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  • 1
    Language: Undetermined
    In: Informationen zur Raumentwicklung : IzR, 2016, pp.543-553
    ISSN: 03032493
    Source: Deutsche Zentralbibliothek für Wirtschaftswissenschaften
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  • 2
    Language: English
    In: Water Research, 01 March 2014, Vol.50, pp.294-306
    Description: Atrazine was banned in Germany in 1991 due to findings of atrazine concentrations in ground- and drinking waters exceeding threshold values. Monitoring of atrazine concentrations in the groundwater since then provides information about the resilience of the groundwater quality to changing agricultural practices. In this study, we present results of a monitoring campaign of atrazine concentrations in the Zwischenscholle aquifer. This phreatic aquifer is exposed to intensive agricultural land use and susceptible to contaminants due to a shallow water table. In total 60 observation wells (OWs) have been monitored since 1991, of which 15 are sampled monthly today. Descriptive statistics of monitoring data were derived using the “regression on order statistics” (ROS) data censoring approach, estimating values for nondetects. The monitoring data shows that even 20 years after the ban of atrazine, the groundwater concentrations of sampled OWs remain on a level close to the threshold value of 0.1 μg l without any considerable decrease. The spatial distribution of atrazine concentrations is highly heterogeneous with OWs exhibiting permanently concentrations above the regulatory threshold on the one hand and OWs were concentrations are mostly below the limit of quantification (LOQ) on the other hand. A deethylatrazine-to-atrazine ratio (DAR) was used to distinguish between diffuse – and point-source contamination, with a global mean value of 0.84 indicating mainly diffuse contamination. Principle Component Analysis (PCA) of the monitoring dataset demonstrated relationships between the metabolite desisopropylatrazine, which was found to be exclusively associated with the parent compound simazine but not with atrazine, and between deethylatrazine, atrazine, nitrate, and the specific electrical conductivity. These parameters indicate agricultural impacts on groundwater quality. The findings presented in this study point at the difficulty to estimate mean concentrations of contamination for entire aquifers and to evaluate groundwater quality based on average parameters. However, analytical data of monthly sampled single observation wells provide adequate information to characterize local contamination and evolutionary trends of pollutant concentration.
    Keywords: Atrazine ; Groundwater Monitoring ; DAR ; Nondetects ; Data Censoring ; Principle Component Analysis ; Engineering
    ISSN: 0043-1354
    E-ISSN: 1879-2448
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  • 3
    Language: English
    In: Chemosphere, April 2017, Vol.172, pp.310-315
    Description: The soil-plant transfer of Cs-137 and Sr-90 in different crops was determined with respect to the present-day amendment practice of using digestate from biogas fermenters. The studies were performed using large lysimeters filled with undisturbed luvisol monoliths. In contrast to the conservative tracer, Br , neither of the studied radionuclides showed a significant vertical translocation nor effect of the applied digestate amendment compared to a non-amended control was found. Furthermore, no significant plant uptake was measured for both nuclides in wheat or oat as indicated by the low transfer factors between soil-shoot for Cs-137 (TF 0.001–0.010) and for Sr-90 (0.10–0.51). The transfer into nutritionally relevant plant parts was even lower with transfer factors for soil-grain for Cs-137 (TF 0.000–0.001) and for Sr-90 (0.01–0.06). Hence, the amendment with biogas digestate is unfortunately not an option to further reduce plant uptake of these radionuclides in agricultural crops, but it does not increase plant uptake either.
    Keywords: Radioactive Contaminants ; Undisturbed Soil Monolith ; Agro-Ecosystem ; Oat ; Wheat ; Transfer Factor ; Chemistry ; Ecology
    ISSN: 0045-6535
    E-ISSN: 1879-1298
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  • 4
    Language: English
    In: Journal of Hydrology, June 2017, Vol.549, pp.731-740
    Description: Weighing lysimeters are considered to be the best means for a precise measurement of water fluxes at the interface between the soil-plant system and the atmosphere. Any decrease of the net mass of the lysimeter can be interpreted as evapotranspiration (ET), any increase as precipitation (P). However, the measured raw data need to be filtered to separate real mass changes from noise. Such filter routines typically apply two steps: (i) a low pass filter, like moving average, which smooths noisy data, and (ii) a threshold filter that separates significant from insignificant mass changes. Recent developments of these filters have identified and solved some problems regarding bias in the data processing. A remaining problem is that each change in flow direction is accompanied with a systematic flow underestimation due to the threshold scheme. In this contribution, we analyze this systematic effect and show that the absolute underestimation is independent of the magnitude of a flux event. Thus, for small events, like dew or rime formation, the relative error is high and can reach the same magnitude as the flux itself. We develop a heuristic solution to the problem by introducing a so-called “snap routine”. The routine is calibrated and tested with synthetic flux data and applied to real measurements obtained with a precision lysimeter for a 10-month period. The heuristic snap routine effectively overcomes these problems and yields an almost unbiased representation of the real signal.
