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The presence of certain pharmaceutical compounds in ground- and surface waters may constitute a serious environmental problem, even at low concentrations. The occurrence of pharmaceuticals in the environment indicates incomplete removal of these pharmaceuticals from municipal wastewater treatment plants (WWTPs). In this study four representative pharmaceutical compounds were identified and quantified in influent and effluent of WWTPs around the Region of Murcia. In addition, the removal efficiencies of the five different treatment systems employed by these WWTPs were evaluated for the four pharmaceutical compounds. Influent and effluent wastewaters were sampled on a weekly basis during four consecutive weeks and compound concentrations were quantitatively determined by HPLC-DAD. Pharmaceuticals were detected at μg/L levels (0.34–26.52 μg/L) in influent and effluent samples from all five different systems of the twelve WWTPs sampled in this work. The two most abundant pharmaceutical compounds were carbamazepine and naproxen. WWTPs that worked with extended aeration activated sludge processes, coagulation-flocculation, sand filtration and as tertiary treatment processes are used ultraviolet and chlorination systems (EAAS + C-F + SF + UV + Cl) removed better carbamazepine and ketoprofen than conventional activated sludge system with a double aeration tank, sand filtration, lamination, coagulation-flocculation and as tertiary treatment processes are used ultraviolet systems (CAS-DS + L + C-F + SF + UV) that removed better naproxen and diclofenac.

Amino acids are an important and highly dynamic fraction of organic N in soils and their determination in soil without derivatization is challenging due to the difficulties in separation and detection of trace amounts of these polar analytes. In the present work, we developed an analytical method to quantify 20 free amino acids in aqueous soil extracts without derivatization. The method employed hydrophilic interaction liquid chromatography–tandem mass spectrometry (HILIC–MS/MS) technique combined with a cation exchange solid phase extraction (SPE). Four stable isotope labelled amino acids were used as internal standards to improve the method performance. Good separation of 20 underivatized amino acids was achieved within 12 min. The limit of detection (LODs) and limit of quantification (LOQs) were in the range of 13–384 ng g−1 and 43–1267 ng g−1 (dry soil basis), respectively. The results showed that overall recoveries with high precision were obtained for the extracted free amino acids from ten different soils. The overall recoveries of 18 amino acids were similar for the ten soils used, which differed substantially in organic C content and in other properties as soil texture and pH. For most of the amino acids, the average recoveries from soil extracts were between 74% and 117%, with the exception of Met (31%), Pro (52%) and Arg (68%). Variability was within acceptable limits (relative standard deviations were between 4% and 13%), with the exception of Met (relative standard deviation = 90%) and Arg (relative standard deviation = 53%). Thus the proposed method with high throughout and high analyte specificity shows great promise for consistent analysis of free amino acids extracted from soils and offers new horizons for the analysis of amino acids in terrestrial and aquatic ecosystem.

Brominated flame retardants account for about 21% of the total production of flame retardants and many of these have been identified as persistent, bioaccumulative and toxic. Nevertheless, debromination of these chemicals under anaerobic conditions is well established, although this can increase their toxicity. Consequently, the production and use of these chemicals has been restricted and alternative products have been developed. Many of these are brominated compounds and share some of the disadvantages of the chemicals they are meant to replace. Therefore, other, nonbrominated, flame retardants such as organophosphorus compounds are also being used in increasing quantities, despite the fact that knowledge of their biodegradation and environmental fate is often lacking.

Few methods are available for comprehensive organophosphate flame retardants (PFRs) detection in water and wastewater. Gas chromatography has been employed previously, but this approach is less selective, not amenable for use with deuterated standards and can suffer unfavorable fragmentation. Ultra-high-pressure liquid chromatography tandem mass spectrometry (UHPLC-QqQ-MS/MS) has become the most promising platform, already applied successfully for analysis of selected PFRs in some environmental matrices like water and wastewater. However, the presence of some interferences from the dissolvent, the equipment and the used materials should be taken into account. The procedure involves: The first determination of PFRs by UHPLC-QqQ-MS/MS using a trap column to distinguish the interferences coming from the instrument and mobile phases.The optimization of the LC separation to distinguish all target compounds and their interferences.This method coupled to a solid-phase extraction (SPE) improve the detection and quantification of PFRs., This work has been supported by the Spanish Ministry of Economy and Competitiveness through the projects GCL2011-29703-C02-02 (http://mefturia.es) and GCL2015-64454-C2-1-R (ECO2risk-dds) and the University of Valencia through the project (UV-INV-AE15-348995). María Lorenzo also acknowledges to the Foundation “Tatiana Pérez de Guzmán el Bueno” for the grant to get the PhD.

The increasing production of fullerenes likely means a release of these chemicals in the environment. Since soils and sediments are expected to act as a sink, analytical tools are needed to assess the presence of fullerenes in these matrices. In the present work, a method was developed for the determination of fullerenes at environmental relevant levels employing Ultra High Performance Liquid Chromatograph coupled with High Resolution Mass Spectrometry (UHPLC-HRMS). Chromatographic separation was achieved with a core–shell biphenyl stationary phase that provided fast analysis with complete baseline separation. Ion Booster Electro Spray Ionization (IB-ESI) resulted in higher ionization efficiency and was much less susceptible to adduct formation in comparison with standard ESI, whereas Quadrupole Time of Flight (QTOF) MS granted high resolution mass spectra used for accurate identification. The Instrumental method limits of detection (ILoD) and quantification (ILoQ) were 6 and 20 fg, respectively, for C60 and 12 and 39 fg, respectively, for C70. Matrix effects related to co-extractants were systematically investigated in soil and sediments extracts through standard addition method (SAM) and monitoring the signal response during the chromatographic run of these samples. Consequently, minor chromatographic modifications were necessary for the analysis of matrices with high organic carbon content. The method limit of detection (MLoD)ranged from 84 pg/kg to 335 pg/kg, whereas limit of quantification (MLoQ) ranged from 279 pg/kg to 1.1 ng/kg. Furthermore, the method was successfully applied for the analysis of functionalized fullerenes (i.e. methanofullerenes). To the best of our knowledge, this is the first analytical method for the analysis of fullerenes in soils and sediments that employ core–shell biphenyl stationary phase as well as IB-ESI-QTOF MS hyphenated with UHPLC.

Worldwide, forests have absorbed around 30% of global anthropogenic emissions of carbon dioxide (CO2) annually, thereby acting as important carbon (C) sinks. It is proposed that leaving large fragments of dead wood, coarse woody debris (CWD), in forest ecosystems may contribute to the forest C sink strength. CWD may take years to centuries to degrade completely, and non-respired C from CWD may enter the forest soil directly or in the form of dissolved organic C. Although aboveground decomposition of CWD has been studied frequently, little is known about the relative size, composition and fate of different C fluxes from CWD to soils under various substrate-specific and environmental conditions. Thus, the exact contribution of C from CWD to C sequestration within forest soils is poorly understood and quantified, although understanding CWD degradation and stabilization processes is essential for effective forest C sink management. This review aims at providing insight into these processes on the interface of forest ecology and soil science, and identifies knowledge gaps that are critical to our understanding of the effects of CWD on the forest soil C sink. It may be seen as a “call-to-action” crossing disciplinary boundaries, which proposes the use of compound-specific analytical studies and manipulation studies to elucidate C fluxes from CWD. Carbon fluxes from decaying CWD can vary considerably due to interspecific and intraspecific differences in composition and different environmental conditions. These variations in C fluxes need to be studied in detail and related to recent advances in soil C sequestration research. Outcomes of this review show that the presence of CWD may enhance the abundance and diversity of the microbial community and constitute additional fluxes of C into the mineral soil by augmented leaching of dissolved organic carbon (DOC). Leached DOC and residues from organic matter (OM) from later decay stages have been shown to be relatively enriched in complex and microbial-derived compounds, which may also be true for CWD-derived OM. Emerging knowledge on soil C stabilization indicates that such complex compounds may be sorbed preferentially to the mineral soil. Moreover, increased abundance and diversity of decomposer organisms may increase the amount of substrate C being diverted into microbial biomass, which may contribute to stable C pools in the forest soil.

Venlafaxine, gemfibrozil, ibuprofen, irbesartan and ofloxacin are highly-consumed pharmaceuticals that show considerable removal efficiencies (between 40 and 98%) in wastewater treatment plants (WWTPs). Consequently, they are expected to generate transformation products (TPs) during wastewater treatment and in surface water (SW) receiving WWTP effluent. In this work, degradation experiments for these five pharmaceuticals have been carried out with SW and WWTP activated sludge under laboratory-controlled aerobic conditions to identify their transformation products by liquid chromatography coupled to time-of-flight mass spectrometry (LC-QTOF MS). Initially, 22 pharmaceutical TPs were tentatively identified. A retrospective analysis was performed in effluent wastewater (EWW) and SW samples. All parent compounds as well as several TPs were found in some of the selected EWW and SW samples. Additionally, valsartan and 3 TPs were also detected by searching for common fragments in these waters. It is important to highlight that some TPs, such as O-desmethyl-venlafaxine and an oxidized gemfibrozil TP, were more frequently found than their corresponding parent compounds. On the basis of these results, it would be recommendable to include these TPs (at least those found in EWW and SW samples analyzed) in monitoring programs in order to gain a more realistic understanding of the impact of pharmaceuticals on water quality.

