Adrian A. Ammann

Influence of catchment quality and altitude on the water and sediment composition of 68 small lakes in Central Europe

Abstract: 68 lakes (63 Swiss, 2 French and 3 Italian) located in an altitudinal range between 334 and 2339m spanning a wide range of land-use have been investigated. The aim of the study was to discuss influences of geographic location, vegetation and land-use in the catchment area on the water and sediment chemistry of small lakes. Detailed quantitative description of land-use, vegetation, and climate in the watershed of all lakes was established. Surface and bottom water samples collected from each lake were analyzed for major ions and nutrients. Correlations were interpreted using linear regression analysis. Chemical parameters of water and sediment reflect the characteristics of the catchment areas. All lakes were alkaline since they were situated on calcareous bedrock. Concentrations of nitrogen and phosphorus strongly increase with increasing agricultural land-use. Na and K, however, are positively correlated with the amount of urbanization within the catchment area. These elements as well as dissolved organic carbon (DOC), Mg, Ca, and alkalinity, increase when the catchment is urbanized or used for agriculture. Total nitrogen and organic carbon in the sediments decrease distinctly if large parts of the catchment consist of bare land. No correlations between sediment composition and maximum water depth or altitude of the lakes were found.¶Striking differences in the water compositions of lakes above and below approximately 700 m of altitude were observed. Concentrations of total nitrogen and nitrate, total phosphorus, DOC, Na, K, Mg, Ca, and alkalinity are distinctly higher in most lakes below 700 m than above, and the pH of the bottom waters of these lakes is generally lower. Estimates of total nitrogen concentrations, even in remote areas, indicate that precipitation is responsible for increased background concentrations. At lower altitudes nitrogen concentrations in lakes is explained by the nitrogen loaded rain from urban areas deposited on the catchment, and with high percentages of agricultural land-use in the watershed.

Determination of strong binding chelators and their metal complexes by anion-exchange chromatography and inductively coupled plasma mass spectrometry

Based on the negative charge of polycarboxylic chelators, an anion-exchange separation has been developed that is compatible with sensitive metal detection by ICP-MS. A low capacity hydrophilic polymer (AS11) was used as the anion exchanger and ammonium nitrate as the eluent. The new procedure provided high selectivity in the isocratic mode as well as a large separation window and high separation efficiency in the gradient mode. This was demonstrated for different types of chelators and their metal complexes. The aminopolycarboxylates NTA, EDTA, CDTA, DTPA, EDDS and for the EDTA derivatives HEDTA, ED3A and EDTMP, the phosphonic acid analogue of EDTA were tested. Their retention times generally depended on the charge, which was lower in 1:1 metal chelator complexes. Evaluation of the separation mechanism demonstrated that they were all separated predominantly by an anion-exchange mechanism with only a minor contribution from hydrophobic attraction. The method is useful for species identification and for predicting the charge of unknown analogous species from retention times. A gradient separation procedure achieved on-column preconcentration and matrix removal for the interference-free detection of metal chelates down to low nanomolar concentration in samples from various fields of environmental research.

Simultaneous determination of small organic and inorganic anions in environmental water samples by ion-exchange chromatography

Anion-exchange chromatography at elevated pH values is the method of choice for the simultaneous determination of weak and strong low-molecular-mass organic and inorganic acids. These are important species found in the environment where most of them are formed and further degraded, particularly if microbial activities are involved. A step gradient procedure with a weak eluent such as borate on a low-capacity column was developed for the simultaneous one-run one-column determination of most of these types of components in environmental water samples. High selectivity and detection limits below 1 μM were achieved. Other yet unknown coelutions of 3-hydroxybutyrate with fluoride and 2-hydroxybutyrate with propionate were found. The different retention characteristics of a high-capacity column was used to obtain additional evidence to identify interfering components. These separation procedures were used to investigate fog, lake sediment pore water and rain after roof run-offs.

