrial estate. This industrial estate, the largest in northern Thailand, has proposed to utilization of reclaimed treated wastewater in their raw water supply so as to cope with the yearly water shortage during the dry season. Water samples were collected four times from four sampling points and evaluated for their dissolved organic matter (DOM) content in terms of dissolved organic carbon (DOC), ultraviolet light absorbance at 254 nm (UV-254), specific ultraviolet absorption (SUVA), trihalomethane formation potential (THMFP) and trihalomethane (THM) species. Average values of DOC, UV-254, SUVA and THMFP in the influent wastewater of 12.9 mg L(-1), 0.165 cm(-1), 1.29 L mg(-1) m(-1) and 1.24 mg L(-1), respectively, were observed. The aeration ponds produced the best results: a 54% reduction of DOC, a 33% reduction of UV-254, and a 57% reduction of THMFP. However, SUVA in the aeration pond effluent showed a moderate increase. The facultative ponds and oxidation ponds did not take part in the reduction of DOC, UV-254, SUVA and THMFP. Average DOC, UV-254, SUVA and THMFP value of the treated wastewater were 5.8 mg L(-1), 0.107 cm(-1), 1.85 L mg(-1) m(-1) and 468 microg L(-1), respectively. Chloroform, at 72.6% of total THMFP, was found to be the predominant THM species. PMID:17975744

  9. Optimizing the industrial wastewater pretreatment by activated carbon and coagulation: effects of hydrophobicity/hydrophilicity and molecular weights of dissolved organics.

    PubMed

    Khan, M Hammad; Ha, Dong-Hwan; Jung, Jinyoung

    2013-01-01

    This study addresses industrial wastewater treatment to remove dissolved organic compounds (DOC) using Fenton and coagulation processes, followed by granular activated carbon (GAC), and powdered activated carbon (PAC) as a pretreatment before reverse osmosis (RO). The effects of the hydrophobic / hydrophilic fractions and the molecular weights (MW) of the organics on DOC removal were tested and used to optimize the combination process. The raw wastewater (RWW) had a dominant hydrophobic fraction, as determined by polymeric resins Amberlite XAD-4. High performance liquid chromatography tandem mass spectrometry (HPLC/MS/MS) results showed that MW of organics were 256, 172, 258, 146, 392, 321, 182, 373, 276, 365, 409 and 453 in increasing order of hydrophobicity. GAC had higher adsorption capacity and was more selective for hydrophobic DOC removal than PAC. The removal efficiency of DOC by PAC and GAC was decreased after Fenton treatment, which decreased the hydrophobic fraction. Coagulation with ferric chloride efficiently removed the non-ionic hydrophilic and anionic hydrophilic organics. The coagulant doses selected as a pretreatment before GAC were 2.1 and 15.5 mg Fe(III)/mg DOC. The effluent total organic carbon (TOC) trends were correlated with the hydrophobic and hydrophilic fractions by using a rapid small-scale column test (RSSCT) for GAC breakthrough with a scale down factor of 5. GAC preferentially adsorbed the hydrophobic and the cationic hydrophilic organics. The effluent TOC trend could be divided into four stages: maximum adsorption, hydrophobic stage, exhaustion, and biological. The TOC removal after the exhaustion stage was almost equal to the hydrophilic fraction of TOC. Therefore these results demonstrated that the combination of coagulation and GAC adsorption was a highly efficient process for reducing DOC. PMID:23383639

  10. PHOTOGENERATION OF SINGLET OXYGEN AND FREE RADICALS IN DISSOLVED ORGANIC MATTER ISOLATED FROM THE MISSISSIPPI AND ATCHAFALAYA RIVER PLUMES

    EPA Science Inventory

    The photoreactivity to UV light of ultrafiltered dissolved organic matter (DOM) collected during cruises along salinity transects in the Mississippi and Atchafalaya River plumes was examined by measuring photogenerated free radicals and singlet molecular oxygen (1O2) photosensiti...

  11. INTERACTIONS BETWEEN PHOTOCHEMICAL AND MICROBIAL DECOMPOSITION IN MODIFYING THE BIOLOGICAL AVAILABILITY AND OPTICAL PROPERTIES OF ESTUARINE DISSOLVED ORGANIC MATTER

    EPA Science Inventory

    Direct photodecomposition and photochemically-mediated bacterial degradation (via photochemical modification of otherwise refractory DOM into biologically labile forms) provide
    important pathways for the loss of dissolved organic matter in coastal waters. Here we report
    lab...

  12. EFFECTS OF PHOTOCHEMICAL, MICROBIAL AND SORPTION PROCESSES ON THE OPTICAL PROPERTIES AND DEGRADATION OF DISSOLVED ORGANIC MATTER FROM COASTAL WETLANDS

    EPA Science Inventory

    The dissolved organic matter (DOM) exported from rivers and intertidal marshes to coastal oceans is rich in light-absorbing, fluorescent constituents, including humic substances and other polyphenolic moieties. Interactions between microbial and photochemical processes have impor...

  13. PHOTOCHEMICALLY-INDUCED ALTERATION OF STABLE CARBON ISOTOPE RATIOS (DELTA C-13) IN TERRIGENOUS DISSOLVED ORGANIC CARBON

    EPA Science Inventory

    Exposure of riverine waters to natural sunlight initiated alterations in stable carbon isotope ratios (delta C-13) of the associated dissolved organic carbon (DOC). Water samples were collected from two compositionally distinct coastal river systems in the southeastern United Sta...

  14. SPATIAL AND TEMPORAL DISTRIBUTION OF COLOURED DISSOLVED ORGANIC MATTER (CDOM) IN NARRAGANSETT BAY, RI: IMPLICATIONS FOR PHYTOPLANKTON IN COASTAL WATERS

    EPA Science Inventory

    One indicator of health in estuarine and coastal ecosystems is the ability of local waters to transmit sunlight to planktonic, macrophytic, and other submerged vegetation for photosynthesis. The concentration of coloured dissolved organic matter (CDOM) is a primary factor affecti...

  15. Characterization of dissolved organic materials in surface waters within the blast zone of Mount St Helens, Washington

    USGS Publications Warehouse

    McKnight, Diane M.; Pereira, W.E.; Ceazan, M.L.; Wissmar, Robert C.

    1982-01-01

    After the May 18, 1980, eruption of Mount St Helens, the concentration of dissolved organic material in surface waters near the volcano increased significantly as a result of the destruction of the surrounding conifer forest. Low molecular weight organic compounds identified in the blast zone surface waters were derived from pyrolysis of plant and soil organic materials incorporated into pyroclastic flow, mud flow and debris avalanche deposits. A major fraction of the dissolved organic material consisted of high molecular weight, colored, organic acids that are similar in their general properties to aquatic fulvic acids found in more typical surface waters except for greater sulfur contents. The other major fraction of the dissolved organic material consisted of hydrophilic acids, which may include compounds capable of supporting heterotrophic microorganisms, and precursors in the formation of aquatic fulvic acids. The organic chemistry of blast zone surface waters will probably be greatly influenced by the May 18, 1980, eruption for many years. ?? 1982.

  16. Cu Binding to Iron Oxide-Organic Matter Coprecipitates in Solid and Dissolved Phases

    NASA Astrophysics Data System (ADS)

    Vadas, T. M.; Koenigsmark, F.

    2015-12-01

    Recent studies indicate that Cu is released from wetlands following storm events. Assymetrical field flow field fractionation (AF4) analyses as well as total and dissolved metal concentration measurements suggest iron oxide-organic matter complexes control Cu retention and release. Coprecipitation products of Fe oxide and organic matter were prepared under conditions similar to the wetland to assess Cu partitioning to and availability from solid phases that settle from solution as well as phases remaining suspended. Cu coprecipitation and sorption to organomineral precipitation solids formed at different Fe:organic carbon (OC) ratios were compared for net Cu removal and extractability. As more humic acid was present during precipitation of Fe, TEM images indicated smaller Fe oxide particles formed within an organic matrix as expected. In coprecipitation reactions, as the ratio of Fe:OC decreased, more Cu was removed from solution at pH 5.5 and below. However, in sorption reactions, there was an inhibition of Cu removal at low OC concentrations. As the pH increased from 5.5 to 7 and as solution phase OC concentration increased, more Cu remained dissolved in both coprecipitation and sorption reactions. The addition of Ca2+, glycine, histidine and citric acid or lowering the pH resulted in more extractable Cu from the coprecipitation compared with the sorption reactions. The variations in Cu extraction were likely due to a combination of a more amorphous structure in CPT products, and the relative abundance of available Fe oxide or OC binding sites. Suspended Fe oxide-organic matter coprecipitates were assessed using AF4 coupled to online TOC analysis and ICP-MS. In laboratory prepared samples, Cu was observed in a mixture of small 1-5 nm colloids of Fe oxide-organic matter precipitates, but the majority was observed in larger organic matter colloids and were not UV absorbing, suggesting more aliphatic carbon materials. In field samples, up to 60% of the dissolved Cu

  17. The occurrence of emerging trace organic chemicals in wastewater effluents in Saudi Arabia.

    PubMed

    Alidina, Mazahirali; Hoppe-Jones, Christiane; Yoon, Min; Hamadeh, Ahmed F; Li, Dong; Drewes, Jörg E

    2014-04-15

    Emerging trace organic chemicals (TOrCs) released into the environment via discharge of wastewater effluents have been detected in rivers and lakes worldwide, raising concerns due to their potential persistence, toxicity and bioaccumulation. This study provides the first reconnaissance of TOrC occurrence in wastewater effluents within Saudi Arabia. Four wastewater treatment plants (WWTPs 1-4) located in Western Saudi Arabia were sampled hourly over twelve-hour periods, for a total of six sampling events. All samples were analyzed for a wide range of TOrC encompassing pharmaceuticals, personal care products and household chemicals. Treatment and capacities of the plants varied from non-nitrifying to full biological nutrient removal providing a representative cross section of different types of plants operational within the country. A comparison of TOrC occurrence in effluents in Saudi Arabia with respective effluent qualities in the United States revealed similar levels for most TOrC. Overall, the occurrence of TOrC was higher at two of the plants. The higher TOrC concentrations at WWTP 1 are likely due to the non-nitrifying biological treatment process. The unique TOrC occurrence observed in the WWTP 3 effluent was unlike any other plant and was attributed to the influence of a large number of international visitors in its sewershed. The occurrence of TOrC in this plant was not expected to be representative of the occurrence elsewhere in the country. Bimodal diurnal variation expected for a range of TOrC was not observed, though some hourly variation in TOrC loading was noted for WWTP 3. Since water reclamation and reuse have received increasing interest in Saudi Arabia within the last few years, results from this study provide a good foundation in deciding whether advanced treatment is necessary to attenuate TOrC deemed to be of concern in effluents, or if natural treatment such as managed aquifer recharge provides sufficient protection to public health. PMID

  18. Identification of effluent organic matter fractions responsible for low-pressure membrane fouling.

    PubMed

    Filloux, Emmanuelle; Gallard, Hervé; Croue, Jean-Philippe

    2012-11-01

    Anion exchange resin (AER), powder activated carbon (PAC) adsorption and ozonation treatments were applied on biologically treated wastewater effluent with the objective to modify the effluent organic matter (EfOM) matrix. Both AER and PAC led to significant total organic carbon (TOC) removal, while the TOC remained nearly constant after ozonation. Liquid Chromatography-Organic Carbon Detection (LC-OCD) analysis showed that the AER treatment preferentially removed high and intermediate molecular weight (MW) humic-like structures while PAC removed low MW compounds. Only a small reduction of the high MW colloids (i.e. biopolymers) was observed for AER and PAC treatments. Ozonation induced a large reduction of the biopolymers and an important increase of the low MW humic substances (i.e. building blocks). Single-cycle microfiltration (MF) and ultrafiltration (UF) tests were conducted using commercially available hollow fibres at a constant flux. After reconcentration to their original organic carbon content, the EfOM matrix modified by AER and PAC treatments exhibited higher UF membrane fouling compared to untreated effluent; result that correlated with the higher concentration of biopolymers. On the contrary, ozonation which induced a significant degradation of the biopolymers led to a minor flux reduction for both UF and MF filtration tests. Based on a single filtration, results indicate that biopolymers play a major role in low pressure membrane fouling and that intermediate and low MW compounds have minor impact. Thus, this approach has shown to be a valid methodology to identify the foulant fractions of EfOM. PMID:22884373

  19. Impacts of ozonation on the competition between organic micro-pollutants and effluent organic matter in powdered activated carbon adsorption.

    PubMed

    Zietzschmann, F; Mitchell, R-L; Jekel, M

    2015-11-01

    This study investigates if ozonation of wastewater treatment plant (WWTP) effluent can reduce the negative impacts of effluent organic matter (EfOM) on the adsorption of organic micro-pollutants (OMP) onto powdered activated carbon (PAC). Pre-treatment of the water included membrane filtration for the removal of suspended/colloidal organics, ozonation with various specific ozone consumptions, and subsequent OMP spiking to comparable initial concentrations in all of the ozonated waters. This approach allowed for comparative PAC adsorption tests. Adsorption analyses show that the adsorbability of EfOM decreases with increasing specific ozone consumptions. This is also reflected by liquid chromatography with online carbon and UV254 detection (LC-OCD) which shows the ozone-induced disintegration of large EfOM into smaller fragments. Also, small organic neutrals are decreased while the small organic acids peak continuously increases with rising specific ozone consumptions. UV254 demonstrates that the aromaticity of all LC-OCD fractions continuously declines together with increasing specific O3 consumptions. This explains the varying EfOM adsorbabilities that occur due to ozonation. The ozone-induced decrease of EfOM adsorbability directly translates into reduced adsorption competition against the adsorption of OMP. With higher specific ozone consumptions, OMP removal and OMP loadings increase. The reduced adsorption competition is reflected in the outputs from equivalent background compound (EBC) modeling. In each of the ozonated waters, correlations between the OMP removals and the UV254 removal were found. PMID:26231581

  20. [Dynamics of soil microbial biomass and dissolved organic carbon and nitrogen under flooded condition].

    PubMed

    Qiu, Shaojun; Peng, Peiqin; Rong, Xiangmin; Liu, Qiang; Tang, Qi

    2006-11-01

    With reddish yellow soil (RYS) and alluvial purple soil (APS), the two typical paddy soils in the Dongting Lake floodplain of China as test soils, an incubation test was conducted at 25 degrees C to study the dynamic changes of soil microbial biomass and dissolved organic carbon and nitrogen under flooded condition. Three treatments were installed, i.e., control (CK), ammonium sulfate (N), and rice straw powder plus ammonium sulfate (S-N). The results showed that during incubation, soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN), soil dissolved organic carbon (SDOC), and soil dissolved organic nitrogen (SDON) reached their maximum initially, decreased thereafter, and tended to be stable. After amending the substrates to the two soils, the averages of SMBC to soil total carbon, SMBN to soil total nitrogen, SDOC to soil total carbon, and SDON to soil total nitrogen were 2% - 3%, 2% - 3%, 1% or so, and 5% - 6%, respectively. In the two soils, the peak values of SMBC in treatment N and those of SMBN, SDOC and SDON in treatment S-N were the highest, while those of SMBC in treatments N and S-N had no significant difference. The peak values of SMBN, SDOC and SDON in RYS were significantly different between treatments N and S-N, while no significant difference was observed between the peak values of SMBN and SDOC in APS, because the fertility of RYS was lower than that of APS. In the first 7 days of incubation, SMBC/SMBN ratio was < 10, while after 14 days of incubation, this ratio was higher in treatment N than in treatment S-N at the same time in the same soil. The SDOC/SDON ratio in all treatments was the highest at the 3rd d, and the lowest at the 28th d of incubation. PMID:17269325

  1. Effects of coral reef benthic primary producers on dissolved organic carbon and microbial activity.

    PubMed

    Haas, Andreas F; Nelson, Craig E; Wegley Kelly, Linda; Carlson, Craig A; Rohwer, Forest; Leichter, James J; Wyatt, Alex; Smith, Jennifer E

    2011-01-01

    Benthic primary producers in marine ecosystems may significantly alter biogeochemical cycling and microbial processes in their surrounding environment. To examine these interactions, we studied dissolved organic matter release by dominant benthic taxa and subsequent microbial remineralization in the lagoonal reefs of Moorea, French Polynesia. Rates of photosynthesis, respiration, and dissolved organic carbon (DOC) release were assessed for several common benthic reef organisms from the backreef habitat. We assessed microbial community response to dissolved exudates of each benthic producer by measuring bacterioplankton growth, respiration, and DOC drawdown in two-day dark dilution culture incubations. Experiments were conducted for six benthic producers: three species of macroalgae (each representing a different algal phylum: Turbinaria ornata--Ochrophyta; Amansia rhodantha--Rhodophyta; Halimeda opuntia--Chlorophyta), a mixed assemblage of turf algae, a species of crustose coralline algae (Hydrolithon reinboldii) and a dominant hermatypic coral (Porites lobata). Our results show that all five types of algae, but not the coral, exuded significant amounts of labile DOC into their surrounding environment. In general, primary producers with the highest rates of photosynthesis released the most DOC and yielded the greatest bacterioplankton growth; turf algae produced nearly twice as much DOC per unit surface area than the other benthic producers (14.0±2.8 µmol h⁻¹ dm⁻²), stimulating rapid bacterioplankton growth (0.044±0.002 log10 cells h⁻¹) and concomitant oxygen drawdown (0.16±0.05 µmol L⁻¹ h⁻¹ dm⁻²). Our results demonstrate that benthic reef algae can release a significant fraction of their photosynthetically-fixed carbon as DOC, these release rates vary by species, and this DOC is available to and consumed by reef associated microbes. These data provide compelling evidence that benthic primary producers differentially influence reef microbial

  2. Redox reactions of dissolved organic matter contribute to anaerobic sulphur cycling in peatland soils

    NASA Astrophysics Data System (ADS)

    Blodau, C.; Margit, R.; Bernhard, M.; Moore, T. R.

    2004-05-01

    Sulphate reduction rates in wetland soils typically account for a large fraction of the anaerobic electron flow, despite small pool sizes of sulphate in the pore waters. The studies objective was to test the hypothesis that recycling of sulphur occurs and that redox-reactions of dissolved organic matter (DOM) are involved in the recycling process. To examine the recycling process we used peat mesocosm from two peatlands in Ontario, Canada and subjected them to sulphur deposition and vertical water flow of about 2 mm/day. Depth profiles of DOC and sulphate concentrations were determined and vertical mass balances calculated. In addition we determined 34S sulphate profiles of pore waters. Batch experiments with addition of H2S to solutions of standard peat humic acid (Pahokee Peat, IHSS) were used to determine whether H2S was oxidized by humic acids, and what the reaction products were. Enrichment with 34S at intermediate depths, constant sulphate concentrations with depth and absence of oxygen suggested that sulphate reduction and anaerobic sulphate release concurrently occurred. In the batch experiments two apparent reactions of H2S with DOM were observed. In the fast initial reaction, H2S was oxidized mostly to elemental sulphur and secondarily to sulphate. Production of thiosulfate was not observed. In a slower reaction step H2S was further consumed and the sum of dissolved inorganic forms of sulphur in the pore water decreased. This was interpreted as H2S being incorporated into the organic substance. No systematic relationship between pH and the oxidation process was found. Overall the results suggest that dissolved organic matter is involved in an anaerobic sulphur cycle allowing for high rates of sulphate reduction in sulphate-poor peatlands.

  3. Effects of Coral Reef Benthic Primary Producers on Dissolved Organic Carbon and Microbial Activity

    PubMed Central

    Haas, Andreas F.; Nelson, Craig E.; Wegley Kelly, Linda; Carlson, Craig A.; Rohwer, Forest; Leichter, James J.; Wyatt, Alex; Smith, Jennifer E.