Monomeric organic nitrogen (N) compounds such as free amino acids (FAAs) are an important resource for both plants and soil microorganisms and a source of ammonium (NH4+) via microbial FAA mineralization. We compared gross FAA dynamics with gross N mineralization in a Dutch heathland soil using a 15N tracing technique. A special focus was made on the effects of climate change factors warming and drought, followed by rewetting. Our aims were to (1) compare FAA mineralization (NH4+ production from FAAs) with gross N mineralization, (2) assess gross FAA production rate (depolymerization) and turnover time relative to gross N mineralization rate, and (3) assess the effects of a 14 years of warming and drought treatment on these rates. The turnover of FAA in the soil was ca. 3 h, which is almost 2 orders of magnitude faster than that of NH4+ (i.e. ca. 4 days). This suggests that FAA is an extensively used resource by soil microorganisms. In control soil (i.e. no climatic treatment), the gross N mineralization rate (10 ± 2.9 μg N g−1 day−1) was 8 times smaller than the total gross FAA production rate of five AAs (alanine, valine, leucine, isoleucine, proline: 127.4 to 25.0 μg N g−1 day−1). Gross FAA mineralization (3.4 ± 0.2 μg N g−1 day−1) contributed 34% to the gross N mineralization rate and is therefore an important component of N mineralization. In the drought treatment, a 6–29% reduction in annual precipitation caused a decrease of gross FAA production by 65% and of gross FAA mineralization by 41% compared to control. On the other hand, gross N mineralization was unaffected by drought, indicating an increased mineralization of other soil organic nitrogen (SON) components. A 0.5–1.5 °C warming did not significantly affect N transformations, even though gross FAA production declined. Overall our results suggest that in heathland soil exposed to droughts a different type of SON pool is mineralized. Furthermore, compared to agricultural soils, FAA mineralization was relatively less important in the investigated heathland. This indicates more complex mineralization dynamics in semi-natural ecosystems.

In our study we investigated the clay fraction composition of Pliocene clay deposits in the Sohag area, Egypt. Our goal was to obtain insights into the origin of the deposits, and to assess their potential for use in inexpensive wastewater purification. The rationale for the latter was that in Egypt both industrial wastewater and irrigation water are often polluted with heavy metals (HMs), the load of which can be significantly reduced using the Pliocene clay. We combined physico-chemical analyses with detailed X-ray diffraction (XRD) mineralogical investigations and Specific Surface Area (SSA) measurements of samples from 16 locations in four areas containing Pliocene clay deposits. The grain size distribution of the studied samples was dominated by silt (75–89%) with lower quantities of clay (6–20%) and sand (2–15%). Neither grain size distribution nor the distribution of individual clay minerals varied between the tested samples, suggesting that they all originate from a single source area. The effect of differential cation saturation (K + and Mg 2 + ) and differential heat treatments (25°C, 300°C, and 550°C) on the XRD patterns of oriented aggregates of the clay-sized fractions revealed 4 different clay mineral groups in the tested samples. The relative abundances of the clay minerals were semi-quantified and revealed a dominance of smectite (69–91% on average) with relatively low contents of kaolinite (9–29% on average) and minor amounts of illite (1–7% on average) and chlorite (0 ≤ 1%). This mineral assemblage suggests chemical weathering and indicates warm climatic conditions of the source area during the period of deposition. The higher CEC values of the Pliocene clay deposits (32.3–65.4 cmol c /kg) also pointed to the occurrence of smectite in the soils. The SSA of the Pliocene clay fractions (26.25–128.97 m 2 /g) correlated well with their exchangeable cation contents (K + and Ca 2 + , R 2 = 0.96 and 1.0 respectively) and micropore volumes (R 2 = 1.0). Micropore volumes and SSA of the studied samples increased with the size of the exchanged cation: K + > Ca 2 + > Na + . The mineralogical composition suggests that Pliocene smectite-rich deposits in the studied area have great potential to be used as raw material for inexpensive, local purification of wastewater polluted with HMs.

Evidence is presented that the oxygen demand associated with photochemical processes in the surface layer of oceans and seas worldwide is of the same order of magnitude as the amount of oxygen released by photosynthesis of the world's marine phytoplankton. Both estimates are of necessity quite rough and therefore the agreement between oxygen loss and production, earlier found only locally in the Atlantic Ocean and the North Sea, came as a surprise. The heavy photochemical oxygen demand of the world's oceans must be explored further in oxygen budget studies by biogeochemical modelling in which special attention is paid to regional and temporal-differences in the vertical stratification regime at the surface. Indeed, stratification is the candid() sine qua non for photochemical processes that are driven by ultraviolet radiation. Oxygen cannot be expected to be released from the sea to the atmosphere in the permanently stratified open ocean when year-round the oxygen loss associated with photochemistry is so high. In the upper layer of sea and ocean regions of the temperate zone vertical stratification is only pronounced during spring, summer and early autumn, so photochemical oxygen demand there is restricted to those months. We argue that the constancy of the oxygen concentration observed at the surface of the oceans in the tropics and subtropics (80% of Earth's marine regions) is the consequence of the balance between three processes that influence oxygen dissolved in seawater: loss due to photochemical processes and to the activity of microheterotrophs on the one hand, photosynthetic oxygen production by phytoplankton on the other. (C) 2015 Elsevier B.V. All rights reserved

In this short communication we report on the technical implementations of coupling an asymmetric flow field-flow fractionation (AF4) instrument to a high resolution mass spectrometer (Orbitrap) using an atmospheric photoionisation interface. This will allow for the first time online identification of different fullerenes in aqueous samples after their aggregates have been fractionated in the FFF channel. Quality parameters such as limits of detection (LODs), limits of quantification (LOQs) or linear range were evaluated and they were in the range of hundreds ng/L for LODs and LOQs and the detector response was linear in the range tested (up to ∼20μg/L). The low detection and quantification limits make this technique useful for future environmental or ecotoxicology studies in which low concentration levels are expected for fullerenes and common on-line detectors such as UV or MALS do not have enough sensitivity and selectivity.

The importance of soil aggregation in determining the dynamics of soil organic carbon (SOC) during erosion, transportation and deposition is poorly understood. Particularly, we do not know how aggregation contributes to the often-observed accumulation of SOC at depositional sites. Our objective was to assess how aggregation affects SOC stabilization in comparison to interactions of SOC with minerals. We determined and compared aggregate size distributions, SOC distribution in density fractions, and lignin-derived phenols from aggregated soil samples at both eroding and depositional sites. The stabilization effect of aggregation was quantified by comparing mineralization from intact and crushed macro-aggregates. Deposition of eroded soil material resulted in carbon (C) enrichment throughout the soil profile. Both macro-aggregate associated SOC and C associated with minerals (heavy fraction) increased in their importance from the eroding to the depositional site. In the uppermost topsoil (0–5 cm), SOC mineralization from intact aggregates was larger at the depositional site than at the eroding site, reflecting the large input of labile organic matter (plant residues) promoting aggregation. Contrastingly, in the subsoil, mineralization rates were lower at the depositional site because of effective stabilization by interactions with soil minerals. Aggregate crushing increased SOC mineralization by 10–80% at the eroding site, but not at the depositional site. The content of lignin-derived phenols did not differ between eroding and depositional sites in the topsoil (24.6–30.9 mg per g C) but was larger in the subsoil of the eroding site, which was accompanied by higher lignin oxidation. Lignin data indicated minor effects of soil erosion and deposition on the composition of SOC. We conclude that SOC is better protected in aggregates at the eroding than at the depositional site. During transport disaggregation and consequently SOC mineralization took place, while at the depositional site re-aggregation occurred mainly in the form of macro-aggregates. However, this macro-aggregation did not result in a direct stabilization of SOC. We propose that the occlusion of C inside aggregates serves as a pathway for the eroded C to be later stabilized by organo-mineral interaction.