    Keywords: Precision Lysimeter ; Dew Measurement ; Evapotranspiration Measurement ; Precipitation Measurement ; Data Processing ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 5
    Language: English
    In: Journal of Hydrology, August 2018, Vol.563, pp.372-381
    Description: Non-rainfall events like dew or hoar frost formation are often neglected in the water budget, because either assumed to be too small or their determination requires time consuming and difficult measurements. These events supply in many dryland ecosystems a substantial amount of water, but their role for northern humid ecosystems is largely unknown. There is a general need to quantify the ecological relevance for ecosystems of the water amount from dew and hoar frost formation. Weighable precision lysimeters were used to determine dew and hoar frost formation for a low mountain range and alpine grassland site for the hydrological years 2013–2015. Together dew and hoar frost formation ranged on a yearly basis between 42.1 and 67.7 mm, which corresponds to 4.2–6% of the total annual amount of precipitation. In drier months dew and hoar frost contributed up to 16.1% of total monthly precipitation amount. In winter months dew and hoar frost formation contributed up to 38% to the total monthly precipitation amount. Our investigation suggests, that dew and hoar frost formation are of ecological importance during droughts as well as cold periods. The amounts and seasonal patterns of dew and hoar frost formation could be predicted relatively well, based on standard meteorological variables with the Penman-Monteith equation. However, our results also showed, that the surface energy balance model from Penman-Monteith underestimated the amount of dew and hoar frost during colder periods and specific meteorological site conditions (i.e. high wind speeds at night). The mean underestimation between calculated and measured dew and hoar frost on a yearly scale were 63.2% and 16.6% at Rollesbroich and Gumpenstein, respectively. Dew and hoar frost formation contributes substantially to the water budgets of a low mountain range and alpine grassland.
    Keywords: Dew ; Hoar Frost ; High Precision Weighable Lysimeter ; Non-Rainfall Water ; Ecological Relevance Dew Hoar Frost ; Estimation Dew Hoar Frost ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 6
    Language: English
    In: Environmental Pollution, September 2013, Vol.180, pp.152-158
    Description: Column experiments were conducted in undisturbed and in repacked soil columns at water contents close to saturation (85–96%) to investigate the transport and retention of functionalized C-labeled multi-walled carbon nanotubes (MWCNT) in two natural soils. Additionally, a field lysimeter experiment was performed to provide long-term information at a larger scale. In all experiments, no breakthrough of MWCNTs was detectable and more than 85% of the applied radioactivity was recovered in the soil profiles. The retention profiles exhibited a hyper-exponential shape with greater retention near the column or lysimeter inlet and were successfully simulated using a numerical model that accounted for depth-dependent retention. In conclusion, results indicated that the soils acted as a strong sink for MWCNTs. Little transport of MWCNTs is therefore likely to occur in the vadose zone, and this implies limited potential for groundwater contamination in the investigated soils. In undisturbed columns and a lysimeter study, complete retention of functionalized multi-walled carbon nanotubes was found in two soils at environmentally relevant conditions.
    Keywords: Undisturbed Soil ; Carbon Nanotube ; Lysimeter ; Retention Profile ; Transport Modeling ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 7
    Language: English
    In: Environmental pollution, 2013, Vol.180, pp.152-158
    Description: Column experiments were conducted in undisturbed and in repacked soil columns at water contents close to saturation (85–96%) to investigate the transport and retention of functionalized ¹⁴C-labeled multi-walled carbon nanotubes (MWCNT) in two natural soils. Additionally, a field lysimeter experiment was performed to provide long-term information at a larger scale. In all experiments, no breakthrough of MWCNTs was detectable and more than 85% of the applied radioactivity was recovered in the soil profiles. The retention profiles exhibited a hyper-exponential shape with greater retention near the column or lysimeter inlet and were successfully simulated using a numerical model that accounted for depth-dependent retention. In conclusion, results indicated that the soils acted as a strong sink for MWCNTs. Little transport of MWCNTs is therefore likely to occur in the vadose zone, and this implies limited potential for groundwater contamination in the investigated soils. ; p. 152-158.