    2011-01-01

    Benthic primary producers in marine ecosystems may significantly alter biogeochemical cycling and microbial processes in their surrounding environment. To examine these interactions, we studied dissolved organic matter release by dominant benthic taxa and subsequent microbial remineralization in the lagoonal reefs of Moorea, French Polynesia. Rates of photosynthesis, respiration, and dissolved organic carbon (DOC) release were assessed for several common benthic reef organisms from the backreef habitat. We assessed microbial community response to dissolved exudates of each benthic producer by measuring bacterioplankton growth, respiration, and DOC drawdown in two-day dark dilution culture incubations. Experiments were conducted for six benthic producers: three species of macroalgae (each representing a different algal phylum: Turbinaria ornata – Ochrophyta; Amansia rhodantha – Rhodophyta; Halimeda opuntia – Chlorophyta), a mixed assemblage of turf algae, a species of crustose coralline algae (Hydrolithon reinboldii) and a dominant hermatypic coral (Porites lobata). Our results show that all five types of algae, but not the coral, exuded significant amounts of labile DOC into their surrounding environment. In general, primary producers with the highest rates of photosynthesis released the most DOC and yielded the greatest bacterioplankton growth; turf algae produced nearly twice as much DOC per unit surface area than the other benthic producers (14.0±2.8 µmol h−1 dm−2), stimulating rapid bacterioplankton growth (0.044±0.002 log10 cells h−1) and concomitant oxygen drawdown (0.16±0.05 µmol L−1 h−1 dm−2). Our results demonstrate that benthic reef algae can release a significant fraction of their photosynthetically-fixed carbon as DOC, these release rates vary by species, and this DOC is available to and consumed by reef associated microbes. These data provide compelling evidence that benthic primary producers differentially influence reef

  4. Origin and sources of dissolved organic matter in snow on the East Antarctic ice sheet.

    PubMed

    Antony, Runa; Grannas, Amanda M; Willoughby, Amanda S; Sleighter, Rachel L; Thamban, Meloth; Hatcher, Patrick G

    2014-06-01

    Polar ice sheets hold a significant pool of the world's carbon reserve and are an integral component of the global carbon cycle. Yet, organic carbon composition and cycling in these systems is least understood. Here, we use ultrahigh resolution mass spectrometry to elucidate, at an unprecedented level, molecular details of dissolved organic matter (DOM) in Antarctic snow. Tens of thousands of distinct molecular species are identified, providing clues to the nature and sources of organic carbon in Antarctica. We show that many of the identified supraglacial organic matter formulas are consistent with material from microbial sources, and terrestrial inputs of vascular plant-derived materials are likely more important sources of organic carbon to Antarctica than previously thought. Black carbon-like material apparently originating from biomass burning in South America is also present, while a smaller fraction originated from soil humics and appears to be photochemically or microbially modified. In addition to remote continental sources, we document signals of oceanic emissions of primary aerosols and secondary organic aerosol precursors. The new insights on the diversity of organic species in Antarctic snowpack reinforce the importance of studying organic carbon associated with the Earth's polar regions in the face of changing climate. PMID:24804819

  5. Dissolved organic matter in newly formed sea ice and surface seawater

    NASA Astrophysics Data System (ADS)

    Longnecker, Krista

    2015-12-01

    Changes in sea ice in the Arctic will have ramifications on regional and global carbon cycling. Research to date has primarily focused on the regional impacts to biological activity and global impacts on atmospheric processes. The current project considers the molecular-level composition of organic carbon within sea ice compared to the organic matter in seawater. The project revealed that the composition of organic matter within sea ice was more variable than the composition of organic matter within the surface ocean. Furthermore, sea ice samples presented two distinct patterns in the composition of organic matter with a portion of the sea ice samples containing protein-like organic matter. Yet, the samples were collected in the early winter period when little biological activity is expected. Thus, one hypothesis is that physical processes acting during the formation of sea ice selectively transferred organic matter from seawater into sea ice. The present project expands our understanding of dissolved organic matter in sea ice and surface seawater and thereby increases our knowledge of carbon cycling in polar regions.

  6. Development of gas chromatographic system for dissolved organic carbon analysis in seawater. Annual progress report

    SciTech Connect

    Chipman, D.W.; Takahashi, T.

    1992-12-01

    During the first six months of this two-year grant, we have completed the construction of the analytical portion of a prototype gas chromatograph-based system for the analysis of dissolved organic carbon in seawater. We also have begun testing the procedures to be used to cryogenically concentrate and transfer carbon dioxide from the oxidizing atmosphere of the high-temperature furnace into the reducing hydrogen carrier gas of the gas chromatograph. During the second half of the first year, we will construct the high-temperature catalytic oxidation furnace and test the entire system on laboratory-prepared aqueous solutions of various organic compounds. Also during this period, we will take part in an initial scoping study within the Cape Hatteras field area on board the R/V Gyre. This study will involve both the collection of samples of seawater for organic and inorganic carbon analysis and the measurement of surface-water pCO{sub 2}.

  7. Development of gas chromatographic system for dissolved organic carbon analysis in seawater

    SciTech Connect

    Chipman, D.W.; Takahashi, T.

    1992-12-01

    During the first six months of this two-year grant, we have completed the construction of the analytical portion of a prototype gas chromatograph-based system for the analysis of dissolved organic carbon in seawater. We also have begun testing the procedures to be used to cryogenically concentrate and transfer carbon dioxide from the oxidizing atmosphere of the high-temperature furnace into the reducing hydrogen carrier gas of the gas chromatograph. During the second half of the first year, we will construct the high-temperature catalytic oxidation furnace and test the entire system on laboratory-prepared aqueous solutions of various organic compounds. Also during this period, we will take part in an initial scoping study within the Cape Hatteras field area on board the R/V Gyre. This study will involve both the collection of samples of seawater for organic and inorganic carbon analysis and the measurement of surface-water pCO[sub 2].

  8. Dissolved and particulate organic carbon fluxes from an agricultural watershed during consecutive tropical storms

    NASA Astrophysics Data System (ADS)

    Caverly, Emma; Kaste, James M.; Hancock, Gregory S.; Chambers, Randolph M.

    2013-10-01

    Low-frequency high-magnitude hydrologic events mobilize a disproportionate amount of dissolved organic carbon (DOC) from watersheds, but few studies measure the role of extreme storms in exporting organic carbon from croplands. We use high-resolution measurements of storm runoff to quantify DOC and particulate organic carbon (POC) fluxes from an agricultural field during consecutive tropical storms that delivered 41 cm of rainfall to the Virginia Coastal Plain. Over a 2 week period, we measured exports of 22 kg DOC ha-1 and 11.3 kg POC ha-1. Ultraviolet absorbance measurements indicate that the aromatic DOC fraction systematically increased as plant-derived aliphatic carbon was depleted during the initial event. Croplands can have event-scale carbon losses that equal or exceed published estimates of annual export for perennial streams draining forested and mixed land use watersheds. We quantify aromatic DOC fractions approaching 50%, indicating that agricultural stormflow can produce a significant load of relatively photoreactive carbon.

  9. Chemical and carbon isotopic composition of dissolved organic carbon in a regional confined methanogenic aquifer

    USGS Publications Warehouse

    Aravena, R.; Wassenaar, L.I.; Spiker, E. C.

    2004-01-01

    This study demonstrates the advantage of a combined use of chemical and isotopic tools to understand the dissolved organic carbon (DOC) cycle in a regional confined methanogenic aquifer. DOC concentration and carbon isotopic data demonstrate that the soil zone is a primary carbon source of groundwater DOC in areas close to recharge zones. An in-situ DOC source linked to organic rich sediments present in the aquifer matrix is controlling the DOC pool in the central part of the groundwater flow system. DOC fractions, 13C-NMR on fulvic acids and 14C data on DOC and CH4 support the hypothesis that the in-situ DOC source is a terrestrial organic matter and discard the Ordovician bedrock as a source of DOC. ?? 2004 Taylor and Francis Ltd.

  10. Linking soils and streams: Sources and chemistry of dissolved organic matter in a small coastal watershed

    NASA Astrophysics Data System (ADS)

    Sanderman, Jonathan; Lohse, Kathleen A.; Baldock, Jeffrey A.; Amundson, Ronald

    2009-03-01

    To understand the hydrologic and biogeochemical controls on the age and recalcitrance of dissolved organic matter (DOM) found in stream waters, we combined hydrometric monitoring along a topographic gradient from ridge to channel with isotopic (13C and 14C) and spectroscopic (UV and 13C nuclear magnetic resonance) analyses of soil and stream water samples in a small coastal watershed in California. With increasing discharge, dissolved organic carbon concentrations increased from 2.2 to 10.9 mg C L-1, Δ14C values increased from -125 to +120‰, δ13C values decreased from -24 to -29‰, C:N ratios increased from 6.5 to 15.4, and specific UV adsorption increased from 1.4 to 3.8 L mg C-1 m-1. These changes in DOM composition are consistent with a shift in source from old and recalcitrant soil organic matter (OM) sources found in deep soil horizons to young and relatively fresh OM sources found in the surface horizons. Results from this study suggest upland soils of the watershed become DOM production limited as indicated by a seasonal depletion and chemical shift in soil DOM, whereas highly productive soils in the hollow act as a near-infinite DOM source. Hydrologic connectivity of this DOM-rich riparian source region to the stream ultimately constrains DOM export, and the stream DOM composition reflects the combined influence of soil biogeochemical cycling of OM and hydrologic routing of water through the landscape.

  11. Catchment influence on nitrate and dissolved organic matter in Alaskan streams across a latitudinal gradient

    NASA Astrophysics Data System (ADS)

    Harms, Tamara K.; Edmonds, Jennifer W.; Genet, Hélène; Creed, Irena F.; Aldred, David; Balser, Andrew; Jones, Jeremy B.

    2016-02-01

    Spatial patterns in carbon (C) and nitrogen (N) cycles of high-latitude catchments have been linked to climate and permafrost and used to infer potential changes in biogeochemical cycles under climate warming. However, inconsistent spatial patterns across regions indicate that factors in addition to permafrost and regional climate may shape responses of C and N cycles to climate change. We hypothesized that physical attributes of catchments modify responses of C and N cycles to climate and permafrost. We measured dissolved organic C (DOC) and nitrate (NO3-) concentrations, and composition of dissolved organic matter (DOM) in 21 streams spanning boreal to arctic Alaska, and assessed permafrost, topography, and attributes of soils and vegetation as predictors of stream chemistry. Multiple regression analyses indicated that catchment slope is a primary driver, with lower DOC and higher NO3- concentration in streams draining steeper catchments, respectively. Depth of the active layer explained additional variation in concentration of DOC and NO3-. Vegetation type explained regional variation in concentration and composition of DOM, which was characterized by optical methods. Composition of DOM was further correlated with attributes of soils, including moisture, temperature, and thickness of the organic layer. Regional patterns of DOC and NO3- concentrations in boreal to arctic Alaska were driven primarily by catchment topography and modified by permafrost, whereas composition of DOM was driven by attributes of soils and vegetation, suggesting that predicting changes to C and N cycling from permafrost-influenced regions should consider catchment setting in addition to dynamics of climate and permafrost.

  12. Associations of free-living bacteria and dissolved organic compounds in a plume of contaminated groundwater

    USGS Publications Warehouse

    Harvey, R.W.; Barber, L.B., II

    1992-01-01

    Associations of free-living bacteria (FLB) and dissolved organic contaminants in a 4-km-long plume of sewage-contaminated groundwater were investigated. Abundance of FLB in the core of the plume (as delineated by maximum specific conductance) steadily decreased in the direction of flow from a point 0.25 km downgradient from the source to the toe of the plume. At 0.25 km downgradient, FLB comprised up to 31% of the total bacterial population, but constituted < 7% of the population at 2 km downgradient. Abundance of FLB correlated strongly (r = 0.80 n = 23) with total dissolved organic carbon (DOC) in contaminated groundwater between 0.64 and 2.1 km downgradient, although distributions of individual contaminants such as di-, tri- and tetrachloroethene were highly variable, and their association with FLB less clear. Numbers of FLB in the downgradient portion of the plume which is contaminated with branched-chain alkylbenzenesulfonate (ABS) surfactants were low (< 5??108/L) in spite of relatively high levels of DOC (up to 4 mg/L). However, abundance of FLB correlated strongly with non-surfactant DOC along vertical transects through the plume. The ratio of FLB to DOC and the ratio of FLB to attached bacteria generally decreased in the direction of flow and, consequently, with the age of the organic contaminants.

  13. Black Carbon in Estuarine (Coastal) High-molecular-weight Dissolved Organic Matter

    NASA Technical Reports Server (NTRS)

    Mannino, Antonio; Harvey, H. Rodger

    2003-01-01

    Dissolved organic matter (DOM) in the ocean constitutes one of the largest pools of organic carbon in the biosphere, yet much of its composition is uncharacterized. Observations of black carbon (BC) particles (by-products of fossil fuel combustion and biomass burning) in the atmosphere, ice, rivers, soils and marine sediments suggest that this material is ubiquitous, yet the contribution of BC to the ocean s DOM pool remains unknown. Analysis of high-molecular-weight DOM isolated from surface waters of two estuaries in the northwest Atlantic Ocean finds that BC is a significant component of DOM, suggesting that river-estuary systems are important exporters of BC to the ocean through DOM. We show that BC comprises 4-7% of the dissolved organic carbon (DOC) at coastal ocean sites, which supports the hypothesis that the DOC pool is the intermediate reservoir in which BC ages prior to sedimentary deposition. Flux calculations suggest that BC could be as important as vascular plant-derived lignin in terms of carbon inputs to the ocean. Production of BC sequesters fossil fuel- and biomass-derived carbon into a refractory carbon pool. Hence, BC may represent a significant sink for carbon to the ocean.

  14. Effects of effluent organic matter (EfOM) on the removal of emerging contaminants by ozonation.

    PubMed

    Cai, Ming-Jhih; Lin, Yi-Pin

    2016-05-01

    Removal of emerging contaminants in wastewater treatment is essential to ensure the ecological health of the receiving water bodies. Ozonation is a promising technology to achieve this purpose but important wastewater characteristics affecting the optimal removal efficiency need to be elucidated. Secondary effluents contain effluent organic matter (EfOM), which can react directly with ozone as well as react as the initiator, promoter and inhibitor in the hydroxyl radical (.OH) chain reactions resulting from ozone decomposition. These different reaction modes of EfOM, coupled with alkalinity and pH value, collectively determine the ozone and .OH exposures and the degradation of pharmaceutical compounds by ozonation. In this study, we determined the rate constants of EfOM collected from two municipal wastewater treatment plants in terms of direct ozone reaction, initiation, promotion and inhibition at various pH values (pH 6.0-7.5) and temperatures (10-30 °C). The rate constants of direct reaction and initiation generally increased with the increasing pH value while the rate constants of promotion and inhibition did not vary significantly. All rate constants increased with the increasing temperature. The removal of ibuprofen, acetylsulfamethoxazole and metoprolol in diluted secondary effluent by ozonation can be fairly-well modeled by using the determined rate constants of EfOM. PMID:26950024

  15. BOREAS TGB-5 Dissolved Organic Carbon Data from NSA Beaver Ponds

    NASA Technical Reports Server (NTRS)

    Bourbonniere, Rick; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor)

    2000-01-01

    The BOReal Ecosystem-Atmosphere Study Trace Gas Biogeochemistry (BOREAS TGB-5) team collected several data sets related to carbon and trace gas fluxes and concentrations in the Northern Study Area (NSA). This data set contains concentrations of dissolved organic and inorganic carbon species from water samples collected at various NSA sites. In particular, this set covers the NSA Tower Beaver Pond Site and the NSA Gillam Road Beaver Pond Site, including data from all visits to open water sampling locations during the BOREAS field campaigns from April to September 1994. The data are provided in tabular ASCII files.

  16. Revealing Aquatic Dissolved Organic Matter Composition using Direct 1H NMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Burns, D. C.; Gueguen, C.

    2009-05-01

    Dissolved organic matter (DOM) is ubiquitous in all aquatic ecosystems, and comprises a variety of chemically heterogeneous molecular structures and functional groups. DOM is often considered to be a major ligand for metals in most natural waters. However DOM reactivity is thought to be strongly dependent on its chemical structure. The purpose of this study is to evaluate the variability in molecular composition of aquatic DOM from different sources. Quantitative proton NMR spectra were obtained without any preconcentration using water suppression techniques. The reproducibility on the determination of aromatic and aliphatic proton was better than 3%. The structural information of DOM from northern rivers was compared to IHSS humic substances.

  17. Temperature dependence of the relationship between pCO2 and dissolved organic carbon in lakes

    NASA Astrophysics Data System (ADS)

    Pinho, L.; Duarte, C. M.; Marotta, H.; Enrich-Prast, A.

    2016-02-01

    The relationship between the partial pressure of carbon dioxide (pCO2) and dissolved organic carbon (DOC) concentration in Brazilian lakes, encompassing 225 samples across a wide latitudinal range in the tropics, was tested. Unlike the positive relationship reported for lake waters, which was largely based on temperate lakes, we found no significant relationship for low-latitude lakes (< 33°), despite very broad ranges in both pCO2 and DOC levels. These results suggest substantial differences in the carbon cycling of low-latitude lakes, which must be considered when upscaling limnetic carbon cycling to global scales.

  18. Relevance of dissolved organic nutrients for the Arctic Ocean nutrient budget

    NASA Astrophysics Data System (ADS)

    Torres-Valdés, Sinhué; Tsubouchi, Takamasa; Davey, Emily; Yashayaev, Igor; Bacon, Sheldon

    2016-06-01

    We ask whether dissolved organic nitrogen (DON) and phosphorus (DOP) could account for previously identified Arctic Ocean (AO) inorganic nutrient budget imbalances. We assess transports to/from the AO by calculating indicative budgets. Marked DON:DOP ratio differences between the Amerasian and Eurasian AO reflect different physical and biogeochemical pathways. DON and DOP are exported to the North Atlantic via Davis Strait potentially being enhanced in transit from Bering Strait. Fram Strait transports are balanced. Barents Sea Opening transports may provide an additional nutrient source to the Barents Sea or may be locked within the wider AO Atlantic Water circulation. Gaps in our knowledge are identified and discussed.

  19. Remotion of organic compounds of actual industrial effluents by electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Sampa, M. H. O.; Duarte, C. L.; Rela, P. R.; Somessari, E. S. R.; Silveira, C. G.; Azevedo, A. L.

    1998-06-01

    Organic compounds has been a great problem of environmental pollution, the traditional methods are not effecient on removing these compounds and most of them are deposited to ambient and stay there for long time causing problems to the environment. Ionizing radiation has been used with success to destroy organic molecules. Actual industrial effluents were irradiated using IPEN's electron beam wastewater pilot plant to study organic compounds degradation. The samples were irradiated with and without air mixture by different doses. Irradiation treatment efficiency was evaluated by the Cromatography Gas Analyses of the samples before and after irradiation. The studied organic compounds were: phenol, chloroform, tetrachloroethylene (PCE), carbon tetrachloride, trichloroethylene (TCE), 1,1-dichloroethane, dichloromethane, benzene, toluene and xilene. A degradation superior to 80% was achieved for the majority of the compounds with air addition and 2kGy delivered dose condition. For the samples that were irradiated without air addition the degradation was higher.

  20. Dissolved organic carbon and disinfection by-product precursor release from managed peat soils.

    PubMed

    Fleck, J A; Bossio, D A; Fujii, R

    2004-01-01

    A wetland restoration demonstration project examined the effects of a permanently flooded wetland on subsidence of peat soils. The project, started in 1997, was done on Twitchell Island, in the Sacramento-San Joaquin Delta of California. Conversion of agricultural land to a wetland has changed many of the biogeochemical processes controlling dissolved organic carbon (DOC) release from the peat soils, relative to the previous land use. Dissolved organic C in delta waters is a concern because it reacts with chlorine, added as a disinfectant in municipal drinking waters, to form carcinogenic disinfection byproducts (DBPs), including trihalomethanes (THMs) and haloacetic acids (HAAs). This study explores the effects of peat soil biogeochemistry on DOC and DBP release under agricultural and wetland management. Results indicate that organic matter source, extent of soil organic matter decomposition, and decomposition pathways all are factors in THM formation. The results show that historical management practices dominate the release of DOC and THM precursors. However, within-site differences indicate that recent management decisions can contribute to changes in DOC quality and THM precursor formation. Not all aromatic forms of carbon are highly reactive and certain environmental conditions produce the specific carbon structures that form THMs. Both HAA and THM precursors are elevated in the DOC released under wetland conditions. The findings of this study emphasize the need to further investigate the roles of organic matter sources, microbial decomposition pathways, and decomposition status of soil organic matter in the release of DOC and DBP precursors from delta soils under varying land-use practices. PMID:15074797

  1. Dissolved Organic Carbon and Disinfection By-Product Precursor Release from Managed Peat Soils

    USGS Publications Warehouse

    Fleck, J.A.; Bossio, D.A.; Fujii, R.