Tomato, cabbage, and zucchini plants were grown hydroponically in a greenhouse. They were exposed to 14 perfluorinated alkyl acids (PFAAs) at four different concentrations via the nutrient solution. At maturity the plants were harvested, and the roots, stems, leaves, twigs (where applicable), and edible parts (tomatoes, cabbage head, zucchinis) were analyzed separately. Uptake and transfer factors were calculated for all plant parts to assess PFAA translocation and distribution within the plants. Root concentration factors were highest for long-chain PFAAs (>C11) in all three plant species, but these chemicals were not found in the edible parts. All other PFAAs were present in all above-ground plant parts, with transpiration stream concentration factors (TSCFs) of 0.05-0.25. These PFAAs are taken up with the transpiration stream and accumulate primarily in the leaves. Although some systematic differences were observed, overall their uptake from nutrient solution to roots and their further distribution within the plants were similar between plant species and among PFAAs.

Fullerenes are carbon-based nanomaterials expected to play a major role in emerging nanotechnology and produced at an increasing rate for industrial and household applications. In the last decade a number of novel compounds (i.e. fullerene derivatives) is being introduced into the market and specific analytical methods are needed for analytical purposes as well as environmental and safety issues. In the present work eight fullerenes (C60 and C70) and functionalized fullerenes (C60 and C70 exohedral-derivatives) were selected and a novel liquid chromatographic method was developed for their analysis with UV absorption as a method of detection. The resulting HPLC-UV method is the first one suitable for the analysis of all eight compounds. This method was applied for the analysis of fullerenes added to clayish, sandy and loess top-soils at concentrations of 20, 10 and 5 μg kg(-1) and extracted with a combination of sonication and shaking extraction. The analytical method limits of detection (LoD) and limits of quantification (LoQ) were in the range of 6-10 μg L(-1) and 15-24 μg L(-1) respectively for the analytical solutions. The extraction from soil was highly reproducible with recoveries ranging from 47±5 to 71±4% whereas LoD and LoQ for all soils tested were of 3 μg kg(-1) and 10 μg kg(-1) respectively. No significant difference in the extraction performance was observed depending of the different soil matrices and between the different concentrations. The developed method can be applied for the study of the fate and toxicity of fullerenes in complex matrices at relatively low concentrations and in principle it will be suitable for the analysis of other types of functionalized fullerenes that were not included in this work.

Because of large-scale production and use of an increasing diversity of chemicals in modern society, estuarine and coastal waters may be contaminated with numerous substances. Some of these compounds have the potential to affect microalgae at the base of the pelagic food chain. Therefore, we identified the main chemical stressors that negatively affect the effective photosystem II efficiency (øPSII) in marine microalgae of the Dutch estuarine and coastal waters. An enhanced effect-directed analysis (EDA) was carried out by combining reversed-phase ultra performance liquid chromatography fractionation of extracts from passive samplers, followed by effect assessment using the pulse amplitude modulation fluorometry assay and chemical analysis of biologically active fractions using high-resolution mass spectrometry. This study focuses on a novel microfractionation technique using 96-well plates to enhance throughput in EDA, structure elucidation, and the analytical and effect confirmation of the compounds that are identified. Although there are numerous unknown compounds present in estuarine and coastal waters, our EDA study shows that atrazine, diuron, irgarol, isoproturon, terbutryn, and terbutylazine are the main contributors to the observed effect on the øPSII of marine microalgae. © 2014 American Chemical Society.

Dust samples were collected from urban, suburban, industrial, highways, and natural sites from the vicinity of Murcia City, Spain. Chemical and physical properties were determined as well as the partitioning of the heavy metals Cu, Pb, Zn and Cd over exchangeable pools, association with carbonates, oxides, organic complexes and a residual phase. The results showed differences in the concentrations and percentages of the metals extracted from the five chemical phases among the dusts studied. These were attributed to the sources of metals, total metal concentration, dust physical and chemical properties, and the specific affinity of some metals for some solid phases. Metal distribution in the different phases was found to depend on each land use. Pb found to mainly reside in the residual phase from natural area; while Pb was mainly bound to Fe and Mn oxides in industrial dust. In dust from the urban and industrial sites Cu was equally distributed over Fe and Mn oxides and the residual phase, while in highway dust it mainly resided in the organic fraction. Zn mainly resided in the residual phase in dust from the urban and natural site, while in dust from the suburban site a large proportion of Zn was bound to Fe and Mn oxides. Cd was mainly associated to Fe and Mn oxides in dust from the urban site. Zn was the most mobile metal; Cu was the least mobile metal, while Cd and Pb showed medium risks of being mobilized.

Halogen-free flame retardants (HFFRs), such as the aromatic organophosphorus flame retardants (OPFRs) triphenyl phosphate (TPHP), resorcinol bis(diphenylphosphate) (PBDPP) and bisphenol A bis(diphenylphosphate) (BPA-BDPP) have been proposed as potential replacements for brominated flame retardants in polymers and textiles. Although these OPFRs are already marketed, their environmental fate and effects are poorly characterised. The aim of this study was therefore to determine the mineralisation and primary biodegradation of these OPFRs by activated sludge. Mineralisation was monitored by measuring CO2 production by means of GC analysis, whereas primary biodegradation was monitored by LC-MS/MS analysis of the OPFRs and their potential metabolites. TPHP was biodegraded and mineralised most rapidly and achieved the requirement for ready biodegradability (60% of theoretical maximum mineralisation). Primary biodegradation was also rapid for PBDPP, but 60% mineralisation was not achieved within the time of the test, suggesting that transformation products of PBDPP may accumulate. Primary degradation of BPA-BDPP was very slow and very low CO2 production was also observed. Based on these results, TPHP and to a lesser extent PBDPP appear to be suitable replacements for the more environmentally persistent brominated flame retardants.

The combination of in vitro bioassays and chemical screening can provide a powerful toolbox to determine biologically relevant compounds in water extracts. In this study, a sample preparation method is evaluated for the suitability for both chemical analysis and in vitro bioassays. A set of 39 chemicals were spiked to surface water, which were extracted using Oasis MCX cartridges. The extracts were chemically analyzed by liquid chromatography linear ion trap Orbitrap analysis and recoveries appeared to be on average 61% Compounds with log Kow values in the range between 0 and 4 are recovered well using this method. In a next step, the same extracts were tested for genotoxic activity using the Comet assay and Ames fluctuation test and for specific endocrine receptor activation using a panel of CALUX assays, for estrogenic (ER), androgenic (AR), glucocorticoid (GR), progestagenic (PR), and thyroidogenic (TR) agonistic activities. The results of the genotoxicity assays indicated that spiked genotoxic compounds were preserved during sample preparation. The measured responses of the GR CALUX and ER CALUX assays were similar to the predicted responses. The measured responses in the AR CALUX and PR CALUX assays were much lower than expected from the analytical concentration, probably due to antagonistic effects of some spiked compounds. Overall, the presented sample preparation method seems to be suitable for both chemical analysis and specific in vitro bioassay applications.

The efficiency of water treatment systems in removing emerging (chemical) substances is often unknown. Consequently, the prediction of the removal of contaminants in the treatment and supply chain of drinking water is of great interest. By collecting and processing existing chemical properties of contaminants, QSARs (quantitative structure-activity relationships) for typical removal parameters can be constructed. Depending on the definition of the predicted endpoint, QSARs are (1) embedded in a process model suite, where they serve to predict a model parameter and the total, hybrid model predicts a removal rate or (2) used to directly predict, e.g., the removal rate, or a rejection coefficient for membrane systems. The different types of resulting prediction models, ranging from mechanistic (causal) to empirical (data-based), allow for hypothesis testing of current physico-chemical mechanisms and interactions between the contaminant, the type of water and the materials or energy (e.g. UV light) of the removal barrier. Two case studies illustrate this viewpoint and also pinpoint that, firstly, QSAR development, validation and residual analysis stress the linkage between the QSAR endpoints and process model predictions, and secondly, they lay bare the need to share data, algorithms and models.

Binding to minerals is one mechanism crucial toward the accumulation and stabilization of organic matter (OM) in soils. Of the various biochemicals produced by plants, lignin-derived phenols are among the most surface-reactive compounds. However, it is not known to what extent mineral-bound lignin-derived phenols can be analytically assessed by alkaline CuO oxidation. We tested the potential irreversible binding of lignin from three litters (blue oak, foothill pine, annual grasses) to five minerals (ferrihydrite, goethite, kaolinite, illite, montmorillonite) using the CuO-oxidation technique, along with bulk organic carbon (OC) sorption. Up to 56% of sorbed lignin could not be extracted from the minerals with the CuO-oxidation technique. The composition of the irreversibly bound lignin component differed markedly between minerals and from that of the parent litter leachates, indicating different bonding strengths related to individual monomers and conformations. The difference in extractability of individual phenols suggests that abiotic processes, such as sorption/desorption, should be taken into account when using CuO oxidation data for assessing lignin turnover in mineral matrixes. However, given the apparent relationship between aromaticity as indicated by carbon-specific UV absorbance (SUVA) and bulk OC sorption, it is likely that irreversible sorption is a concern for any technique that addresses the broad class of aromatic/phenolic compounds in soils and sediments.