    Keywords: Carbon Nanotubes ; Vadose Zone ; Soil Profiles ; Mathematical Models ; Lysimeters ; Groundwater Contamination
    ISSN: 0269-7491
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 8
    Language: English
    In: Geochimica et Cosmochimica Acta, 01 April 2016, Vol.178, pp.76-86
    Description: Hydroxylamine (NH OH), a reactive intermediate of several microbial nitrogen turnover processes, is a potential precursor of nitrous oxide (N O) formation in the soil. However, the contribution of soil NH OH to soil N O emission rates in natural ecosystems is unclear. Here, we determined the spatial variability of NH OH content and potential N O emission rates of organic (Oh) and mineral (Ah) soil layers of a Norway spruce forest, using a recently developed analytical method for the determination of soil NH OH content, combined with a geostatistical Kriging approach. Potential soil N O emission rates were determined by laboratory incubations under oxic conditions, followed by gas chromatographic analysis and complemented by ancillary measurements of soil characteristics. Stepwise multiple regressions demonstrated that the potential N O emission rates, NH OH and nitrate (NO ) content were spatially highly correlated, with hotspots for all three parameters observed in the headwater of a small creek flowing through the sampling area. In contrast, soil ammonium (NH ) was only weakly correlated with potential N O emission rates, and was excluded from the multiple regression models. While soil NH OH content explained the potential soil N O emission rates best for both layers, also NO and Mn content turned out to be significant parameters explaining N O formation in both soil layers. The Kriging approach was improved markedly by the addition of the co-variable information of soil NH OH and NO content. The results indicate that determination of soil NH OH content could provide crucial information for the prediction of the spatial variability of soil N O emissions.
    Keywords: Geology
    ISSN: 0016-7037
    E-ISSN: 1872-9533
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  • 9
    Language: English
    In: Environmental Pollution, September 2012, Vol.168, pp.29-36
    Description: The fate of the C-labeled herbicides ethidimuron (ETD), methabenzthiazuron (MBT), and the fungicide anilazine (ANI) in soils was evaluated after long-term aging (9–17 years) in field based lysimeters subject to crop rotation. Analysis of residual C activity in the soils revealed 19% (ETD soil; 0–10 cm depth), 35% (MBT soil; 0–30), and 43% (ANI soil; 0–30) of the total initially applied. Accelerated solvent extraction yielded 90% (ETD soil), 26% (MBT soil), and 41% (ANI soil) of residual pesticide C activity in the samples. LC-MS/MS analysis revealed the parent compounds ETD and MBT, accounting for 3% and 2% of applied active ingredient in the soil layer, as well as dihydroxy-anilazine as the primary ANI metabolite. The results for ETD and MBT were matching with values obtained from samples of a 12 year old field plot experiment. The data demonstrate the long-term persistence of these pesticides in soils based on outdoor trials. ► The environmental persistence of three C-labeled pesticides in soils is presented. ► Extract analysis revealed the pesticides and metabolites after 9–17 years of aging. ► Pesticide residues may represent a long-term soil burden. ► The bioaccessibility and/or bioavailability of long-term aged pesticide residues remain unknown. Residual fractions of the pesticides ethidimuron, methabenzthiazuron, and metabolites of anilazine are highly persistent in soils and remain extractable after long-term environmental aging.
    Keywords: Ethidimuron ; Methabenzthiazuron ; Anilazine ; Persistence ; Bound Residues ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 10
    Language: English
    In: Environmental pollution, 2012, Vol.168, pp.29-36
    Description: The fate of the ¹⁴C-labeled herbicides ethidimuron (ETD), methabenzthiazuron (MBT), and the fungicide anilazine (ANI) in soils was evaluated after long-term aging (9–17 years) in field based lysimeters subject to crop rotation. Analysis of residual ¹⁴C activity in the soils revealed 19% (ETD soil; 0–10 cm depth), 35% (MBT soil; 0–30), and 43% (ANI soil; 0–30) of the total initially applied. Accelerated solvent extraction yielded 90% (ETD soil), 26% (MBT soil), and 41% (ANI soil) of residual pesticide ¹⁴C activity in the samples. LC-MS/MS analysis revealed the parent compounds ETD and MBT, accounting for 3% and 2% of applied active ingredient in the soil layer, as well as dihydroxy-anilazine as the primary ANI metabolite. The results for ETD and MBT were matching with values obtained from samples of a 12 year old field plot experiment. The data demonstrate the long-term persistence of these pesticides in soils based on outdoor trials. ; p. 29-36.
    Keywords: Metabolites ; Ingredients ; Crop Rotation ; Methabenzthiazuron ; Ethidimuron ; Lysimeters ; Anilazine ; Soil
    ISSN: 0269-7491
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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