    2004-01-01

    A wetland restoration demonstration project examined the effects of a permanently flooded wetland on subsidence of peat soils. The project, started in 1997, was done on Twitchell Island, in the Sacramento-San Joaquin Delta of California. Conversion of agricultural land to a wetland has changed many of the biogeochemical processes controlling dissolved organic carbon (DOC) release from the peat soils, relative to the previous land use. Dissolved organic C in delta waters is a concern because it reacts with chlorine, added as a disinfectant in municipal drinking waters, to form carcinogenic disinfection byproducts (DBPs), including trihalomethanes (THMs) and haloacetic acids (HAAs). This study explores the effects of peat soil biogeochemistry on DOC and DBP release under agricultural and wetland management. Results indicate that organic matter source, extent of soil organic matter decomposition, and decomposition pathways all are factors in THM formation. The results show that historical management practices dominate the release of DOC and THM precursors. However, within-site differences indicate that recent management decisions can contribute to changes in DOC quality and THM precursor formation. Not all aromatic forms of carbon are highly reactive and certain environmental conditions produce the specific carbon structures that form THMs. Both HAA and THM precursors are elevated in the DOC released under wetland conditions. The findings of this study emphasize the need to further investigate the roles of organic matter sources, microbial decomposition pathways, and decomposition status of soil organic matter in the release of DOC and DBP precursors from delta soils under varying land-use practices.

  2. Detrital control on the release of dissolved organic nitrogen (DON) and dissolved inorganic nitrogen (DIN) from the forest floor under chronic N deposition.

    PubMed

    Park, Ji-Hyung; Matzner, Egbert

    2006-09-01

    The role of detrital quantity and quality in forest floor N leaching was investigated in a litter manipulation experiment at a deciduous forest under chronic N deposition. Dissolved inorganic nitrogen (DIN) comprised the bulk of nitrogen leaching from the control except a short period following autumn litterfall. The dominance of DIN was strengthened by litter exclusion, whereas the addition of glucose or fresh litter led to a small increase in dissolved organic nitrogen (DON) and either a temporary or gradual reduction in NO(3)(-) release, respectively. Changes in soluble organic C and microbial C in the forest floor implied that increased availability of C sources might have enhanced microbial immobilization of DIN, either temporarily following glucose application or over the longer term following litter addition. The results suggest that detrital quantity and quality can play a crucial role in determining the balance between DIN and DON in N-enriched forest soils. PMID:16406164

  3. Methods for measuring the acute toxicity of effluents and receiving waters to freshwater and marine organisms (fourth edition)

    SciTech Connect

    Weber, C.I.

    1991-09-01

    The manual describes methods for measuring the acute toxicity of effluents and receiving waters to freshwater, estuarine, and marine macroinvertebrates and fish. The methods include single and multiple concentration static nonrenewal, static-renewal, and flow-through toxicity tests for effluents and receiving waters. Also included are guidelines on laboratory safety; quality assurance; facilities and equipment; test species selection and handling; dilution water; effluent and receiving water sample collection, preservation, shipping, and holding; test conditions; toxicity test data analysis; report preparation; and organism culturing.

  4. Characterization of Dissolved Organic Carbon in Deep Groundwater from the Witwatersrand Basin

    NASA Astrophysics Data System (ADS)

    Pullin, M. J.; Hendrickson, S.; Simon, P.; Sherwood Lollar, B.; Wilkie, K.; Onstott, T. C.; Washton, N.; Clewett, C.

    2013-12-01

    This work describes the isolation, fractionation, and chemical analysis of dissolved organic carbon (DOC) in deep groundwater in the Witwatersrand Basin, South Africa. The groundwater was accessed through mining boreholes in gold and diamond mine shafts. Filtered water samples were collected and preserved for later analysis. In some cases, the organic carbon was also collected on DAX-8 and XAD-4 adsorption resins in situ and then transported to the surface for removal, clean-up, and lyophilization. Solid state C-13 NMR analysis of that organic carbon was conducted. Organic compounds were also isolated from the water using solid phase extraction cartridges for later analysis by GC-MS. Absorbance, fluorescence, and HPLC analyses was were used to analyze the DOC in the filtered water samples. C-14 and C-13 isotopic analysis of the organic carbon was also conducted. Identifiable components of the DOC include both organic acids and amino acids. However, initial results indicate that the majority of the subsurface DOC is a complex heterogeneous mixture with an average molecular weight of approximately 1000 Da, although this DOC is less complex than that found in soils or surface water. Finally, we will discuss possible sources of the organic carbon and its biogeochemical cycling in the subsurface.

  5. Landscape controls on dissolved nutrients, organic matter and major ions in a suburbanizing watershed

    NASA Astrophysics Data System (ADS)

    Daley, M. L.; McDowell, W. H.

    2010-12-01

    Understanding the relative importance of anthropogenic and natural landscape features that drive spatial variability in water quality is a central challenge in studying the biogeochemistry of heterogeneous landscapes. We quantified the average annual flux and concentration of dissolved inorganic nitrogen (DIN), dissolved organic nitrogen (DON), dissolved organic carbon (DOC), phosphate-P (PO4-P), sodium (Na+) and chloride (Cl-) at ~40 stream sites in three major (51 to 903 km2) NH basins. We used GIS to quantify anthropogenic (e.g. human population density, % impervious surface cover and % agriculture) and natural (e.g. % forest, % wetlands and soil C:N) landscape features for each sub-basin and then employed multiple-regression analysis to relate water quality parameters to landscape characteristics. Anthropogenic features were strong predictors of DIN flux and Na+ and Cl- concentrations, whereas wetland cover (a natural feature) was a significant, but weak predictor of DOC (r2=0.26, p<0.01) and DON (r2 = 0.14, p<0.05) flux. Anthropogenic features could not explain a significant amount of variance in DON or DOC flux. Mean PO4-P concentrations were surprisingly low (<0.015 mg P/L) when compared to the larger range in mean DIN concentrations (0.03 to 0.96 mg/L) and consequently no landscape characteristics could explain a significant amount of spatial variability in PO4-P flux or concentration. Human population density was the single best predictor of DIN flux (r2=0.76, p<0.01), and together with % impervious surface and % agriculture explained 86% (p<0.01) of the total variance. Among all sites, % road pavement was a strong predictor of stream Na+ and Cl- concentrations (r2 = 0.75 to 0.78, p<0.01) and % impervious surface was a stronger predictor (r2 = 0.86 to 0.92, p<0.01) among a subset of sites. Our results suggest that DIN and DON result from different sources in the landscape and although sources of DON and DOC are similar, DON and DOC concentrations respond

  6. Colloidal organic matter from wastewater treatment plant effluents: Characterization and role in metal distribution.

    PubMed

    Worms, Isabelle A M; Al-Gorani Szigeti, Zsofia; Dubascoux, Stephane; Lespes, Gaetane; Traber, Jacqueline; Sigg, Laura; Slaveykova, Vera I

    2010-01-01

    Colloidal organic matter from wastewater treatment plants was characterized and examined with respect to its role in metal distribution by using tangential flow ultrafiltration, liquid chromatography coupled with organic carbon and UV detectors, and an asymmetrical flow field-flow fractionation (AFlFFF) multidetection platform. Results revealed that a humic-like fraction of low aromaticity with an average molar mass ranging from 1600 to 2600Da was the main colloidal component. High molar mass fractions (HMM), with molar mass ranges between 20 and 200kDa, were present in lower proportions. Ag, Cd, Cu, Cr, Mn and Zn were found mainly in the dissolved phase (<0.45microm) and their distribution between colloidal and truly dissolved fractions was strongly influenced by the distribution of dissolved organic carbon. AFlFFF coupled to ICP-MS showed that Ag, Cd, Cu, Cr, Mn and Zn associate to the low molar mass fraction of the colloidal pool, whereas Al, Fe and Pb were equally bound to low and high molar mass fractions. PMID:19836819

  7. Photochemical Flocculation of Terrestrial Dissolved Organic Matter (tDOM) and Iron: Mechanisms and Geochemical Implications

    NASA Astrophysics Data System (ADS)

    Mopper, K.; Helms, J. R.; Mao, J.; Abdulla, H. A.; Schmidt-Rohr, K.

    2013-12-01

    Photoflocculation of DOM has received relatively little attention. No previous studies have examined the chemical composition of the flocs nor investigated the coagulation mechanisms. We observed that, after 30 days of simulated solar UV irradiation of 0.1-um filtered Great Dismal Swamp (Virginia) water, 7.1% of the DOC was converted to POC while 75% was remineralized. Approximately 87% of the iron was removed from the dissolved phase after 30 days, but iron did not flocculate until a major fraction of DOM was removed by photochemical degradation and flocculation (>10 days); thus, during the initial 10 days, there were sufficient organic ligands present and/or the pH was low enough to keep iron in solution. Although photoflocculation of iron did eventually occur, it is not clear if iron is required for the initial flocculation of DOM. Using NMR and FT-IR techniques, we found that photochemically flocculated POM was enriched in aliphatics and amide functionality relative to the residual non-flocculated DOM, while carbohydrate-like material was neither photochemical degraded nor flocculated. Based on this spectroscopic evidence, we propose several mechanisms for the formation of the flocs during irradiation. We also speculate that abiotic photochemical flocculation may remove a significant fraction of tDOM and iron from the upper water column between headwaters and the ocean, including estuaries. Fig. 1. Concentrations of dissolved (gray), particulate (black), and adsorbed (white) material as a function of irradiation time: (a) organic carbon, (b) absorption at 300 nm, (c) total iron by atomic absorption, and (d) total nitrogen. Error bars represent the combined standard deviations of the 'total,' 'dissolved,' and 'adsorbed' terms from which the 'particulate' term was calculated. Total nitrogen was not determined for the 'adsorbed' material

  8. Co-precipitation of dissolved organic matter by calcium carbonate in Pyramid Lake, Nevada

    USGS Publications Warehouse

    Leenheer, Jerry A.; Reddy, Michael M.

    2008-01-01

    Our previous research has demonstrated that dissolved organic matter (DOM) influences calcium carbonate mineral formation in surface and ground water. To better understand DOM mediation of carbonate precipitation and DOM co-precipitation and/or incorporation with carbonate minerals, we characterized the content and speciation of DOM in carbonate minerals and in the lake water of Pyramid Lake, Nevada, USA. A 400-gram block of precipitated calcium carbonate from the Pyramid Lake shore was dissolved in 8 liters of 10% acetic acid. Particulate matter not dissolved by acetic acid was removed by centrifugation. DOM from the carbonate rock was fractionated into nine portions using evaporation, dialysis, resin adsorption, and selective precipitations to remove acetic acid and inorganic constituents. The calcium carbonate rock contained 0.23% DOM by weight. This DOM was enriched in polycarboxylic proteinaceous acids and hydroxy-acids in comparison with the present lake water. DOM in lake water was composed of aliphatic, alicyclic polycarboxylic acids. These compound classes were found in previous studies to inhibit calcium carbonate precipitation. DOM fractions from the carbonate rock were 14C-age dated at about 3,100 to 3,500 years before present. The mechanism of DOM co-precipitation and/or physical incorporation in the calcium carbonate is believed to be due to formation of insoluble calcium complexes with polycarboxylic proteinaceous acids and hydroxy-acids that have moderately large stability constants at the alkaline pH of the lake. DOM co-precipitation with calcium carbonate and incorporation in precipitated carbonate minerals removes proteinaceous DOM, but nearly equivalent concentrations of neutral and acidic forms of organic nitrogen in DOM remain in solution. Calcium carbonate precipitation during lime softening pretreatment of drinking water may have practical applications for removal of proteinaceous disinfection by-product precursors.

  9. Dissolved organic phosphorus speciation in the waters of the Tamar estuary (SW England)

    NASA Astrophysics Data System (ADS)

    Monbet, Phil; McKelvie, Ian D.; Worsfold, Paul J.

    2009-02-01

    The speciation of dissolved organic phosphorus (DOP) in the temperate Tamar estuary of SW England is described. Eight stations from the riverine to marine end-members were sampled during four seasonal campaigns in 2007 and the DOP pool in the water column and sediment porewater was characterized and quantified using a flow injection manifold after sequential enzymatic hydrolysis. This enabled the enzymatically hydrolysable phosphorus (EHP) fraction and its component labile monoester phosphates, diester phosphates and a phytase-hydrolysable fraction that includes myo-inositol hexakisphosphate (phytic acid), to be determined and compared with the total DOP, dissolved reactive phosphorus (DRP) and total dissolved phosphorus (TDP) pools. The results showed that the DOP pool in the water column varied temporally and spatially within the estuary (1.1-22 μg L -1) and constituted 6-40% of TDP. The EHP fraction of DOP ranged from 1.1-15 μg L -1 and represented a significant and potentially bioavailable phosphorus fraction. Furthermore the spatial profiles of the three components of the EHP pool generally showed non-conservative behavior along the salinity gradient, with apparent internal estuarine sources. Porewater profiles followed broadly similar trends but were notably higher at the marine station throughout the year. In contrast to soil organic phosphorus profiles, the labile monoester phosphate fraction was the largest component, with diester phosphates also prevalent. Phytic acid concentrations were higher in the lower estuary, possibly due to salinity induced desorption processes. The EHP fraction is not commonly determined in aquatic systems due to the lack of a suitable measurement technique and the Tamar results reported here have important implications for phosphorus biogeochemistry, estuarine ecology and the development of efficient strategies for limiting the effects of phosphorus on water quality.

  10. The removal kinetics of dissolved organic matter and the optical clarity of groundwater

    NASA Astrophysics Data System (ADS)

    Chapelle, Francis H.; Shen, Yuan; Strom, Eric W.; Benner, Ronald

    2016-04-01

    Concentrations of dissolved organic matter (DOM) and ultraviolet/visible light absorbance decrease systematically as groundwater moves through the unsaturated zones overlying aquifers and along flowpaths within aquifers. These changes occur over distances of tens of meters (m) implying rapid removal kinetics of the chromophoric DOM that imparts color to groundwater. A one-compartment input-output model was used to derive a differential equation describing the removal of DOM from the dissolved phase due to the combined effects of biodegradation and sorption. The general solution to the equation was parameterized using a 2-year record of dissolved organic carbon (DOC) concentration changes in groundwater at a long-term observation well. Estimated rates of DOC loss were rapid and ranged from 0.093 to 0.21 micromoles per liter per day (μM d-1), and rate constants for DOC removal ranged from 0.0021 to 0.011 per day (d-1). Applying these removal rate constants to an advective-dispersion model illustrates substantial depletion of DOC over flow-path distances of 200 m or less and in timeframes of 2 years or less. These results explain the low to moderate DOC concentrations (20-75 μM; 0.26-1 mg L-1) and ultraviolet absorption coefficient values (a 254 < 5 m-1) observed in groundwater produced from 59 wells tapping eight different aquifer systems of the United States. The nearly uniform optical clarity of groundwater, therefore, results from similarly rapid DOM-removal kinetics exhibited by geologically and hydrologically dissimilar aquifers.

  11. Nitrogen solutes in an Adirondack forested watershed: Importance of dissolved organic nitrogen

    USGS Publications Warehouse

    McHale, M.R.; Mitchell, M.J.; McDonnell, Jeffery J.; Cirmo, C.P.

    2000-01-01

    Nitrogen (N) dynamics were evaluated from 1 June 1995 through 31 May 1996 within the Arbutus Lake watershed in the Adirondack Mountains of New York State, U.S.A. At the Arbutus Lake outlet dissolved organic nitrogen (DON), NO3/- and NH4/+ contributed 61%, 33%, and 6% respectively, to the total dissolved nitrogen (TDN) flux (259 mol ha-1 yr-1). At the lake inlet DON, NO3/-, and NH4/+ constituted 36%, 61%, and 3% respectively, of TDN flux (349 mol ha-1 yr-1). Differences between the factors that control DON, NO3/-, and NH4+ stream water concentrations were evaluated using two methods for estimating annual N flux at the lake inlet. Using biweekly sampling NO3/- and NH4/+ flux was 10 and 4 mol ha-1 yr-1 respectively, less than flux estimates using biweekly plus storm and snowmelt sampling. DON flux was 18 mol ha-1 yr-1 greater using only biweekly sampling. These differences are probably not of ecological significance relative to the total flux of N from the watershed (349 mol ha-1 yr-1). Dissolved organic N concentrations were positively related to discharge during both the dormant (R2 = 0.31; P<0.01) and growing season (R2= 0.09; P<0.01). There was no significant relationship between NO3/- concentration and discharge during the dormant season, but a significant negative relationship was found during the growing season (R2 = 0.29; P<0.01). Biotic controls in the growing season appeared to have had a larger impact on stream water NO3- concentrations than on DON concentrations. Arbutus Lake had a major impact on stream water N concentrations of the four landscape positions sampled, suggesting the need to quantify within lake processes to interpret N solute losses and patterns in watershed-lake systems.

  12. High molecular weight dissolved organic matter enrichment selects for methylotrophs in dilution to extinction cultures

    PubMed Central

    Sosa, Oscar A; Gifford, Scott M; Repeta, Daniel J; DeLong, Edward F

    2015-01-01

    The role of bacterioplankton in the cycling of marine dissolved organic matter (DOM) is central to the carbon and energy balance in the ocean, yet there are few model organisms available to investigate the genes, metabolic pathways, and biochemical mechanisms involved in the degradation of this globally important carbon pool. To obtain microbial isolates capable of degrading semi-labile DOM for growth, we conducted dilution to extinction cultivation experiments using seawater enriched with high molecular weight (HMW) DOM. In total, 93 isolates were obtained. Amendments using HMW DOM to increase the dissolved organic carbon concentration 4x (280 μM) or 10x (700 μM) the ocean surface water concentrations yielded positive growth in 4–6% of replicate dilutions, whereas <1% scored positive for growth in non-DOM-amended controls. The majority (71%) of isolates displayed a distinct increase in cell yields when grown in increasing concentrations of HMW DOM. Whole-genome sequencing was used to screen the culture collection for purity and to determine the phylogenetic identity of the isolates. Eleven percent of the isolates belonged to the gammaproteobacteria including Alteromonadales (the SAR92 clade) and Vibrio. Surprisingly, 85% of isolates belonged to the methylotrophic OM43 clade of betaproteobacteria, bacteria thought to metabolically specialize in degrading C1 compounds. Growth of these isolates on methanol confirmed their methylotrophic phenotype. Our results indicate that dilution to extinction cultivation enriched with natural sources of organic substrates has a potential to reveal the previously unsuspected relationships between naturally occurring organic nutrients and the microorganisms that consume them. PMID:25978545

  13. Formation of trihalomethanes of dissolved organic matter fractions in reservoir and canal waters.

    PubMed

    Musikavong, Charongpun; Srimuang, Kanjanee; Tachapattaworakul Suksaroj, Thunwadee; Suksaroj, Chaisri

    2016-07-28

    The formation of trihalomethanes (THMs) of hydrophobic organic fraction (HPO), transphilic organic fraction (TPI), and hydrophilic organic fraction (HPI) of reservoir and canal waters from the U-Tapao River Basin, Songkhla, Thailand was investigated. Water samples were collected three times from two reservoirs, upstream, midstream, and downstream of the U-Tapao canal. The HPO was the major dissolved organic matter (DOM) fraction in reservoir and canal waters. On average, the HPO accounted for 53 and 45% of the DOM in reservoir and canal waters, respectively. The TPI of 19 and 23% in reservoir and canal waters were determined, respectively. The HPI of 29% of the reservoir water and HPI of 32% of the canal water were detected. For the reservoir water, the highest trihalomethane formation potential (THMFP)/dissolved organic carbon (DOC) was determined for the HPI, followed by the TPI and HPO, respectively. The average values of the THMFP/DOC of the HPI, TPI, and HPO of the reservoir water were 78, 52, and 49 µg THMs/mg C, respectively. The highest THMFP/DOC of the canal water was detected for the HPI, followed by HPO and TPI, respectively. Average values of the THMFP/DOC of HPI of water at upstream and midstream locations of 58 µg THMs/mg C and downstream location of 113 µg THMs/mg C were determined. Average values of THMFP/DOC of HPO of water at upstream and midstream and downstream locations were 48 and 93 µg THMs/mg C, respectively. For the lowest THMFP/DOC fraction, the average values of THMFP/DOC of TPI of water at upstream and midstream and downstream locations were 35 and 73 µg THMs/mg C, respectively. PMID:27166524

  14. High molecular weight dissolved organic matter enrichment selects for methylotrophs in dilution to extinction cultures.