Plaggen soils, formed by various vegetational inputs during century-long plaggen (i.e. sod) application, comprise remarkably stable organic matter. Source identification could contribute to a better understanding of carbon stabilization mechanisms in soils and reconstruction of Holocene vegetation and land-use history. Cuticular-derived n-alkane distribution patterns as present in current vegetation are recognized as valuable tools to discriminate input sources, but an assessment of their consistency and variability is lacking to date. Therefore, this review synthesizes information on published n-alkane patterns of vegetation species and their various parts that contributed to plaggen soil formation (i.e. Calluna vulgaris, Betula pendula, Quercus robur, Pinus sylvestris, Lolium perenne, Deschampsia flexuosa, Molinia caerulea and Poa annua). This provided in addition valuable information on potential sources of systematic variation (e.g. geography/climate, environmental conditions, ontogeny and seasonality). Method of extraction/analysis showed no evident effects on n-alkanes. n-Alkanes showed predominantly distinct patterns for different plaggen vegetation species and parts in the range C17–36. Prominent n-alkanes C27, C29, C31 and C33 allowed clear distinction between input by shrubs, trees and grasses to plaggen soils. Nevertheless, systematic variability was indicated among n-alkane patterns. Unfortunately, the current limited data set of n-alkane patterns did not allow for exact quantification of the controls of variation. The need for more systematic studies and the setup of a reference data base for vegetation species is highlighted to (1) advance application of n-alkane patterns in source identification, (2) gain more insight into controls on, magnitude and timing of variations and (3) improve our knowledge concerning input sources, carbon dynamics and stabilization mechanisms in (plaggen) soils.

Background and aimsWe studied the response of lignin oxidation in soils of a beech/oak forest to changes in litter fall. Additionally we considered possible factors in lignin oxidation, including altered (i) input of fresh organic matter and (ii) fungi-to-bacteria ratios.MethodsThe field-based experiment included (i) doubling and (ii) exclusion of litter fall and (iii) controls with ambient litter fall. Soil (0-20 cm depth) was sampled after 8 years. We analyzed (i) lignin using the CuO oxidation method, (ii) stocks of free and mineral-bound organic carbon (OC), (iii) the response of soil organic matter (SOM) decomposition to addition of labile organic compounds in laboratory incubations, and (iv) ratios of fungal- vs. bacterial-derived amino sugars (F/B ratios).ResultsLitter exclusion increased stocks of free-light fraction OC, F/B ratios, the ability of the microbial community to use labile compounds for SOM decomposition, as well as acid-to-aldehyde ratios of vanillyl-type lignin phenols in A horizons. Litter addition had no such effects. We assume that litter exclusion caused enhanced transport of organic debris from lower forest floor horizons with rainwater into the A horizon. Enhanced input of organic debris might have increased (i) the availability of labile compounds and (ii) F/B ratios. Consequently, lignin oxidation increased.ConclusionsEnhanced input of organic debris from forest floors can increase lignin oxidation in mineral topsoils of the studied forest. The expected gradual changes in litter fall due to climate change likely will cause no such effects.

This work illustrates the potential of liquid chromatography coupled to a hybrid linear ion trap Fourier Transform Orbitrap mass spectrometer for the simultaneous identification and quantification of 24 drugs of abuse and relevant metabolites in sewage water. The developed methodology consisted of automatic solid-phase extraction using Oasis HLB cartridges, chromatographic separation of the targeted drugs, full-scan accurate mass data acquisition under positive electrospray ionization mode over an m/z range of 50-600 Da at a resolution of 30,000 FWHM and simultaneous MSn measurements to obtain information of fragment ions generated in the linear ion trap. Accurate mass of the protonated molecule, together with at least one nominal mass product ion and retention time allowed the confident identification of the compounds detected in these complex matrices. In addition to the highly reliable qualitative analysis, Orbitrap analyzer also proved to have satisfactory potential for quantification at sub-ppb analyte levels, a possibility that has been very little explored in the literature until now. The limits of quantification ranged from 4 to 68 ng L−1 in influent sewage water, and from 2 to 35 ng L−1 in effluent, with the exception of MDA, morphine and THC that presented higher values as a consequence of the high ionization suppression in this type of samples. Satisfactory recoveries (70-120%) and precision (

Relatively hazardous brominated flame retardants (BFRs) are currently substituted with halogen-free flame retardants (HFFRs). Consequently, information on their persistence, bioaccumulation and toxicity (PBT) is urgently needed. Therefore, we investigated the chronic toxicity to the water flea Daphnia magna of two HFFRs, aluminum diethylphosphinate (ALPI) and 9,10-dihyro-9-oxa-10-phosphaphenanthrene-oxide (DOPO). The toxicity of ALPI increased from a 48 h LC50 of 18 mg L(-1) to a 21 day LC50 value of 3.2 mg L(-1), resulting in an acute-to-chronic ratio of 5.6. This may imply a change in classification from low to moderate toxicity. ALPI also affected sublethal life cycle parameters, with an EC50 of 2.8 mg L(-1) for cumulative reproductive output and of 3.4 mg L(-1) for population growth rate, revealing a nonspecific mode of action. DOPO showed only sublethal effects with an EC50 value of 48 mg L(-1) for cumulative reproductive output and an EC50 value of 73 mg L(-1) for population growth rate. The toxicity of DOPO to D. magna was classified as low and likely occurred above environmentally relevant concentrations, but we identified specific effects on reproduction. Given the low chronic toxicity of DOPO and the moderate toxicity of ALPI, based on this study only, DOPO seems to be more suitable than ALPI for BFR replacement in polymers.

There is a tendency to substitute frequently used, but relatively hazardous brominated flame retardants (BFRs) with halogen-free flame retardants (HFFRs). Consequently, information on the persistence, bioaccumulation and toxicity (PBT) of these HFFRs is urgently needed, but large data gaps and inconsistencies exist. Therefore, in the present study the toxicity of a wide range of HFFRs to the water flea Daphnia magna was investigated. Our results revealed that four HFFRs were showing no effect at their Sw (saturated water concentration) and three had a low toxicity (EC50 > 10 mg L− 1), suggesting that these compounds are not hazardous. Antimony trioxide had a moderate toxicity (EC50 = 3.01 mg L− 1, 95% CL: 2.76-3.25) and triphenyl phosphate and the brominated reference compound tetra bromobisphenol A were highly toxic to D. magna (EC50 = 0.55 mg L− 1, 95% CL: 0.53-0.55 and EC50 = 0.60 mg L− 1, 95% CL: 0.24-0.97 respectively). Aluminum trihydroxide and bisphenol A bis(diphenyl phosphate) caused limited mortality at Sw (26 and 25% respectively) and have a low solubility (< 10 mg L− 1). Hence, increased toxicity of these compounds may be observed when for instance decreasing pH could increase solubility. By testing all compounds under identical conditions we provided missing insights in the environmental hazards of new generation flame retardants and propose as best candidates for BFR replacements: APP, ALPI, DOPO, MHO, MPP, ZHS and ZS.

Stability of organic matter in soils of the Belgium Loess Belt upon erosion and deposition X. Wang, L.H. Cammeraat, Z. Wang, G. Govers, K. Kalbitz. Abstract: Soil erosion has significant impacts on terrestrial C dynamics, which removes C from topsoil and continually exposes subsoil that has lower C content. However limited studies have paid attention to the mechanisms of stabilization of the eroded and deposited carbon against microbial decay. We analyzed factors governing organic C mineralization in topsoil (from depths of 5-10 cm) and subsoil (from depths of 75-100 cm and 160-200 cm) from depositional and eroding sites of Belgian Loess Belt. In 28-days incubations we studied the effects of oxygen concentrations (0%, 5%, and 20%), soil microbial biomass, substrate (glucose) availability and the amount and chemical features of soil organic carbon (SOC) on C mineralization. Soil erosion and deposition significantly affected SOC concentrations in 0~200 cm profiles and microbial biomass C, N in the topsoil. Carbon enrichment at the depositional site could be related to smaller mineralization. Concentrations of water-extractable C were larger in the soils of the eroding sites. Glucose addition stimulated microbial growth, enhanced soil respiration in all soils, particularly in the topsoil.. Carbon mineralization per unit organic carbon was larger in topsoils than in subsoils at both depositional and eroding sites. Oxygen availability showed the expected positive relationship to C mineralization in topsoils. However, small O2 concentrations did not result in decreased C mineralization in subsoils indicating that the controls on C dynamics might be different in different soil layers. The experimental results suggest that the observed C accumulation at depositional sites are also the result of smaller C mineralization. However, we are just at the beginning of understanding the reasons of this decreased mineralization. Keywords: Soil erosion and deposition; organic carbon and nitrogen; oxygen availability; mineralization; methane; microbial biomass C