Ground water pollution by roof runoff infiltration evidenced with multi-tracer experiments

The infiltration of urban roof runoff into well permeable subsurface material may have adverse effects on the ground water quality and endanger drinking water resources. Precipitation water from three different roofs of an industrial complex was channelled to a pit and infiltrated into a perialpine glaciofluvial gravel-and-sand aquifer. A shaft was constructed at the bottom of the pit and equipped with an array of TDR probes, lysimeters and suction cups that allowed measuring and sampling soil water at different depths. A fast infiltration flow was observed during natural rainfall events and during artificial infiltration experiments. For a better understanding of the behaviour of contaminants, experiments were conducted with cocktails of compounds of different reactivity (ammonium, strontium, atratone) and of non-reactive tracers (uranine, bromide, naphthionate), which represent different classes of pollutants. The experiment identified cation exchange reactions influencing the composition of the infiltrating water. These processes occurred under preferential flow conditions in macropores of the material. Measuring concentration changes under the controlled inflow of tracer experiments, the pollution potential was found to be high. Non-reactive tracers exhibited fast breakthrough and little sorption.

Simultaneous determination of TOC and TNb in surface and wastewater by optimised high temperature catalytic combustion

Abstract Total nutrition parameters as e.g. total organic carbon (TOC) and total bound nitrogen (TNb) are indispensable to water quality and elemental nutrient balances. The recommended and most often applied wet chemical digestion for TNb measurement, however, is discouragingly labour intensive. Therefore, high temperature (690°) catalytic (Pt/Al2O3) combustion (HTC) was investigated for simultaneous determination of TOC and TNb. Using commercially available instruments a fast and simple procedure was established by coupling a TOC-analyzer to a chemiluminescence detector (CLD) for determination of NOx gases in the combustion exhaust. Dissolved compounds as well as particulate matter were used to test carrier gases, hot zone fillings and injection volumes influencing N-recovery rates. Injecting dissolved wastewater components (e.g. ammonium, urea, antipyrine) direct onto the catalyst yielded low N-recovery rates (40–90%) depending on concentration. Instead of increasing the oven temperature the evaporation of injected sample solution was improved which resulted in quantitative recovery rates for all investigated compounds except hydrazine. A representative number of TNb values from river and domestic wastewater obtained by HTC-CLD were compared to wet chemical digestion. No significant differences between the two methods were found.

Arsenic speciation by gradient anion exchange narrow bore ion chromatography and high resolution inductively coupled plasma mass spectrometry detection.

Based on gradient anion exchange chromatography (AEC), a new strategy in As-speciation was evaluated. A narrow bore chromatographic system with lower flow rates (<or=300 microL) well suitable for the low flow requirements of higher efficiency nebulizers was splitless coupled to a high resolution sector field ICP MS. The AEC system takes full advantage of the detector sensitivity allowing more diluted samples (50-100 times) to be injected, delivering substantially less sample matrix to the column and a lower eluent load to the plasma. The unique plasma compatibility of the NH(4)NO(3)-eluent salt used in this study enabled high linear salt ramps in gradient applications, highly reproducible retention times (+/-1%) and detection limits in the low ng/L range. The separation conditions were applied on two different polymeric anion-exchangers: a low capacity, weakly hydrophobic material (AS11, Dionex) and a more frequently used higher capacity, higher hydrophobic material (AS7, Dionex). On both columns, As-species (As(III/V), MMA, DMA, AsB) and Cl(-) were separated in less than nine minutes and co-elution was circumvented by adapting the separation pH to the optimal column selectivity. The key-advantage of the NH(4)NO(3)-eluent is that it can adopt any separation pH without compromising the eluent strength which is not possible with all other eluents used so far. The influences of chloride and methanol were investigated and found not to affect the chromatographic performance. Column deposits caused strong reversible As(v) adsorption which reduced As(v) to As(III). A corresponding phosphate excess in the injected sample eliminated the adsorption and prevented artefacts in As(v)/As(III) ratios. The method applied to ground water samples provided robust separations and is compatible with any sample preservation procedure.

Quantification of methylated selenium, sulfur, and arsenic in the environment.

