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1.
Evaluating the variability of aquatic acidification and photochemical ozone formation characterization factors for Canadian emissions 总被引:1,自引:0,他引:1
Samuel Fréchette-Marleau Valérie Bécaert Manuele Margni Réjean Samson Louise Deschênes 《The International Journal of Life Cycle Assessment》2008,13(7):593-604
Background, aim, and scope The Canadian life cycle impact assessment method LUCAS proposes a characterization of the impact categories aquatic acidification
and photochemical ozone formation using a resolution scale based on 15 terrestrial ecozones. Each ecozone represents areas
of the country which can be identified easily by general living (biotic) and nonliving (abiotic) characteristics. The three
main purposes of this research are to improve the characterization models of both impact categories including regional exposure
and effect factors, to investigate what is the best resolution scale between Canadian provinces or ecozones, and to analyze
the extent of spatial variability.
Materials and methods A model framework accounting for variability in fate, exposure and effect factors has been elaborated. The same fate factor,
based on Advanced Statistical Trajectory Regional Air Pollution matrices, applies to both impact categories. For the aquatic
acidification impact category, the fate factor also accounts for the fraction of the deposition transferred to the aquatic
ecosystem. The exposure factor for this impact category is considered to be 1 and the effect factor is based on the critical
load exceedance, where the potential impacts are only considered in provinces or ecozones in which the critical load is exceeded.
For the photochemical ozone formation impact category, the exposure factor is considered to be proportional to the population
density in each province or ecozone, and the effect factor is represented by the chemical reactivity estimated with the maximum
incremental reactivity model. The calculation of the new characterization factors using both a province-based and ecozone
resolution scale was performed using a matrix which converts data from one resolution scale to another.
Results Results with the inclusion of the effect and the exposure factors show that the spatial variability between provinces remains
within a factor of 10 and 5 for aquatic acidification and photochemical ozone formation, respectively.
Discussion Analysis of the results show that regionalization by province is preferable to regionalization by ecozone. It is more accurate
in regard to atmospheric modeling and more representative of population distribution. However, averaging the fate factor and
the population density over a whole province results in a serious limitation.
Conclusions The spatial variability of characterization factors between provinces is in the same order of magnitude as the overall range
between chemicals for aquatic acidification while much smaller for photochemical ozone formation. Hence, at this stage of
knowledge, province-based regionalization seems to be more relevant for the aquatic acidification impact category than for
photochemical ozone formation.
Recommendations and perspectives Research must be pursued to integrate a better transport and deposition model with improved spatial capabilities and a successive
modeling step properly describing the cause–effect chain up to the damage level, such as the biotic environment and the human
population. 相似文献
2.
Pierre-Olivier Roy Louise Deschênes Manuele Margni 《The International Journal of Life Cycle Assessment》2014,19(4):882-890
Purpose
Characterization factors (CFs) quantifying the potential impact of acidifying emissions on inland aquatic environments in life cycle assessment are typically available on a generic level. The lack of spatial differentiation may weaken the relevance of generic CFs since it was shown that regional impact categories such as aquatic acidification were influenced by the surroundings of the emission location. This paper presents a novel approach for the development of spatially differentiated CFs at a global scale for the aquatic acidification impact category.Methods
CFs were defined as the change in relative decrease of lake fish species richness due to a change in acidifying chemicals emissions. The characterization model includes the modelling steps linking emission to atmospheric acid deposition (atmospheric fate factor) change, which lead to lake H+ concentration (receiving environment fate factor) change and a decrease in relative fish species richness (effect factor). We also evaluated the significance of each factor (i.e. atmospheric fate, receiving environment fate and effects) to the overall CFs spatial variability and parameter uncertainty.Results and discussion
The highest CFs were found for emissions occurring in Canada, Scandinavia and the northern central Asia because of the extensive lake areas in these regions (lake areas being one of the parameters of the CFs; the bigger the lake areas, the higher the CFs). The CFs’ spatial variability ranged over 5, 6 and 8 orders of magnitude for NOx, SO2 and NH3 emissions, respectively. We found that the aquatic receiving environment fate factor is the dominant contributor to the overall spatial variability of the CFs, while the effect factors contributed to 98 % of the total parameter uncertainty.Conclusions
The resulting characterization model and factors enable a consistent evaluation of spatially explicit acidifying emissions impacts at the global scale. 相似文献3.
