TY  - JOUR
AB  - Natural organic matter (NOM) is critical for the biogeochemical cycles of energy and many elements in terrestrial and aquatic ecosystems, and protonation-active functional groups in NOM molecules, notably carboxylic and phenolic groups often mediate these critical environmental functions. Molecular heterogeneity, polydispersity and dynamic behavior of NOM complicate achieving an unambiguous description of its molecular properties and reactivity. This study demonstrates that differential ultraviolet-visible (UV/VIS) absorbance spectra (DAS) of NOM acquired at varying pH values exhibit several distinct features associated with the deprotonation of NOM molecules, independent of the environmental provenance of NOM (e.g., surface water, seawater, sediment, and wastewater). The protonation-active functionalities that contribute to the Gaussian distribution bands present in the DAS were identified here by comparing characteristic properties of the bands with the stoichiometries of NOM molecules ascertained by Ultrahigh-Resolution Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS). The protonation-active individual chromophores universally present in NOM molecules were identified by a genetic molecular network analysis. The observed DAS features were closely modeled via superimposing DAS spectra of 51 individual protonation-active chromophores. Molecular orbital theory was applied to further interpret the deprotonation of these chromophores, their molecular structure, electron distribution, and electron transitions measured using DAS. The high sensitivity and easy implementation of the DAS approach allows using it as a powerful tool to quantify the molecular properties and reactivity of NOM at environmental concentrations.
AU  - Zhang, C.*
AU  - Mo, S.*
AU  - Liu, Z.*
AU  - Chen, B.*
AU  - Korshin, G.*
AU  - Hertkorn, N.
AU  - Ni, J.*
AU  - Yan, M.*
C1  - 68306
C2  - 54750
CY  - The Boulevard, Langford Lane, Kidlington, Oxford Ox5 1gb, England
TI  - Interpreting pH-dependent differential UV/VIS absorbance spectra to characterize carboxylic and phenolic chromophores in natural organic matter.
JO  - Water Res.
VL  - 244
PB  - Pergamon-elsevier Science Ltd
PY  - 2023
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - The input of nitrate and other agricultural pollutants in higher-order streams largely derives from first-order streams. The streambed as the transition zone between groundwater and stream water has a decisive impact on the attenuation of such pollutants. This reactivity is not yet well understood for lower-order agricultural streams, which are often anthropogenically altered and lack the streambed complexity allowing for extensive hyporheic exchange. Reactive hot spots in such streambeds have been hypothesized as a function of hydrology, which controls the local gaining (groundwater exfiltration) or losing (infiltration) of stream water. However, streambed microbial communities and activities associated with such reactive zones remain mostly uncharted. In this study, sediments of a first-order agriculturally impacted stream in southern Germany were investigated. Along with a hydraulic dissection of distinct gaining and losing reaches of the stream, community composition and the abundance of bacterial communities in the streambed were investigated using PacBio long-read sequencing of bacterial 16S rRNA gene amplicons, and qPCR of bacterial 16S rRNA and denitrification genes (nirK and nirS). We show that bidirectional water exchange between groundwater and the stream represents an important control for sediment microbiota, especially for nitrate-reducing populations. Typical heterotrophic denitrifiers were most abundant in a midstream net losing section, while up- and downstream net gaining sections were associated with an enrichment of sulfur-oxidizing potential nitrate reducers affiliated with Sulfuricurvum and Thiobacillus spp. Dispersal-based community assembly was found to dominate such spots of groundwater exfiltration. Our results indicate a coupling of N- and S-cycling processes in the streambed of an agricultural first-order stream, and a prominent control of microbiology by hydrology and hydrochemistry in situ. Such detailed local heterogeneities in exchange fluxes and streambed microbiomes have not been reported to date, but seem relevant for understanding the reactivity of lower-order streams.
AU  - Wang, Z.
AU  - Jimenez-Fernandez, O.*
AU  - Osenbrück, K.*
AU  - Schwientek, M.*
AU  - Schloter, M.
AU  - Fleckenstein, J.H.*
AU  - Lueders, T.*
C1  - 64738
C2  - 51952
TI  - Streambed microbial communities in the transition zone between groundwater and a first-order stream as impacted by bidirectional water exchange.
JO  - Water Res.
VL  - 217
PY  - 2022
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - Riverbank filtration has gained increasing importance for balancing rising groundwater demands and securing drinking water supplies. While microbial communities are the pillar of vital ecosystem functions in groundwater, the impact of riverbank filtration on these communities has been understudied so far. Here, we followed changes in microbial community composition based on 16S rRNA gene amplicon sequence variants (ASVs) in an initially pristine shallow porous aquifer in response to surface water intrusion during the early stages of induced riverbank filtration over a course of seven weeks. We further analyzed sediment cores for imprints of river-derived ASVs after seven weeks of riverbank filtration. The onset of the surface water intrusion caused loss of taxa and significant changes in community composition, revealing low disturbance resistance of the initial aquifer microbial communities. SourceTracker analysis revealed that proportions of river-derived ASVs in the groundwater were generally <25%, but locally could reach up to 62% during a period of intense precipitation. However, variation partitioning showed that the impact of dispersal of river-derived ASVs on changes in aquifer microbial community composition was overall outweighed by species sorting due to changes in environmental conditions caused by the infiltrating river water. Proportions of river-derived ASVs on aquifer sediments were <0.5%, showing that taxa transported from the river into the aquifer over the course of the study mainly resided as planktonic microorganisms in the groundwater. Our study demonstrates that groundwater microbial communities react sensitively to changes in environmental conditions caused by surface water intrusion, whereas mass effects resulting from the influx of river-derived taxa play a comparatively minor role.
AU  - Fillinger, L.
AU  - Hug, K.
AU  - Griebler, C.
C1  - 60682
C2  - 49430
CY  - The Boulevard, Langford Lane, Kidlington, Oxford Ox5 1gb, England
TI  - Aquifer recharge viewed through the lens of microbial community ecology: Initial disturbance response, and impacts of species sorting versus mass effects on microbial community assembly in groundwater during riverbank filtration.
JO  - Water Res.