    PubMed

    Sosa, Oscar A; Gifford, Scott M; Repeta, Daniel J; DeLong, Edward F

    2015-12-01

    The role of bacterioplankton in the cycling of marine dissolved organic matter (DOM) is central to the carbon and energy balance in the ocean, yet there are few model organisms available to investigate the genes, metabolic pathways, and biochemical mechanisms involved in the degradation of this globally important carbon pool. To obtain microbial isolates capable of degrading semi-labile DOM for growth, we conducted dilution to extinction cultivation experiments using seawater enriched with high molecular weight (HMW) DOM. In total, 93 isolates were obtained. Amendments using HMW DOM to increase the dissolved organic carbon concentration 4x (280 μM) or 10x (700 μM) the ocean surface water concentrations yielded positive growth in 4-6% of replicate dilutions, whereas <1% scored positive for growth in non-DOM-amended controls. The majority (71%) of isolates displayed a distinct increase in cell yields when grown in increasing concentrations of HMW DOM. Whole-genome sequencing was used to screen the culture collection for purity and to determine the phylogenetic identity of the isolates. Eleven percent of the isolates belonged to the gammaproteobacteria including Alteromonadales (the SAR92 clade) and Vibrio. Surprisingly, 85% of isolates belonged to the methylotrophic OM43 clade of betaproteobacteria, bacteria thought to metabolically specialize in degrading C1 compounds. Growth of these isolates on methanol confirmed their methylotrophic phenotype. Our results indicate that dilution to extinction cultivation enriched with natural sources of organic substrates has a potential to reveal the previously unsuspected relationships between naturally occurring organic nutrients and the microorganisms that consume them. PMID:25978545

  15. Spatial and temporal variation in dissolved organic carbon composition in a peaty catchment draining a windfarm

    NASA Astrophysics Data System (ADS)

    Zheng, Ying; Waldron, Susan; Flowers, Hugh

    2015-04-01

    Peatlands are an important terrestrial carbon reserve and a principal source of dissolved organic carbon (DOC) to the fluvial environment (Wallage et al. 2006). Recently it has been observed that DOC concentrations [DOC] in surface waters have increased in Europe and North America (Monteith et al. 2007). This has been attributed primarily to reduced acid deposition. However, land use change can also release C from peat soils. A significant land use change in Scotland is hosting windfarms. Whether windfarm construction causes such impacts has been a research focus, particularly considering fluvial losses, but usually assessing if there are changes in DOC concentration rather than composition. Our study area is a peaty catchment that hosts wind turbines, has peat restoration activities and forest felling and is drained by two streams. We are using UV-visible and fluorescence spectrophotometry to assess if there are differences between the two steams or temporal changes in DOC composition. We will present data from samples collected since February 2014. The parameters we are focusing on are SUVA254, E4/E6 and E2/E4 ratios as these are indicators of DOC aromaticity, humic acid (HA): fulvic acid (FA) ratio and the proportion of humic substances in DOC (Weishaar, 2003; Spencer et al. 2007; Graham et al. 2012). To assess these we have measured UV-visible absorbance spectra from 200 nm to 800 nm. Meanwhile sample fluorescence emission and excitation matrix (EEM) will be applied with the PARAFAC model to obtain more information about the variations in humic substances in this catchment. Our current analysis indicates spatial differences not only in DOC concentration but also in composition. For example, the mainstem draining the windfarm area had a smaller [DOC] but higher E4/E6 and lower E2/E4 ratio values than the tributary draining an area of felled forestry. This may be indicative of more HAs in the mainstem DOC. Seasonal variations have also been observed. Both streams

  16. Experimental evidence of dust-induced shaping of surface dissolved organic matter in the oligotrophic ocean

    NASA Astrophysics Data System (ADS)

    Pulido-Villena, Elvira; Djaoudi, Kahina; Barani, Aude; Charrière, Bruno; Delmont, Anne; Hélias-Nunige, Sandra; Marc, Tedetti; Wambeke France, Van

    2016-04-01

    Recent research has shown that dust deposition may impact the functioning of the microbial loop. On one hand, it enhances bacterial mineralization of dissolved organic matter (DOM), and so may limit the carbon export. On the other hand, the interaction between heterotrophic bacteria and DOM in the surface ocean can increase the residence time of DOM, promoting its export and sequestration in the deep ocean. The main goal of this study was to experimentally assess whether the bacterial response to dust deposition is prone to have an effect on the residence time of the DOM pool by modifying its bioavailability. The bacterial degradation of DOM was followed on dust-amended and control treatments during long-term incubations. Dissolved organic carbon concentration decreased by 9 μmol L-1 over the course of the experiment in both control and dust-enriched conditions, with no significant differences between treatments. However, significant differences in DOM optical properties appeared at the latest stage of the incubations suggesting an accumulation of DOM of high molecular weight in the dust-amended treatment. At the end of the incubations, the remaining water was filtered and re-used as a new culture medium for a bacterial natural assemblage. Bacterial abundance and production was lower in the treatment previously submitted to dust enrichment, suggesting a decrease in DOM lability after a dust deposition event. These preliminary results point to a new link between dust and ocean carbon cycle through the modification of the residence time of the DOM pool.

  17. Characterisation of dissolved organic matter in stormwater using high-performance size exclusion chromatography.

    PubMed

    Huang, Huiping; Chow, Christopher W K; Jin, Bo

    2016-04-01

    Understanding the complexity of dissolved organic matter (DOM) in stormwater has drawn a lot of interest, since DOM from stormwater causes not only environmental impacts, but also worsens downstream aquatic quality associated with water supply and treatability. This study introduced and employed high-performance size exclusion chromatography (HPSEC) coupled with an ultraviolet-visible (UV-vis) diode array detector to assess changes in stormwater-associated DOM characteristics. Stormwater DOM was also analysed in relation to storm event characteristics, water quality and spectroscopic analysis. Statistical tools were used to determine the correlations within DOM and water quality measurements. Results showed that dissolved organic carbon (DOC) and UV absorbance at 254 nm (UV254) as conventional DOM parameters were found to be correlated well to the changes in stormwater quality during each of the three storm events studied. Both detector wavelengths (210 and 254 nm) and their ratio (A210/A254) were found to provide additional information on the physiochemical properties of stormwater-associated DOM. This study indicated that A210/A254 is an important parameter which could be used to estimate the DOM proportions of functional groups and conjugated carbon species. This study provided also an understanding of stormwater quality constituents through assessing variability and sensitivity for various parameters, and the additional information of rainfall characteristics on runoff quality data for a better understanding of parameter correlations and influences. PMID:27090716

  18. Removal of dissolved natural organic matter from source water with alum coagulation.

    PubMed

    Wang, C S; Kang, S F; Yang, H J; Pa, S Y; Chen, H W

    2002-12-01

    In this study, the effectiveness of enhanced alum coagulation for removal of natural organic matter (NOM) at various alum dosages and pH conditions was assessed for three source waters. Results from the laboratory jar tests at various conditions were compared. Tested pH ranged from 5.0 to 8.0, with alum dosages ranging from 60-120 mg l(-1) for removal of dissolved NOM with various concentration of dissolved organic carbon (DOC) and alkalinity. Alum coagulation profiles of the three source waters were also compared. For Cheng-Kung Water Treatment Plant (high DOC, high alkalinity), laboratory tests showed 50% DOC removal with alum dosage of 70-110 mg (-1). after acidifying the raw water to pH = 6. For Tai Lake Water Treatment Plant (high DOC, low alkalinity), laboratory tests showed that the highest DOC removal (approximately 50%) was achieved at an alum dosage of 80 mg l(-1) at pH = 8 (natural condition). However, alum coagulation showed little DOC removal for source water from Kee-Lung River (low DOC, low alkalinity). Higher alkalinity in Cheng-Kung Reservoir accounts for the necessity to acidify the raw water before enhanced coagulation for optimum DOC removal. PMID:12523512

  19. Removal of fluorescence and ultraviolet absorbance of dissolved organic matter in reclaimed water by solar light.

    PubMed

    Wu, Qianyuan; Li, Chao; Wang, Wenlong; He, Tao; Hu, Hongying; Du, Ye; Wang, Ting

    2016-05-01

    Storing reclaimed water in lakes is a widely used method of accommodating changes in the consumption of reclaimed water during wastewater reclamation and reuse. Solar light serves as an important function in degrading pollutants during storage, and its effect on dissolved organic matter (DOM) was investigated in this study. Solar light significantly decreased the UV254 absorbance and fluorescence (FLU) intensity of reclaimed water. However, its effect on the dissolved organic carbon (DOC) value of reclaimed water was very limited. The decrease in the UV254 absorbance intensity and FLU excitation-emission matrix regional integration volume (FLU volume) of reclaimed water during solar light irradiation was fit with pseudo-first order reaction kinetics. The decrease of UV254 absorbance was much slower than that of the FLU volume. Ultraviolet light in solar light had a key role in decreasing the UV254 absorbance and FLU intensity during solar light irradiation. The light fluence-based removal kinetic constants of the UV254 and FLU intensity were independent of light intensity. The peaks of the UV254 absorbance and FLU intensity with an apparent molecular weight (AMW) of 100Da to 2000Da decreased after solar irradiation, whereas the DOC value of the major peaks did not significantly change. PMID:27155416

  20. Radioacarbon in dissolved organic carbon, a possible groundwater dating method: Case studies from western Canada

    SciTech Connect

    Wassenaar, L.; Aravena, R. ); Hendry, J. ); Fritz, P. )

    1991-08-01

    This paper explores the feasibility of using {sup 14}C in dissolved organic carbon (DOC) as an alternative isotopic groundwater dating method. Two hydrogeologically contrasting groundwater systems were tested; the Cretaceous age Milk River aquifer, and low-permeability, organic rich, Wisconsinan age Prairie tills in southern Alberta, Canada. Comparisons of radiocarbon data were made between DOC fractions, dissolved inorganic carbon (DIC), and several DIC geochemical age correction models along well defined flow paths. The data presented demonstrate that {sup 14}C dating of DOC fractions can indeed provide an alternative method for determining isotopic groundwater ages, under suitable conditions. However, detailed information may be required regarding (1) the geologic nature of the aquifer and its flow system, (2) the isotopically conservative behavior of DOC, (3) the initial {sup 14}C activity of DOC in recharge, and (4) the effect of bacterial redox processes on the {sup 14}C activity of DOC. In the Milk River aquifer, DOC {sup 14}C ages were successfully used to estimate groundwater residence times, as well as to further refine input parameter assumptions for the DIC method. In the Prairie tills, DOC {sup 14}C ages were used to establish a maximum age for the pore waters in an environment where the DIC method is especially problematic.

  1. Controls on the dynamics of dissolved organic matter in boreal lakes

    NASA Astrophysics Data System (ADS)

    Kothawala, Dolly; Kellerman, Anne; Catalan, Nuria; Tranvik, Lars

    2016-04-01

    The reactivity of dissolved organic matter (DOM) strongly influences the biogeochemical cycling of key nutrients including carbon and nitrogen. Dissolved organic nitrogen (DON) comprises a small, yet functionally important, fraction of total DOM in boreal lakes. This pool of DON can influence the fate of total DOM by catalyzing microbial degradation pathways, or alternatively being less reactive to photo-degradation. Upon mineralization, it may also constitute an important nutrient for planktonic primary producers. By examining the optical and detailed molecular characteristics of DOM from several hundred lakes spanning a 13 degree latitude gradient across Sweden, we found that the molecular composition of DOM was influenced primarily by the water residence time of lakes, followed by mean annual temperature, which spanned from -6.1 to 6.5 degrees C, from north to south, respectively. Land cover across Sweden is typical of the boreal zone, being comprised of primarily forest and wetland cover; however, at this large spatial scale, land cover did not influence the molecular composition of DOM. We discuss how these results provide insight into predicting the relative influence of climatic, hydrological and catchment characteristics on the fate of DOM under a changing climate. In particular, we explore how DON constituents play a pivotal role in the overall chemical diversity of DOM and how this diversity ultimately drives its reactivity or persistence through freshwaters.

  2. [Impact of dissolved organic matter on plant uptake of phenanthrene and its mechanisms].

    PubMed

    Zhan, Xin-hua; Zhou, Li-xiang; Wan, Yin-jing; Jiang, Ting-hui

    2006-09-01

    Hydroponic assays were conducted to investigate the influence of dissolved organic matter on uptake of phenanthrene by wheat as well as its mechanisms. The results showed that, under hydroponic condition, phenanthrene impairment of plant growth occurred with wheat growth inhibited rate of 18.01%. The impairment would be greatly enhanced in the presence of dissolved organic matter (DOM) derived from pig manure, and the inhibited rate increased to 24.38%. Wheat could uptake and accumulate phenanthrene in the nutrient solution, which could be escalated by DOM, as indicated by wheat root bioconcentration factor being increased to 37.63 L x kg(-1) in the presence of DOM from 2.84 L x kg(-1) in the absence of DOM. At the same time, DOM could facilitate phenanthrene translocation from plant roots to the upper. As a result, the pH value of nutrient solution could increase by more than 1 unit when the co-existence of DOM and phenanthrene occurred in solution, suggesting that H+ -phenanthrene cotransport system is involved in the uptake of phenanthrene by plants. A synergism was also found between wheat uptakes of phenanthrene and inorganic nutrients, Moreover, DOM accelerated markedly the synergism. It is concluded that DOM affects the uptake of phenanthrene by plants and the environmental behaviors of phenanthrene. PMID:17117650

  3. Transformation of dissolved organic matter in a novel groundwater recharge system with reclaimed water.

    PubMed

    Wu, Linlin; Zhao, Xuan; Zhang, Meng

    2011-12-01

    A novel process, enhanced direct injection-well recharge system (EnDir), can overcome the technical difficulties during the application of conventional surface spreading and has been developed to recharge groundwater with reclaimed water. In this study, removal and transformation of dissolved organic matter (DOM) in the system were investigated in laboratory-scale experiments. Results demonstrated that dissolved organic carbon and trihalomethane formation potential values could be reduced from 6.54 +/- 1.30 mg/L and 267.9 +/- 24.3 microg/L to 1.59 +/- 0.64 mg/L and 104.5 +/- 10.2 microg/L, respectively, as a result of DOM biodegradation in the aerobic short-term vadose soil treatment. Fluorescence spectra showed that aromatic protein-like substances and soluble microbial byproducts could be removed, to a great extent, in the soil system. Despite different removal efficiencies of DOM in different molecular weight fractions, the residual DOM was composed mainly of fulvic acid-like and humic acid-like substances, with molecular weights of 500 Da to 1 kDa. PMID:22368955

  4. Identification of Reactive and Refractory Components of Dissolved Organic Nitrogen by FT-ICR Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Cooper, W. T.; Podgorski, D. C.; Osborne, D. M.; Corbett, J.; Chanton, J.

    2010-12-01

    Dissolved organic nitrogen is an often overlooked but potentially significant bioavailable component of dissolved organic matter. Studies of bulk DON turnover have been reported, but the compositions of the reactive and refractory components of DON are largely unknown. Here we show the unique ability of atmospheric pressure photoionization (APPI) coupled to ultrahigh resolution mass spectrometry to identify the reactive and refractory components of DON. Figure 1 is an isolated 0.30 m/z window from an ultrahigh resolution APPI FT-ICR mass spectrum of DON in surface waters draining an agricultural area in South Florida. Using this optimized, negative-ion APPI strategy we have been able to identify the reactive and refractory components of DON in these nitrogen-rich waters. Similar results were observed with samples from soil porewaters in sedge-dominated fens and sphagnum-dominated bogs within the Glacial Lake Agassiz Peatlands (GLAP) of northern Minnesota. Surprisingly, microbes appear to initially use similar enzymatic pathways to degrade DON and DOC, often with little release of nitrogen. Figure 1. Isolated 0.30 m/z window at nominal mass 432 from negative-ion APPI FT-ICR mass spectrum of DOM from waters draining an agricultural area in South Florida. Peaks marked contain nitrogen.

  5. Geomorphic controls on riparian zone hydrology, carbon pools and fluxes of dissolved organic carbon

    NASA Astrophysics Data System (ADS)

    Grabs, T.; Ledesma, J.; Laudon, H.; Seibert, J.; Kohler, S. J.; Bishop, K. H.

    2014-12-01

    Near stream (riparian) zones are an important link between terrestrial and aquatic ecosystems and influence a wide range of processes including solute transport or hydrologic behavior of headwater catchments. Understanding the links between geomorphology and riparian soils, vegetation and hydrology is, thus, a prerequisite for relating small scale processes to observations at the watershed scale. Geographic information systems (GIS) have traditionally been used to study links between geomorphology and properties of terrestrial ecosystems. Applying this approach to riparian zones, however, has only recently become feasible with the availability of high-resolution digital elevation models and the new development of suitable computational methods. In this study we present links between geomorphology and riparian zone hydrology, carbon pools and fluxes of dissolved organic carbon. Geomorphometric attributes were successfully used to predict (1) riparian groundwater levels and flow pathways, (2) the size of riparian soil carbon pools, (3) the vertical variation of dissolved organic carbon (DOC) in riparian soil profiles, as well as (4) riparian carbon fluxes and turnover times.

  6. Dissolved organic matter in the Florida everglades: Implications for ecosystem restoration

    USGS Publications Warehouse

    Aiken, G.R.; Gilmour, C.C.; Krabbenhoft, D.P.; Orem, W.

    2011-01-01

    Dissolved organic matter (DOM) in the Florida Everglades controls a number of environmental processes important for ecosystem function including the absorption of light, mineral dissolution/precipitation, transport of hydrophobic compounds (e.g., pesticides), and the transport and reactivity of metals, such as mercury. Proposed attempts to return the Everglades to more natural flow conditions will result in changes to the present transport of DOM from the Everglades Agricultural Area and the northern conservation areas to Florida Bay. In part, the restoration plan calls for increasing water flow throughout the Everglades by removing some of the manmade barriers to flow in place today. The land- and water-use practices associated with the plan will likely result in changes in the quality, quantity, and reactivity of DOM throughout the greater Everglades ecosystem. The authors discuss the factors controlling DOM concentrations and chemistry, present distribution of DOM throughout the Everglades, the potential effects of DOM on key water-quality issues, and the potential utility of dissolved organic matter as an indicator of success of restoration efforts. Copyright ?? 2011 Taylor & Francis Group, LLC.

  7. Efficient removal of recalcitrant deep-ocean dissolved organic matter during hydrothermal circulation

    NASA Astrophysics Data System (ADS)

    Hawkes, Jeffrey A.; Rossel, Pamela E.; Stubbins, Aron; Butterfield, David; Connelly, Douglas P.; Achterberg, Eric P.; Koschinsky, Andrea; Chavagnac, Valérie; Hansen, Christian T.; Bach, Wolfgang; Dittmar, Thorsten

    2015-11-01

    Oceanic dissolved organic carbon (DOC) is an important carbon pool, similar in magnitude to atmospheric CO2, but the fate of its oldest forms is not well understood. Hot hydrothermal circulation may facilitate the degradation of otherwise un-reactive dissolved organic matter, playing an important role in the long-term global carbon cycle. The oldest, most recalcitrant forms of DOC, which make up most of oceanic DOC, can be recovered by solid-phase extraction. Here we present measurements of solid-phase extractable DOC from samples collected between 2009 and 2013 at seven vent sites in the Atlantic, Pacific and Southern oceans, along with magnesium concentrations, a conservative tracer of water circulation through hydrothermal systems. We find that magnesium and solid-phase extractable DOC concentrations are correlated, suggesting that solid-phase extractable DOC is almost entirely lost from solution through mineralization or deposition during circulation through hydrothermal vents with fluid temperatures of 212-401 °C. In laboratory experiments, where we heated samples to 380 °C for four days, we found a similar removal efficiency. We conclude that thermal degradation alone can account for the loss of solid-phase extractable DOC in natural hydrothermal systems, and that its maximum lifetime is constrained by the timescale of hydrothermal cycling, at about 40 million years.

  8. Dissolved Organic Matter in Arctic and Boreal Streams: Rates and Fates of Decomposition

    NASA Astrophysics Data System (ADS)

    Mutschlecner, A.; Harms, T.