The photochemical release of inorganic nitrogen from dissolved organic matter is an important source of bio-available nitrogen (N) in N-limited aquatic ecosystems. We conducted photochemical experiments and used mathematical models based on pseudo-first-order reaction kinetics to quantify the photochemical transformations of individual N species and their seasonal effects on N cycling in a mountain forest stream and lake (Plešné Lake, Czech Republic). Results from laboratory experiments on photochemical changes in N speciation were compared to measured lake N budgets. Concentrations of organic nitrogen (Norg; 40–58 µmol L−1) decreased from 3 to 26% during 48-hour laboratory irradiation (an equivalent of 4–5 days of natural solar insolation) due to photochemical mineralization to ammonium (NH4
+) and other N forms (Nx; possibly N oxides and N2). In addition to Norg mineralization, Nx also originated from photochemical nitrate (NO3
−) reduction. Laboratory exposure of a first-order forest stream water samples showed a high amount of seasonality, with the maximum rates of Norg mineralization and NH4
+ production in winter and spring, and the maximum NO3
− reduction occurring in summer. These photochemical changes could have an ecologically significant effect on NH4
+ concentrations in streams (doubling their terrestrial fluxes from soils) and on concentrations of dissolved Norg in the lake. In contrast, photochemical reactions reduced NO3
− fluxes by a negligible (<1%) amount and had a negligible effect on the aquatic cycle of this N form. 相似文献
4.
Nitrate and nitrite inhibition of methanogenesis during denitrification in granular biofilms and digested domestic sludges 总被引:4,自引:0,他引:4
Anaerobic bioreactors that can support simultaneous microbial processes of denitrification and methanogenesis are of interest
to nutrient nitrogen removal. However, an important concern is the potential toxicity of nitrate (NO3
−) and nitrite (NO2
−) to methanogenesis. The methanogenic toxicity of the NOx− compounds to anaerobic granular biofilms and municipal anaerobic digested sludge with two types of substrates, acetate and
hydrogen, was studied. The inhibition was the severest when the NOx− compounds were still present in the media (exposure period). During this period, 95% or greater inhibition of methanogenesis
was evident at the lowest concentrations of added NO2
− tested (7.6–10.2 mg NO2
−-N l−1) or 8.3–121 mg NO3
−-N l−1 of added NO3
−, depending on substrate and inoculum source. The inhibition imparted by NO3
− was not due directly to NO3
− itself, but instead due to reduced intermediates (e.g., NO2
−) formed during the denitrification process. The toxicity of NOx− was found to be reversible after the exposure period. The recovery of activity was nearly complete at low added NOx− concentrations; whereas the recovery was only partial at high added NOx− concentrations. The recovery is attributed to the metabolism of the NOx− compounds. The assay substrate had a large impact on the rate of NO2
− metabolism. Hydrogen reduced NO2
− slowly such that NO2
− accumulated more and as a result, the toxicity was greater compared to acetate as a substrate. The final methane yield was
inversely proportional to the amount of NOx− compounds added indicating that they were the preferred electron acceptors compared to methanogenesis. 相似文献
5.