VL  - 189
PB  - Pergamon-elsevier Science Ltd
PY  - 2021
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - Boreal lakes are considered hot spots of dissolved organic matter (DOM) processing within the global carbon cycle. This study has used FT-ICR mass spectrometry and comprehensive data evaluation to assess the molecular differences of SPE-DOM between lake column water SPE-DOM and sedimentary pore water SPE-DOM in 10 Swedish boreal lakes of the Malingsbo area, which were selected for their large diversity of physicochemical and morphological characteristics. While lake column water is well mixed and fairly oxygenated, sedimentary pore water is subject to depletion of oxygen and to confinement of molecules. Robust trends were deduced from molecular compositions present in all compartments and in all 10 lakes ("common compositions") with recognition of relative abundance. Sedimentary pore water SPE-DOM featured higher proportions of heteroatoms N and S, higher average WC ratios in presence of higher DBE/C ratios, and higher average oxygenation than lake column water SPE-DOM. These trends were observed in all lakes except Ljustjarn, which is a ground water fed kettle lake with an unique lake biogeochemistry. Analogous trends were also observed in case of single or a few lakes and operated also for compounds present solely in either lake column water or sedimentary pore water. Unique compounds detected in either compartments and/or in a few lakes showed higher molecular diversity than the "common compositions". Processing of DOM molecules in sediments included selective preservation for polyphenolic compounds and microbial resynthesis of selected molecules of considerable diversity.
AU  - Valle Das Neves, J.
AU  - Harir, M.
AU  - Gonsior, M.*
AU  - Enrich-Prast, A.*
AU  - Schmitt-Kopplin, P.
AU  - Bastviken, D.*
AU  - Hertkorn, N.
C1  - 57652
C2  - 47964
CY  - The Boulevard, Langford Lane, Kidlington, Oxford Ox5 1gb, England
TI  - Molecular differences between water column and sediment pore water SPE-DOM in ten Swedish boreal lakes.
JO  - Water Res.
VL  - 170
PB  - Pergamon-elsevier Science Ltd
PY  - 2020
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - Groundwater is not only a vital resource, but also one of the largest terrestrial aquatic ecosystems on Earth. However, to date, ecological criteria are often not considered in routine groundwater monitoring, mainly because of the lack of suitable ecological assessment tools. Prokaryotic microorganisms are ubiquitous in groundwater ecosystems even under the harshest conditions, making them ideal bioindicators for ecological monitoring. We have developed a simple, inexpensive approach that enables ecological groundwater monitoring based on three microbiological parameters that can be easily integrated into existing routine monitoring practices: prokaryotic cell density (D) measured by flow cytometry; activity (A) measured as prokaryotic intracellular ATP concentrations using a simple celllysis-luminescence assay; and, as an optional parameter, the bioavailable carbon (C) measured as the concentration of assimilable organic carbon in a simple batch growth assay. We analyzed data for three case studies of different disturbances representing some of the main threats to groundwater ecosystems, i.e. organic contamination with hydrocarbons, surface water intrusion, and agricultural land use. For all three disturbances, disturbed samples could be reliably distinguished from undisturbed samples based on a single index value obtained from multivariate outlier analyses of the microbial variables. We could show that this multivariate approach allowed for a significantly more sensitive and reliable detection of disturbed samples compared to separate univariate outlier analyses of the measured variables. Furthermore, a comparison of non-contaminated aquifers from nine different regions across Germany revealed distinct multivariate signatures along the three microbial variables, which should be considered when applying our approach in practice. In essence, our approach offers a practical tool for the detection of disturbances of groundwater ecosystems based on microbial parameters which can be seamlessly extended in the future by additional parameters for higher sensitivity as well as flexibility. (C) 2019 Elsevier Ltd. All rights reserved.
AU  - Fillinger, L.
AU  - Hug, K.
AU  - Trimbach, A.M.*
AU  - Wang, H.
AU  - Kellermann, C.S.
AU  - Meyer, A.
AU  - Bendinger, B.*
AU  - Griebler, C.
C1  - 56696
C2  - 47186
CY  - The Boulevard, Langford Lane, Kidlington, Oxford Ox5 1gb, England
TI  - The D-A-(C) index: A practical approach towards the microbiological - ecological monitoring of groundwater ecosystems.
JO  - Water Res.
VL  - 163
PB  - Pergamon-elsevier Science Ltd
PY  - 2019
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - Algal-derived dissolved organic matter (ADOM) originating from lysed Microcystis aeruginosa cells was investigated as precursor material to form disinfection by-products upon disinfection with free chlorine. Non-targeted ultrahigh resolution 12 T negative mode electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) revealed high molecular diversity in solid-phase extracted and ionizable components of Microcystis aeruginosa ADOM. The toxin microcystin LR was effectively degraded by free chlorine, which was expected. However, we found a high diversity of disinfection by-products associated with the addition of free chlorine to the water-soluble and solid-phase extractable fraction of ADOM and of double-bond moieties in abundant and known unsaturated fatty acids. Aromatic DOM precursors were absent from known metabolites of Microcystis aeruginosa and no evidence for aromatic disinfection by-products (DBPs) was found, despite N-containing compounds. A large diversification of N-containing molecular formulas was observed after chlorination, which seems indicative for the breakdown and oxidation of larger peptides. Additionally, a diverse group of N-compounds with presumed chloramine functional groups was observed. This study highlights the importance to evaluate ADOM and its ability to form different DBPs when compared to allochthonous or terrestrially-derived DOM. (C) 2019 The Author(s). Published by Elsevier Ltd.
AU  - Gonsior, M.*
AU  - Powers, L.C.*
AU  - Williams, E.*
AU  - Place, A.*
AU  - Chen, F.*
AU  - Ruf, A.
AU  - Hertkorn, N.
AU  - Schmitt-Kopplin, P.
C1  - 55639
C2  - 46495
CY  - The Boulevard, Langford Lane, Kidlington, Oxford Ox5 1gb, England
SP  - 300-309
TI  - The chemodiversity of algal dissolved organic matter from lysed Microcystis aeruginosa cells and its ability to form disinfection by-products during chlorination.
JO  - Water Res.