    2015-12-01

    As high-latitude regions warm, new inputs of carbon from thawing permafrost may influence the carbon cycle. Some of this newly released carbon, bound up in molecules of dissolved organic matter (DOM), will be exported into streams and rivers where it may be incorporated into microbial biomass, released to the atmosphere as carbon dioxide, or exported downstream. The factors that control the fate of dissolved organic carbon (DOC) are not fully understood, nor are the seasonal and spatial dynamics of these relationships. We sampled six streams along an arctic-boreal gradient in interior Alaska, collecting water from under ice in April, during snowmelt (May), and in early summer (June). These samples were incubated in the laboratory to determine the fraction of DOC that is susceptible to microbial decomposition and the fraction released as carbon dioxide. Nitrogen and phosphorous additions were used to determine the effect of nutrient limitation on DOC processing. Percent DOC loss across sites ranged from 37-71% in April before snowmelt, 0-9% during snowmelt, and 0-53% in June. We observed no effect of nutrient addition on lability of DOC. Seasonal data are critical to predicting how the processing of DOC in streams will respond to changes in permafrost extent, as well as to changes in the timing of snowmelt and ice-off.

  9. The Photodegradation of Ibuprofen and Dissolved Organic Matter in Lake Superior and St. Louis River Water

    PubMed Central

    Moynan, Angela B.

    2012-01-01

    Abstract Ibuprofen can enter bodies of water via waste water treatment. The question was what effect does photodegradation have on ibuprofen and dissolved organic matter (DOM) in Lake Superior (oligiotrophic) and St. Louis (tannic stained) River water? Ibuprofen concentrations of 15,000, 30,000, and 60,000 μg/L were made from lake, river, and distilled water, as well as additional distilled concentrations of 7,500 and 120,000 μg/L. Half of the eighty-four trial cups were placed in an ultraviolet light cabinet and half of the set were placed in a dark cabinet for three days. After the exposure period, a UV-Vis was performed to measure change in molar mass and the summed absorbance of colored dissolved organic matter (CDOM). It appears that ibuprofen decreases in molar mass after exposure to light in distilled and lake water with 15,000 μg/L of ibuprofen. Surprisingly, the molar mass of DOM in river water increases after UV exposure. Possibly, this occurred because the river water has such a high molar mass of DOM and was not filtered. Microbial biomass could also have contributed to this increase. Ibuprofen entering bodies of water via the waste water treatment system appears to be affected by UV light exposure, but in different ways. PMID:23244688

  10. The photodegradation of ibuprofen and dissolved organic matter in Lake Superior and St. Louis River water.

    PubMed

    Moynan, Angela B; Welsh, Cynthia A

    2012-12-01

    Ibuprofen can enter bodies of water via waste water treatment. The question was what effect does photodegradation have on ibuprofen and dissolved organic matter (DOM) in Lake Superior (oligiotrophic) and St. Louis (tannic stained) River water? Ibuprofen concentrations of 15,000, 30,000, and 60,000 μg/L were made from lake, river, and distilled water, as well as additional distilled concentrations of 7,500 and 120,000 μg/L. Half of the eighty-four trial cups were placed in an ultraviolet light cabinet and half of the set were placed in a dark cabinet for three days. After the exposure period, a UV-Vis was performed to measure change in molar mass and the summed absorbance of colored dissolved organic matter (CDOM). It appears that ibuprofen decreases in molar mass after exposure to light in distilled and lake water with 15,000 μg/L of ibuprofen. Surprisingly, the molar mass of DOM in river water increases after UV exposure. Possibly, this occurred because the river water has such a high molar mass of DOM and was not filtered. Microbial biomass could also have contributed to this increase. Ibuprofen entering bodies of water via the waste water treatment system appears to be affected by UV light exposure, but in different ways. PMID:23244688

  11. [Linking optical properties of dissolved organic matter with NDMA formation potential in the Huangpu River].

    PubMed

    Dong, Qian-Qian; Zhang, Ai; Li, Yong-Mei; Chen, Ling; Huang, Qing-Hui

    2014-03-01

    Surface water samples from the Huangpu River were filtered to measure the UV absorption and fluorescence spectrum. Dissolved organic carbon (DOC), N-nitrosodimethylamine (NDMA), and its formation potential (NDMA-FP) were also analyzed to explore relationships between the properties of dissolved organic matter (DOM) and the formation potential of disinfection byproducts-NDMA in the Huangpu River. The study found that: NDMA-FP concentration increased with the increasing of DOC concentration (r = 0.487, P < 0.01), but it had negative relationships with SUVA254 and HIX (r = -0.605, P < 0.01; r = -0.396, P < 0.01). NDMA-FP concentration had positive relationships with the fluorescence intensity of protein-like substances such as low-molecular-weight (LMW) tyrosine-like and tryptophan-like substances (r = 0.421, P < 0.01; r = 0.426, P < 0.01), but had a negative relationship with humic-like substance (r = -0.422, P < 0.01). Therefore, NDMA formation potential increases with the increasing DOM content in the Huangpu River, which is significantly related with the protein-like substances, but decreases with the increasing aromaticity and humification of DOM. PMID:24881383

  12. Transformation of dissolved organic matters in swine, cow and chicken manures during composting.

    PubMed

    Wang, Ke; Li, Xiangkun; He, Chao; Chen, Chia-Lung; Bai, Jianwei; Ren, Nanqi; Wang, Jing-Yuan

    2014-09-01

    The changes of dissolved organic matters (DOMs) extracted from swine, cow and chicken manures were assessed by Fourier transform infrared, ultraviolet, gel permeation chromatography (GPC), excitation-emission-matrix fluorescence (EEM-FL), Biolog Eco and (1)H NMR during 60-day composting. Pumice was adopted to eliminate the disturbing of common organic bulking agents. The results showed chicken manure had the highest DOC, DTN (dissolved total nitrogen) and lowest DOC/DTN among the three manures; cow manure had the highest volatile solids, lowest DTN, slowest DOMs hydrolysis rate and the fastest bio-stabilization rate. (1)H NMR showed the decrease rates of OC band and saturated carbon chain were distinctly faster than that of olefinic and aromatic structures. The molecular size distribution of DOMs in the three manures was in the range of 1-10 kDa detected by GPC. Microbial carbon utilization capacity decreased in cow manure with composting time, but the contrast was observed in the chicken and swine manures. PMID:24813566

  13. The river as a chemostat: fresh perspectives on dissolved organic matter flowing down the river continuum

    USGS Publications Warehouse

    Creed, Irena F.; McKnight, Diane M.; Pellerin, Brian; Green, Mark B.; Bergamaschi, Brian; Aiken, George R.; Burns, Douglas A.; Findlay, Stuart E G; Shanley, James B.; Striegl, Rob; Aulenbach, Brent T.; Clow, David W.; Laudon, Hjalmar; McGlynn, Brian L.; McGuire, Kevin J.; Smith, Richard A.; Stackpoole, Sarah M.

    2015-01-01

    A better understanding is needed of how hydrological and biogeochemical processes control dissolved organic carbon (DOC) concentrations and dissolved organic matter (DOM) composition from headwaters downstream to large rivers. We examined a large DOM dataset from the National Water Information System of the US Geological Survey, which represents approximately 100 000 measurements of DOC concentration and DOM composition at many sites along rivers across the United States. Application of quantile regression revealed a tendency towards downstream spatial and temporal homogenization of DOC concentrations and a shift from dominance of aromatic DOM in headwaters to more aliphatic DOM downstream. The DOC concentration–discharge (C-Q) relationships at each site revealed a downstream tendency towards a slope of zero. We propose that despite complexities in river networks that have driven many revisions to the River Continuum Concept, rivers show a tendency towards chemostasis (C-Q slope of zero) because of a downstream shift from a dominance of hydrologic drivers that connect terrestrial DOM sources to streams in the headwaters towards a dominance of instream and near-stream biogeochemical processes that result in preferential losses of aromatic DOM and preferential gains of aliphatic DOM.

  14. Hydrologic Controls on Dissolved Organic Matter Mobilization and Transport within Undisturbed Soils

    NASA Astrophysics Data System (ADS)

    Xu, N.; Saiers, J.

    2007-12-01

    Dissolved organic matter (DOM) in soils plays an important role in the transport of nutrients and contaminants through the terrestrial environment. Subsurface pathways deliver a significant portion of carbon to streams that drain forested and agricultural watersheds. Although the importance of rainfall events to the DOM soil-water flux is well known, the hydrologic factors that govern this flux have not been fully examined. The primary purpose of this study is to investigate the soil and rainfall characteristics controlling the mobilization and transport of DOM in undisturbed soils. Intact soil columns including topsoil and subsoil layers were taken from the Harvard forest in Petersham, MA. Unsaturated flow conditions were maintained by applying suction to the bottom of the soil columns. The columns were irrigated by series of interrupted rainfall events using the same total volume of artificial rain water. Preliminary experiments showed continuous leaching of DOM (measured by dissolved organic carbon) with an initial peak in concentration that coincided with the passage of the wetting front. The leached DOM was also characterized by UV absorbance, fluorescence spectroscopy in the emission mode, and additional spectroscopic derived indexes such as the humification index. Ongoing column experiments are focusing on the effects of rainfall intensity, frequency, and rainfall history on DOM mobilization and transport through natural, structured soils. These investigations can elucidate the influence of factors that are associated with climate change on DOC dynamics. Results of our analyses should also provide insight into the mechanisms that govern DOM mobilization in soils.

  15. Investigating extent of dissolved organic carbon stabilization by metal based coagulant in a wetland environment

    NASA Astrophysics Data System (ADS)

    Henneberry, Y.; Mourad, D.; Kraus, T.; Bachand, P.; Fujii, R.; Horwath, W.

    2008-12-01

    This study is part of a larger project designed to investigate the feasibility of using metal-based coagulants to remove dissolved organic carbon (DOC) from island drainage water in the San Joaquin Delta and subsequently retaining the metal-DOC precipitate (floc) in wetlands constructed at the foot of levees to promote levee stability. Dissolved organic carbon is a constituent of concern as some forms of DOC can be converted to carcinogenic compounds during drinking water treatment. The focus of this work is to assess floc stability over time and to determine whether floc can be permanently sequestered as part of wetland sediment. Drainage water collected seasonally from Twitchell Island was coagulated with ferric sulfate and polyaluminum chloride at optimal and 50%-optimal dosage levels. Floc was incubated in the laboratory under anaerobic conditions for six weeks under various conditions including different DOC concentrations, microbial inoculants, and addition of nutrients. Preliminary results indicate the floc is a stable system; little to no DOC was released from the floc into the water column under incubations with native microbial inoculate. In addition, floc incubated with previously coagulated water appeared to remove additional DOC from the water column. Future work will involve field and laboratory studies using 13C labeled plant material to examine the effects of fresh plant matter and the effects of peat soil DOC on floc stability, in order to elucidate mechanisms behind carbon stabilization by metal-based floc.

  16. The contribution of macroalgae to the coastal dissolved organic matter pool

    NASA Astrophysics Data System (ADS)

    Wada, Shigeki; Hama, Takeo

    2013-09-01

    Dissolved organic matter (DOM) in coastal environments has various origins; one of the most intensely studied sources is terrestrial DOM input via rivers. On the other hand, contributions from other significant DOM sources, such as macroalgae, to the coastal DOM pool have not been extensively studied. The present study quantified the contribution of macroalgae to the DOM pool in the coastal environment using, firstly, a bag-covering experiment on a brown alga, Ecklonia cava, and identifying fluorescent DOM components by parallel factor analysis of three-dimensional excitation-emission matrix spectra. Using the fluorescent DOM as an indicator, we evaluated the horizontal distribution of macroalgal DOM in the coastal area, showing that the fluorescent DOM component had a synchronous gradient with dissolved organic carbon (DOC) concentrations along the transect line from the coast to offshore. On the basis of the correlation between DOC and fluorescent DOM, we evaluated concentrations of DOC originating from macroalgae, accounting for up to 20% of total DOC concentrations. This implies that in contrast to previous studies, macroalgae do make a measurable contribution to the coastal DOM pool.

  17. Distinct Optical Chemistry of Dissolved Organic Matter in Urban Pond Ecosystems

    PubMed Central

    McEnroe, Nicola A.; Williams, Clayton J.; Xenopoulos, Marguerite A.; Porcal, Petr; Frost, Paul C.

    2013-01-01

    Urbanization has the potential to dramatically alter the biogeochemistry of receiving freshwater ecosystems. We examined the optical chemistry of dissolved organic matter (DOM) in forty-five urban ponds across southern Ontario, Canada to examine whether optical characteristics in these relatively new ecosystems are distinct from other freshwater systems. Dissolved organic carbon (DOC) concentrations ranged from 2 to 16 mg C L-1 across the ponds with an average value of 5.3 mg C L-1. Excitation-emission matrix (EEM) spectroscopy and parallel factor analysis (PARAFAC) modelling showed urban pond DOM to be characterized by microbial-like and, less importantly, by terrestrial derived humic-like components. The relatively transparent, non-humic DOM in urban ponds was more similar to that found in open water, lake ecosystems than to rivers or wetlands. After irradiation equivalent to 1.7 days of natural solar radiation, DOC concentrations, on average, decreased by 38% and UV absorbance decreased by 25%. Irradiation decreased the relative abundances of terrestrial humic-like components and increased protein-like aspects of the DOM pool. These findings suggest that high internal production and/or prolonged exposure to sunlight exerts a distinct and significant influence on the chemistry of urban pond DOM, which likely reduces its chemical similarity with upstream sources. These properties of urban pond DOM may alter its biogeochemical role in these relatively novel aquatic ecosystems. PMID:24348908

  18. Seasonal and temporal characterization of dissolved organic matter in rainwater by proton nuclear magnetic resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Seaton, Pamela J.; Kieber, Robert J.; Willey, Joan D.; Avery, G. Brooks; Dixon, Joshua L.

    2013-02-01

    Dissolved organic carbon in rainwater was concentrated by two separate techniques and characterized by 1H-NMR. The total 1H-NMR integral of lyophilized rainwater was higher in every rain sample than that of C18 solid phase extracted samples and always contained a higher percentage integral in the region of protons bound to carbon atoms singly bound to oxygen (H-C-O), such as alcohols, polyols and carbohydrate-like compounds. C18 extracted samples had higher % integral in the alkyl region, consistent with reverse phase extraction of more hydrophobic components in rainwater. Differences in both the 1H-NMR integration and spectral pattern of lyophilized rainwater samples were especially apparent between spring and winter rains, with spring samples having higher percent carbohydrate (H-C-O) signal and winter rains having higher percent alkyl protons and a spectral pattern consistent with the presence of saturated fatty acids. Spring rains are characterized by lower % Alkyl signal coupled with higher % H-C-O than all other events while marine winter events appear in regions characterized by relatively high % Alkyl and average % H-C-O, consistent with increased abundance of fatty acids or fatty acid oxidation products. The 1H-NMR data presented in this manuscript are important because they provide spectral data relating to the source and chemical characteristics of dissolved organic carbon in rainwater as a function of season and air mass back trajectory.

  19. Headspace analysis: A new application for isotopic characterization of dissolved organic contaminants

    SciTech Connect

    Slater, G.F.; Dempster, H.S.; Lollar, B.S.; Ahad, J.

    1999-01-01

    Petroleum products and industrial solvents are among the most ubiquitous contaminants of soil and groundwater and the source of several common and hazardous volatile organic chemicals (VOCs). Volatilization is a key determinant of the fate of VOCs in the subsurface environment, impacting contaminant partitioning between the aqueous, gaseous, and nonaqueous liquid phases. This study uses stable carbon isotope analysis to investigate the isotopic effects involved in volatilization of trichloroethylene (TCE) and toluene from both free product (or pure phase) and aqueous solutions. Results indicate that, during volatilization from the aqueous phase and from free product, the isotopic composition of TCE and toluene remains unchanged within reproducibility limits. These results have two important implications for contaminant hydrogeology. First, they suggest that carbon isotopic signatures may be useful in tracing contaminant transport between the vapor, aqueous, and NAPL phases since they remain conservative during phase changes. Second, they demonstrate the utility of headspace extraction (sampling of the vapor phase or headspace above an aqueous solution) as a preparatory technique for isotopic analysis of dissolved VOCs. Headspace isotopic analysis provides a straightforward and rapid technique for {delta}{sup 13}C analysis of dissolved organic contaminants at concentrations as low as hundreds of ppb.

  20. Quantifying and correcting the impacts of freezing samples on dissolved organic matter absorbance

    NASA Astrophysics Data System (ADS)

    Griffin, C. G.; McClelland, J. W.; Frey, K. E.; Holmes, R. M.

    2012-12-01

    The use of optical measurements as proxies for organic matter concentration and composition has become increasingly popular in recent years. Absorbance of chromophoric dissolved organic matter (CDOM) can be used to estimate concentrations of dissolved organic carbon (DOC), as a qualitative assessment of dissolved organic matter (DOM) average molecular weight and is often used to calibrate satellite remote sensing of organic matter. However, there is evidence that preservation of samples can lead to significant changes in CDOM absorbance spectra. Freezing is a popular means of preservation, but can result in flocculation of DOM when samples are thawed for analysis. We hypothesize that the particles generated as a result of a freeze/thaw cycle lead to increasing absorption in visible wavelengths (400-800 nm). Yet, absorbance in the UV spectra should remain similar to original values. These hypotheses are tested on CDOM spectra collected from two large Arctic watersheds (the Mackenzie and Yukon rivers) and four smaller Texas watersheds (the Colorado, Guadalupe, Nueces and San Antonio rivers). In addition, we experiment with additional filtering and sonication to correct for flocculation from frozen samples. Preliminary data show that short wavelengths are relatively well preserved (200-300 nm). However, CDOM absorption changes unpredictably from 350-450 nm, the wavelengths most commonly used to estimate DOC. Absorption coefficients tend to be higher in these wavelengths after a freeze/thaw cycle, but the magnitude of this increase varies. Some of these impacts can be corrected for with sonication. For instance, when comparing experimental treatments to initial absorption at 365 nm from Mackenzie River samples, R2 increases from 0.60 to 0.79 for samples undergoing one freeze/thaw cycle to those that were also sonicated. Regardless of treatment, however, no spectral slopes were well preserved after a freeze/thaw cycle. These results reinforce earlier work that it is

  1. Molecular evidence for abiotic sulfurization of dissolved organic matter in marine shallow hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Gomez-Saez, Gonzalo V.; Niggemann, Jutta; Dittmar, Thorsten; Pohlabeln, Anika M.; Lang, Susan Q.; Noowong, Ann; Pichler, Thomas; Wörmer, Lars; Bühring, Solveig I.

    2016-10-01

    Shallow submarine hydrothermal systems are extreme environments with strong redox gradients at the interface of hot, reduced fluids and cold, oxygenated seawater. Hydrothermal fluids are often depleted in sulfate when compared to surrounding seawater and can contain high concentrations of hydrogen sulfide (H2S). It is well known that sulfur in its various oxidation states plays an important role in processing and transformation of organic matter. However, the formation and the reactivity of dissolved organic sulfur (DOS) in the water column at hydrothermal systems are so far not well understood. We investigated DOS dynamics and its relation to the physicochemical environment by studying the molecular composition of dissolved organic matter (DOM) in three contrasting shallow hydrothermal systems off Milos (Eastern Mediterranean), Dominica (Caribbean Sea) and Iceland (North Atlantic). We used ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) to characterize the DOM on a molecular level. The molecular information was complemented with general geochemical data, quantitative dissolved organic carbon (DOC) and DOS analyses as well as isotopic measurements (δ2H, δ18O and F14C). In contrast to the predominantly meteoric fluids from Dominica and Iceland, hydrothermal fluids from Milos were mainly fed by recirculating seawater. The hydrothermal fluids from Milos were enriched in H2S and DOS, as indicated by high DOS/DOC ratios and by the fact that >90% of all assigned DOM formulas that were exclusively present in the fluids contained sulfur. In all three systems, DOS from hydrothermal fluids had on average lower O/C ratios (0.26-0.34) than surrounding surface seawater DOS (0.45-0.52), suggesting shallow hydrothermal systems as a source of reduced DOS, which will likely get oxidized upon contact with oxygenated seawater. Evaluation of hypothetical sulfurization reactions suggests DOM reduction and sulfurization during seawater

  2. Characterization of water dissolved organic matter under woody vegetation patches in semi-arid Mediterranean soils.

    PubMed

    Cerdán, M; Sánchez-Sánchez, A; Jordá, J D; Amat, B; Cortina, J; Ruiz-Vicedo, N; El-Khattabi, M

    2016-05-15

    Woody patches in semiarid environments favor the establishment of other plants. Facilitation may be favored by an increase in soil fertility. Dissolved organic matter (DOM), is the most active fraction of soil organic matter and may contain compounds affecting plant establishment, as allelochemicals, hormone-like substances and metal carriers. However, information on DOM contents and composition in these environments is scarce. In this paper, we study the impact of woody patches on DOM in Stipa tenacissima L. steppes and discuss its implications for community dynamics. DOM under patch- and inter-patch areas, was analyzed for elemental composition, UV-Vis indices and organic acid content. Element concentration and composition in DOM, and organic acid concentration were similar in patch- and inter-patch areas. Yet, soils under patches were richer in DOC, aromatic species and organic acids (particularly fumaric acid) than soils in inter-patch areas. Dominant species affected organic matter concentration and quality in complex ways. Thus, patches dominated by Ephedra fragilis showed higher concentrations of TOC and aromatics than those dominated by other species. Rhamnus lycioides patches showed the highest accumulation of fumaric acid, which may contribute to its successful recruitment rate and expansion in the area. Our results show substantial differences in the amount and composition of DOM and specific compounds affecting soil functionality and plant dynamics. Further studies on the effects of such changes on seedling performance are needed to increase our understanding of plant-plant interactions in semiarid environments. PMID:26930307

  3. Advanced treatment of textile dyeing secondary effluent using magnetic anion exchange resin and its effect on organic fouling in subsequent RO membrane.

