This study compares speciated model-predicted concentrations (i.e., mixing ratios) of volatile organic compounds (VOCs) with measurements from the Photochemical Assessment Monitoring Stations (PAMS) network at sites within the northeastern US during June–August of 2006. Measurements of total non-methane organic compounds (NMOC), ozone (O3), oxides of nitrogen (NOx) and reactive nitrogen species (NOy) are used for supporting analysis. The measured VOC species were grouped into the surrogate classes used by the Carbon Bond IV (CB4) chemical mechanism. It was found that the model typically over-predicted all the CB4 VOC species, except isoprene, which might be linked to overestimated emissions. Even with over-predictions in the CB4 VOC species, model performance for daily maximum O3 was typically within ±15%. Analysis at an urban site in NY, where both NMOC and NOx data were available, suggested that the reasonable ozone performance may be possibly due to compensating overestimated NOx concentrations, thus modulating the NMOC/NOx ratio to be in similar ranges as that of observations. 相似文献
Two spatial optimization approaches, developed from the opposing perspectives of ecological economics and landscape planning
and aimed at the definition of new distributions of farming systems and of land use elements, are compared and integrated
into a general framework. The first approach, applied to a small river catchment in southwestern France, uses SWAT (Soil and
Water Assessment Tool) and a weighted goal programming model in combination with a geographical information system (GIS) for
the determination of optimal farming system patterns, based on selected objective functions to minimize deviations from the
goals of reducing nitrogen and maintaining income. The second approach, demonstrated in a suburban landscape near Leipzig,
Germany, defines a GIS-based predictive habitat model for the search of unfragmented regions suitable for hare populations
(Lepus europaeus), followed by compromise optimization with the aim of planning a new habitat structure distribution for the hare. The multifunctional
problem is solved by the integration of the three landscape functions (“production of cereals,” “resistance to soil erosion
by water,” and “landscape water retention”). Through the comparison, we propose a framework for the definition of optimal
land use patterns based on optimization techniques. The framework includes the main aspects to solve land use distribution
problems with the aim of finding the optimal or best land use decisions. It integrates indicators, goals of spatial developments
and stakeholders, including weighting, and model tools for the prediction of objective functions and risk assessments. Methodological
limits of the uncertainty of data and model outcomes are stressed. The framework clarifies the use of optimization techniques
in spatial planning. 相似文献
Large volumes of CO2 captured from carbon emitters (such as coal-fired power plants) may be stored in deep saline aquifers as a means of mitigating climate change. Storing these additional fluids may cause pressure changes and displacement of native brines, affecting subsurface volumes that can be significantly larger than the CO2 plume itself. This study aimed at determining the three-dimensional region of influence during/after injection of CO2 and evaluating the possible implications for shallow groundwater resources, with particular focus on the effects of interlayer communication through low-permeability seals. To address these issues quantitatively, we conducted numerical simulations that provide a basic understanding of the large-scale flow and pressure conditions in response to industrial-scale CO2 injection into a laterally open saline aquifer. The model domain included an idealized multilayered groundwater system, with a sequence of aquifers and aquitards (sealing units) extending from the deep saline storage formation to the uppermost freshwater aquifer. Both the local CO2-brine flow around the single injection site and the single-phase water flow (with salinity changes) in the region away from the CO2 plume were simulated. Our simulation results indicate considerable pressure buildup in the storage formation more than 100 km away from the injection zone, whereas the lateral distance migration of brine is rather small. In the vertical direction, the pressure perturbation from CO2 storage may reach shallow groundwater resources only if the deep storage formation communicates with the shallow aquifers through sealing units of relatively high permeabilities (higher than 10?18 m2). Vertical brine migration through a sequence of layers into shallow groundwater bodies is extremely unlikely. Overall, large-scale pressure changes appear to be of more concern to groundwater resources than changes in water quality caused by the migration of displaced saline water. 相似文献