VL  - 155
PB  - Pergamon-elsevier Science Ltd
PY  - 2019
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - Fluvial networks are globally relevant for the processing of dissolved organic matter (DOM). To investigate the change in molecular DOM diversity along the river course, high-field FTICR mass spectrometry and NMR spectroscopy of riverine DOM as well as bacterial abundance and activity were measured in a third order stream along a land-use gradient from pristine, agricultural to urban landscapes. DOM composition showed a clear evolution along the river course with an initial decrease of average oxidation and unsaturation followed by an increased relative abundance of CHNO and CHOS compounds introduced by agriculture and waste water, respectively. DOM composition was dominated by rather unsaturated CHO compounds (H/C ≤ 1) in headwaters and by more aliphatic molecules at downstream sites. Oxygenated functional groups shifted from aromatic ethers and hydroxyl groups to aliphatic carboxylic acids and aliphatic hydroxyl groups. This massive dislocation of oxygen significantly increased the diversity of atomic environments in branched aliphatic groups from headwater to downstream DOM. Mass spectra of DOM enabled the detection of compositional relationships to bacterial abundance and activity which was positively related to more aliphatic components (H/C > 1) and negatively related to unsaturated components. FTICR mass and NMR spectra corroborated the initial decline in DOM molecular diversity predicted by the River Continuum Concept (RCC) but demonstrated an anthropogenic increase in the molecular diversity of DOM further downstream. While the high DOM molecular diversity in first order headwater streams was the result of small scale ecosystem plurality, agriculture and waste water treatment introduced many components in the lower reaches. These anthropogenic influences together with massive bacterial oxidation of DOM contributed to a growth of molecular diversity of downstream DOM whose composition and structure differed entirely from those found in pristine headwaters.
AU  - Kamjunke, N.*
AU  - Hertkorn, N.
AU  - Harir, M.
AU  - Schmitt-Kopplin, P.
AU  - Griebler, C.
AU  - Brauns, M.*
AU  - von Tümpling, W.*
AU  - Weitere, M.*
AU  - Herzsprung, P.*
C1  - 56877
C2  - 47406
TI  - Molecular change of dissolved organic matter and patterns of bacterial activity in a stream along a land-use gradient.
JO  - Water Res.
VL  - 164
PY  - 2019
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - The chemistry of hydraulic fracturing fluids and wastewaters is complex and is known to vary by operator, geologic formation, and fluid age. A time series of hydraulic fracturing fluids, flowback fluids, and produced waters was collected from two adjacent Marcellus Shale gas wells for organic chemical composition analyses using ultrahigh resolution mass spectrometry. Hierarchical clustering was used to compare and extract ions related to different fluid ages and many halogenated organic molecular ions were identified in flowback fluids and early produced waters based on exact mass. Iodinated organic compounds were the dominant halogen class in these clusters and were nearly undetectable in hydraulic fracturing fluid prior to injection. The iodinated ions increased in flowback and remained elevated after ten months of well production. We suggest that these trends are mainly driven by dissolved organic matter reacting with reactive halogen species formed abiotically through oxidizing chemical additives applied to the well and biotically via iodide-oxidizing bacteria. Understanding the implications of these identified halogenated organic compounds will require future investigation in to their structures and environmental fate.
AU  - Luek, J.L.*
AU  - Harir, M.
AU  - Schmitt-Kopplin, P.
AU  - Mouser, P.J.*
AU  - Gonsior, M.*
C1  - 53215
C2  - 44651
SP  - 200-206
TI  - Temporal dynamics of halogenated organic compounds in Marcellus Shale flowback.
JO  - Water Res.
VL  - 136
PY  - 2018
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - Dissolved organic matter (DOM) contained in lake sediments is a carbon source for many microbial degradation processes, including aerobic and anaerobic mineralization. During anaerobic degradation, DOM is partially consumed and transformed into new molecules while the greenhouse gases methane (CH4) and carbon dioxide (CO2) are produced. In this study, we used ultrahigh resolution mass spectrometry to trace differences in the composition of solid-phase extractable (PPL resin) pore water DOM (SPE-DOM) isolated from surface sediments of three boreal lakes before and after 40 days of anoxic incubation, with concomitant determination of CH4 and CO2 evolution. CH4 and CO2 production detected by gas chromatography varied considerably among replicates and accounted for fractions of similar to 2-4 x 10(-4) of sedimentary organic carbon for CO2 and similar to 0.8-2.4 x 10(-5) for CH4. In contrast, the relative changes of key bulk parameters during incubation, such as relative proportions of molecular series, elemental ratios, average mass and unsaturation, were regularly in the percent range (1-3% for compounds decreasing and 4-10% for compounds increasing), i.e. several orders of magnitude higher than mineralization alone. Computation of the average carbon oxidation state in CHO molecules of lake pore water DOM revealed rather non-selective large scale transformations of organic matter during incubation, with depletion of highly oxidized and highly reduced CHO molecules, and formation of rather non-labile fulvic acid type molecules. In general, proportions of CHO compounds slightly decreased. Nearly saturated CHO and CHOS lipid-like substances declined during incubation: these rather commonplace molecules were less specific indicators of lake sediment alteration than the particular compounds, such as certain oxygenated aromatics and carboxyl-rich alicyclic acids (CRAM) found more abundant after incubation. There was a remarkable general increase in many CHNO compounds during incubation across all lakes. Differences in DOM transformation between lakes corresponded with lake size and water residence time. While in the small lake Svarttjarn, CRAM increased during incubation, lignin-and tannin-like compounds were enriched in the large lake Bisen, suggesting selective preservation of these rather non-labile aromatic compounds rather than recent synthesis. SPE-DOM after incubation may represent freshly synthesized compounds, leftover bulk DOM which is primarily composed of intrinsically refractory molecules and/or microbial metabolites which were not consumed in our experiments. In spite of a low fraction of the total DOM being mineralized to CO2 and CH4, the more pronounced change in molecular DOM composition during the incubation indicates that diagenetic modification of organic matter can be substantial compared to complete mineralization. (C) 2017 Elsevier Ltd. All rights reserved.
AU  - Valle Das Neves, J.
AU  - Gonsior, M.*
AU  - Harir, M.
AU  - Enrich-Prast, A.*
AU  - Schmitt-Kopplin, P.
AU  - Bastviken, D.*
AU  - Conrad, R.*
AU  - Hertkorn, N.
C1  - 52371
C2  - 43940
CY  - Oxford
SP  - 252-263
TI  - Extensive processing of sediment pore water dissolved organic matter during anoxic incubation as observed by high-field mass spectrometry (FTICR-MS).
JO  - Water Res.