Biomethylation and volatilization of trace elements may contribute to their redistribution in the environment. However, quantification of volatile, methylated species in the environment is complicated by a lack of straightforward and field-deployable air sampling methods that preserve element speciation. This paper presents a robust and versatile gas trapping method for the simultaneous preconcentration of volatile selenium (Se), sulfur (S), and arsenic (As) species. Using HPLC-HR-ICP-MS and ESI-MS/MS analyses, we demonstrate that volatile Se and S species efficiently transform into specific non-volatile compounds during trapping, which enables the deduction of the original gaseous speciation. With minor adaptations, the presented HPLC-HR-ICP-MS method also allows for the quantification of 13 non-volatile methylated species and oxyanions of Se, S, and As in natural waters. Application of these methods in a peatland indicated that, at the selected sites, fluxes varied between 190–210 ng Se·m−2·d−1, 90–270 ng As·m−2·d−1, and 4–14 µg S·m−2·d−1, and contained at least 70% methylated Se and S species. In the surface water, methylated species were particularly abundant for As (>50% of total As). Our results indicate that methylation plays a significant role in the biogeochemical cycles of these elements.

Multimode gradient high performance liquid chromatography mass spectrometry method applicable to metabolomics and environmental monitoring.

Metabolomics or environmental investigations generate samples containing very large numbers of small molecular weight analytes. A single mode chromatographic separation excludes a substantial part of such complex analyte mixtures. For instance, a reversed-phase separation would not retain ionic species, resulting in a correspondingly huge front peak. To address this problem, we used two commercially available mixed-mode ion-exchange reversed-phase columns (WAX-1 and WCX-1) in sequence in a novel multimode separation method. After trapping hydrophobics on a C18-trap in loop position, hydrophilics passing the trap are separated by a simultaneous gradient for HILIC, anion and cation exchange chromatography. This gradient ends in a washout phase with a high percentage of water, the correct starting conditions for a reversed-phase gradient eluting hydrophobics from the trap in a second step of the run. Amino acids (9), organic acids (2), sugars (8), fatty acid derived compounds (11), antioxidants (4), miscellanea (6) and xenobiotics (4) were analyzed. Compounds were separated after a single sample injection during a 50min run. Lipids derived small fatty acids up to a chain length of 12 carbons were also accessible within this run time.

Interactions of TiO2 nanoparticles and the freshwater nematode Plectus aquatilis: particle properties, kinetic parameters and bioconcentration factors

Principles for determining uptake kinetics and bioconcentration factors for nanoparticles and test organisms have only been cursorily explored. Here we report the derivation of bioconcentration factors (BCFs) and the role of surface functionalization in the interactions between the nematode Plectus aquatilis and titanium dioxide nanoparticles (TiO2 NPs) dispersed in freshwater. Because of the high background concentration of titanium in natural waters, TiO2 NPs irradiated to produce 48V labeled TiO2 NPs, or doped with 1% niobium, were used to determine BCFs taking either an equilibrium partitioning or a kinetic modelling approach. The BCFs based on equilibrium partitioning increased from 71 (±17) L kg−1 at the highest exposure concentrations to 5.1 (±3.2) × 103 L kg−1 at the lowest exposure concentration, indicating that this approach is not valid. A kinetic modeling approach, based on the uptake rate and elimination rates for a two-phase elimination, best reflected the experimental data and was then used to determine BCFs. To further rationalize the kinetic interactions between the TiO2 NPs and the nematode, organisms were exposed to surface-functionalized TiO2 NPs with positively charged, negatively charged, steric stabilizing and environmentally relevant coatings. Correlations between the extent of TiO2 NP association (i.e. attached and internalized) with the nematode, and TiO2 NP properties, were examined. For all parameters considered, association of the surface functionalized TiO2 NPs with the nematode best correlated with the TiO2 NP sedimentation rate. These results indicate that concepts developed for hydrophobic contaminants are not applicable to nanoparticles and concepts specific to nanoparticles will be of greater utility.

LC-MS/MS determination of potential endocrine disruptors of cortico signalling in rivers and wastewaters (vol 406, pg 7653, 2014)

Reference EPFL-ARTICLE-221784doi:10.1007/s00216-016-9581-1View record in Web of Science Record created on 2016-10-18, modified on 2017-02-06