As engineered nanoparticles of zinc oxide, titanium dioxide and silver, are increasingly used in consumer products, they will most probably enter the natural environment via wastewater, atmospheric deposition and other routes. The aim of this study is to predict the concentrations of these nanoparticles via wastewater emissions in a typical river system by means of a numerical model. The calculations rely on estimates of the use of nanomaterials in consumer products and the removal efficiency in wastewater treatment plants as well as model calculations of the fate and transport of nanoparticles in a riverine system. The river Rhine was chosen for this work as it is one of the major and best studied rivers in Europe. The study gives insight in the concentrations that can be expected and, by comparing the model results with measurements of the total metal concentrations, of the relative contribution of these emerging contaminants.Six scenarios were examined. Two scenarios concerned the total emission: in the first it was assumed that nanoparticles are only released via wastewater (treated or untreated) and in the second it was assumed that in addition nanoparticles can enter the river system via runoff from the application of sludge as a fertilizer. In both cases the assumption was that the nanoparticles enter the river system as free, unattached particles. Four additional scenarios, based on the total emissions from the second scenario, were examined to highlight the consequences of the assumption of free nanoparticles and the uncertainties about the aggregation processes.If all nanoparticles enter as free particles, roughly a third would end up attached to suspended particulate matter due to the aggregation processes nanoparticles are subject to. For the other scenarios the contribution varies from 20 to 45%. Since the Rhine is a fast flowing river, sedimentation is unlikely to occur, except at the floodplains and the lakes in the downstream regions, as in fact shown by the sediment mass balance. Nanoparticles will therefore be transported along the whole river until they enter the North Sea.For the first scenario, the concentrations predicted for zinc oxide and titanium dioxide nanoparticles are in the order of 0.5 μg/l, for silver nanoparticles in the order of 5 ng/l. For zinc and titanium compounds this amounts to 5-10% of the measured total metal concentrations, for silver to 2%. For the other scenarios, the predicted nanoparticle concentrations are two to three times higher.While there are still considerable uncertainties in the inputs and consequently the model results, this study predicts that nanoparticles are capable of being transported over long distances, in much the same way as suspended particulate matter.

© 2016, National Academy of Sciences. All rights reserved. The respiratory release of carbon dioxide (CO2) from soil is a major yet poorly understood flux in the global carbon cycle. Climatic warming is hypothesized to increase rates of soil respiration, potentially fueling further increases in global temperatures. However, despite considerable scientific attention in recent decades, the overall response of soil respiration to anticipated climatic warming remains unclear. We synthesize the largest global dataset to date of soil respiration, moisture, and temperature measurements, totaling >3,800 observations representing 27 temperature manipulation studies, spanning nine biomes and over 2 decades of warming. Our analysis reveals no significant differences in the temperature sensitivity of soil respiration between control and warmed plots in all biomes, with the exception of deserts and boreal forests. Thus, our data provide limited evidence of acclimation of soil respiration to experimental warming in several major biome types, contrary to the results from multiple single-site studies. Moreover, across all nondesert biomes, respiration rates with and without experimental warming follow a Gaussian response, increasing with soil temperature up to a threshold of ∼25 °C, above which respiration rates decrease with further increases in temperature. This consistent decrease in temperature sensitivity at higher temperatures demonstrates that rising global temperatures may result in regionally variable responses in soil respiration, with colder climates being considerably more responsive to increased ambient temperatures compared with warmer regions. Our analysis adds a unique cross-biome perspective on the temperature response of soil respiration, information critical to improving our mechanistic understanding of how soil carbon dynamics change with climatic warming.

The aim of this revision was to build an updated collection of information focused on the mechanisms and elements involved in metabolic pathways of aromatic hydrocarbons by bacteria. Enzymes as an expression of the genetic load and the type of electron acceptor available, as an environmental factor, were highlighted. In general, the review showed that both aerobic routes and anaerobic routes for the degradation of aromatic hydrocarbons are divided into two pathways. The first, named the upper pathways, from the original compound to central intermediate compounds still containing the aromatic ring but with the benzene nucleus chemically destabilized. The second, named the lower pathway, begins with ring de-aromatização and subsequent cleavage, resulting in metabolites that can be used by bacteria in the production of biomass. Under anaerobic conditions the five mechanisms of activation of the benzene ring described show the diversity of chemical reactions that take place. Obtaining carbon and energy from an aromatic hydrocarbon molecule is a process that exhibits the high complexity level of the metabolic apparatus of anaerobic microorganisms. The ability of these bacteria to express enzymes that catalyze reactions, known only in non-biological conditions, using final electron acceptors with a low redox potential, is a most interesting topic. The discovery of phylogenetic and functional characteristics of cultivable and non-cultivable hydrocarbon degrading bacteria has been made possible by improvements in molecular research techniques such as SIP (stable isotope probing) making trace of 13C, 15N and 18O into nucleic acids and proteins.

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are formed jointly with numerous products of incomplete combustion during waste incineration. Chlorobenzenes (CBz) are often cited as surrogates or precursors of PCDD/Fs. Experiments were conducted to investigate the effect of some key parameters on CBz formation, including moisture (H2O), chlorine gas (Cl2), cupric chloride (CuCl2), urea [(NH2)2CO], ammonia (NH3), and ammonium sulfate [(NH4)2SO4]. Cl2 and CuCl2 promoted CBz formation from fly ash, increasing the chlorination degree. In addition, Cl in cupric compound was more active than chlorine atom of Cl2, and chlorine type significantly affected the chlorination process. Less CBz yield was detected after S- and N-containing compounds [(NH2)2CO, NH3, and (NH4)2SO4] were added into reactive ash. High content of moisture in gas prevented CBz synthesis and reduced chlorination. These experimental results are useful to optimize CBz emission control and realize the mechanism of the correlation between CBz and PCDD/Fs.

Background and aims Environmental factors such as climate and atmospheric CO2 control inputs of plant-derived matter into soils, which then determines properties and decomposition of soil organic matter. We studied how dissolved organic matter (DOM) in forest floors responded to six years of litter fall manipulation at a spruce site. Methods Experimental treatments included (i) ambient litter fall, as well as (ii) reduction or (iii) increase of litter fall, each by 80%. Results Reduced litter input did not change fluxes of dissolved organic carbon (DOC), which suggests that much of the mobile DOM in forest floors is not from recent litter but older, partly degraded material. Litter addition increased DOC fluxes over 6 years by 68% (Oi), 23% (Oe) and 12% (Oa). This was mainly due to excessive DOM production in Oi horizons, while net DOM production in Oe and Oa horizons decreased. Upon litter addition, aromaticity and molecule complexity of DOM released from the Oi horizon increased, but decreased for DOM leaving Oa horizons. The results suggest that DOM production by lignin degradation was enhanced in Oi but reduced in Oe and Oa horizons upon litter addition. Conclusions Recent litter is not an important source for DOM entering mineral soils, but increased litter input changes organic matter decomposition, thus affecting fluxes and properties of DOM within forest floors.

On-line thermally assisted hydrolysis and methylation (THM) in the presence of both unlabelled and 13C-labelled tetramethylammonium hydroxide (TMAH) was used to assess the relative contributions of phenolics (lignin, demethylated lignin and non-lignin phenolics) in a peaty gley soil profile beneath an unimproved grassland (LL), from a study site located at Harwood (Northumberland, northeast England, UK). This site also includes an unforested moorland (ML) and a second rotation Sitka spruce stand (SS). The common lignin proxies have been corrected for contributions of non-lignin phenols and demethylated lignin in the LL ecosystem and then compared with those from the ML and SS ecosystems. The phenolic compositions from the contributory vegetation inputs (i.e. grasses, heather and Sitka spruce) to all three soils (LL, ML and SS) were also analysed. By using 13C-labelled TMAH it was possible to show that the chemical composition of soil organic matter (SOM) reflected the different vegetation inputs in each of the L/F layers but these characteristics were lost from the deeper organic and mineral layers. Similar changes in the yield of lignin monomers (Λ) with increasing soil depth were displayed in the LL soil profile as reported previously in the ML soil in that no maxima were observed in these amount-depth profiles. The tannin input to the LL soil is low and as a consequence, unlike the ML and SS soils, there is no progressive decrease in the amounts of these non-lignin phenolics with increasing depth. Finally the methylated carbohydrate derivatives (MC) become more abundant relative to the phenolics with increasing soil depth in all three ecosystems (LL, ML and SS).