Goal, Scope and Background
Photochemical ozone creation potentials (POCPs) typically used in life cycle impact assessment (LCIA) to address the impact category ‘photo-oxidant formation’ only provide factors for particular volatile organic compounds and do not take into account background concentrations and meteorological conditions. However, the formation of ozone from volatile organic compounds (VOCs), carbon monoxide (CO) and nitrogen oxides (NOx) is highly dependent on the background pollutant concentrations and meteorological conditions. Some LCIA manuals therefore recommend working with potentials for high background concentrations of NOx (Derwent 1998), and potentials for low background concentrations of NOx (Andersson-Sköld 1992).Objectives
This study has introduced an improved set of POCPs independently of meteorological and emission conditions specific to a given period or location. Whereas current POCP values may be relevant to estimate the photo-oxidant formation over a certain (temporally and spatially well-defined) domain, this study has further introduced more relevant values with respect to potential impacts of ozone on human health and environment.Methods
For the computation of POCP values on the scale of Western Europe, independently of meteorological and emission conditions specific to a given period or location, a Eulerian chemistry-transport numerical model (CHIMERE-continental) has been implemented over three summer seasons. POCPs have been evaluated for ten VOC species (including the whole VOC group), CO and NOx. The coherence of this new set of POCP values with previous studies has been checked. The spatial representa-tivity of POCP values over the simulation domain in Europe has also been addressed. The robustness of these POCP values to changes in the implemented chemical mechanism used in our model has been checked.Results and Discussion
The POCPs computed in this study were generally lower than the POCPs calculated in previous studies. In the previous studies, but not here, the POCPs have been calculated with particular meteorological conditions (during anti-cyclonic, fair weather conditions) or emission levels (high polluted backgrounds) known to be optimal with respect to ozone formation. Despite the quantitative variations in the POCP values, we have found a good agreement in the relative ranking of the pollutant species between this study and previous studies. It was also shown that POCP values display significant spatial variability over Western Europe (the largest spatial differences were obtained for NOx where the sign of the POCP value even changes from region to region).Conclusions
Finally, the temporally and spatially averaged values obtained here for the POCP index update previous values and represent an attempt to generate the most appropriate and accurate scale for European conditions independently of meteorological and emission conditions specific to a given period or location.Recommendations and Outlook
These new PCOPs should be useful to LCIA-practitioners in further life cycle impact assessment. However, for the NOx species, we do not recommend the use of the POCP value for LCIA.6.
Spatial variability in nutrient concentration and biofilm nutrient limitation in an urban watershed 总被引:1,自引:0,他引:1
Nutrient enrichment threatens river ecosystem health in urban watersheds, but the influence of urbanization on spatial variation
in nutrient concentrations and nutrient limitation of biofilm activity are infrequently measured simultaneously. In summer
2009, we used synoptic sampling to measure spatial patterns of nitrate (NO3
−), ammonium (NH4
+), and soluble reactive phosphorus (SRP) concentration, flux, and instantaneous yield throughout the Bronx River watershed
within New York City and adjacent suburbs. We also quantified biofilm response to addition of NO3
−, phosphate (PO4
3−), and NO3
− + PO4
3− on organic and inorganic surfaces in the river mainstem and tributaries. Longitudinal variation in NO3
− was low and related to impervious surface cover across sub-watersheds, but spatial variation in NH4
+ and SRP was higher and unrelated to sub-watershed land-use. Biofilm respiration on organic surfaces was frequently limited
by PO4
3− or NO3
− + PO4
3−, while primary production on organic and inorganic surfaces was nutrient-limited at just one site. Infrequent NO3
− limitation and low spatial variability of NO3
− throughout the watershed suggested saturation of biological N demand. For P, both higher biological demand and point-sources
contributed to greater spatial variability. Finally, a comparison of our data to synoptic studies of forested, temperate watersheds
showed lower spatial variation of N and P in urban watersheds. Reduced spatial variation in nutrients as a result of biological
saturation may represent an overlooked effect of urbanization on watershed ecology, and may influence urban stream biota and
downstream environments. 相似文献
7.
Serum concentration of nitric oxide metabolites (NOx) is associated with cardiovascular disease risk factors in pediatrics. The aim of this study was to determine sex- and age-specific reference ranges for serum NOx concentrations in pediatrics. Serum NOx levels were measured in 401 subjects (189 boys and 212 girls), aged 4–19 years, using the Griess method. Study subjects selected from participants of Tehran lipid and glucose study, an ongoing cohort study aimed at determining of noncommunicable disease risk factors among Tehranian subjects. The International Federation of Clinical Chemistry guidelines and the robust method were used for determining reference values for sample sizes greater or less than 120 respectively. The 95% reference values for serum NOx concentrations were 13.6–69.2, 11.4–66.0, and 12.2–69.4 μmol/L in boys, girls, and total population respectively. The upper limit of serum NOx was 28% lower in otherwise healthy overweight and obese boys while it was 6% higher in overweight and obese girls, for both groups compared to their corresponding normal weight subjects. In conclusion, this study, for the first time, reports reference values for serum NOx levels in healthy children and adolescents. 相似文献
8.