VL  - 129
PB  - Pergamon-elsevier Science Ltd
PY  - 2018
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - The use of reclaimed wastewater (RWW) for the irrigation of crops may result in the continuous exposure of the agricultural environment to antibiotics, antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). In recent years, certain evidence indicate that antibiotics and resistance genes may become disseminated in agricultural soils as a result of the amendment with manure and biosolids and irrigation with RWW. Antibiotic residues and other contaminants may undergo sorption/desorption and transformation processes (both biotic and abiotic), and have the potential to affect the soil microbiota. Antibiotics found in the soil pore water (bioavailable fraction) as a result of RWW irrigation may be taken up by crop plants, bioaccumulate within plant tissues and subsequently enter the food webs; potentially resulting in detrimental public health implications. It can be also hypothesized that ARGs can spread among soil and plant-associated bacteria, a fact that may have serious human health implications. The majority of studies dealing with these environmental and social challenges related with the use of RWW for irrigation were conducted under laboratory or using, somehow, controlled conditions. This critical review discusses the state of the art on the fate of antibiotics, ARB and ARGs in agricultural environment where RWW is applied for irrigation. The implications associated with the uptake of antibiotics by plants (uptake mechanisms) and the potential risks to public health are highlighted. Additionally, knowledge gaps as well as challenges and opportunities are addressed, with the aim of boosting future research towards an enhanced understanding of the fate and implications of these contaminants of emerging concern in the agricultural environment. These are key issues in a world where the increasing water scarcity and the continuous appeal of circular economy demand answers for a long-term safe use of RWW for irrigation.
AU  - Christou, A.*
AU  - Agüera, A.*
AU  - Bayona, J.M.*
AU  - Cytryn, E.*
AU  - Fotopoulos, V.*
AU  - Lambropoulou, D.*
AU  - Manaia, C.M.*
AU  - Michael, C.*
AU  - Revitt, M.*
AU  - Schröder, P.
AU  - Fatta-Kassinos, D.*
C1  - 51496
C2  - 43281
CY  - Oxford
SP  - 448-467
TI  - The potential implications of reclaimed wastewater reuse for irrigation on the agricultural environment: The knowns and unknowns of the fate of antibiotics and antibiotic resistant bacteria and resistance genes - A review.
JO  - Water Res.
VL  - 123
PB  - Pergamon-elsevier Science Ltd
PY  - 2017
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - Iopromide is frequently detected in water bodies due to its widespread use as an X-ray contrast agent in medicine. Due to its rapid clearance from the human body and its incomplete removal by wastewater treatment, an elevation of its concentration in the environment is observed that might lead to a serious impact on human and environmental health. Alternative or additional removal technologies may be more effective to remove iopromide from the effluents of wastewater treatment facilities, like phytoremediation with aquatic macrophytes. To test this, a hydroponic experiment was carried out to assess the fate of iopromide in Typha latifolia. The transformation products (TPs) in the plant were investigated to predict possible transformation mechanisms. The removal process followed first order kinetics with a linear regression R(2) value of 0.983. The iopromide concentration in roots and rhizomes reached a maximum value of 20.70 ± 0.81 and 16.82 ± 1.78 nmol g(-1) on the 7th day, respectively, thereafter decreased until the end of experiment. A different result was found in leaves, where iopromide concentration decreased over the whole experimental period. A total of eight transformation products were detected in T. latifolia, including 23 isomers. The relative content of aldehyde and ketone TPs decreased in roots and rhizomes while the relative content of carboxylic TPs increased. However, the relative content of aldehyde and ketone TPs only showed a slight decrease in leaves while the relative content of carboxylic TPs remained stable during the experimental period. In addition, a significant increase of decarboxylated TPs was found in leaves, but not in roots and rhizomes. These results indicate that a difference in transformation mechanisms exists among plant tissues. The findings of this study are important to better understand the transformation mechanisms of iopromide in plants and to improve phytoremediation technologies for such kind of compounds.
AU  - Cui, H.
AU  - Hrabě de Angelis, M.
AU  - Schröder, P.
C1  - 51350
C2  - 43188
SP  - 290-298
TI  - Iopromide exposure in Typha latifolia L.: Evaluation of uptake, translocation and different transformation mechanisms in planta.
JO  - Water Res.
VL  - 122
PY  - 2017
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - Streams are important sites of transformation of dissolved organic matter (DOM). The molecular characterization of DOM-quality changes requires sophisticated analytical evaluation techniques. The goal of our study was to link molecular DOM transformation with bacterial activity. We measured the degradation of leaf leachate over a gradient of bacterial production obtained by different rates of percolation of sediments in seven experimental flumes on five sampling dates. We developed a new strategy for evaluating molecular formula data sets obtained by ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS), in which the time-dependent change of component abundance was fitted by a linear regression model after normalization of mass peak intensities. All components were categorized by calculating the slope (change of percent intensity per day) in each of the seven flumes. These slopes were then related to cumulative bacterial production. The concentration of DOM decreased quickly in all flumes. Bacterial activity was higher in flumes with percolated sediment than in those without percolation, whereas plankton bacterial activity was higher in flumes without percolation or without sediment. There were no differences in molecular-DOM characteristics between flumes, but there were distinct changes over time. Positive slopes, i.e. increasing intensities over time, were found for small molecules (MW < 450 Da) and high O/C ratios, whereas decreasing intensities were observed less often and only for large molecules and low O/C ratios. The positive slopes of produced components showed a positive relationship to bacterial production for small and for oxygen-rich components. The negative slopes of degraded components were negatively related to bacterial production for large and for oxygen-deficient molecules. Overall, the approach provided new insights into the transformation of specific molecular DOM components.
AU  - Kamjunke, N.*
AU  - von Tümpling, W.*
AU  - Hertkorn, N.
AU  - Harir, M.
AU  - Schmitt-Kopplin, P.
AU  - Norf, H.*
AU  - Weitere, M.*
AU  - Herzsprung, P.*
C1  - 51503
C2  - 43291
CY  - Oxford
SP  - 513-523
TI  - A new approach for evaluating transformations of dissolved organic matter (DOM) via high-resolution mass spectrometry and relating it to bacterial activity.
JO  - Water Res.
VL  - 123
PB  - Pergamon-elsevier Science Ltd
PY  - 2017
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - Solid phase extraction (SPE) has become a widespread method for isolating dissolved organic matter (DOM) of diverse origin such as fresh and marine waters. This study investigated the DOM extraction selectivity of 24 commercially available SPE sorbents under identical conditions (pH = 2, methanol elution) on the example of Suwannee River (SR) water and North Sea (NS) water by using DOC analysis and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Proton nuclear magnetic resonance ((1)H NMR) spectroscopy was employed to assess leaching behavior, and HLB sorbent was found to leach substantially, among others. Variable DOC recoveries observed for SR DOM and NS DOM were primarily caused by the respective molecular composition, with subordinated and heterogeneous contributions of relative salinity. Scatter of average H/C and O/C elemental ratios and gross alignment in mass-edited H/C ratios according to five established coarse SPE characteristics was near identical for SR DOM and NS DOM. FTMS-based principal component analysis (PCA) provided essentially analogous alignment of SR DOM and NS DOM molecular compositions according to the five established groups of SPE classification, and corroborated the sorption-mechanism-based selectivity of DOM extraction in both cases. Evaluation of structural blanks and leaching of SPE cartridges requires NMR spectroscopy because FT-ICR mass spectrometry alone will not reveal inconspicuous displacements of continual bulk signatures caused by leaching of SPE resin constituents.