    PubMed

    Yang, Cheng; Li, Li; Shi, Jialu; Long, Chao; Li, Aimin

    2015-03-01

    Strict regulations are forcing dyeing factory to upgrade existing waste treatment system. In this study, advanced treatment of dyeing secondary effluent by magnetic anion exchange resin (NDMP) was investigated and compared with ultrafiltration (UF); NDMP as a pre-treatment of reverse osmosis (RO) was also studied. NDMP resin (20 mL/L) gave higher removal of dissolved organic carbon (DOC) (83.9%) and colority (94.9%) than UF with a cut-off of 10 kDa (only 48.6% and 44.1%, respectively), showing that NDMP treatment was effective to meet the stringent discharge limit of DOC and colority. Besides, NDMP resin (20 mL/L) as a pretreatment of RO increased the permeate flux by 12.5% and reduced irreversible membrane fouling by 6.6%, but UF pretreatment did not mitigate RO membrane fouling. The results of excitation-emission matrix fluorescence spectra and resin fractions showed that NDMP had more efficient removal than UF for transphilic acid and hydrophilic fraction, such as protein-like organic matters and soluble microbial products, which contributed to a significant proportion of RO membrane fouling. In sum, NDMP resin treatment not only gave effective removal of DOC and colority of dyeing secondary effluent, but exhibited some improvement for RO membrane flux and irreversible fouling. PMID:25463217

  4. Significant anaerobic production of fluorescent dissolved organic matter in the deep East Sea (Sea of Japan)

    NASA Astrophysics Data System (ADS)

    Kim, Jeonghyun; Kim, Guebuem

    2016-07-01

    The distribution of fluorescent dissolved organic matter (FDOM) in the East Sea (Sea of Japan) was examined by excitation-emission matrix spectroscopy with parallel factor analysis (PARAFAC). Humic-like FDOM (FDOMH) increased with depth and was significantly correlated with Apparent Oxygen Utilization (AOU), indicating that FDOMH in the deep water is mainly produced by oxidation of organic matter. In addition, a surprisingly large excess of FDOMH relative to that expected from the observed AOU was found from 1000 m to the bottom (up to 3500 m). Based on the high-resolution geographical distribution and characteristics of FDOM in the East Sea, we conclude that this excess likely originates from anaerobic FDOMH production in subsurface bottom sediments. This FDOMH flux accounts for 8-15% of the total FDOM production in the water column. Our results suggest that anaerobic activities in subsurface sediments are an important hidden source of FDOM in the ocean.

  5. Effect of dissolved organic matter source on phytotoxicity to Lemna aequinoctialis.

    PubMed

    Shoji, Ryo

    2008-05-01

    The effect of dissolved organic matter (DOM) on metal toxicity to aquatic organisms has been reported. Biotic ligand model (BLM) can account for this factor to predict metal toxicity. However, few attempts have been made to assess the effect of the DOM on metal phytotoxicity to duckweeds. The objectives of this study were to examine the effect of DOM on copper toxicity to the duckweed Lemna aequinoctialis, and to determine if DOM concentration alone, regardless of DOM source, is an acceptable input parameter for the BLM for copper. Nine different DOM isolates from nine different sites in Japan were used in this study. A significant difference was observed between the lowest and the highest copper binding capacity. Phytotoxicity for copper decreased with increasing DOM concentration. These observations support use of the copper biotic ligand model (BLM) with AFA% (active fulvic acid percent) as a regulatory tool to predict copper phytotoxicity on duckweeds. PMID:18359523

  6. Adsorption and structural fractionation of dissolved organic matter (DOM) by soil mineral surfaces

    NASA Astrophysics Data System (ADS)

    Avneri, Shani; Polubesova, Tamara; Chefetz, Benny

    2015-04-01

    Dissolved organic matter (DOM) represents a small but highly reactive fraction of the soil organic matter (SOM). One of the important processes affecting the fate of DOM in soils is its interactions with mineral phases. Adsorptive fractionation of DOM by soils and minerals has been observed previously, however detailed changes in composition of DOM due to its interactions with mineral soils were not yet elucidated. In this research the adsorption and physico-chemical fractionation of DOM by soil poor with organic matter and rich with iron oxides and clay fraction was investigated. The changes in DOM structural composition were studied using separation with polymeric resins. The following fractions were obtained: hydrophobic acid (HoA), hydrophobic neutral (HoN), hydrophilic acid (HiA), hydrophilic base (HiB), and hydrophilic neutral (HiN). Two types of DOM were studied: DOM extracted from composted biosolids (compost DOM) and DOM from Suwanee River (SRNOM). Sorption affinity of DOM to soil mineral surfaces was source and chemistry dependent. SRNOM, which was characterized by higher content of aromatic and carboxylic groups demonstrated higher affinity to the studied soil than compost DOM. For both DOM samples preferential adsorption of HoA by soil (50-85% from adsorbed carbon) was observed. Desorption of both DOM types demonstrated significant hysteresis (up to 90-100% of dissolved organic carbon was retained by the soil after 3 cycles of desorption stages). This suggests that DOM desorption behavior was affected by HoA dominant adsorption to the soil mineral fraction, and not by DOM source. Results of this study indicate that interactions of different types of DOM with mineral soil may result in similar changes in composition and properties of DOM both in the supernatant as well as in the adsorbed phase. The change in DOM composition due to its interaction with soil minerals may influence the interactions of pollutants with DOM and soil particle surfaces.

  7. The Influence of Regional Groundwater on the Dissolved Organic Matter in Costa Rican Streams

    NASA Astrophysics Data System (ADS)

    Barnett, E.; Osburn, C. L.; Oviedo-Vargas, D.; Genereux, D. P.; Oberbauer, S. F.; Dierick, D.

    2015-12-01

    The aim of this study was to better understand the role of regional groundwater in stream organic matter in two tropical watersheds in Costa Rica. Dissolved organic matter (DOM) concentration, stable C isotopes, absorbance, and fluorescence were used to distinguish DOM sources in two adjacent watersheds, the Arboleda and the Taconazo, which are similar in size, soils, rainfall, and vegetation, yet differ because the Arboleda receives a significant input of regional groundwater that is chemically distinct from the local groundwater, whereas the Taconazo does not. Characteristics of the DOM differed largely among the two streams. Fluorescence and isotope data suggested that more degraded DOM was predominant during dry periods in the Arboleda due to the influence of regional groundwater in that stream. During wet periods, fresher soil-derived DOM was predominant in both streams, similar to the quality of DOM in the Taconazo during base flow. DOM δ13C values of the Arboleda during baseflow ranged from -23 to -34‰, while in the Taconazo values ranged from -25 to -34‰. During storm flow the ranges were smaller and more similar. The Taconazo ranged from -23 to -29‰ and the Arboleda ranged from -23 to -31‰. These differences were more noticeable at baseflow and during the dry season (December to April), suggesting that the DOM from regional groundwater entering the Arboleda had less of an impact when heavily diluted by soil DOM mobilized by precipitation. In both streams, during periods of heavy precipitation, DOM concentrations were much higher than during base flow. Further, at baseflow the Arboleda showed generally lower concentrations of dissolved organic carbon (DOC) than the Taconazo, yet export of DOC from the Arboleda watershed was far higher than from the Taconazo due to the large contribution by regional groundwater to the Arboleda water export. Results from this research emphasize the role of regional groundwater in shaping the quality of the organic

  8. Variable C : N : P stoichiometry of dissolved organic matter cycling in the Community Earth System Model

    DOE PAGESBeta

    Letscher, R. T.; Moore, J. K.; Teng, Y. -C.; Primeau, F.

    2014-06-16

    Dissolved organic matter (DOM) plays an important role in the ocean's biological carbon pump by providing an advective/mixing pathway for ~ 20% of export production. DOM is known to have a stoichiometry depleted in nitrogen (N) and phosphorus (P) compared to the particulate organic matter pool, a~fact that is often omitted from biogeochemical-ocean general circulation models. However the variable C : N : P stoichiometry of DOM becomes important when quantifying carbon export from the upper ocean and linking the nutrient cycles of N and P with that of carbon. Here we utilize recent advances in DOM observational data coveragemore » and offline tracer-modeling techniques to objectively constrain the variable production and remineralization rates of the DOM C / N / P pools in a simple biogeochemical-ocean model of DOM cycling. The optimized DOM cycling parameters are then incorporated within the Biogeochemical Elemental Cycling (BEC) component of the Community Earth System Model and validated against the compilation of marine DOM observations. The optimized BEC simulation including variable DOM C : N : P cycling was found to better reproduce the observed DOM spatial gradients than simulations that used the canonical Redfield ratio. Global annual average export of dissolved organic C, N, and P below 100 m was found to be 2.28 Pg C yr-1 (143 Tmol C yr-1), 16.4 Tmol N yr-1, and 1 Tmol P yr-1, respectively with an average export C : N : P stoichiometry of 225 : 19 : 1 for the semilabile (degradable) DOM pool. DOC export contributed ~ 25% of the combined organic C export to depths greater than 100 m.« less

  9. Characterization of Dissolved Organic Matter in the Northwest River and the Formation of THM

    NASA Astrophysics Data System (ADS)

    McKeon, K.; Dias, R. F.; Minor, E.

    2001-12-01

    Given recent health and legal issues surrounding trihalomethane (THM) spikes in the Hampton Roads and Chesapeake drinking water supplies, we investigated the molecular characteristics of dissolved organic carbon (DOC) in the Northwest River / Currituck Sound system in southeastern Virginia / North Carolina with respect to trihalomethane (THM) formation. Past studies of THM-formation potential have focused on the aromatic humic and fulvic acid components of DOC (XAD resin isolates), usually comprising less than 50-percent of all dissolved organic material. Using a stirred-cell filtration unit equipped with a 500 Da nominal cut-off membrane, we isolated DOM from three sites along the Northwest River (feeds the Chesapeake Treatment Plant) down to 500 Da with a recovery of better than 90-percent. The sampling sites were selected so as to represent the potential contributions of organic material at the treatment plant intake pipe with samples taken just above the intake pipe, at the mouth of the river as it empties into Currituck Sound and at a point half-way between the intake and the Sound. The DOM fractions were characterized by HPLC using RI and UV detectors and by Curie-point pyrolysis GCMS for molecular fingerprinting. Raw, filtered (0.2um) water samples were used for THM formation analysis. Pyrolysis-GCMS fingerprints of the DOM isolates show that waters above and below the intake pipe were more similar in organic composition, while water from the Sound potentially contained more algae, due to the presence of a homologous series of fatty acids. THM formation in the raw waters was consistent with more fresh water (chloroform only) at the intake pipe and more saline water at the Sound (brominated chloroforms).

  10. Inhibition of hydroxyl radical reaction with aromatics by dissolved natural organic matter

    USGS Publications Warehouse

    Lindsey, M.E.; Tarr, M.A.

    2000-01-01

    Reaction of aromatic compounds with hydroxyl radical is inhibited by dissolved natural organic matter (NOM). The degree of inhibition is significantly greater than that expected based on a simple model in which aromatic compound molecules bound to NOM are considered to be unreactive. In this study, hydroxyl radical was produced at steady-state concentrations using Fenton chemistry (H2O2 + Fe2+ ??? Fe3+ + HO- + HO??). Suwannee River fulvic acid and humic acid were used as NOM. The most likely mechanism for the observed inhibition is that hydroxyl radical formation occurs in microenvironmental sites remote from the aromatic compounds. In addition to changes in kinetics, pyrene hydroxyl radical reaction also exhibited a mechanistic change in the presence of fulvic acid. The mechanism changed from a reaction that was apparently firstorder in pyrene to one that was apparently secondorder in pyrene, indicating that pyrene self-reaction may have become the dominant mechanism in the presence of fulvic acid. Dissolved NOM causes significant changes in the rate and mechanism of hydroxyl radical degradation of aromatic compounds. Consequently, literature rate constants measured in pure water will not be useful for predicting the degradation of pollutants in environmental systems. The kinetic and mechanistic information in this study will be useful for developing improved degradation methods involving Fenton chemistry.Reaction of aromatic compounds with hydroxyl radical is inhibited by dissolved natural organic matter (NOM). The degree of inhibition is significantly greater than that expected based on a simple model in which aromatic compounds molecules bounds to NOM are considered to be unreactive. In this study, hydroxyl radical was produced at steady-state concentrations using Fenton chemistry (H2O2 + Fe2+ ??? Fe3+ + HO- + HO??). Suwannee River fulvic acid and humic acid were used as NOM. The most likely mechanisms for the observed inhibition is that hydroxyl radical

  11. Colored dissolved organic matter in shallow estuaries: relationships between carbon sources and light attenuation

    NASA Astrophysics Data System (ADS)

    Oestreich, W. K.; Ganju, N. K.; Pohlman, J. W.; Suttles, S. E.

    2016-02-01

    Light availability is of primary importance to the ecological function of shallow estuaries. For example, benthic primary production by submerged aquatic vegetation is contingent upon light penetration to the seabed. A major component that attenuates light in estuaries is colored dissolved organic matter (CDOM). CDOM is often measured via a proxy, fluorescing dissolved organic matter (fDOM), due to the ease of in situ fDOM sensor measurements. Fluorescence must be converted to CDOM absorbance for use in light attenuation calculations. However, this CDOM-fDOM relationship varies among and within estuaries. We quantified the variability in this relationship within three estuaries along the mid-Atlantic margin of the eastern United States: West Falmouth Harbor (MA), Barnegat Bay (NJ), and Chincoteague Bay (MD/VA). Land use surrounding these estuaries ranges from urban to developed, with varying sources of nutrients and organic matter. Measurements of fDOM (excitation and emission wavelengths of 365 nm (±5 nm) and 460 nm (±40 nm), respectively) and CDOM absorbance were taken along a terrestrial-to-marine gradient in all three estuaries. The ratio of the absorption coefficient at 340 nm (m-1) to fDOM (QSU) was higher in West Falmouth Harbor (1.22) than in Barnegat Bay (0.22) and Chincoteague Bay (0.17). The CDOM : fDOM absorption ratio was variable between sites within West Falmouth Harbor and Barnegat Bay, but consistent between sites within Chincoteague Bay. Stable carbon isotope analysis for constraining the source of dissolved organic matter (DOM) in West Falmouth Harbor and Barnegat Bay yielded δ13C values ranging from -19.7 to -26.1 ‰ and -20.8 to -26.7 ‰, respectively. Concentration and stable carbon isotope mixing models of DOC (dissolved organic carbon) indicate a contribution of 13C-enriched DOC in the estuaries. The most likely source of 13C-enriched DOC for the systems we investigated is Spartina cordgrass. Comparison of DOC source to CDOM : f

  12. Seasonal Variability in Dissolved Organic Matter Quantity and Composition from the Yukon River Basin

    NASA Astrophysics Data System (ADS)

    Spencer, R. G.; Aiken, G. R.; Wickland, K. P.; Striegl, R. G.; Hernes, P. J.

    2007-12-01

    The Yukon River basin (YRB) is one of the largest in North America draining an area of 855 x 103 km2 in northwestern Canada and central Alaska and is a major source of terrigenous organic matter to the eastern Bering Sea and Arctic Ocean. The Yukon is also a relatively pristine catchment draining a vast area of taiga that is exceptionally susceptible to climatic change. Dissolved organic matter (DOM) plays a fundamental role in ecosystem biogeochemistry and is ubiquitous in aquatic systems. Samples were collected over a five year period from 2001 to 2005 from a number of locations and at different points in the hydrologic regime throughout the YRB. Sample locations represented different locations on the mainstream of the Yukon River, as well as tributaries ranging from organic rich black waters draining permafrost impacted watersheds to those dominated by glacial melt waters and groundwater. Dissolved organic carbon (DOC) concentrations were observed to vary greatly from 1.5 to 26.1 mgCL-1 depending on source waters and time of year. Specific UV absorbance at 254 nm (SUVA) was also determined and ranged from to 1.3 to 4 highlighting the range in dissolved aromatic carbon content from different sources within the YRB. The hydrophobic acid (HPOA) fraction of the DOM was isolated from samples by XAD-8 resin adsorption for further investigation of DOM composition. The HPOA fraction represented 32 to 57 % of the total DOC for the range of samples studied. SUVA values from the HPOA fraction were higher than the unfractionated water samples (2.5 to 4.4) indicating a higher aromatic content for the HPOA fractions relative to the unfractionated DOM. However, the HPOA SUVA showed a good correlation to the unfractionated water samples SUVA (r2 = 0.84, p<0.01). Dissolved lignin phenols were measured on the HPOA fraction in order to trace vascular plant derived material. The ratios of different lignin phenols (e.g. syringyl to vanillyl; S:V and cinnamyl to vanillyl; C:V) can be

  13. Dissolved organic phosphorus (DOP) and its potential role for ecosystem nutrition

    NASA Astrophysics Data System (ADS)

    Brödlin, Dominik; Hagedorn, Frank; Kaiser, Klaus

    2016-04-01

    During ecosystem development and soil formation, primary mineral sources of phosphorus are becoming increasingly depleted. Inorganic phosphorus forms tend to be bound strongly to or within secondary minerals, thus, are hardly available to plants and are not leached from soil. What about organic forms of phosphorus? Since rarely studied, little is known about the fluxes of dissolved organic phosphorus (DOP) forms and their role in the P cycle. However, there is evidence that DOP is composed of some plant-derived organic phosphorus compounds, such as phytate, which are less mobile and prone to be sorbed to mineral surfaces, whereas microbial-derived compounds like nucleic acids and simple phospho-monoester may represent more mobile forms of soil phosphorus. In our study, we estimated fluxes, composition, and bioavailability of DOP along a gradient in phosphorus availability at five sites on silicate bedrock across Germany (Bad Brückenau, Conventwald, Vessertal, Mitterfels and Lüss) and at a calcareous site in Switzerland (Schänis). Soil solution was collected at 0 down to 60 to 150 cm soil depth at different intervals. Since most solutions had very low P concentrations (<0.05 mg total dissolved P/L), soil solutions had to be concentrated by freeze-drying for the enzymatic characterization of DOP. In order to test the potential bioavailability, we used an enzyme assay distinguishing between phytate-like P (phytate), diester-like P (nucleic acids), monoester-like P (glucose-6-phosphate), and pyrophosphate of bulk molybdate unreactive phosphorus (MUP). First results from the enzymatic assay indicated that monoester-like P and diester-like P were the most prominent form of the hydrolysable DOP constituents. In leachates from the organic layer, there was a high enzymatic activity for monoester-like P, indicating high recycling efficiency and rapid hydrolysis of labile DOP constituents. DOP was the dominating P form in soil solution at some of the sites, with a greater

  14. Molecular insights into the microbial formation of marine dissolved organic matter: recalcitrant or labile?

    NASA Astrophysics Data System (ADS)

    Koch, B. P.; Kattner, G.; Witt, M.; Passow, U.

