Bottom-up approach for the reaction of xenobiotics and their metabolites with model substances for natural organic matter by electrochemistry-mass spectrometry (EC-MS)

Risk assessment of xenobiotics requires a comprehensive understanding of their transformation in the environment. As most of the transformation processes usually involve a redox reaction or a hydrolysis as the first steps of the transformation, we applied an approach that uses an electrochemical cell to investigate model “redox” reactions in aqueous solutions for environmental processes. We investigated the degradation of a variety of xenobiotics from polar to nonpolar and analyzed their degradation products by on-line coupling of electrochemistry with mass spectrometry (EC-MS). Furthermore, we evaluated possible binding reactions with regard to the generation of non-extractable residues with some model substances (catechol, phthalic acid, γ-l-Glutamyl-l-cysteinyl-glycine (GSH) and l-histidine) deduced from a natural organic matter (NOM) structure model and identified possible binding-sites.Whereas typically investigations in soil/water-systems have been applied, we used to our knowledge for the first time a bottom-up approach, starting from the chemicals of interest and different model substances for natural organic matter to evaluate chemical binding mechanisms (or processes) in the EC-MS under redox conditions. Under oxidative conditions, bindings of the xenobiotics with catechol, GSH and histidine were found, but no reactions with the model compound phthalic acid were observed. In general, no chemical binding has yet been found under reductive conditions. In some cases (i.e. benzo[a]anthracene) the oxidation product only underwent a binding reaction, whereas the xenobiotic itself did not undergo any reactions.EC-MS is a promising fast and simple screening method to investigate the environmental behavior of xenobiotics and to evaluate the potential risks of newly synthesized substances.     

Molecular effects and bioaccumulation of levonorgestrel in the non-target organism Dreissena polymorpha

Bioaccumulation and effects of the contraceptive hormone levonorgestrel were examined in the non-target organism Dreissena polymorpha. Molecular biomarkers of biotransformation, elimination, antioxidant defence and protein damage were analyzed after exposure to increasing concentrations of levonorgestrel in a flow-through system. The lowest concentration (0.312 μg L⁻¹) was 100-fold bioconcentrated within four days. A decrease of the bioconcentration factor was observed within one week for the highest test concentrations (3.12 and 6.24 μg L⁻¹) suggesting enhanced excretory processes. The immediate mRNA up-regulation of pi class glutathione S-transferase proved that phase II biotransformation processes were induced. Disturbance of fundamental cell functions was assumed since the aryl hydrocarbon receptor has been permanently down-regulated. mRNA up-regulation of P-glycoprotein, superoxide dismutase and metallothioneine suggested enhanced elimination processes and ongoing oxidative stress. mRNA up-regulation of heat shock protein 70 in mussels exposed to the two highest concentrations clearly indicated impacts on protein damage.     

The hygroscopic behaviour of individual aerosol particles in nickel refineries as investigated by environmental scanning electron microscopy

The hygroscopic properties of individual aerosol particles (1-35 microm equivalent projected area diameter) from the Roasting, Anode Casting and Electrorefining Departments of two Ni refineries were studied by environmental scanning electron microscopy (ESEM) and energy-dispersive X-ray microanalysis (EDX) at a relative humidity of 96-98% (at a temperature of 5 degrees C). In the Roasting and Anode Casting Departments, most particles (60-85% by number) showed no visible change in size or surface morphology when exposed to high relative humidity. Approximately 15-30% of the particles developed a thin water film (growth factors between 1.006 and 1.06) indicating the presence of thin surface coatings of sulfates. About 10% of the particles in the Roasting Department formed droplets (growth factors between 1.1 and 2.6) which always contained a large portion of insoluble material. In the Electrorefining Department, most particles (approximately 60%) were residues from the electrolysis bath solution. At a relative humidity of 96-98% these particles formed a solution which contained only small insoluble inclusions. About 30% of the particles in the Electrorefining Department developed thin water films. As only a small fraction of the particles increased substantially in size when exposed to high relative humidity, the deposition pattern of the total aerosol mass fraction will not be changed substantially by hygroscopic growth. The frequent occurrence of thin surface coatings of soluble material on insoluble Ni compounds has to be considered for health assessment purposes.     