AU  - Li, Y.
AU  - Harir, M.
AU  - Uhl, J.
AU  - Kanawati, B.
AU  - Lucio, M.
AU  - Smirnov, K.
AU  - Koch, B.P.*
AU  - Schmitt-Kopplin, P.
AU  - Hertkorn, N.
C1  - 50832
C2  - 42773
CY  - Oxford
SP  - 316-323
TI  - How representative are dissolved organic matter (DOM) extracts? A comprehensive study of sorbent selectivity for DOM isolation.
JO  - Water Res.
VL  - 116
PB  - Pergamon-elsevier Science Ltd
PY  - 2017
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - Rising organic matter concentrations in surface waters in many Nordic countries require current drinking water treatment processes to be adapted. Accordingly, the use of a novel nanofiltration (NF) membrane was studied during a nine month period in pilot scale at a large drinking water treatment plant in Stockholm, Sweden. A chemically resistant hollow-fibre NF membrane was fed with full scale process water from a rapid sand filter after aluminum sulfate coagulation. The combined coagulation and NF process removed more than 90% of the incoming lake water dissolved organic carbon (DOC) (8.7 mg C L(-1)), and 96% of the absorbance at 254 nm (A254) (0.28 cm(-1) incoming absorbance). Including granulated active carbon GAC) filter, the complete pilot plant treatment process we observed decreases in DOC concentration (8.7-0.5 mg C L(-1)), SUVA (3.1-1.7 mg(-1) L m(-1)), and the average nominal molecular mass (670-440 Da). Meanwhile, water hardness was practically unaffected (<20% reduction). Humic substances (HS) and biopolymers were almost completely eliminated (6510-140 and 260 to 10 μg C L(-1) respectively) and low molecular weight (LMW) neutrals decreased substantially (880-190 μg C L(-1)). Differential excitation emission matrices (EEMs), which illustrate the removal of fluorescing organic matter (FDOM) over a range of excitation and emission wavelengths, demonstrate that coagulation removed 35 ± 2% of protein-like material and 65 ± 2% of longer emission wavelength, humic-like FDOM. The subsequent NF treatment was somewhat less selective but still preferentially targeted humic-like FDOM (83 ± 1%) to a larger extent than protein-like material (66 ± 3%). The high selectivity of organic matter during coagulation compared to NF separation was confirmed from analyses with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), and liquid chromatography with organic carbon detection (LC-OCD), as coagulation exclusively targeted oxidized organic matter components while NF removed both chemically reduced and oxidized components. DOC removal and change in DOC character in the GAC filters showed marked differences with slower saturation and more pronounced shifts in DOC character using NF as pre-treatment. Fluorescence derived parameters showed a similar decrease over time of GAC performance for the first 150 days but also indicated ongoing change of DOM character in the post NF GAC filtrate over time even after LC-OCD indicated steady state with respect to outgoing carbon. During our trial iron concentrations were low (<30 ppb) and thus A254 could be directly related to the concentration of HS (R(2) = 0.9). The fluorescence derived freshness index (β:α) proved to be an excellent variable for estimating the fraction of HS present in all samples. Given the recommended limit of 4 mg L(-1) for chemical oxygen demand (COD) for Swedish drinking water, coagulation will need to be supplemented with one or more treatment steps irrespective whether climate change will lead to drier or wetter conditions in order to maintain sufficient DOC removal with the current increasing concentrations in raw waters.
AU  - Kohler, S.J.*
AU  - Lavonen, E.E.*
AU  - Keucken, A.*
AU  - Schmitt-Kopplin, P.
AU  - Spanjer, T.*
AU  - Persson, K.*
C1  - 47574
C2  - 38730
CY  - Oxford
SP  - 232-240
TI  - Upgrading coagulation with hollow-fibre nanofiltration for improved organic matter removal during surface water treatment.
JO  - Water Res.
VL  - 89
PB  - Pergamon-elsevier Science Ltd
PY  - 2016
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - Deciphering the molecular codes of dissolved organic matter (DOM) improves our understanding of its role in the global element cycles and its active involvement in ecosystem services. This study demonstrates comprehensive characterization of DOM by an initial polarity-based stepwise solid phase extraction (SPE) with single methanol elution of the cartridges, but separate collection of equal aliquots of eluate. The reduction of molecular complexity in the individual DOM fractions attenuates intermolecular interactions and substantially increases the disposable resolution of any structure selective characterization. Suwannee River DOM (SR DOM) was used to collect five distinct SPE fractions with overall 91% DOC recovery. Optical spectroscopy (UV and fluorescence spectroscopy), high-field Fourier transform ion cyclotron mass spectrometry (FTICR MS) and nuclear magnetic resonance (NMR) spectroscopy showed analogous hierarchical clustering among the five eluates corroborating the robustness of this approach. Two abundant moderately hydrophobic fractions contained most of the SR DOM compounds, with substantial proportions of aliphatics, carboxylic-rich alicyclic molecules, carbohydrates and aromatics. A minor early eluting hydrophilic fraction was highly aliphatic and presented a large diversity of alicyclic carboxylic acids, whereas the two late eluting, minor hydrophobic fractions appeared as a largely defunctionalized mixture of aliphatic molecules. Comparative mass analysis showed that fractionation of SR DOM was governed by multiple molecular interactions depending on O/C ratio, molecular weight and aromaticity. The traditional optical indices SUVA254 and fluorescence index (FI) indicated the relative aromaticity in agreement with FTICR mass and NMR spectra; the classical fluorescent peaks A and C were observed in all four latter eluates. This versatile approach can be easily expanded to preparative scale under field conditions, and transferred to different DOM sources and SPE conditions.
AU  - Li, Y.
AU  - Harir, M.
AU  - Lucio, M.
AU  - Gonsior, M.*
AU  - Koch, B.P.*
AU  - Schmitt-Kopplin, P.