Hsien Hui Khoo Reginald B. H. Tan Masayuki Sagisaka 《The International Journal of Life Cycle Assessment》2008,13(4):312-318
Background, aim and scope The interest in the use of biomass as a renewable energy resource has rapidly grown over the past few years. In Singapore,
biomass resources are mostly from waste wood. This article presents a few technological options, namely carbonization, for
the conversion of woody biomass into a solid fuel, charcoal.
Materials and methods In the first stage, a life cycle assessment (LCA) ‘gate-to-gate’ system was developed for a conventional carbonizer system,
a modern carbonizer from Japan, and a proposed four-stage partial furnace carbonizer from Tunisia. The potential environmental
impacts were generated for global warming potential, acidification, human toxicity and photochemical oxidant potential. Based
on the first set of results, the second LCA investigation was carried out comparing the selected carbonizer from Japan and
an existing incinerator in Singapore. The second LCA adopted a unique approach combining social costs of pollution with the
economic factors of the two biomass conversion technologies.
Results The carbonizer from Japan resulted in approximately 85% less greenhouse gases than the conventional carbonization system and
54% less than the proposed four-stage carbonizer from Tunisia. In terms of acidification and human toxicity, the carbonizers
from Japan and Tunisia display nearly similar results—both were considerably lower than the conventional carbonizer. For photochemical
oxidant potential, very minimal emissions are generated from the four-stage carbonizer and nearly zero impact is realized
for the carbonization technology from Japan.
Discussion From the first set of LCA results, the Japanese carbonizer is favored in terms of its environmental results. The highest environmental
impacts from the conventional carbonizer were due to large and uncontrolled emissions of acidic gases, greenhouse gases (particularly
CO2 and CH4), particulates, and non-methane volatile organic compounds from both fugitive sources and energy requirements. The second
LCA addressed the performance of the carbonizer from Japan against an existing incinerator in terms of environmental as well
as cost performances. This unique approach translated pollution emissions into monetary costs to highlight the impacts of
social health.
Conclusions For the first LCA, the accumulated impacts from the Japanese carbonizer proved to display significantly lower environmental
impacts, especially for global warming potential. The overall environmental performance of the four-stage carbonizer from
Tunisia ranked slightly lower than the one from Japan and much higher than the conventional carbonizer. The second LCA results
displayed a noteworthy improvement of 90% for human health from the modern Japanese carbonizer technology—when compared against
conventional incinerators. Without considering health issues or social costs, the total value per ton of wood treated is nearly
similar for both incinerator and carbonizer.
Recommendations and perspectives The interest in biomass as raw material for producing energy has emerged rapidly in many countries. However, careful analysis
and comparison of technologies are necessary to ensure favorable environmental outcomes. A full life cycle study, along with
costs and the impact of pollution on society, should be performed before any large-scale biomass conversion technology is
implemented. LCA can be applied to quantify and verify the overall environmental performance of a particular technology of
interest as well as further explore the proposed technology in terms of costs and social implications. 相似文献
9.
We used terrestrial ecosystem models to estimate spatial and temporal variability in and uncertainty of estimated soil carbon
dioxide (CO2) efflux, or soil respiration, over the Japanese Archipelago. We compared five carbon-cycle models to assess inter-model variability:
Biome-BGC, CASA, LPJ, SEIB, and VISIT. These models differ in approaches to soil carbon dynamics, root respiration estimation,
and relationships between decomposition and environmental factors. We simulated the carbon budget of natural ecosystems over
the archipelago for 2001–2006 at 1-day time steps and 2-min (latitude and longitude) spatial resolution. The models were calibrated
using measured flux data to accurately represent net ecosystem CO2 exchange. Each model successfully reproduced seasonal changes and latitudinal gradients in soil respiration. The five-model
average of estimated total soil respiration of Japanese ecosystems was 295 Tg C year−1, with individual model estimates ranging from 210 to 396 Tg C year−1 (1 Tg = 1012 g). The differences between modeled estimates were more evident in summer and in warmer years, implying that they were mainly
attributable to differences in modeling the temperature dependence of soil respiration. There was a large discrepancy between
models in the estimated contribution of roots to total soil respiration, ranging from 3.9 to 48.4%. Although model calibration
reduced the uncertainty of flux estimates, substantial uncertainties still remained in estimates of underground processes
from these terrestrial carbon-cycle models. 相似文献
10.