Numerous polar anthropogenic organic chemicals have been found in the aqueous environment. Solid phase extraction (SPE) has been applied for the isolation of these from aqueous matrices, employing various materials. Nevertheless, little is known about the influence of functional groups on the sorption of the solutes onto these materials. Therefore, the sorption interactions of (charged) polar organic solutes to neutral (HLB), cation-exchanging (MCX, WCX), and anion-exchanging (MAX, WAX) OASIS polymers have been studied. For neutral solutes HLB has the highest capacity and affinity. Van der Waals interaction, rather than hydrogen bonding, appears to be the predominant factor determining sorption. For charged molecules, MCX and MAX show by far the highest affinity and capacity. Adsorption is already efficient at low concentrations and the maximum sorption capacity equals the amount of charged functional groups on the material. The results from this study allow semiquantitative predictions if a solute will adsorb on one of the OASIS materials and which functional groups govern adsorption.

A wide variety of environmental compounds of concern, e.g. pharmaceuticals or illicit drugs, are acids or bases that may predominantly be present as charged species in drinking water sources. These charged micropollutants may prove difficult to remove by currently used water treatment steps (e.g. UV/H2O2, activated carbon (AC) or membranes). We studied the sorption affinity of some ionic organic compounds to both AC and different charged polymeric materials. Ion-exchange polymers may be effective as additional extraction phases in water treatment, because sorption of all charged compounds to oppositely charged polymers was stronger than to AC, especially for the double-charged cation metformin. Tested below 1% of the polymer ion-exchange capacity, the sorption affinity of charged micropollutants is nonlinear and depends on the composition of the aqueous medium. Whereas oppositely charged electrolytes do not impact sorption of organic ions, equally charged electrolytes do influence sorption indicating ion-exchange (IE) to be the main sorption mechanism. For the tested polymers, a tenfold increased salt concentration lowered the IE-sorption affinity by a factor two. Different electrolytes affect IE with organic ions in a similar way as inorganic ions on IE-resins, and no clear differences in this trend were observed between the sulphonated and the carboxylated cation-exchanger. Sorption of organic cations is five fold less in Ca2+ solutions compared to similar concentrations of Na+, while that of anionic compounds is three fold weaker in SO42- solutions compared to equal concentrations of Cl-. (C) 2012 Elsevier Ltd. All rights reserved.

Density fractionation is frequently applied to separate soil organic matter according to the degree and the mode of interaction with minerals. Density fractions are operationally defined by density cut-off and sonication intensity, which determine the nature of the separated material. However, no tests or general agreements exist on the most appropriate density cut-off as well as on method and intensity of dispersion. Numerous variants have been proposed and applied, with results often contrasting each other and being hard to interpret. Here, we aimed at separating two light fractions (free and occluded into aggregates) composed of almost pure organic material, and one heavy fraction comprising the organic-mineral associations. We tested effects of different density cut-offs and sonication intensities, in combination and separately, on fraction yields, as well as on the fractions' organic carbon, total nitrogen and lignin-derived phenols. We tried to find optimum density cut-offs and sonication intensities, providing light fractions with maximum organic material and minimum contamination by mineral material. Under the test conditions, a density of 1.6 g cm−3 gave best results for all test soils, allowing for separation of maximums amounts of almost pure organic material. The density cut-off at 1.6 g cm−3 is well in line with previous studies and theoretical considerations, therefore we recommend the use of this density as most suitable for separation of organic debris. Sonication levels for aggregate disruption to achieve complete separation of occluded light organic matter varied amongst soils. The necessary intensity of dispersion relates to the type of soil, depending on the stability of contained aggregates. The application of one single dispersion energy level to different soils may result either in mineral contamination or in incomplete separation of light and heavy fractions as well as in redistribution of organic material amongst fractions. This means there is no single sonication level that can be applied to all soils. Thus, obtaining a meaningful light fraction residing within aggregates (occluded light fraction) requires assessment of the dispersion energy necessary to disrupt the aggregate system of a given soil without dispersion of organic-mineral associations. This can be done in pre-experiments where the soil is fractionated at different sonication levels. The appropriate dispersion is determined by mass yields and OC content of the obtained occluded fractions.

Environmental contextPerfluorinated compounds are synthetic chemicals shown to be present in the blood of humans. To study how these contaminants get into our blood requires a good understanding of their physicochemical properties. We describe an alternative way to obtain values for how perfluorinated compounds distribute between water and fatty phases (mimicking e.g. gut content and gut wall), which is essential information for modelling and understanding the environmental fate of these chemicals. AbstractCapacity factors of perfluorinated alkylated substances were obtained from isocratic reversed-phase high-performance liquid chromatography–mass spectrometry experiments at different organic modifier strengths of the mobile phase. The resulting capacity factor v. modifier strengths plots were extrapolated to obtain capacity factors at 100% water (k0) that can serve as indicators of the hydrophobicity of the perfluorinated acids. Values of log k0 were shown to increase linearly with the number of CF2 units in the fluorinated alkyl chain.

Effects of anthropogenic nitrogen (N) deposition and the ability of terrestrial ecosystems to store carbon (C) depend in part on the amount of N retained in the system and its partitioning among plant and soil pools. We conducted a meta-analysis of studies at 48 sites across four continents that used enriched 15N isotope tracers in order to synthesize information about total ecosystem N retention (i.e., total ecosystem 15N recovery in plant and soil pools) across natural systems and N partitioning among ecosystem pools. The greatest recoveries of ecosystem 15N tracer occurred in shrublands (mean, 89.5%) and wetlands (84.8%) followed by forests (74.9%) and grasslands (51.8%). In the short term (< 1 week after 15N tracer application), total ecosystem 15N recovery was negatively correlated with fine-root and soil 15N natural abundance, and organic soil C and N concentration but was positively correlated with mean annual temperature and mineral soil C:N. In the longer term (3-18 months after 15N tracer application), total ecosystem 15N retention was negatively correlated with foliar natural-abundance 15N but was positively correlated with mineral soil C and N concentration and C:N, showing that plant and soil natural-abundance 15N and soil C:N are good indicators of total ecosystem N retention. Foliar N concentration was not significantly related to ecosystem 15N tracer recovery, suggesting that plant N status is not a good predictor of total ecosystem N retention. Because the largest ecosystem sinks for 15N tracer were below ground in forests, shrublands, and grasslands, we conclude that growth enhancement and potential for increased C storage in aboveground biomass from atmospheric N deposition is likely to be modest in these ecosystems. Total ecosystem 15N recovery decreased with N fertilization, with an apparent threshold fertilization rate of 46 kg N x ha(-1) x yr(-1) above which most ecosystems showed net losses of applied 15N tracer in response to N fertilizer addition.

During the last decade, compound-specific hydrogen isotope analysis of plant leaf-wax and sedimentary n -alkyl lipids has become a promising tool for paleohydrological reconstructions. However, with the exception of several previous studies, there is a lack of knowledge regarding possible effects of early diagenesis on the δD values of n -alkanes. We therefore investigated the n -alkane patterns and δD values of long-chain n -alkanes from three different C3 higher plant species ( Acer pseudoplatanus L., Fagus sylvatica L. and Sorbus aucuparia L.) that have been degraded in a field leaf litterbag experiment for 27 months. We found that after an initial increase of long-chain n -alkane masses (up to ∼50%), decomposition took place with mean turnover times of 11.7 months. Intermittently, the masses of mid-chain n -alkanes increased significantly during periods of highest total mass losses. Furthermore, initially high odd-over-even predominances (OEP) declined and long-chain n -alkane ratios like n -C 31 /C 27 and n -C 31 /C 29 started to converge to the value of 1. While bulk leaf litter became systematically D-enriched especially during summer seasons (by ∼8‰ on average over 27 months), the δD values of long-chain n -alkanes reveal no systematic overall shifts, but seasonal variations of up to 25‰ ( Fagus , n -C 27 , average ∼13‰). Although a partly contribution by leaf-wax n -alkanes by throughfall cannot be excluded, these findings suggest that a microbial n- alkane pool sensitive to seasonal variations of soil water δD rapidly builds up. We propose a conceptual model based on an isotope mass balance calculation that accounts for the decomposition of plant-derived n -alkanes and the build-up of microbial n -alkanes. Model results are in good agreement with measured n -alkane δD results. Since microbial ‘contamination’ is not necessarily discernible from n -alkane concentration patterns alone, care may have to be taken not to over-interpret δD values of sedimentary n -alkanes. Furthermore, since leaf-water is generally D-enriched compared to soil and lake waters, soil and water microbial n -alkane pools may help explain why soil and sediment n -alkanes are D-depleted compared to leaves.