Education and advice contribute to increased density of broadleaved conservation trees, but not saplings, in young forest in Sweden

The effectiveness of different conservation policies is debated, but the policies are rarely evaluated quantitatively. A voluntary or 'soft' policy based mainly on education provides information about ecosystems and effects of land use, to encourage conservation action. Swedish forestry relies mainly on soft policy, with substantial resources for education and advice to more than 200,000 forest owners, while legal regulation is weak. Increased retention of broadleaved trees at clear-cutting, with environmental benefits in the conifer-dominated forestry, is important in the policy. We used the Swedish National Forest Inventory to analyse this policy for young forests in southern Sweden. Between 1983-1987 and 1998-2002 the policy had no positive effect on saplings (1.3m tall to 4.9 cm dbh) of birch, oak, beech and other species that mostly decreased in density, due to planting of conifers and browsing by ungulates. However, broadleaved conservation trees (>or=15 cm dbh) increased in density, e.g. to about one oak and six birches per ha in young coniferous forest in 1998-2002. The relative increase in density was higher for large (>or=20 cm dbh) than for small trees (15-20 cm dbh). The density of conservation trees was higher on forestland of high than of low productivity. Thus, the soft conservation policy did not influence regeneration of saplings in this type of forestry system, but large broadleaved trees were increasingly saved at 'clear-cuttings'. Advice and educational programmes probably contributed to this result. A continued increase in conservation trees at harvest may require economical support to forest owners.     

Persistence of C-labeled atrazine and its residues in a field lysimeter soil after 22 years

Twenty-two years after the last application of ring-¹⁴C-labeled atrazine at customary rate (1.7 kg ha⁻¹) on an agriculturally used outdoor lysimeter, atrazine is still detectable by means of accelerated solvent extraction and LC-MS/MS analysis. Extractions of the 0-10 cm soil layer yielded 60% of the residual ¹⁴C-activity. The extracts contained atrazine (1.0 μg kg⁻¹) and 2-hydroxy-atrazine (42.5 μg kg⁻¹). Extractions of the material of the lowest layer 55-60 cm consisting of fine gravel yielded 93% of residual ¹⁴C-activity, of which 3.4 μg kg⁻¹ was detected as atrazine and 17.7 μg kg⁻¹ was 2-hydroxy-atrazine. The detection of atrazine in the lowest layer was of almost four times higher mass than in the upper soil layer. These findings highlight the fact that atrazine is unexpectedly persistent in soil. The overall persistence of atrazine in the environment might represent a potential risk for successive groundwater contamination by leaching even after 22 years of environmental exposure.     

Spatio-temporal covariation of urban particle number concentration and ambient noise

Mobile measurements of ambient noise and particle number concentrations were carried out within an urban residential area in Essen, Germany, during summer 2008. A busy major road with a traffic intensity of about 44,000 vehicles per day was situated within the study area. The spatio-temporal distribution of noise and particles was closely coupled to road traffic on the major road. Total particle number concentrations in proximity to the main road were on average between 25,000 cm^?3 and 35,000 cm^?3 while sound levels reached 70–78 dB(A). These estimates were more than double-fold (factor 2.4) in comparison to the urban residential background. At a 50 m distance off the road particle number concentrations were decaying to about 50% of the initial value. The measurements were characterised by close spatial correlation between total particle number concentration and ambient noise with correlation coefficients of up to r = 0.74. However, during one measurement day coupling between both quantities was weak due to higher turbulent mixing within the canopy layer and a change in ambient wind directions. Enhanced dilution of particle emission from road traffic by turbulent mixing and ‘decoupling’ from the influence of road traffic are believed to be responsible.     

Combining functional data with hierarchical Gaussian process models

Gaussian process models have been used in applications ranging from machine learning to fisheries management. In the Bayesian framework, the Gaussian process is used as a prior for unknown functions, allowing the data to drive the relationship between inputs and outputs. In our research, we consider a scenario in which response and input data are available from several similar, but not necessarily identical, sources. When little information is known about one or more of the populations it may be advantageous to model all populations together. We present a hierarchical Gaussian process model with a structure that allows distinct features for each source as well as shared underlying characteristics. Key features and properties of the model are discussed and demonstrated in a number of simulation examples. The model is then applied to a data set consisting of three populations of Rotifer Brachionus calyciflorus Pallas. Specifically, we model the log growth rate of the populations using a combination of lagged population sizes. The various lag combinations are formally compared to obtain the best model inputs. We then formally compare the leading hierarchical Gaussian process model with the inferential results obtained under the independent Gaussian process model.     