The effects of elevated O3 on photosynthetic properties in adult beech trees (Fagus sylvatica) were investigated in relation to leaf mass per area as a measure of the gradually changing, within-canopy light availability. Leaves under elevated O3 showed decreased stomatal conductance at unchanged carboxylation capacity of Rubisco, which was consistent with enhanced δ13C of leaf organic matter, regardless of the light environment during growth. In parallel, increased energy demand for O3 detoxification and repair was suggested under elevated O3 owing to enhanced dark respiration. Only in shade-grown leaves, light-limited photosynthesis was reduced under elevated O3, this effect being accompanied by lowered Fv/Fm. These results suggest that chronic O3 exposure primarily caused stomatal closure to adult beech trees in the field regardless of the within-canopy light gradient. However, light limitation apparently raised the O3 sensitivity of photosynthesis and accelerated senescence in shade leaves. 相似文献
A method intercomparison study of analytical methods for the determination of neutral, volatile polyfluorinated alkyl substances (PFAS) was carried out in March, 2006. Environmental air samples were collected in triplicate at the European background site Mace Head on the west coast of Ireland, a site dominated by ‘clean’ westerly winds coming across the Atlantic. Extraction and analysis were performed at two laboratories active in PFAS research using their in-house methods. Airborne polyfluorinated telomer alcohols (FTOHs), fluorooctane sulfonamides and sulfonamidoethanols (FOSAs/FOSEs) as well as additional polyfluorinated compounds were investigated. Different native and isotope-labelled internal standards (IS) were applied at various steps in the analytical procedure to evaluate the different quantification strategies. Field blanks revealed no major blank problems. European background concentrations observed at Mace Head were found to be in a similar range to Arctic data reported in the literature. Due to trace-levels at the remote site, only FTOH data sets were complete and could therefore be compared between the laboratories. Additionally, FOSEs could partly be included. Data comparison revealed that despite the challenges inherent in analysis of airborne PFAS and the low concentrations, all methods applied in this study obtained similar results. However, application of isotope-labelled IS early in the analytical procedure leads to more precise results and is therefore recommended. 相似文献
Background, aim, and scope Pharmaceuticals and their metabolites are detected in the aquatic environment and our drinking water supplies. The need for
high quality drinking water is one of the most challenging problems of our times, but still only little knowledge exists on
the impact of these compounds on ecosystems, animals, and man. Biological waste water treatment in constructed wetlands is
an effective and low-cost alternative, especially for the treatment of non-industrial, municipal waste water. In this situation,
plants get in contact with pharmaceutical compounds and have to tackle their detoxification. The mechanisms for the detoxification
of xenobiotics in plants are closely related to the mammalian system. An activation reaction (phase I) is followed by a conjugation
(phase II) with hydrophilic molecules like glutathione or glucose. Phase III reactions can be summarized as storage, degradation,
and transport of the xenobiotic conjugate. Until now, there is no information available on the fate of pharmaceuticals in
plants. In this study, we want to investigate the fate and metabolism of N-acetyl-4-aminophenol (paracetamol) in plant tissues using the cell culture of Armoracia rusticana L. as a model system.
Materials and methods A hairy root culture of A. rusticana was treated with acetaminophen in a liquid culture. The formation and identification of metabolites over time were analyzed
using HPLC-DAD and LC–MSn techniques.
Results With LC–MS technique, we were able to detect paracetamol and identify three of its metabolites in root cells of A. rusticana. Six hours after incubation with 1 mM of acetaminophen, the distribution of acetaminophen and related metabolites in the
cells resulted in 18% paracetamol, 64% paracetamol–glucoside, 17% paracetamol glutathione, and 1% of the corresponding cysteine
conjugate.
Discussion The formation of two independently formed metabolites in plant root cells again revealed strong similarities between plant
and mammalian detoxification systems. The detoxification mechanism of glucuronization in mammals is mirrored by glucosidation
of xenobiotics in plants. Furthermore, in both systems, a glutathione conjugate is formed. Due to the existence of P450 enzymes
in plants, the formation of the highly reactive NAPQI intermediate is possible.
Conclusions In this study, we introduce the hairy root cell culture of A. rusticana L. as a suitable model system to study the fate of acetaminophen in plant tissues. Our first results point to the direction
of plants being able to take up and detoxify the model substrate paracetamol. These first findings underline the great potential
of using plants for waste water treatments in constructed wetlands.