Lycia Aziz Louise Deschênes Rifat-Ara Karim Laure Patouillard Cécile Bulle 《The International Journal of Life Cycle Assessment》2018,23(11):2178-2188
Purpose
The aim of the study is to calculate regionalized characterization factors for the atmospheric emissions of metals transferred to soil for zinc, copper, and nickel taking into account the atmospheric fate and speciation.Methods
In order to calculate characterization factors for all possible atmospheric emission locations around the world, the link between atmospheric deposition with regionalized soil fate factors and bioavailability factors accounting for the metal’s speciation was established. The methodology to develop the regionalized fate factors and characterization factors is threefold. First, the emitted metal fraction that is deposited on soils is calculated from atmospheric source-receptor matrices providing for each emission location the fraction of an emission that is deposited on each worldwide receiving cell (2°?×?2.5° resolution). Second, the fraction of metal deposited in different soil types is determined by overlapping the deposition map with a soil map, based on the 4513 different soil types from the Harmonized World Soil Database. Third, bioavailability factors are calculated for each soil type, which allows determining the bioavailable fraction of the deposited metal depending on the soil properties. Combining these steps with the effect factors results in a series of terrestrial ecotoxicological characterization factors. These characterization factors are then applied in an illustrative example and compared to results obtained with generic characterization factors. The case study focuses on the electricity production process in Québec, whose ecosystem impacts are currently dominated by metal ecotoxicity impacts. The uncertainty due to the spatial variability of the impact is quantified.Results and discussion
Our results show that regionalized characterization factors are over three orders of magnitude lower than generic characterization factors. They are presented on maps and their spatial variability was evaluated at different regional scales (region, country, world). The use of regionalized characterization factors with their spatial variability at different geographic resolution scales in the case study gives a result more or less precise depending on the level of resolution of the characterization factor applied (country or global-default). The impact scores of the three metals in the case study are three orders of magnitude lower when compared to the scores obtained with generic characterization factors.Conclusions
The development of those regionalized characterization factors improves the terrestrial ecotoxicity assessment in life cycle impact assessment by taking into account the atmospheric fate and the speciation of the metal for new 3 metals for the different soil types in the world and by documenting their spatial variability.11.
《Journal of plant physiology》2014,171(10):868-875
Gaseous nitrogen dioxide (NO2) can disturb normal plant growth and trigger complex physiological responses. NO2-induced responses are influenced by biotic or abiotic factors. In this study, we investigated the effects of exogenous sodium sulfide (Na2S, 5 mmol L−1) on epidermis and stomata related physico-chemical responses of hybrid poplar cuttings (Pouplus alba × P. berolinensis) to gaseous NO2 (4 μl 1−1) for three time periods (0, 14 and 48 h). We also investigated hydrogen sulfide (H2S), nitrate-nitrogen and nitrate reductase activity (NR) in control and Na2S treated plants. Our results showed that NO2 exposure for 48 h led to the decline of NR, maximal PSII quantum yield (Fv/Fm), net photosynthetic rate (Pn), and dark respiration rate (Rd). The maximum rate for the post-illumination carbon dioxide burst (PIB) occurred in 48-h exposed leaves 13–15 s after darkening. Moreover, NO2 exposure resulted in a significant increase in nitrogen percentage (from 0 to 33%) and a decrease in the macro and micro-elements of leaf surface. Spraying Na2S aqueous solution on the leaf surfaces significantly increased the thicknesses of palisade/spongy tissue and H2S content. Na2S pretreatment alleviated NO2-caused toxic effects as indicated by increased NR and higher values of Pn, Fv/Fm, and actual photochemical efficiency in light (ФPSII) compared with the control. Na2S pretreatment had no significant impacts on PIB-based photorespiration or elements composition of a leaf surface. 相似文献
12.