Current and future suitability areas of kermes oak (<Emphasis Type="Italic">Quercus coccifera</Emphasis> L.) in the Levant under climate change

Quercus coccifera L. (Kermes oak) is an evergreen oak, typical of the maquis in the eastern and south-eastern part of the Mediterranean. It occurs almost continuously along the Syrian–Lebanese coast up to 1500 m and is more scattered inland, up to the arid southernmost area of Petra in Jordan. Human impact and global warming both strongly affect the natural distribution of the species, thus leading to a widespread forest fragmentation in the whole region. In this study, we investigate the current bioclimatic range of Kermes oak and forecast which areas are potentially most suitable over the course of the twenty-first century. Ecological niche modelling was used to retrieve the environmental envelope of the species according to 23 topographic and climate variables. Five algorithms and three general circulation models were applied to provide the potential distribution of Kermes oak at the present time and project it to the future. Results showed a current suitability area in the Middle East extending from NW of Syria, rather continuously along the Lebanese coasts and inland up to the Mediterranean western slopes of Palestine and the Golan area (Israel), encompassing the Jordan Valley towards Dana and Wadi Rum (Jordan), with an isolated patch in Jabal Al-Arab (South Syria). Future scenarios depict a significant fragmentation and restriction of Kermes oak range, especially in the north of Syria and Golan, with a general shifting in altitude. This information may be useful in helping the foresters to cope with the challenge of climate changes by identifying the most suitable areas climatically effective for successful ecosystem restoration and management, including reforestation programmes.     

Weighting Nitrogen and Phosphorus Pixel Pollutant Loads to Represent Runoff and Buffering Likelihoods

Watershed models often estimate annual nitrogen (N) or phosphorus (P) pollutant loads in rural areas with export coefficient (EC) (kg/ha/yr) values based on land cover, and in urban areas as the product of spatially uniform event mean concentration (EMC) (mg/L) values and runoff volume. Actual N and P nonpoint source (NPS) pollutant loading has more spatial complexity due to watershed variation in runoff likelihood and buffering likelihood along surface and subsurface pathways, which can be represented in a contributing area dispersal area (CADA) NPS model. This research develops a CADA NPS model to simulate how watershed properties of elevation, land cover, and soils upslope and downslope of each watershed pixel influence nutrient loading. The model uses both surface and subsurface runoff indices (RI), and surface and subsurface buffer indices (BI), to quantify the runoff and buffering likelihood for each watershed pixel, and generate maps of weighted EC and EMC values that identify NPS pollutant loading hotspots. The research illustrates how CADA NPS model maps and pixel loading values are sensitive to the spatial resolution and accuracy of elevation and land cover data, and model predictions can represent the lower and upper bounds of NPS loading. The model provides managers with a tool to rapidly visualize, rank, and investigate likely areas of high nutrient export.     

Evaluating common drivers for color,iron and organic carbon in Swedish watercourses

The recent browning (increase in color) of surface waters across much of the northern hemisphere has important implications for light climate, ecosystem functioning, and drinking water treatability. Using log-linear regressions and long-term (6–21 years) data from 112 Swedish watercourses, we identified temporal and spatial patterns in browning-related parameters [iron, absorbance, and total organic carbon (TOC)]. Flow variability and lakes in the catchment were major influences on all parameters. Co-variation between seasonal, discharge-related, and trend effects on iron, TOC, and absorbance were dependent on pH, landscape position, catchment size, latitude, and dominant land cover. Large agriculture-dominated catchments had significantly larger trends in iron, TOC, and water color than small forest catchments. Our results suggest that while similarities exist, no single mechanism can explain the observed browning but show that multiple mechanisms related to land cover, climate, and acidification history are responsible for the ongoing browning of surface waters.