Recommendations and perspectives This very first study on the detoxification of a widely used antipyretic agent in plant tissues again shows the flexibility
of plant detoxification systems and their potential in waste water treatment facilities. This study covers only the very first
steps of acetaminophen detoxification in plants; still, there is no data on long-term exposure as well as the possible impact
of pharmaceuticals on the plant health and stress defense. Long-term experiments need to be performed to follow the fate of
acetaminophen in root and leaf cells in a whole plant system, and to evaluate possible usage of plants for the remediation
of acetaminophen from waste water. 相似文献
Understanding patterns, dynamics, and drivers of land use is crucial for improving our ability to cope with sustainability challenges. The human appropriation of net primary production (HANPP) framework provides a set of integrated socio-ecological indicators that quantify how land use alters energy flows in ecosystems via land conversions and biomass harvest. Thus, HANPP enables researchers to systematically and consistently assess the outcome of changes in land cover and land-use intensity across spatio-temporal scales. Yet, fine-scale HANPP assessments are so far missing, an information important to address site-specific ecological implications of land use. Here, we provide such an assessment for Europe at a 1-km scale for the years 1990, 2000, and 2006. The assessment was based on a consistent land-use/biomass flow dataset derived from statistical data, remote sensing maps, and a dynamic global vegetation model. We find that HANPP in Europe amounted to ~43 % of potential productivity, well above the global average of ~25 %, with little variation in the European average since 1990. HANPP was highest in Central Europe and lower in Northern and Southern Europe. At the regional level, distinct changes in land-use intensity were observed, most importantly the decline of cropland areas and yields following the breakdown of socialism in Eastern Europe and the subsequent recovery after 2000, or strong dynamics related to storm events that resulted in massive salvage loggings. In sum, however, these local dynamics cancelled each other out at the aggregate level. We conclude that this finding warrants further research into aspects of the scale-dependency of dynamics and stability of land use. 相似文献
The presented research concerned the compatibility of cosolvents with in situ alkaline hydrolysis (ISAH) for treatment of organophosphorous (OPP) pesticide contaminated sites. In addition, the influence of moderate temperature heat increments was studied as a possible enhancement method. A complex dense non-aqueous phase liquid (DNAPL) of primarily parathion (~50 %) and methyl parathion (~15 %) obtained from the Danish Groyne 42 site was used as a contaminant source, and ethanol and propan-2-ol (0, 25, and 50 v/v%) was used as cosolvents in tap water and 0.34 M NaOH. Both cosolvents showed OPP solubility enhancement at 50 v/v% cosolvent content, with slightly higher OPP concentrations reached with propan-2-ol. Data on hydrolysis products did not show a clear trend with respect to alkaline hydrolysis reactivity in the presence of cosolvents. Results indicated that the hydrolysis rate of methyl-parathion (MP3) decreased with addition of cosolvent, whereas the hydrolysis rate of ethyl-parathion (EP3) remained constant, and overall indications were that the hydrolysis reactions were limited by the rate of hydrolysis rather than NAPL dissolution. In addition to cosolvents, the influence of low-temperature heating on ISAH was studied. Increasing reaction temperature from 10 to 30 °C provided an average rate of hydrolysis enhancement by a factor of 1.4–4.8 dependent on the base of calculation. When combining 50 v/v% cosolvent addition and heating to 30 °C, EP3 solubility was significantly enhanced and results for O,O-diethyl-thiophosphoric acid (EP2 acid) showed a significant enhancement of hydrolysis as well. However, this could not be supported by para-nitrophenol (PNP) data indicating the instability of this product in the presence of cosolvent.
Dissolved organic matter (DOM) has been shown to affect phytoplankton species directly. These interactions largely depend on the origin and molecular size of DOM and are different in prokaryotes and eukaryotes. In a preceding study, however, two humic substance preparations did not adversely affect coccal green algae or cyanobacterial growth even at high concentrations of dissolved organic carbon (DOC). These results contradicted previous findings, showing a clear, negative response of different phototrophs to much lower DOC concentrations. To test whether or not at least defined building blocks of humic substances (HSs) are effective algicidal structures, we enriched two humic preparations with hydroquinone and p-benzoquinone, respectively, and exposed two different green algae, Pseudokirchneriella subcapitata and Monoraphidium braunii, and two cyanobacterial species, Synechocystis sp. and Microcystis aeruginosa, to the unmodified and enriched HSs. As response variables, growth rates in terms of biomass increase, chlorophyll-a content, and photosynthetic yield were measured. The highest concentration (4.17 mM DOC) of the modified HSs clearly inhibited growth; the cyanobacterial species were much more sensitive than the green algal species. However, realistic ecological concentrations did not adversely affect growth. Aerating the exposure solution for 24 h strongly reduced the inhibitory effect of the modified HSs. The algicidal effect was obviously caused by monomers and not by polymerised high molecular weight HSs themselves. Furthermore, the maximum quantum yield (Φ PSII max) was stimulated in the green algal species by low and medium DOC concentrations, but reduced in the cyanobacterial species upon exposure to higher HS concentrations. The quinone- and phenol-enriched HSs only showed algicidal activity at high concentrations of 4.17 mM DOC and lost their effects over time, presumably by oxidation and subsequent polymerisation. This study confirms that the applied humic substances themselves are not effective algicides even if enriched in effective structures. 相似文献