Denitrification in Aquatic Environments: A Cross-system Analysis 总被引:7,自引:0,他引:7
A meta-analysis was conducted on 136 data sets of denitrification rates (DR) recorded both during the period of highest water temperature and monthly in five types of aquatic ecosystems: oceans, coastal environments, estuaries, lakes and rivers. There was a gradual increase of DR from the ocean to rivers and lakes at both scales, with the rivers showing the highest DR variability. Denitrification peaked during summertime and showed highest seasonal variability in lakes and rivers. High concentrations of nitrate and interstitially-dissolved organic carbon as well as low oxygen concentration in the overlying water enhanced DR both during summer and at a seasonal scale whereas total phosphorus did at the seasonal scale only. There was a positive linear relationship between overlying nitrate and DR over the range of 1–970 μmol NO3 (r
2 = 0.86, P = 0.001). DR in lakes and rivers might reach values doubling those in the more denitrifying terrestrial ecosystems (e.g. agrosystems). Discrepancies in DR and its controlling factors between site-specific studies and this meta-analysis may arise from environmental variability at two, often confounded, scales of observation: the habitat and the ecosystem level. Future studies on denitrification in aquatic environments should address the topic of spatial heterogeneity more thoroughly. 相似文献
13.
Background Acidification is one of the important impact categories for life cycle impact assessment. Although its characterization has
progressed during this decade through the employment of midpoint approaches, only limited studies of endpoint approaches have
been performed. Objective. This study aimed at developing damage function of acidification for terrestrial ecosystems in Japan.
Damage function expresses a quantitative relationship between the inventory and endpoint damage.
Methods The geographical boundary was limited in Japan both for emission and impact. In this study, sulfur dioxide (SO2), nitrogen monoxide (NO), nitrogen dioxide (NO2) (NO and NO2 collectively mean NOx), hydrogen chloride (HC1), and ammonia (NH3) were considered as major causative substances of acidification. Net primary production (NPP) of existing vegetation was
adopted as an impact indicator of terrestrial ecosystems. The aluminum toxicity was adopted as the major factor of effect
on terrestrial ecosystems due to acidification. The leachate concentration of monomeric inorganic aluminum ions was selected
to express the plant toxicity of aluminum.
Results and Discussion The results of damage function gave utilizable factors both for a midpoint approach and an endpoint approach; Atmospheric
Deposition Factor (ADF) and Damage Factor (DF) applicable to the former and the latter, respectively. The ADF indicates an
increase of H+ deposition per unit area to an additional emission of causative sustance. The additional emission corresponds to some alternatives
in industry, not the baseline emission. The DF indicates the total NPP damage in all of Japan due to the additional emission
of causative substances. The derived NPP damage is on the order of one millionth of the NPP itself. HC1 and NH3 showed larger
ADFs and DFs than that of SO2 and NOx. The reason was ascribed to the relatively large source-receptor relationships (SRR) of HC1 and NH3. However, since the method applied to determine the SRR of HC1 and NH3 has larger uncertainties than that of SO2 and NOx, attention is needed to handle the difference.
Conclusion The damage function easily defines the concrete NPP damage due to an additional emission. The impact indica tor, NPP, also
has an advantage in its mass unit that is directly summable through the entire impact categories. Expansion of endpoints,
such as in aquatic ecosystems, material degradation, human health, and biodiversity aspects of terrestrial ecosystems, is
an important subject for future work. Further, uncertain analyses for major parameters will provide helpful information on
the reliability of damage function. 相似文献
14.