AU  - Hertkorn, N.
C1  - 49804
C2  - 40959
CY  - Oxford
SP  - 477-487
TI  - Comprehensive structure-selective characterization of dissolved organic matter by reducing molecular complexity and increasing analytical dimensions.
JO  - Water Res.
VL  - 106
PB  - Pergamon-elsevier Science Ltd
PY  - 2016
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - Absorbance, 3D fluorescence and ultrahigh resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) were used to explain patterns in the removal of chromophoric and fluorescent dissolved organic matter (CDOM and FDOM) at the molecular level during drinking water production at four large drinking water treatment plants in Sweden. When dissolved organic carbon (DOC) removal was low, shifts in the dissolved organic matter (DOM) composition could not be detected with commonly used DOC-normalized parameters (e.g. specific UV254 absorbance - SUVA), but was clearly observed by using differential absorbance and fluorescence or ESI-FT-ICR-MS. In addition, we took a novel approach by identifying how optical parameters were correlated to the elemental composition of DOM by using rank correlation to connect optical properties to chemical formulas assigned to mass peaks from FT-ICR-MS analyses. Coagulation treatment selectively removed FDOM at longer emission wavelengths (450-600 nm), which significantly correlated with chemical formulas containing oxidized carbon (average carbon oxidation state ≥0), low hydrogen to carbon ratios (H/C: average ± SD = 0.83 ± 0.13), and abundant oxygen-containing functional groups (O/C = 0.62 ± 0.10). Slow sand filtration was less efficient in removing DOM, yet selectively targeted FDOM at shorter emission wavelengths (between 300 and 450 nm), which commonly represents algal rather than terrestrial sources. This shorter wavelength FDOM correlated with chemical formulas containing reduced carbon (average carbon oxidation state ≤0), with relatively few carbon-carbon double bonds (H/C = 1.32 ± 0.16) and less oxygen per carbon (O/C = 0.43 ± 0.10) than those removed during coagulation. By coupling optical approaches with FT-ICR-MS to characterize DOM, we were for the first time able to confirm the molecular composition of absorbing and fluorescing DOM selectively targeted during drinking water treatment.
AU  - Lavonen, E.E.*
AU  - Kothawala, D.N.*
AU  - Tranvik, L.J.*
AU  - Gonsior, M.*
AU  - Schmitt-Kopplin, P.
AU  - Kohler, S.J.*
C1  - 46732
C2  - 37760
SP  - 286-294
TI  - Tracking changes in the optical properties and molecular composition of dissolved organic matter during drinking water production.
JO  - Water Res.
VL  - 85
PY  - 2015
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - Ultrahigh resolution Fourier transform ion cyclotron mass spectrometry and nuclear magnetic resonance spectroscopy were combined to evaluate the molecular changes of dissolved organic matter (DOM) through an ultrafiltration-nanofiltration (UF-NF) pilot plant, using two dissimilar NF membranes tested in parallel. The sampling was performed on seven key locations within the pilot plant: pretreated water, UF effluent, UF effluent after addition of reagents, permeate NF 1, permeate NF 2, brine NF 1 and brine NF 2, during two sampling campaigns. The study showed that there is no significant change in the nature of DOM at molecular level, when the water was treated with UF and/or with the addition of sodium metabisulfite and antiscaling agents. However, enormous decrease of DOM concentration was observed when the water was treated on the NF membranes. The NF process preferentially removed compounds with higher oxygen and nitrogen content (more hydrophilic compounds), whereas molecules with longer pure aliphatic chains and less content of oxygen were the ones capable of passing through the membranes. Moreover, slight molecular selectivity between the two NF membranes was also observed.
AU  - Cortés-Francisco, N.*
AU  - Harir, M.
AU  - Lucio, M.
AU  - Ribera, G.*
AU  - Martínez-Lladó, X.*
AU  - Rovira, M.*
AU  - Schmitt-Kopplin, P.
AU  - Hertkorn, N.
AU  - Caixach, J.*
C1  - 32410
C2  - 35092
SP  - 154-165
TI  - High-field FT-ICR mass spectrometry and NMR spectroscopy to characterize DOM removal through a nanofiltration pilot plant.
JO  - Water Res.
VL  - 67
PY  - 2014
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - Seasonal molecular changes in dissolved organic matter (DOM) isolated from Tai Lake (Taihu) both during (June) and following (November) an algal bloom event in 2007 were characterized by nuclear magnetic resonance spectroscopy (NMR) and Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. Considerable biosignatures were present in summer DOM, yet with a near absence of algal extract compounds. Extensive molecular alteration resulting from multistep and massively parallel biotic and subordinated abiotic transformations of algal biomass to DOM included loss and synthesis of carbohydrates, fundamental changes of aromatic compounds and progressive formation of carboxyl-rich alicyclic compounds (CRAM). The DOM transformation from summer to fall resulted in smaller molecules, increased abundance of CHNO continuous molecular series and overall molecular diversity. Analysis of MS-derived compositional networks placed summer DOM in-between the algal extract and fall DOM. Metabolic pathway annotation by means of high-resolution mass analysis provided a wide range of pathways associated with secondary metabolites in DOM and more basic ones like carbohydrate metabolism characteristic of algal extract compounds. Overall, the time-dependent molecular signature of Taihu DOM was likely dominated by microbial metabolism rather than abiotic chemical transformations. Results from this study indicate that high-resolution organic structural spectroscopy resolves meaningful structural detail out of complex environmental mixtures and has the potential to contribute significantly to future functional biodiversity studies.
AU  - Zhang, F.*
AU  - Harir, M.
AU  - Moritz, F.
AU  - Zhang, J.*
AU  - Witting, M.
AU  - Wu, Y.*
AU  - Schmitt-Kopplin, P.
AU  - Fekete, A.
AU  - Gáspár, A.
AU  - Hertkorn, N.
C1  - 31066
C2  - 34144
CY  - Oxford
SP  - 280-294
TI  - Molecular and structural characterization of dissolved organic matter during and post cyanobacterial bloom in Taihu by combination of NMR spectroscopy and FTICR mass spectrometry.
JO  - Water Res.