Dissolved organic nitrogen (DON) plays a key role in the N cycle of many ecosystems, as DON availability and biodegradation are important for plant growth, microbial metabolism and N transport in soils. However, biodegradation of DON (defined as the sum of mineralization and microbial immobilization) is only poorly understood. In laboratory incubations, biodegradation of DON and dissolved organic carbon (DOC) from Oi and Oa horizons of spruce, beech and cypress forests ranged from 6 to 72%. Biodegradation of DON and DOC was similar in most samples, and mineralization of DON was more important than microbial immobilization. Nitrate additions (0–10 mg N L−1) never influenced either DON immobilization by microorganisms or mineralization. We conclude that soil microorganisms do not necessarily prefer mineral N over DON for meeting their N demand, and that biodegradation of DON seems to be driven by the microbial demand for C rather than N. Quantifying the dynamics of DON in soils should include consideration of both C and N demands by microbes.

Lignin is a main component of plant litter. Its degradation is thought to be critical for litter decomposition rates and the build-up of soil organic matter. We studied the relationships between lignin degradation and the production of dissolved organic carbon (DOC) and of CO2 during litter decomposition. Needle or leaf litter of five species (Norway spruce, Scots pine, mountain ash, European beech, sycamore maple) and of different decomposition stage (freshly fallen and up to 27 months of field exposure) was incubated in the laboratory for two years. Lignin degradation was followed with the CuO method. Strong lignin degradation occurred during the first 200 incubation days, as revealed by decreasing yields of lignin-derived phenols. Thereafter lignin degradation leveled off. This pattern was similar for fresh and decomposed litter, and it stands in contrast to the common view of limited lignin degradation in fresh litter. Dissolved organic carbon and CO2 also peaked in thefirst period of the incubation but were not interrelated. In the later phase of incubation, CO2 production was positively correlated with DOC amounts, suggesting that bioavailable, soluble compounds became a limiting factor for CO2 production. Lignin degradation occurred only when CO2 production was high, and not limited by bioavailable carbon. Thus carbon availability was the most important control on lignin degradation. In turn, lignin degradation could not explain differences in DOC and CO2 production over the study period. Our results challenge the traditional view regarding the fate and role of lignin during litter decomposition. Lignin degradation is controlled by the availability of easily decomposable carbon sources. Consequently, it occurs particularly in the initial phase of litter decomposition and is hampered at later stages if easily decomposable resources decline.

We studied the degradation of lignin in leaf and needle litter of ash, beech, maple, pine and spruce using 13C-labelled tetramethylammonium hydroxide (13C TMAH) thermochemolysis. Samples were allowed to decompose for 27 months in litter bags at a German spruce forest site, resulting in a range of mass loss from 26% (beech) to 58% (ash). In contrast to conventional unlabelled TMAH thermochemolysis, 13C-labelling allows thermochemolysis products from lignin, demethylated lignin and other polyphenolic litter compounds (e.g. tannins) to be distinguished. Proxies for lignin degradation (phenol yield; acid/aldehyde ratio of products) changed considerably upon correction for the contribution of non-lignin sources to the thermochemolysis products. Using the corrected values, we found increasing acid/aldehyde values as well as decreasing or constant yield of lignin derived phenols normalised to litter carbon, suggesting pronounced lignin degradation by wood-rotting fungi. No indication for build up of demethylated lignin through the action of brown rot fungi on ring methoxyls was found. The results were compared with those of other analytical techniques applied in previous studies. Like 13C-TMAH thermochemolysis, CuO oxidation showed increasing lignin oxidation (acid/aldehyde ratio) and no/little enrichment of lignin derived phenols in the litter. Molecular lignin degradation patterns did not match those from analysis of total acid unhydrolysable residues (AURs). In particular, the long assumed selective preservation of lignin during the first months of litter decomposition, based on AUR analysis, was not supported by results from the CuO and 13C TMAH methods.

The primary aim of this article is to provide an overview of perfluoroalkyl and polyfluoroalkyl substances (PFASs) detected in the environment, wildlife, and humans, and recommend clear, specific, and descriptive terminology, names, and acronyms for PFASs. The overarching objective is to unify and harmonize communication on PFASs by offering terminology for use by the global scientific, regulatory, and industrial communities. A particular emphasis is placed on long-chain perfluoroalkyl acids, substances related to the long-chain perfluoroalkyl acids, and substances intended as alternatives to the use of the long-chain perfluoroalkyl acids or their precursors. First, we define PFASs, classify them into various families, and recommend a pragmatic set of common names and acronyms for both the families and their individual members. Terminology related to fluorinated polymers is an important aspect of our classification. Second, we provide a brief description of the 2 main production processes, electrochemical fluorination and telomerization, used for introducing perfluoroalkyl moieties into organic compounds, and we specify the types of byproducts (isomers and homologues) likely to arise in these processes. Third, we show how the principal families of PFASs are interrelated as industrial, environmental, or metabolic precursors or transformation products of one another. We pay particular attention to those PFASs that have the potential to be converted, by abiotic or biotic environmental processes or by human metabolism, into long-chain perfluoroalkyl carboxylic or sulfonic acids, which are currently the focus of regulatory action. The Supplemental Data lists 42 families and subfamilies of PFASs and 268 selected individual compounds, providing recommended names and acronyms, and structural formulas, as well as Chemical Abstracts Service registry numbers. Integr Environ Assess Manag 2011;7:513–541. © 2011 SETAC

The effect of salinity induced by CaCl2, MgCl2, NaCl and Na2SO4 on the mobility of Cu, Cd, Pb and Zn was studied. An increase of ionic strength by any salts promoted a higher release of Cd than the others metals. When CaCl2 and NaCl were applied, Cd and Pb showed the highest degree of mobilization. When MgCl2 was applied, Cd and Cu were mobilized the most. Finally, an increase of Na2SO4 also promoted the strongest mobilization of Cd and Cu.As the total heavy metal content was higher, the percentage of Pb and Cu released upon salinization decreased, indicating that these metals are strongly bound to soil constituents. An increase of carbonates in the soil promoted a higher release of Pb for all used salts and for Zn when MgCl2 and NaCl were used. This indicates that Pb and Zn are adsorbed on the surface of carbonate crystals. An increase of fine particles promoted a decrease of percentage of released Cd for all salts, indicating that Cd is strongly retained in the fine fractions.The main mechanism regulating Pb and Cd mobility was competition with Ca2+ for sorption sites followed for metal chloro-complexation, association between the Cd/Pb-sulfates and competition with Mg2+. The main mechanism regulating Cu mobility was the formation of Cu-sulfate, followed by competition with cations (Mg > Ca) and chloride. For Zn, competition with Ca2+ for sorption sites was the most important process for its mobility; followed by Zn-sulfate association and, finally, chloride and competition with Mg with the same effect.

Montane volcanic ash soils contain disproportionate amounts of soil organic carbon and thereby play an often underestimated role in the global carbon cycle. Given the central role of Al and Fe in stabilizing organic matter in volcanic ash soils, we assessed various extraction methods of Al, Fe, and C fractions from montane volcanic ash soils in northern Ecuador, aiming at elucidating the role of Al and Fe in stabilizing soil organic matter (SOM). We found extractions with cold sodium hydroxide, ammonium oxalate/oxalic acid, sodium pyrophosphate, and sodium tetraborate to be particularly useful. Combination of these methods yielded information about the role of the mineral phase in stabilizing organic matter and the differences in type and degree of complexation of organic matter with Al and Fe in the various horizons and soil profiles. Sodium tetraborate extraction proved the only soft extraction method that yielded simultaneous information about the Al, Fe, and C fractions extracted. It also appeared to differentiate between SOM fractions of different stability. The fractions of copper chloride- and potassium chloride-extractable Al were useful in assessing the total reactive and toxic Al fractions, respectively. The classical subdivision of organic matter into humic acids, fulvic acids, and humin added little useful information. The use of fulvic acids as a proxy for mobile organic matter as done in several model-based approaches seems invalid in the soils studied.

Differences in molecular properties between linear and branched alkanes as well as between compounds with branched alkyl groups is of relevance due to the large number of branched isomers of environmentally relevant compounds (e.g. fuels, fuel additives, surfactants). For branched alkane vapor pressures, the McGowan specific volume is a poor predictor. Therefore, in this study a correction on the McGowan specific volume is derived in terms of the number of branches and the number of pairs of vicinal branches to improve the prediction of branched alkane vapor pressures. This branching correction also brought branched /alkane solvent accessible volumes, octanol/water partition coefficients, air/hexadecane partition coefficients, and aqueous solubilities as well as alkyl-branched substituted aliphatic hydrocarbon air/hexadecane partition coefficients more in line with corresponding linear hydrocarbon properties when compared on a McGowan specific volume basis. Even for air–hexadecane partition coefficients of substituted aliphatic hydrocarbons with substituents at non-terminal carbons, application of the branching correction to the carbon bearing the substituent caused these partition coefficients to be more in line with those for linear compounds. Values for the Abraham A and B solvation parameters for nonlinear aliphatic ethers, amines, and alcohols, recalculated using branching corrected McGowan specific volumes, turned out to be closer to chemical expectations based on linear aliphatic ether, amine and alcohol values compared to previously reported experimental values obtained using uncorrected McGowan specific volumes. A comparison of alkylbenzene and alkene partition coefficient estimates from two different linear solvation energy relations, one containing a McGowan specific volume term and one without such a term, suggests that no branching correction is needed for alkyl groups at sp2 carbons. The main advantage of using branching corrected McGowan specific volumes is that the values of other solvation parameters become chemically more consistent.

