We assessed nitrous oxide (N₂O) emissions at shoulder and foot-slope positions along three sloping sites (1.6–2.1%) to identify the factors controlling the spatial variations in emissions. The three sites received same amounts of total nitrogen (N) input at 170kgNha⁻¹. Results showed that landscape positions had a significant, but not consistent effect on N₂O fluxes with larger emission in the foot-slope at only one of the three sites. The effect of soil inorganic N (NH₄ ⁺+NO₃ ⁻) contents on N₂O fluxes (r²=0.55, p<0.001) was influenced by water-filled pore space (WFPS). Soil N₂O fluxes were related to inorganic N at WFPS>60% (r²=0.81, p<0.001), and NH₄ ⁺ contents at WFPS<60% (r²=0.40, p<0.01), respectively. Differences in WFPS between shoulder and foot-slope correlated linearly with differences in N₂O fluxes (r²=0.45, p<0.001). We conclude that spatial variations in N₂O emission were regulated by the influence of hydrological processes on soil aeration intensity.

The aim of this study is to illustrate the importance of farm scale heterogeneity on nitrogen (N) losses in agricultural landscapes. Results are exemplified with a chain of N models calculating farm-N balances and distributing the N-surplus to N-losses (volatilisation, denitrification, leaching) and soil-N accumulation/release in a Danish landscape. Possible non-linearities in upscaling are assessed by comparing average model results based on (i) individual farm level calculations and (ii) averaged inputs at landscape level. Effects of the non-linearities that appear when scaling up from farm to landscape are demonstrated. Especially in relation to ammonia losses the non-linearity between livestock density and N-loss is significant (p > 0.999), with around 20–30% difference compared to a scaling procedure not taking this non-linearity into account. A significant effect of farm type on soil N accumulation (p > 0.95) was also identified and needs to be included when modelling landscape level N-fluxes and greenhouse gas emissions.

Here, we addressed biodegradation vs. volatilization processes, and also bioavailability limitations during biopile remediation of soil initially contaminated by more than 5,000 mg/kg of hydrocarbons. In order to select bioremediation strategies, we first conducted a biotreatability study, which included geochemical, textural, and microbiological characterization of the soil matrix. Next, we implemented five bioremediation approaches onsite in real-scale biopiles. In order to monitor hydrocarbon depletion and to distinguish between biological and non-biological processes, we analyzed chemical biomarkers by means of gas chromatography–mass spectrometry. In addition, a comprehensive study of soil grain size and its implications on bioavailability were studied. Furthermore, the evolution of microbial populations was also examined. Two of the strategies implemented in the biopiles (the combination of a slow-release fertilizer and a surfactant, and the use of an oleophilic fertilizer respectively) reduced the soil hydrocarbon content to under 500 mg/kg in 5 months. Additional results from this study indicate that volatilization was the predominant degradation process for light hydrocarbons (below 12 carbon atoms), whereas heavier compounds were mainly biodegraded. However, even in the most favorable situation, a residual concentration of hydrocarbons linked to the finer fraction of the soil was found.

Polymeric quaternary ammonium salts or polyquaterniums used in cosmetics have been categorised as chemicals of concern in wastewater treatment plant (WWTP) effluent largely on the basis of emerging evidence of toxicity to aquatic organisms. However, little is known of their environmental fate and behaviour due to analytical difficulties with sample matrices. Their properties of negligible volatilisation and biotransformation enable the common fugacity-based model for WWTPs to be simplified to an equifugacity one where a compound has the same fugacity regardless of phase or position in the plant’s process train. To gain an appreciation of their fate, this approach is used to calculate removal efficiencies in WWTPs. These can be determined without calculating phase-specific fugacity capacity constants. To predict effluent concentrations however, an aquivalence approach is necessary because of the lack of volatility of these compounds. Using previously measured biosolids/water distribution coefficients for common polyquaterniums found in cosmetics and flow rate data from a local municipal WWTP in South East Queensland, Australia, the removal efficiencies of the polyquaterniums of interest are predicted to be only 25% or less, meaning relatively little attenuation in the WWTP. A Monte Carlo simulation shows a roughly normal distribution in the model output of polyquaternium removal efficiency, with a mean and mode of approximately 26%. A sensitivity analysis confirms that the model output is most sensitive to the magnitude of the biosolids/water distribution coefficient compound and shows WWTP data such as biosolids removal efficiency have only a relatively small effect.

Purpose Hexachlorocyclohexane (HCH) isomers (α-, β- and γ- (Lindane)) were recently included as new persistent organic pollutants (POPs) in the Stockholm Convention, and therefore, the legacy of HCH and Lindane production became a contemporary topic of global relevance. This article wants to briefly summarise the outcomes of the Stockholm Convention process and make an estimation of the amount of HCH waste generated and dumped in the former Lindane/HCH-producing countries. Results In a preliminary assessment, the countries and the respective amount of HCH residues stored and deposited from Lindane production are estimated. Between 4 and 7 million tonnes of wastes of toxic, persistent and bioaccumulative residues (largely consisting of alpha- (approx. 80%) and beta-HCH) are estimated to have been produced and discarded around the globe during 60 years of Lindane production. For approximately 1.9 million tonnes, information is available regarding deposition. Countries are: Austria, Brazil, China, Czech Republic, France, Germany, Hungary, India, Italy, Japan, Macedonia, Nigeria, Poland, Romania, Slovakia, South Africa, Spain, Switzerland, Turkey, The Netherlands, UK, USA, and former USSR. The paper highlights the environmental relevance of deposited HCH wastes and the related POPs' contaminated sites and provides suggestions for further steps to address the challenge of the legacy of HCH/Lindane production. Conclusion It can be expected that most locations where HCH waste was discarded/stockpiled are not secured and that critical environmental impacts are resulting from leaching and volatilisation. As parties to the Stockholm Convention are legally required to take action to stop further POPs pollution, identification and evaluation of such sites are necessary.

PURPOSE: Heterocyclic aromatic compounds containing nitrogen, sulfur, or oxygen heteroatoms (NSO-HET) have been detected in air, soil, marine, and freshwater systems. However, only few publications are available investigating NSO-HET using in vitro bioassays. To support better characterization of environmental samples, selected NSO-HET were screened for dioxin-like activity in two bioassays. METHODS: The present study focuses on the identification and quantification of dioxin-like effects of 12 NSO-HET using the DR-CALUX assay, and the 7-ethoxyresorufin-O-deethylase (EROD) assay with the permanent fish liver cell line RTL-W1. Changes of the total medium compound concentrations during the test procedure due to, e.g., sorption or volatilization were quantified using GC/MS. RESULTS: The NSO-HET benzofuran, 2,3-dimethylbenzofuran, dibenzofuran, dibenzothiophen, acridine, xanthene, and carbazole caused a response in the DR-CALUX assay. Only benzofuran and 2,3-dimethylbenzofuran were also positive in the EROD assay. All other compounds were inactive in the EROD assay. Relative potency (REP) values ranged from (2.80 ± 1.32) · 10−8 to (3.26 ± 2.03) · 10−6 in the DR-CALUX and from (3.26 ± 0.91) · 10−7 to (4.87 ± 1.97) · 10−7 in the EROD assay. CONCLUSIONS: The REP values were comparable to those of larger polycyclic aromatic hydrocarbons, e.g., fluoranthene and pyrene. Thus, and because of the ubiquitous distribution of heterocyclic aromatic compounds in the environment, the provided data will further facilitate the bioanalytical and analytical characterization of environmental samples towards these toxicants.