VL  - 57
PB  - Pergamon-elsevier Science Ltd
PY  - 2014
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - Phenoxy acid herbicides and their potential metabolites represent industrial or agricultural waste that impacts groundwater and surface waters through leaching from old landfills throughout the world. Fate assessment of dichlorprop and its putative metabolite 4-CPP (2-(4-chlorophenoxy)propionic acid) is frequently obstructed by inconclusive evidence from redox conditions, heterogeneous geologic settings (e.g. clay till) and ambiguous parent daughter relationships (i.e. 4-CPP may be daughter product or impurity of dichlorprop). For the first time, a combination of four methods was tested to assess transformation of phenoxy acids at a contaminated landfill (Risby site): analysis of (i) parent and daughter compound concentrations, (ii) enantiomer ratios (iii) compound-specific isotope analysis and (iv) enantiomer-specific isotope analysis. Additionally, water isotopes and chloride were used as conservative tracers to delineate two distinct groundwater flow paths in the clay till. Metabolite concentrations and isotope ratios of chlorinated ethenes demonstrated dechlorination activity in the area with highest leachate concentrations (hotspot) indicating favorable conditions also for dechlorination of dichlorprop to 4-CPP and further to phenoxypropionic acid. Combined evidence from concentrations, enantiomer ratios and isotope ratios of dichlorprop and 4-CPP confirmed their dechlorination in the hotspot and gave evidence for further degradation of 4-CPP downgradient of the hotspot. A combination of 4-CPP enantiomer and isotope analysis indicated different enantioselectivity and isotope fractionation, i.e. different modes of 4-CPP degradation, at different locations. This combined information was beyond the reach of any of the methods applied alone demonstrating the power of the new combined approach.
AU  - Milosevic, N.*
AU  - Qiu, S.
AU  - Elsner, M.
AU  - Einsiedl, F.*
AU  - Maier, M.
AU  - Bensch, H.K.V.
AU  - Albrechtsen, H.J.*
AU  - Bjerg, P.L.*
C1  - 23618
C2  - 31236
SP  - 637-649
TI  - Combined isotope and enantiomer analysis to assess the fate of phenoxy acids in a heterogeneous geologic setting at an old landfill.
JO  - Water Res.
VL  - 47
IS  - 2
PB  - Pergamon-Elsevier Science
PY  - 2013
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - Chlorinated aliphatic hydrocarbons (CAHs) often discharge into rivers as contaminated groundwater baseflow. Biotransformation, sorption and dilution of CAHs in the impacted river sediments have been reported to reduce discharge, but the effect of temporal variations in environmental conditions on the occurrence and extent of those processes in river sediments is largely unknown. We monitored the reduction of CAH discharge into the Zenne River during a 21-month period. Despite a relatively stable influx of CAHs from the groundwater, the total reduction in CAH discharge from 120 to 20cm depth in the river sediments, on average 74±21%, showed moderate to large temporal variations, depending on the riverbed location. High organic carbon and anaerobic conditions in the river sediments allowed microbial reductive dechlorination of both chlorinated ethenes and chlorinated ethanes. δ(13)C values of the CAHs showed that this biotransformation was remarkably stable over time, despite fluctuating pore water temperatures. Daughter products of the CAHs, however, were not detected in stoichiometric amounts and suggested the co-occurrence of a physical process reducing the concentrations of CAHs in the riverbed. This process was the main process causing temporal variations in natural attenuation of the CAHs and was most likely dilution by surface water-mixing. However, higher spatial resolution monitoring of flow transients in the riverbed is required to prove dilution contributions due to dynamic surface water-groundwater flow exchanges. δ(13)C values and a site-specific isotope enrichment factor for reductive dechlorination of the main groundwater pollutant vinyl chloride (VC) allowed assessment of changes over time in the extent of both biotransformation and dilution of VC for different scenarios in which those processes either occurred consecutively or simultaneously between 120 and 20cm depth in the riverbed. The extent of reductive dechlorination of VC ranged from 27 to 89% and differed spatially but was remarkably stable over time, whereas the extent of VC reduction by dilution ranged from 6 to 94%, showed large temporal variations, and was often the main process contributing to the reduction of VC discharge into the river.
AU  - Hamonts, K.*
AU  - Kuhn, T.
AU  - Vos, J.*
AU  - Maesen, M.*
AU  - Kalka, H.*
AU  - Smidt, H.*
AU  - Springael, D.*
AU  - Meckenstock, R.U.
AU  - Dejonghe, W.*
C1  - 7181
C2  - 29524
SP  - 1873-1888
TI  - Temporal variations in natural attenuation of chlorinated aliphatic hydrocarbons in eutrophic river sediments impacted by a contaminated groundwater plume.
JO  - Water Res.
VL  - 46
IS  - 6
PB  - Elsevier
PY  - 2012
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - Effluent dissolved organic matter (EfOM) collected from the secondary-treated wastewater of the Orange County Sanitation District (OCSD) located in Fountain Valley, California, USA was compared to natural organic matter collected from the Suwannee River (SRNOM), Florida using ultrahigh resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Furthermore, the two different treatment processes at OCSD, activated sludge and trickling filter, were separately investigated. The blend of these two effluents was further evaluated after it had passed through the microfiltration process of the Advanced Water Purification Facility (AWPF) at Orange County Water District (OCWD). EfOM contained 872 different m/z peaks that were unambiguously assigned to exact molecular formulae containing a single sulfur atom and carbon, hydrogen and oxygen atoms (CHOS formulae). In contrast, the SRNOM sample only contained 152 CHOS formulae. The trend in CHO molecular compositions was opposite with 2500 CHO formulae assigned for SRNOM but only about 1000 for EfOM. The CHOS-derived mass peaks with highest abundances in EfOM could be attributed to surfactants such as linear alkyl benzene sulfonates (LAS), their co-products dialkyl tetralin sulfonates (DATS) and their biodegraded metabolites such as sulfophenyl carboxylic acids (SPC). The differences between the treatments were found minor with greater differences between sampling dates than treatment methods used.
AU  - Gonsior, M.*
AU  - Zwartjes, M.*
AU  - Cooper, W.J.*
AU  - Song, W.*
AU  - Ishida, K.P.*
AU  - Tseng, L.Y.*
AU  - Jeung, M.K.*
AU  - Rosso, D.*
AU  - Hertkorn, N.
AU  - Schmitt-Kopplin, P.
C1  - 6309
C2  - 28284
SP  - 2943-2953
TI  - Molecular characterization of effluent organic matter identified by ultrahigh resolution mass spectrometry.
JO  - Water Res.