Britta Gribsholt Eric Struyf Anton Tramper Maria G. I. Andersson Natacha Brion Loreto De Brabandere Stefan Van Damme Patrick Meire Jack J. Middelburg Frank Dehairs Henricus T. S. Boschker 《Biogeochemistry》2006,80(3):289-298
The fate and transport of watershed-derived ammonium in a tidal freshwater marsh fringing the nutrient rich Scheldt River,
Belgium, was quantified in a whole ecosystem 15N labeling experiment. In late summer (September) we added 15N-NH4+ to the flood water entering a 3477 m2 tidal freshwater marsh area, and traced the ammonium processing and retention in four subsequent tide cycles. In this paper
we present the results for the water-phase components of the marsh system and compare them to a similar experiment conducted
in spring/early summer (May). Changes in concentration and isotopic enrichment of NO3− + NO2−, N2O, N2, NH4+ and suspended particulate nitrogen (SPN) were measured in concert with a mass balance study. All analyzed N-pools were labeled,
and 49% of the added 15NH4+ was retained or transformed. The most important pool for 15N was nitrate, accounting for 17% of 15N-transformation. N2, N2O and SPN accounted for 2.4, 0.02 and 1.4%, respectively. The temporal and spatial patterns of 15N transformation in the water phase component of the system were remarkably similar to those observed in May, indicating good
reproducibility of the whole ecosystem labeling approach, but the absolute ammonium transformation rate was 3 times higher
in May. While the marsh surface area was crucial for nitrification in May this was less pronounced in September. Denitrification,
on the other hand, appeared more important in September compared to May. 相似文献
15.
USEtox fate and ecotoxicity factors for comparative assessment of toxic emissions in life cycle analysis: sensitivity to key chemical properties 总被引:1,自引:0,他引:1
Andrew D. Henderson Michael Z. Hauschild Dik van de Meent Mark A. J. Huijbregts Henrik Fred Larsen Manuele Margni Thomas E. McKone Jerome Payet Ralph K. Rosenbaum Olivier Jolliet 《The International Journal of Life Cycle Assessment》2011,16(8):701-709
Purpose
The USEtox model was developed in a scientific consensus process involving comparison of and harmonization between existing environmental multimedia fate models. USEtox quantitatively models the continuum from chemical emission to freshwater ecosystem toxicity via chemical-specific characterization factors (CFs) for Life Cycle Impact Assessment (LCIA). This work provides understanding of the key mechanisms and chemical parameters influencing fate in the environment and impact on aquatic ecosystems. 相似文献16.
Jeffrey Morris Jennifer Bagby 《The International Journal of Life Cycle Assessment》2008,13(3):226-234
Background, Aims and Scope
Measuring Environmental Value for Natural Lawn and Garden Care Practices provides a life cycle assessment and impacts valuation methodology to quantify environmental (public health and ecological)
and water conservation benefits from natural lawn and garden care practices in Seattle. Seattle Public Utilities (SPU) initiated
this study as part of a triple-bottom-line analysis of its Natural Lawn and Garden Care program.
Methods The study uses life cycle assessment (LCA) methods, including the Carnegie-Mellon Economic Input-Output Life Cycle Assessment
(EIOLCA) tool publicly available on the Internet, to inventory pollutant generation from a synthetic nutrients and pesticide
approach to lawn and garden care compared against a natural/organic care approach. The study applies US Environmental Protection
Agency’s TRACI (Tool for the Reduction and Assessment of Chemical and other environmental Impacts) climate change, acidification,
eutrophication, and human health-criteria air pollutant stressor factors, along with the Lawrence Berkeley National Laboratory’s
CalTOX risk assessment model’s human and ecosystem toxicity potentials to roll up the numerous pollutant quantities into six
environmental impact categories (global warming potential, human respiratory disease potential, human toxicity potential,
ecological toxicity potential, acidification potential and eutrophication potential). The study develops cost valuation estimates
for each impact category to produce a dollar estimate of the environmental cost of the two archetypical lawn and garden care
methods.
Results Lawns and gardens account for 25% of Seattle’s land area, so lawn and garden care methods potentially have substantial impacts
on the city’s land-and water-based ecosystems. LCA methods provide an informative methodology for comparing environmental
impacts from lawn and garden care practices. These methods reveal the importance of more natural lawn and garden care practices.
They also show that resource extraction and manufacturing impacts of pesticides and synthetic fertilizers dominate their on
site use impacts in the case of global warming, but that the reverse holds for human and ecological toxicity, and eutrophication.
In addition, releases of particulates, SOx and NOx associated with gasoline-powered lawn mowing are nearly an order of magnitude larger than releases of these pollutants as
a result of the production of pesticides and fertilizers.