Extracellular polymeric substances (EPS) are continuously produced by bacteria during their growth and metabolism. In soils, EPS are bound to cell surfaces, associated with biofilms, or released into solution where they can react with other solutes and soil particle surfaces. If such reaction results in a decrease in EPS bioaccessibility, it may contribute to stabilization of microbial-derived organic carbon (OC) in soil. Here we examined: (i) the chemical fractionation of EPS produced by a common Gram positive soil bacterial strain (Bacillus subtilis) during reaction with dissolved and colloidal Al species and (ii) the resulting stabilization against desorption and microbial decay by the respective coprecipitation (with dissolved Al) and adsorption (with Al(OH)3(am)) processes. Coprecipitates and adsorption complexes obtained following EPS-Al reaction as a function of pH and ionic strength were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The stability of adsorbed and coprecipitated EPS against biodegradation was assessed by mineralizationexperiments for 1100 h. Up to 60% of the initial 100 mg/L EPS-C was adsorbed at the highest initial molar Al:C ratio (1.86), but this still resulted only in a moderate OC mass fraction in the solid phase (17 mg/g Al(OH)3(am)). In contrast, while coprecipitation by Al was less efficient in removing EPS from solution (maximum values of 33% at molar Al:C ratios of 0.1-0.2), the OC mass fraction in the solid product was substantially larger than that in adsorption complexes. Organic Pcompounds were preferentially bound during both adsorption and coprecipitation. Data are consistent with strong ligand exchange of EPS phosphoryl groups during adsorption to Al(OH)3(am), whereas for coprecipitation weaker sorption mechanismsare also involved. X-ray photoelectron analyses indicate an intimate mixing of EPS with Al in the coprecipitates, which is not observed in the case of EPS adsorption complexes. The incubation experiments showed that both processes result in overall stabilization of EPS against microbial decay. Stabilization of adsorbed or coprecipitated EPS increased with increasing molar Al:C ratio and biodegradation was correlated with EPS desorption, implying that detachment of EPS from surface sites is a prerequisite for microbial utilization. Results indicate that the mechanisms transferring EPS into Al-organic associations may significantly affect the composition and stability of biomolecular C, N and P in soils. The observed efficient stabilization of EPS might explain the strong microbial character of organic matter in subsoils.

This study shows that the recently published polychlorinated biphenyl (PCB) Abraham solvation parameters predict PCB air−n-hexadecane and n-octanol−water partition coefficients very poorly, especially for highly ortho-chlorinated congeners. Therefore, an updated set of PCB solvation parameters was derived from four PCB properties and associated Abraham solvation equations. Additionally, the influence of ortho-chlorination on PCB solvent accessible volume and surface area was investigated. The updated PCB solvation parameters were tested on partitioning between five other phase combinations. Compared to the original PCB solvation parameter set, the updated PCB solvation parameters resulted in substantially improved estimates from Abraham solvation equations for (subcooled) liquid vapor pressures, aqueous solubilities, HPLC capacity factors, and for coefficients of air−n-hexadecane, air−water, organic carbon−water, and n-octanol−water partitioning. For water to polydimethyl siloxane and sodium dodecylsulphate (SDS) partitioning, the updated PCB solvation parameters yielded no improvement compared to the original data set. The main difference between the updated and the original parameter set is that updated PCB McGowan specific volumes depend on the degree of ortho-chlorination, which is qualitatively confirmed by trends in the PCB solvent accessible volumes and surface areas. The use of the updated PCB solvation parameters instead of the original values is therefore recommended.

Amorphous Al hydroxides (am-Al(OH)(3)) strongly sorb and by this means likely protect dissolved organic matter (OM) against microbial decay in soils. We carried out batch sorption experiments (pH 4.5; 40 mg organic C L-1) with OM extracted from organic horizons under a Norway spruce and a European beech forest. The stabilization of OM by sorption was analyzed by comparing the CO2 mineralized during the incubation of sorbed and non-sorbed OM. The mineralization of OM was evaluated based in terms of (i) the availability of the am-Al(OH)(3), thus surface OM loadings, (ii) spectral properties of OM, and (iii) the presence of phosphate as a competitor for OM. This was done by varying the solid-to-solution ratio (SSR = 0.02-1.2 g L-1) during sorption. At low SSRs, hence limited am-Al(OH)(3) availability, only small portions of dissolved OM were sorbed; for OM from Oa horizons, the mineralization of the sorbed fraction exceeded that of the original dissolved OM. The likely reason is competition with phosphate for sorption sites favouring the formation of weak mineral-organic bindings and the surface accumulation of N-rich, less aromatic and less complex OM. This small fraction controlled the mineralization of sorbed OM even at higher SSRs. At higher SSRs, i.e., with am-Al(OH)(3) more available, competition of phosphate decreased and aromatic compounds were sorbed selectively, which resulted in pronounced resistance of sorbed OM against decay. The combined OC mineralization of sorbed and non-sorbed OM was 12-65% less than that of the original DOM. Sorbed OM contributed only little to the overall OC mineralization. Stabilization of OC increased in direct proportion to am-Al(OH)(3) availability, despite constant aromatic C (similar to 30%). The strong stabilization at higher mineral availability is primarily governed by strong Al-OM bonds formed under less competitive conditions. Due to these strong bonds and the resulting strong stabilization, the surface loading, a proxy for the mineral's occupation by OM, was not a factor in the mineralization of sorbed OM over a wide range of C sorption (0.2-1.1 mg C m(-2)). This study demonstrates that sorption to am-Al(OH)(3) results in stabilization of OM. The mineral availability as well as the inorganic solution chemistry control sorptive interactions, thereby the properties of sorbed OM, and the stability of OM against microbial decay.

Isothiazolinones are used as preservatives, biocides and disinfectants in a variety of industrial and domestic applications. Some of the isothiazolinones are difficult to isolate from water due their high polarity. A sensitive and selective analytical method was developed and optimized for the determination of sub-μg/L levels of three isothiazolinones in water samples. Three isothiazolinones are described in this paper: 2-methyl-3-isothiazolinone, 5-chloro-2-methyl-3-isothiazolinone and 4,5-dichloro-2-methyl-3-isothiazolinone. The analytical method involves a robust large-volume direct on-column loop injection of 2 mL on an Aqua ODS HPLC column and tandem MS detection (HPLC–MS/MS). After filtration, samples are directly injected without further pretreatment. Detection limits of the individual target compounds were between 0.03 and 0.1 μg/L employing Multi-Reaction Monitoring (MRM) mass spectrometry. Based on the constant ratio of two selected product-ions together with the retention time, the identification is very selective and quantification is reliable. The method was successfully applied to real samples of membrane flushings, drinking water, surface waters and waste water. Additional investigations showed the instability of the isothiazolinones in river- and waste water. Preservation of river water and waste water samples with sodium azide (NaN3) promotes the stability of the isothiazolines in solution. In membrane flushings, waste water, surface waters and drinking water, levels of the three isothiazolinones were all below the limit of detection. In effluents of households containing washings from normal shampoo use, isothiazolinones could be detected.

Dissolved organic nitrogen (DON) dynamics in the North Sea was explored by means of long-term time series of nitrogen parameters from the Dutch national monitoring program. Generally, the data quality was good with little missing data points. Different imputation methods were used to verify the robustness of the patterns against these missing data. No long-term trends in DON concentrations were found over the sampling period (1995-2005). Inter-annual variability in the different time series showed both common and station-specific behavior. The stations could be divided into two regions, based on absolute concentrations and the dominant times scales of variability. Average DON concentrations were 11 μmol l−1 in the coastal region and 5 μmol l−1 in the open sea. Organic fractions of total dissolved nitrogen (TDN) averaged 38 and 71% in the coastal zone and open sea, respectively, but increased over time due to decreasing dissolved inorganic nitrogen (DIN) concentrations. In both regions intra-annual variability dominated over inter-annual variability, but DON variation in the open sea was markedly shifted towards shorter time scales relative to coastal stations. In the coastal zone a consistent seasonal DON cycle existed with high values in spring-summer and low values in autumn-winter. In the open sea seasonality was weak. A marked shift in the seasonality was found at the Dogger Bank, with DON accumulation towards summer and low values in winter prior to 1999, and accumulation in spring and decline throughout summer after 1999. This study clearly shows that DON is a dynamic actor in the North Sea and should be monitored systematically to enable us to understand fully the functioning of this ecosystem.