VL  - 45
IS  - 9
PB  - Elsevier
PY  - 2011
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - Bioaccumulation of PCDD/F in the foodweb was investigated in the Ya-Er Lake area, which was heavily polluted by PCDD/F. The high concentrations of PCDD/F in sediment can be transferred and bioaccumulated by aquatic organisms and humans through various pathways. Benthonic invertebrate animals and aquatic plants with a lot of fibers in the root can accumulate PCDD/F from sediment and water. Snail (Bellamya aeruginosa), shrimp (Macrobranchium sp.) and freshwater mussel (Acuticosta chinensis (Lea)) took up PCDD/F from the water and maintained the emission patterns, whereas fish tended to selectively accumulate 2,3,7,8-substituted isomers. The tissues of fish-eating bird and duck (Anas platyrhynchos) were very highly contaminated by PCDD/F due to ingestion of fish and other aquatic organisms from sediment. The residual concentration in breast milk depended on the original concentration of PCDD/F in the food. A resident in Ya-Er Lake area showed a daily intake of PCDD/ F of about 9.14 pg TEQ/kg body weight/day. This is higher than the tolerable daily intake (TDI) for PCDD/F (1 pg TEQ/kg body weight/day), which was recommended by the World Health Organization (WHO).
AU  - Wu, W.Z.*
AU  - Schramm, K.-W.
AU  - Kettrup, A.
C1  - 9829
C2  - 19821
SP  - 1141-1148
TI  - Bioaccumulation of Polychlorinated Dibenzo-p-Dioxins and Dibenzofurans in the Foodweb of YA-Er Lake Area, China.
JO  - Water Res.
VL  - 35 
IS  - 5
PB  - Elsevier Science Ltd.
PY  - 2001
SN  - 0043-1354
ER  - 

TY  - JOUR
AU  - Fischer, K.
C1  - 19988
C2  - 13156
SP  - 485-493
TI  - Distribution and Elimination of HEDP in Aquatic Test System.
JO  - Water Res.
VL  - 27
PY  - 1993
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - The influence of dissolved humic materials (DHM) on the acute toxicity of diazinon, tetrabromobisphenol-A (TBP), 4-chloroanilin (4-CA) and pentachlorophenol (PCP) was evaluated using the zebrafish (Brachydanio rerio Hamilton-Buchanan) and waterflea (Daphnia magna Straus). The 96-h LC50 (zebrafish) and 48-h EC50 values for four chemicals were determined in the presence of 0, 0.5, 5.0 and 50 TOC mg/l. The effects of DHM on the toxicity of four test chemicals to B. rerio were not observed in all of the DHM treatments. In the daphnid toxicity test, DHM significantly reduced the toxicity of diazinon and 4-CA, while no reduction of the toxicity of TBP and PCP was observed. These results indicate that the interaction between DHM and chemicals can alter the toxicity of some chemicals to D.magna. | The influence of dissolved humic materials (DHM) on the acute toxicity of diazinon, tetrabromobisphenol-A (TBP), 4-chloroanilin (4-CA) and pentachlorophenol (PCP) was evaluated using the zebrafish (Brachydanio rerio Hamilton-Buchanan) and waterflea (Daphnia magna Straus). The 96-h LC50 (zebrafish) and 48-h EC50 values for four chemicals determined in the presence of 0, 0.5, 5.0 and 50 TOC mg/l. The effects of DHM on the toxicity of four test chemicals to B. rerio were not observed in all of the DHM treatments. In the daphnid toxicity test, DHM significantly reduced the toxicity of diazinon and 4-CA, while no reduction of the toxicity of TBP and PCP was observed. These results indicate that the interaction between DHM and chemicals can alter toxicity of some chemicals to D. magna.
AU  - Lee, S.
AU  - Freitag, D.
AU  - Steinberg, C.E.W.
AU  - Kettrup, A.
AU  - Kim, Y.-H.
C1  - 40282
C2  - 38990
SP  - 199-204
TI  - Effects of dissolved humic materials on acute toxicity of some organic chemicals to aquatic organisms.
JO  - Water Res.
VL  - 27
IS  - 2
PY  - 1993
SN  - 0043-1354
ER  - 

TY  - JOUR
AU  - Lee, S.K.
AU  - Freitag, D.
AU  - Steinberg, C.E.W.
AU  - Kettrup, A.
AU  - Kim, Y.H.
C1  - 20132
C2  - 13308
SP  - 199-204
TI  - Effects of Dissolved Humic Materials on Acute Toxicity of Some Organic Chemicals to Aquatic Organisms.
JO  - Water Res.
VL  - 27
PY  - 1993
SN  - 0043-1354
ER  - 

TY  - JOUR
AB  - In Grosser Arbersee, a cirque lake in the Bavarian Forest (Germany) the acidification chronology since the late-glacial period has been studied paleolimnologically, applying subfossil diatom assemblages. Distinct phases of acidification could be detected, both natural ones by post-glacial development of soils and vegetation in the catchment and anthropogenic ones by mineral acid depositions. Whereas the first phases were accompanied (and most probably caused as well) by increases in organic carbon contents, the recent phases are characterized by losses of organic carbon contents in the lake. In various sensitive lakes in Central Europe the fate of organic carbon (measured as loss on ignition) is documented for the anthropogenic acidification period. In lowland as well as in high alpine lakes this process is accompanied by loss of organic carbon. These losses are by no means uniform. On the contrary, they range between 10 and 90% per drop of one pH-unit, in each lake calculated from estimated preacidification pH-conditions. | In Grosser Arbersee, a cirque lake in the Bavarian Forest (Germany), the acidification chronology since the late-glacial period has been studied paleolimnologically applying subfossil diatom assemblages. Distinct phases of acidification could be detected, both natural ones by post-glacial development of soils and vegetation in the catchment and anthropogenic ones by mineral acid depositions. Whereas the first phases were accompanied (and most probably caused as well) by increases in organic carbon contents, the recent phases are characterized by losses of organic carbon contents in the lake. In various sensitive lakes in Central Europe the fate of organic carbon (measured as loss on ignition) is documented for the anthropogenic acidification period. In lowland as well as in high alpine lakes this process is accompanied by loss of organic carbon. These losses are by no means uniform. On the contrary, they range between 10 and 90% per drop of one pH-unit, in each lake calculated from estimated preacidification pH-conditions.
AU  - Steinberg, C.E.W.
C1  - 40815
C2  - 11839
SP  - 1453-1458
TI  - Fate of organic matter during natural and anthropogenic lake acidification.
JO  - Water Res.
VL  - 25
IS  - 12
PY  - 1991
SN  - 0043-1354
ER  -