    2014-08-01

    The degradation of marine dissolved organic matter (DOM) is an important control variable in the global carbon cycle. For our understanding of the kinetics of organic matter cycling in the ocean, it is crucial to achieve a mechanistic and molecular understanding of its transformation processes. A long-term microbial experiment was performed to follow the production of non-labile DOM by marine bacteria. Two different glucose concentrations and dissolved algal exudates were used as substrates. We monitored the bacterial abundance, concentrations of dissolved and particulate organic carbon (DOC, POC), nutrients, amino acids and transparent exopolymer particles (TEP) for 2 years. The molecular characterization of extracted DOM was performed by ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) after 70 days and after ∼2 years of incubation. Although glucose quickly degraded, a non-labile DOC background (5-9% of the initial DOC) was generated in the glucose incubations. Only 20% of the organic carbon from the algal exudate degraded within the 2 years of incubation. The degradation rates for the non-labile DOC background in the different treatments varied between 1 and 11 μmol DOC L-1 year-1. Transparent exopolymer particles, which are released by microorganisms, were produced during glucose degradation but decreased back to half of the maximum concentration within less than 3 weeks (degradation rate: 25 μg xanthan gum equivalents L-1 d-1) and were below detection in all treatments after 2 years. Additional glucose was added after 2 years to test whether labile substrate can promote the degradation of background DOC (co-metabolism; priming effect). A priming effect was not observed but the glucose addition led to a slight increase of background DOC. The molecular analysis demonstrated that DOM generated during glucose degradation differed appreciably from DOM transformed during the degradation of the algal exudates. Our

  15. Dissolved inorganic and organic nitrogen uptake in the coastal North Sea: A seasonal study

    NASA Astrophysics Data System (ADS)

    Moneta, Alessia; Veuger, Bart; van Rijswijk, Pieter; Meysman, Filip; Soetaert, Karline; Middelburg, Jack J.

    2014-06-01

    Nitrogen incorporation into total particulate suspended matter, hydrolysable amino acids and bacterial biomarker D-Alanine was assessed seasonally in the coastal North Sea using 15N-labeled ammonium, nitrate, nitrite and 15N- and 13C-labeled urea, glycine, leucine, phenylalanine, and two complex pools of dissolved organic matter (DOM) derived from algal and bacterial cultures (A-DOM, B-DOM). We investigated: 1) uptake rates for the various substrates and their contribution to total N uptake; 2) microbial preferences for the different N sources; 3) the coupling of C and N uptake from organic substrates; 4) the contribution of bacteria to the total microbial uptake of these substrates, and 5) the role of a complex pool of organic matter for plankton nutrition. Seasonality in the preferences for N substrates was observed, with A-DOM and B-DOM being preferred in autumn and winter whereas NH4+ was preferentially taken up in spring and summer. C and N uptake was coupled for all the organic substrates, except urea that was mainly used as a nitrogen source in summer and spring. Bacterial contribution to the uptake of A-DOM and B-DOM was, on an annual average, the lowest among the N-substrates. This suggests an important role for phytoplankton in the incorporation of complex organic matter and the importance of DOM for phytoplankton nutrition.

  16. Improved analysis of dissolved organic nitrogen in water via electrodialysis pretreatment.

    PubMed

    Zhu, Anbang; Chen, Baiyang; Zhang, Liang; Westerhoff, Paul

    2015-02-17

    This study evaluated electrodialysis (ED) for direct, accurate, and precise dissolved organic nitrogen (DON) analysis in water. Unlike conventional methods that calculate DON as the difference between total dissolved nitrogen (TDN) and dissolved inorganic nitrogen (DIN), we designed a compact ED reactor as a pretreatment tool that completely separates DIN from DON in water and then measures DON by equating DON to TDN. The experiments confirmed that the ED pretreatment process can achieve 99% removal of all three major DIN species (i.e., ammonia, nitrite, and nitrate) and an average recovery rate of 88% for an array of model DON compounds of varying characteristics (e.g., urea, amino acids, tripeptide, protein, and humic substances). Variations in nitrogen removal and recovery might be explained by a combined effect of molecular weight, acid dissociation ability (pK(a)), aromaticity, and ED reactor configurations. For model solutions with DIN/DON ratios varying from 1 to 10 mg-N/mg-N, the relative standard deviations in DON concentrations were considerably lower with ED pretreatment (<10%) than without pretreatment (47%). A survey of seven field samples, including lake water, tap water, and treated wastewater, also demonstrated the benefits of using ED pretreatment as compared with a conventional DON analysis method. Overall, this study provides evidence and mechanistic insight for a new DON detection method that uses ED pretreatment. The ED unit is robust for separating DIN and DON, and thus it may facilitate more frequent detection of DON and ultimately enhances understanding of DON issues in the environmental studies. PMID:25621718

  17. Dissolved organic nitrogen budgets for upland, forested ecosystems in New England

    USGS Publications Warehouse

    Campbell, J.L.; Hornbeck, J.W.; McDowell, W.H.; Buso, D.C.; Shanley, J.B.; Likens, G.E.

    2000-01-01

    Relatively high deposition of nitrogen (N) in the northeastern United States has caused concern because sites could become N saturated. In the past, mass-balance studies have been used to monitor the N status of sites and to investigate the impact of increased N deposition. Typically, these efforts have focused on dissolved inorganic forms of N (DIN = NH4-N + NO3-N) and have largely ignored dissolved organic nitrogen (DON) due to difficulties in its analysis. Recent advances in the measurement of total dissolved nitrogen (TDN) have facilitated measurement of DON as the residual of TDN - DIN. We calculated DON and DIN budgets using data on precipitation and streamwater chemistry collected from 9 forested watersheds at 4 sites in New England. TDN in precipitation was composed primarily of DIN. Net retention of TDN ranged from 62 to 89% (4.7 to 10 kg ha-1 yr-1) of annual inputs. DON made up the majority of TDN in stream exports, suggesting that inclusion of DON is critical to assessing N dynamics even in areas with large anthropogenic inputs of DIN. Despite the dominance of DON in streamwater, precipitation inputs of DON were approximately equal to outputs. DON concentrations in streamwater did not appear significantly influenced by seasonal biological controls, but did increase with discharge on some watersheds. Streamwater NO3-N was the only fraction of N that exhibited a seasonal pattern, with concentrations increasing during the winter months and peaking during snowmelt runoff. Concentrations of NO3-N varied considerably among watersheds and are related to DOC:DON ratios in streamwater. Annual DIN exports were negatively correlated with streamwater DOC:DON ratios, indicating that these ratios might be a useful index of N status of upland forests.

  18. Dissolved Organic Phosphorus Production during Simulated Phytoplankton Blooms in a Coastal Upwelling System

    PubMed Central

    Ruttenberg, K. C.; Dyhrman, S. T.

    2012-01-01

    Dissolved organic phosphorus (DOP) is increasingly recognized as an important phosphorus source to marine primary producers. Despite its importance, the production rate and fate of DOP is poorly understood. In this study, patterns of DOP production were evaluated by tracking the evolution of DOP during simulated phytoplankton blooms initiated with nutrient amended surface waters, relative to controls, from the Oregon (USA) coastal upwelling system. Nitrogen (N) and phosphorus (P) additions were used to decouple DOP production and hydrolysis by inducing or repressing, respectively, community alkaline phosphatase activity. In order to examine the progression of nutrient uptake and DOP production under upwelling versus relaxation conditions, two experiments were initiated with waters collected during upwelling events, and two with waters collected during relaxation events. Maximum [under (+P) conditions] and minimum [under (+N) conditions] DOP production rates were calculated and applied to in situ DOP levels to evaluate which end-member rate most closely approximates the in situ DOP production rate at the four study sites in this coastal system. Increases in DOP concentration occurred by day-5 in control treatments in all experiments. N treatments displayed increased chlorophyll a, increased alkaline phosphatase activity, and yielded lower net DOP production rates relative to controls, suggesting that DOP levels were depressed as a consequence of increased hydrolysis of bioavailable DOP substrates. Phosphorus additions resulted in a significant net production of DOP at all stations, but no increase in chlorophyll a relative to control treatments. The contrasting patterns in DOP production between treatments suggests that changes in the ambient dissolved inorganic nitrogen:dissolved inorganic phosphorus (DIN:DIP) ratio could exert profound control over DOP production rates in this system. Patterns of DOP production across the different experiments also suggest that

  19. Modeling the contribution of dissolved organic carbon to carbon sequestration during the last glacial maximum

    NASA Astrophysics Data System (ADS)

    Ma, Wentao; Tian, Jun

    2014-10-01

    Dissolved organic carbon (DOC) is a carbon reservoir that is as large as the atmospheric CO2 pool, and its contribution to the global carbon cycle is gaining attention. As DOC is a dissolved tracer, its distribution can serve to trace the mixing of water masses and the pathways of ocean circulation. Published proxy and model reconstructions have revealed that, during the last glacial maximum (LGM), the pattern of deep ocean circulation differed from that of the modern ocean, whereby additional carbon is assumed to have been sequestered in stratified LGM deep water. The aim of this study is to explore the distribution of DOC and its production/removal rate during the LGM using the Grid ENabled Integrated Earth system model (GENIE). Modeled results reveal that increased salinity of bottom waters in the Southern Ocean is associated with stronger stratification and oxygen depletion. The stratified LGM deep ocean traps more nutrients, resulting in a decrease in the DOC reservoir size that, in turn, causes a negative feedback for carbon sequestration. This finding requires an increase in DOC lifetime to compensate for the negative feedback. The upper limit of DOC lifetime is assumed to be 20,000 years. Modeled results derive an increase (decrease) in DOC reservoir by 100 Pg C leading to an atmospheric CO2 decrease (increase) of 9.1 ppm and a dissolved inorganic carbon δ13C increase (decrease) of 0.06‰. The DOC removal rate is estimated to be 39.5 Tg C year-1 in the deep sea during the LGM. The contribution of DOC to the LGM carbon cycle elucidates potential carbon sink-increasing strategies.

  20. Reconnaissance of selected organic contaminants in effluent and ground water at fifteen municipal wastewater treatment plants in Florida, 1983- 84

    USGS Publications Warehouse

    Pruitt, J.B.; Troutman, D.E.; Irwin, G.A.

    1985-01-01

    Results of a 1983-84 reconnaissance of 15 municipal wastewater treatment plants in Florida indicated that effluent from most of the plants contains trace concentrations of volatile organic compounds. Chloroform was detected in the effluent at 11 of the 15 plants and its common occurrence was likely the result of chlorination. The maximum concentration of chloroform detected in the effluent sampled was 120 micrograms/L. Detectable concentrations of selected organophosphorus insecticides were also common. For example, diazinon was detected in the effluent at 12 of the 15 plants with a maximum concentration of 1.5 micrograms/L. Organochlorine insecticides, primarily lindane, were detected in the effluent at 8 of the 15 plants with a maximum concentration of 1.0 micrograms/L. Volatile compounds, primarily chloroform, were detected in water from monitor wells at four plants and organophosphorus insecticides, primarily diazinon, were present in the groundwater at three treatment plants. Organochlorine insecticides were not detected in any samples from monitor wells. Based on the limited data available, this cursory reconaissance suggests that the organic contaminants commonly occurring in the effluent of many of the treatment plants are not transported into the local groundwater. (Author 's abstract)

  1. Characterization of dissolved organic matter in fogwater by excitation-emission matrix fluorescence spectroscopy

    USGS Publications Warehouse

    Birdwell, J.E.; Valsaraj, K.T.

    2010-01-01

    Dissolved organic matter (DOM) present in fogwater samples collected in southeastern Louisiana and central-eastern China has been characterized using excitation-emission matrix fluorescence spectroscopy. The goal of the study was to illustrate the utility of fluorescence for obtaining information on the large fraction of organic carbon in fogwaters (typically >40% by weight) that defies characterization in terms of specific chemical compounds without the difficulty inherent in obtaining sufficient fogwater volume to isolate DOM for assessment using other spectroscopic and chemical analyses. Based on the findings of previous studies using other characterization methods, it was anticipated that the unidentified organic carbon fraction would have characteristic peaks associated with humic substances and fluorescent amino acids. Both humic- and protein-like fluorophores were observed in the fogwater spectra and fluorescence-derived indices for the fogwater had similar values to those of soil and sediment porewater. Greater biological character was observed in samples with higher organic carbon concentrations. Fogwaters are shown to contain a mixture of terrestrially- and microbially-derived fluorescent organic material, which is expected to be derived from an array of different sources, such as suspended soil and dust particles, biogenic emissions and organic substances generated by atmospheric processes. The fluorescence results indicate that much of the unidentified organic carbon present in fogwater can be represented by humic-like and biologically-derived substances similar to those present in other aquatic systems, though it should be noted that fluorescent signatures representative of DOM produced by atmospheric processing of organic aerosols may be contributing to or masked by humic-like fluorophores. ?? 2010.

  2. Characterization of dissolved organic matter in fogwater by excitation-emission matrix fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Birdwell, Justin E.; Valsaraj, Kalliat T.

    Dissolved organic matter (DOM) present in fogwater samples collected in southeastern Louisiana and central-eastern China has been characterized using excitation-emission matrix fluorescence spectroscopy. The goal of the study was to illustrate the utility of fluorescence for obtaining information on the large fraction of organic carbon in fogwaters (typically >40% by weight) that defies characterization in terms of specific chemical compounds without the difficulty inherent in obtaining sufficient fogwater volume to isolate DOM for assessment using other spectroscopic and chemical analyses. Based on the findings of previous studies using other characterization methods, it was anticipated that the unidentified organic carbon fraction would have characteristic peaks associated with humic substances and fluorescent amino acids. Both humic- and protein-like fluorophores were observed in the fogwater spectra and fluorescence-derived indices for the fogwater had similar values to those of soil and sediment porewater. Greater biological character was observed in samples with higher organic carbon concentrations. Fogwaters are shown to contain a mixture of terrestrially- and microbially-derived fluorescent organic material, which is expected to be derived from an array of different sources, such as suspended soil and dust particles, biogenic emissions and organic substances generated by atmospheric processes. The fluorescence results indicate that much of the unidentified organic carbon present in fogwater can be represented by humic-like and biologically-derived substances similar to those present in other aquatic systems, though it should be noted that fluorescent signatures representative of DOM produced by atmospheric processing of organic aerosols may be contributing to or masked by humic-like fluorophores.

  3. Influence of subsurface drainage on quantity and quality of dissolved organic matter export from agricultural landscapes

    NASA Astrophysics Data System (ADS)

    Dalzell, Brent J.; King, Jennifer Y.; Mulla, David J.; Finlay, Jacques C.; Sands, Gary R.

    2011-06-01

    Despite its importance for aquatic ecosystem function and watershed carbon budgets, little is known about how land use influences dissolved organic matter (DOM) export. We investigated the influence of subsurface soil drainage, widespread in the Midwestern United States, on DOM export from agricultural fields designed to drain water at either 13 mm d-1 (conventional) or 51 mm d-1 (intense). Intense drainage exported 55% (±22%) more dissolved organic carbon (DOC) per year than conventional drainage due to both increased concentration and water yield. DOC export from plots was strongly dependent on precipitation and showed considerable interannual variability. Mean DOC concentrations in drainage water were low (1.62 and 1.87 mg L-1 for conventional and intense treatments), and fluorescence index (FI) measurements showed that it had a microbial source with little evidence of terrestrially derived material, suggesting that flow through deeper, organic-poor soil horizons is important in regulating DOC export from these plots. We compared DOM in subsurface drains with downstream ditch and stream sites. Increases in DOC concentration and molecular weight accompanied by decreasing FI values at downstream sites showed that streams gain a large amount of terrestrially derived DOM during base flow transport through agricultural landscapes, probably from riparian zones. These results show that DOM compositional characteristics change with catchment area and that the relevant observation scale for DOM dynamics is likely to vary among watersheds. This study also demonstrates that land management practices can directly affect DOC via changes to water flow paths. These results are critical for improving model estimates of DOM export from agricultural landscapes as well as predicting how DOC export will respond to changing land use and climate.

  4. Dissolved organic matter and terrestrial-lotic linkages in the Central Amazon Basin of Brazil

    NASA Astrophysics Data System (ADS)

    McClain, Michael E.; Richey, Jeffrey E.; Brandes, Jay A.; Pimentel, Tania P.

    1997-09-01

    We evaluate the hypothesis that decomposition and adsorption reactions operating in upland soils of headwater catchments control the concentration and composition of dissolved and fine particulate organic matter in rivers of the Amazon basin. In two contrasting first-order catchments characteristic of the central Amazon basin, we analyzed plant, litter, soil, groundwater, and stream water chemistry. Our results indicate that clear and persistent differences exist in the concentration and elemental composition of dissolved organic matter (DOM) in stream waters and groundwaters from the two catchments, due mainly to corresponding differences in soil texture and chemistry. Within the more oxide and clay rich Oxisols underlying terra firme forest, groundwater DOM concentrations were uniformly low (120 μMC) and C/N ratios averaged 10. Conversely, within the oxide and clay deficient Spodosols underlying campinarana forest, groundwater DOM concentrations were greatly elevated (3000 μMC), and C/N ratios averaged near 60. We found that, in the terra firme/Oxisol terrain, the majority of DOM contributions to the stream derived from the riparian zone, while in the campinarana/Spodosol terrain, upland groundwater contributions could account for the concentration and composition of DOM in the stream. The implications of our findings are that in the terra firme terrains which dominate the region, upland soil profiles are not the site of definitive processes which impart compositional signatures to organic matter carried by the largest rivers of the Amazon basin, as was hypothesized. Instead, we suggest that definitive reactions are focused primarily in the river corridor.

  5. Dissolved Organic Matter Composition of Arctic Rivers: Linking Permafrost, Parent Material, and Groundwater to Riverine Carbon

    NASA Astrophysics Data System (ADS)

    O'Donnell, J. A.; Aiken, G.; Butler, K. D.; Swanson, D. K.

    2015-12-01

    Recent warming in the Arctic is modifying the chemical composition of riverine dissolved organic matter (DOM) through changes in growing season length, wildfire, and permafrost thaw. In arctic rivers, DOM composition is an important control on nutrient availability, trace metal mobilization, and greenhouse gas emissions. As a result, shifts in DOM associated with a changing arctic landscape may alter how aquatic ecosystems function in this region. Here, we examined spatial variation in DOM composition in 72 rivers in the Brooks Range and Seward Peninsula of northern Alaska. We characterized DOM using a suite of techniques, including dissolved organic carbon (DOC) concentration, absorbance spectra, fluorescence, and chemical fractionation. Watersheds were classified based on traits that influence subsurface hydrology, including parent material (volcanic deposits, loess, sand, glacial moraine, bedrock) and permafrost extent (continuous vs. discontinuous zone) and state (ice-rich vs. ice-poor). We observed considerable variability in DOM composition across rivers. DOC concentrations were lowest in rivers influenced by glacial deposits (<2 mgC L-1) and highest in rivers draining lowland tundra or extensive wetlands (>10 mgC L-1). Specific ultraviolet absorbance (SUVA254), which serves as an index of DOM aromaticity, was also variable across rivers; spring-fed mountain streams had the lowest SUVA254 values (<1.5 L mgC-1 m-1), whereas tundra and wetland-dominated streams had the highest values (>4 L mgC-1 m-1). While hydrophobic organic acids were the dominant DOM fraction in all rivers, we observed a significant increase in the proportion of hydrophilic compounds during winter flow and in groundwater-fed systems. We also observed variation in DOM composition with permafrost extent and ground ice distribution across the region. Model projections over the next century suggest a heterogeneous response of DOM to thaw, likely mediated by spatial variations in ground ice and

  6. Dissolved organic matter transport reflects hillslope to stream connectivity during snowmelt in a montane catchment

    NASA Astrophysics Data System (ADS)

    Burns, Margaret A.; Barnard, Holly R.; Gabor, Rachel S.; McKnight, Diane M.; Brooks, Paul D.

    2016-06-01

    Dissolved organic matter (DOM) transport is a key biogeochemical linkage across the terrestrial-aquatic interface in headwater catchments, and quantifying the biological and hydrological controls on DOM composition provides insight into DOM cycling at the catchment scale. We evaluated the mobility of DOM components during snowmelt in a montane, semiarid catchment. DOM composition was evaluated on a near-daily basis within the soil and the stream during snowmelt, and was compared to groundwater samples using a site-specific parallel factor analysis (PARAFAC) model derived from soil extracts. The fluorescent component loadings in the interstitial soil water and in the groundwater were significantly different and did not temporally change during snowmelt. In the stream, a transition occurred during snowmelt from fluorescent DOM with higher contributions of amino acid-like components indicative of groundwater to higher humic-like contributions indicative of soil water. Furthermore, we identified a humic-like fluorescent component in the soil water and the stream that is typically only observed in extracted water soluble organic matter from soil which may suggest hillslope to stream connectivity over very short time scales. Qualitative interpretations of changes in stream fluorescent DOM were supported by two end-member mixing analyses of conservative tracers. After normalizing fluorescent DOM loadings for dissolved organic carbon (DOC) concentration, we found that the peak in DOC concentration in the stream was driven by the nonfluorescent fraction of DOM. This study demonstrated how PARAFAC analysis can be used to refine our conceptual models of runoff generation sources, as well as provide a more detailed understanding of stream chemistry dynamics.

  7. Biochar amendment to soil changes dissolved organic matter content and composition.

    PubMed

    Smebye, Andreas; Alling, Vanja; Vogt, Rolf D; Gadmar, Tone C; Mulder, Jan; Cornelissen, Gerard; Hale, Sarah E

    2016-01-01

    Amendments of biochar, a product of pyrolysis of biomass, have been shown to increase fertility of acidic soils by enhancing soil properties such as pH, cation-exchange-capacity and water-holding-capacity. These parameters are important in the context of natural organic matter contained in soils, of which dissolved organic matter (DOM) is the mobile and most bioavailable fraction. The effect of biochar on the content and composition of DOM in soils has received little research attention. This study focuses on the effects of amendments of two different biochars to an acidic acrisol and a pH-neutral brown soil. A batch experiment showed that mixing biochar with the acrisols at a 10 wt.% dose increased the pH from 4.9 to 8.7, and this resulted in a 15-fold increase in the dissolved organic carbon concentration (from 4.5 to 69 mg L(-1)). The pH-increase followed the same trend as the release of DOM in the experiment, causing higher DOM solubility and desorption of DOM from mineral sites. The binding to biochar of several well-characterised reference DOM materials was also investigated and results showed a higher sorption of aliphatic DOM to biochar than aromatic DOM, with DOM-water partitioning coefficients (Kd-values) ranging from 0.2 to 590 L kg(-1). A size exclusion occurring in biochar's micropores, could result in a higher sorption of smaller aliphatic DOM molecules than larger aromatic ones. These findings indicate that biochar could increase the leaching of DOM from soil, as well as change the DOM composition towards molecules with a larger size and higher aromaticity. PMID:25980657

  8. Assessing the drivers of dissolved organic matter export from two contrasting lowland catchments, U.K.

    PubMed

    Yates, Christopher A; Johnes, Penny J; Spencer, Robert G M

    2016-11-01

    Two lowland catchments in the U.K. were sampled throughout 2010-11 to investigate the dominant controls on dissolved organic matter quantity and composition. The catchments had marked differences in terms of nutrient status, land cover and contrasting lithologies resulting in differences in the dominant flow pathways (groundwater vs. surface water dominated). The Upper Wylye is a chalk stream with a baseflow index of 0.98, draining a catchment dominated by intensive agricultural production. Millersford Brook is a lowland peat catchment with a baseflow index of 0.43, draining a semi-natural catchment with heather moorland and coniferous forest. Samples were collected weekly between October 2010 and September 2011 from eleven sampling locations. Samples were analysed to determine dissolved organic carbon, nitrogen and phosphorus fractions with DOM composition evaluated via the DOC:DON ratio, DOC:DOP ratio, specific UV absorption at 254nm, absorbance ratio (a250:a365) and the spectral slope parameter between 350 and 400nm (S350-400). Significant differences were observed in all determinands between the catchments, over time, and spatially along nutrient enrichment and geoclimatic gradients. Seasonal variation in preferential flow pathways mobilising groundwater-derived DOM were identified as likely controls on the delivery of DOM in the permeable chalk dominated catchment. Steeper S350-400 values and elevated a250:a365 ratios in this catchment suggest material of a lower bulk aromatic C content and molecular weight delivered during the winter months when compared to the summer. DOC:DON ratios were markedly lower in the chalk catchment than the peatland catchment, reflecting the paucity of organic matter within the mineral soils of the chalk landscape, and higher fertiliser application rates. This manuscript highlights that DOM composition varies according to catchment landscape character and hydrological function. PMID:27422728

  9. Non-conservative behavior of fluorescent dissolved organic matter (FDOM) within a subterranean estuary

    NASA Astrophysics Data System (ADS)

    Suryaputra, I. G. N. A.; Santos, I. R.; Huettel, M.; Burnett, W. C.; Dittmar, T.

    2015-11-01

    The role of submarine groundwater discharge (SGD) in releasing fluorescent dissolved organic matter (FDOM) to the coastal ocean and the possibility of using FDOM as a proxy for dissolved organic carbon (DOC) was investigated in a subterranean estuary in the northeastern Gulf of Mexico (Turkey Point, Florida). FDOM was continuously monitored for three weeks in shallow beach groundwater and in the adjacent coastal ocean. Radon (222Rn) was used as a natural groundwater tracer. FDOM and DOC correlated in groundwater and seawater samples, implying that FDOM may be a proxy of DOC in waters influenced by SGD. A mixing model using salinity as a seawater tracer revealed FDOM production in the high salinity region of the subterranean estuary. This production was probably a result of infiltration and transformation of labile marine organic matter in the beach sediments. The non-conservative FDOM behavior in this subterranean estuary differs from most surface estuaries where FDOM typically behaves conservatively. At the study site, fresh and saline SGD delivered about 1800 mg d-1 of FDOM (quinine equivalents) to the coastal ocean per meter of shoreline. About 11% of this input was related to fresh SGD, while 89% were related to saline SGD resulting from FDOM production within the shallow aquifer. If these fluxes are representative of the Florida Gulf Coast, SGD-derived FDOM fluxes would be equivalent to at least 18% of the potential regional riverine FDOM inputs. To reduce uncertainties related to the scarcity of FDOM data, further investigations of river and groundwater FDOM inputs in Florida and elsewhere are necessary.

  10. Predicting Sources of Dissolved Organic Nitrogen to an Estuary from an Agro-Urban Coastal Watershed.

    PubMed

    Osburn, Christopher L; Handsel, Lauren T; Peierls, Benjamin L; Paerl, Hans W

    2016-08-16

    Dissolved organic nitrogen (DON) is the nitrogen (N)-containing component of dissolved organic matter (DOM) and in aquatic ecosystems is part of the biologically reactive nitrogen pool that can degrade water quality in N-sensitive waters. Unlike inorganic N (nitrate and ammonium) DON is comprised of many different molecules of variable reactivity. Few methods exist to track the sources of DON in watersheds. In this study, DOM excitation-emission matrix (EEM) fluorescence of eight discrete DON sources was measured and modeled with parallel factor analysis (PARAFAC) and the resulting model ("FluorMod") was fit to 516 EEMs measured in surface waters from the main stem of the Neuse River and its tributaries, located in eastern North Carolina. PARAFAC components were positively correlated to DON concentration. Principle components analysis (PCA) was used to confirm separation of the eight sources and model validation was achieved by measurement of source samples not included in the model development with an error of <10%. Application of FluorMod to surface waters of streams within the Neuse River Basin showed that while >70% of DON was attributed to natural sources, nonpoint sources, such as soil and poultry litter leachates and street runoff, accounted for the remaining 30%. This result was consistent with changes in land use from urbanized Raleigh metropolitan area to the largely agricultural Southeastern coastal plain. Overall, the predicted fraction of nonpoint DON sources was consistent with previous reports of increased organic N inputs in this river basin, which are suspected of impacting the water quality of its estuary. PMID:27404466

  11. Chromophoric Dissolved Organic Matter across a Marine Distributed Biological Observatory in the Pacific Arctic Region

    NASA Astrophysics Data System (ADS)

    Berman, S. L.; Frey, K. E.; Shake, K. L.; Cooper, L. W.; Grebmeier, J. M.

    2014-12-01

    Dissolved organic matter (DOM) plays an important role in marine ecosystems as both a carbon source for the microbial food web (and thus a source of CO2 to the atmosphere) and as a light inhibitor in marine environments. The presence of chromophoric dissolved organic matter (CDOM; the optically active portion of total DOM) can have significant controlling effects on transmittance of sunlight through the water column and therefore on primary production as well as the heat balance of the upper ocean. However, CDOM is also susceptible to photochemical degradation, which decreases the flux of solar radiation that is absorbed. Knowledge of the current spatial and temporal distribution of CDOM in marine environments is thus critical for understanding how ongoing and future changes in climate may impact these biological, biogeochemical, and physical processes. We describe the quantity and quality of CDOM along five key productive transects across a developing Distributed Biological Observatory (DBO) in the Pacific Arctic region. The samples were collected onboard the CCGS Sir Wilfred Laurier in July 2013 and 2014. Monitoring of the variability of CDOM along transects of high productivity can provide important insights into biological and biogeochemical cycling across the region. Our analyses include overall concentrations of CDOM, as well as proxy information such as molecular weight, lability, and source (i.e., autochthonous vs. allochthonous) of organic matter. We utilize these field observations to compare with satellite-derived CDOM concentrations determined from the Aqua MODIS satellite platform, which ultimately provides a spatially and temporally continuous synoptic view of CDOM concentrations throughout the region. Examining the current relationships among CDOM, sea ice variability, biological productivity, and biogeochemical cycling in the Pacific Arctic region will likely provide key insights for how ecosystems throughout the region will respond in future

  12. Fluorescence Characterization of Dissolved Organic Matter Isolates from Sediments and the Association with Phenanthrene Binding Affinity

    NASA Astrophysics Data System (ADS)

    Hur, Jin; Lee, Bo-Mi; Shin, Kyung-Hoon

    2014-05-01

    In this study, selected spectroscopic characteristics of sediment organic matter (SOM) were compared and discussed with respect to their different isolation methods, the source discrimination capabilities, and the association with the extent of phenanthrene binding. A total of 16 sediments were collected from three categorized locations including a costal lake, industrial areas, and the upper streams, each of which is likely influenced by the organic sources of algal production, industrial effluent, and terrestrial input, respectively. The spectroscopic properties related to aromatic structures and terrestrial humic acids were more pronounced for alkaline extractable organic matter (AEOM) isolates than for the SOM isolates based on water soluble extracts and porewater. The three categorized sampling locations were the most differentiated in the AEOM isolates, suggesting AEOM may be the most representative SOM isolates in describing the chemical properties and the organic sources of SOM. Parallel factor analysis (PARAFAC) based on fluorescence excitation-emission matrix (EEM) showed that a combination of four fluorescent groups could represent all the fluorescence features of SOM. The three categorized sampling locations were well discriminated by the percent distributions of terrestrial and microbial humic-like fluorescent groups of the AEOM isolates. The relative distribution of terrestrial humic-like fluorophores was highly correlated with the extent of phenanthrene binding (r=0.676; p<0.01), suggesting that the presence of terrestrial humic acids in SOM may contribute to the enhancement of binding with hydrophobic organic contaminants in sediments. Principal component analysis (PCA) further demonstrated that the extent of SOM's binding affinity might be affected by the degree of biological transformation in SOM as well as the abundance of aromatic carbon structures.

  13. Dissolved pesticides, dissolved organic carbon, and water-quality characteristics in selected Idaho streams, April--December 2010

    USGS Publications Warehouse

    Reilly, Timothy J.; Smalling, Kelly L.; Wilson, Emma R.; Battaglin, William A.

    2012-01-01

    Water-quality samples were collected from April through December 2010 from four streams in Idaho and analyzed for a suite of pesticides, including fungicides, by the U.S. Geological Survey. Water samples were collected from two agricultural and two nonagricultural (control) streams approximately biweekly from the beginning of the growing season (April) through the end of the calendar year (December). Samples were analyzed for 90 pesticides using gas chromatography/mass spectrometry. Twenty-three pesticides, including 8 fungicides, 10 herbicides, 3 insecticides, and 2 pesticide degradates, were detected in 45 water samples. The most frequently detected compounds in the two agricultural streams and their detection frequencies were metolachlor, 96 percent; azoxystrobin, 79 percent; boscalid, 79 percent; atrazine, 46 percent; pendimethalin, 33 percent; and trifluralin, 33 percent. Dissolved-pesticide concentrations ranged from below instrumental limits of detection (0.5-1.0 nanograms per liter) to 771 nanograms per liter (hexazinone). The total number of pesticides detected in any given water sample ranged from 0 to 11. Only three pesticides (atrazine, fipronil, and simazine) were detected in samples from the control streams during the sampling period.

  14. The effect of drain blocking on dissolved organic carbon under the peak flow conditions

    NASA Astrophysics Data System (ADS)

    zhang, zhuoli

    2014-05-01

    There are numerous studies that have shown increasing dissolved organic carbon (DOC) concentration down stream of upland peat catchments (eg. Worrall et al., 2007; Clark et al., 2007; Gibson et al., 200). In the UK, upland peat soils are both an important water source and an important carbon store, therefore, the transportation of DOC from soil to the aquatic system remains a critical part of the impact that upland peat environments have on wider society. The majority of the DOC is delivered from the peat soil during the peak flow events (Clark et al., 2008), however, most of the storm events analysis has been developed for organo-mineral soil rather than for peat soil catchments. Worrall et al., (2007) suggested that drain blocking as a potential method for controlling DOC release from peat soil. An events analysis was conducted on the drain blocking data collected from 2008 to 2010 from Cronkley Fell (UK National grid reference NY 83800 26996). A total of 756 peak flow events were chosen to access the impact of drain blocking on DOC concentration and flux during the events. The data was analysed by the combination of principal components analysis (PCA) and end member mixing analysis (EMMA). The results showed that during the peak flow events, the effects of drain blocking was minimised by the rapid flushing of the event water: the DOC concentration on storm events increased after blocking rather than decreased; DOC flux did decrease after blocking but rather as a result of the increased volume of the event water. Worrall, F., Armstrong, A., Holden, J., 2007. Short term impact of peat drain blocking on water color, dissolved organic carbon concentration and water table depth. Journal of Hydrology 337,315-325 Clark, J.M., Lane, S.N., Chapman, P.J., Adamson, J.K., 2007. Export of dissolved organic carbon from an upland peat during storm events: Implication for flux estimates. Journal of Hydrology 347, 438-447. Aitkenhead, J.A., McDowell, W. H., 2000. Soil C: N ratio

  15. Excitation Emission Matrix Spectra (EEMS) of Chromophoric Dissolved Organic Matter Produced during Microbial Incubation

    NASA Astrophysics Data System (ADS)

    McDonald, N.; Nelson, N. B.; Parsons, R.

    2013-12-01

    The chromophoric or light-absorbing fraction of dissolved organic matter (CDOM) is present ubiquitously in natural waters and has a significant impact on ocean biogeochemistry, affecting photosynthesis and primary production as well direct and indirect photochemical reactions (Siegel et al., 2002; Nelson et al., 2007). It has been largely researched in the past few decades, however the exact chemical composition remains unknown. Instrumental methods of analysis including simultaneous excitation-emission fluorescence spectra have allowed for further insight into source and chemical composition. While certain excitation-emission peaks have been associated with ';marine' sources, they have not been exclusively linked to bacterial production of CDOM (Coble, 1996; Zepp et al., 2004). In this study, ';grazer diluted' seawater samples (70% 0.2μm filtered water; 30% whole water) were collected at the Bermuda Atlantic Time Series (BATS) site in the Sargasso Sea (31° 41' N; 64° 10' W) and incubated with an amendment of labile dissolved organic carbon (10μM C6H12O6), ammonium (1μM NH4Cl) and phosphate (0.1μM K2HPO4) to facilitate bacterial production. These substrates and concentrations have been previously shown to facilitate optimum bacterial and CDOM production (Nelson et al., 2004). Sample depths were chosen at 1m and 200m as water at these depths has been exposed to UV light (the Subtropical Mode Water at 200m has been subducted from the surface) and therefore has low initial concentrations of CDOM. After the samples were amended, they were incubated at in-situ temperatures in the dark for 72 hours, with bacteria counts, UV-Vis absorption and EEMS measurements taken at 6-8 hour intervals. Dissolved organic carbon (DOC) measurements were collected daily. For the surface water experiment specific bacteria populations were investigated using Fluorescence In-Situ Hybridization (FISH) analysis. Results showed a clear production of bacteria and production of CDOM, which

  16. Transport of dissolved organic carbon from soil to surface water: Identifying the transport pathways

    NASA Astrophysics Data System (ADS)

    Van Gaelen, Nele

    2013-04-01

    Over the last decades, increasing concentrations of dissolved organic carbon (DOC) have been found in surface waters. It has also become clear that land use is an important driver for DOC export. However, causal factors controlling this temporal and spatial variation are not clear. Efforts to model DOC export on a catchment scale are rare. In this research, we aim to determine the factors controlling variations in DOC concentration and quality in surface waters. Secondly, the importance of the different pathways (surface runoff, subsurface flow and groundwater flow) for the transport of dissolved organic matter from the soil to the surface water is investigated. Six headwater catchments (100 - 400 ha) were selected in Belgium, representing three different types of land use, namely forest, grassland and arable land. At the outlet of each catchment, a flow-proportional sampler has been collecting samples of base flow and peak discharge since January 2010. In addition, samples of groundwater, subsurface water and precipitation water were collected on a regular base in three of the catchments. Samples were analyzed for DOC, specific UV absorbance (SUVA) and dissolved silica (DSi). Elemental analysis was carried out using ICP-OES. Since 2012, precipitation water and a selection of river water samples was also analyzed for O and H isotopes. Overall, DOC concentrations were highest in forest catchments and lowest in grassland catchments. For all land use types, measured DOC concentrations were highest during peak discharge. The rise in DOC concentrations was associated with a change in DOC quality. During periods of greater discharge, higher SUVA values were measured, indicating DOC with higher aromaticity (humic and fulvic fractions) reaches the outlet. ICP and DSi results also showed a significant difference in geochemical composition of the river water if peak events are compared to base flow samples. During an event, Ca, Mg, Na, S and DSi concentrations were lowered

  17. Biochemical Composition of Dissolved Organic Matter Released During Experimental Diatom Blooms

    NASA Technical Reports Server (NTRS)

    Mannino, Antonio; Harvey, H. Rodger

    2002-01-01

    An axenic culture of Skeletonema costatum was grown to late-log phase to examine the molecular weight distribution and the biochemical composition of high molecular weight dissolved organic matter released in the absence of actively growing bacteria. A second culture was grown in a 5 m(exp 3) mesocosm and placed in darkness for a period of 51 days to examine the impact of phytoplankton bloom dynamics and microbial decomposition on dissolved (DOM) and particulate organic matter (POM) composition. DOM was separated using tangential-flow ultrafiltration into three nominal size fractions: LDOM (less than 1 kDa DOM), HDOM (1-30 kDa) and VHDOM (30 kDa-0.2 micron) and characterized. Both axenic and mesocosm diatom blooms released 28-33% of net primary production as dissolved organic carbon (DOC). In the axenic culture, HDOM and LDOM each comprised about half of the diatom-released DOC with less than l% as VHDOM. Diatoms from both experiments released carbohydrate-rich high molecular weight DOM. Much of the axenic diatom-released high molecular weight DOC could be chemically characterized (61% of HDOM and 78% of VHDOM) with carbohydrates as the primary component (45% of HDOM and 55% of VHDOM). Substantial amounts of hydrolyzable amino acids (16% of HDOM and 22% of VHDOM) and small amounts of lipids (less than 1%) were also released. Proportions of recognizable biochemical components in DOM produced in the mesocosm bloom were lower compared to the axenic culture. The presence of bacterial fatty acids and peptidoglycan-derived D-amino acids within high molecular weight fractions from the mesocosm bloom revealed that bacteria contributed a variety of macromolecules to DOM during the growth and decay of the diatom bloom. Release of significant amounts of DOC by diatoms demonstrates that DOM excretion is an important component of phytoplankton primary production. Similarities in high molecular weight DOM composition in marine waters and diatom cultures highlight the importance

  18. Linkages between the circulation and distribution of dissolved organic matter in the White Sea, Arctic Ocean