Discussion The study proceeds by using available data and research to build a desktop model that characterizes and contrasts two archetypical
lawn and garden care practices: (1) Petroleum-based fertilizers and pesticides, a gasoline-powered lawn mower, and substantial
irrigation to maintain a traditional weed-free, always-green lawn and garden, versus (2) A backyard compost system to provide
lawn and garden nutrients, supplemented moderately by purchased non-synthetic soil amendments, an electricity-powered mower,
no pesticides, and drought tolerant lawn and garden species having little need for irrigation.
Conclusions The study concludes that each household converting from synthetic to natural practices produces nearly $75 in annual ongoing
public health, ecological, water conservation and hazardous waste management benefits — between $16 and $21 of environmental
benefits from reduced use of synthetic fertilizers and pesticides, $8 of environmental benefits for switching from gas to
electricity for lawn mowing, $42 in cost savings due to reduced irrigation, and $5 or $6 from lower hazardous waste management
costs. There also is a potential one time avoidance of $31 in construction costs resulting from reduced need for storm water
detention and diversion capacity.
Recommendations and Perspectives This study’s estimates of environmental value would benefit from comprehensive information on direct exposure to active ingredients
in insecticides during their application. Estimates of impacts are based only on volatilization and runoff of active ingredients
after application. Furthermore, the study would benefit from estimates of carbon sequestration in soils promoted by natural
lawn and garden care techniques, and on the upstream pollutant releases from production of synthetic versus organic fertilizers.
All three of these data gaps suggest that the estimated $75 per single family residence for environmental value is probably
a lower bound on benefits from natural lawn and garden care versus more traditional pesticide-and-synthetic-fertilizer-based
approaches.
ESS-Submission Editor: Mary Ann Curran (curran.maryann@epa.gov) 相似文献
17.
Winter and summer nitrous oxide and nitrogen oxides fluxes from a seasonally snow-covered subalpine meadow at Niwot Ridge,Colorado 总被引:4,自引:3,他引:1
Gianluca Filippa Michele Freppaz Mark W. Williams Detlev Helmig Daniel Liptzin Brian Seok Brad Hall Kurt Chowanski 《Biogeochemistry》2009,95(1):131-149
The soil emission rates (fluxes) of nitrous oxide (N2O) and nitrogen oxides (NO + NO2 = NO
x
) through a seasonal snowpack were determined by a flux gradient method from near-continuous 2-year measurements using an
automated system for sampling interstitial air at various heights within the snowpack from a subalpine site at Niwot Ridge,
Colorado. The winter seasonal-averaged N2O fluxes of 0.047–0.069 nmol m−2 s−1 were ~15 times higher than observed NO
x
fluxes of 0.0030–0.0067 nmol m−2 s−1. During spring N2O emissions first peaked and then dropped sharply as the soil water content increased from the release of snowpack meltwater,
while other gases, including NO
x
and CO2 did not show this behavior. To compare and contrast the winter fluxes with snow-free conditions, N2O fluxes were also measured at the same site in the summers of 2006 and 2007 using a closed soil chamber method. Summer N2O fluxes followed a decreasing trend during the dry-out period after snowmelt, interrupted by higher values related to precipitation
events. These peaks were up to 2–3 times higher than the background summer levels. The integrated N2O-N loss over the summer period was calculated to be 1.1–2.4 kg N ha−1, compared to ~0.24–0.34 kg N ha−1 for the winter season. These wintertime N2O fluxes from subniveal soil are generally higher than the few previously published data. These results are of the same order
of magnitude as data from more productive ecosystems such as fertilized grasslands and high-N-cycling forests, most likely
because of a combination of the relatively well-developed soils and the fact that subnivean biogeochemical processes are promoted
by the deep, insulating snowpack. Hence, microbially mediated oxidized nitrogen emissions occurring during the winter can
be a significant part of the N-cycle in seasonally snow-covered subalpine ecosystems. 相似文献
18.
Maximilian Posch Jyri Seppälä Jean-Paul Hettelingh Matti Johansson Manuele Margni Olivier Jolliet 《The International Journal of Life Cycle Assessment》2008,13(6):477-486
Background, aim and scope The methodological choices and framework to assess environmental impacts in life cycle assessment are still under discussion.
Despite intensive developments worldwide, few attempts have been made hitherto to systematically present the role of different
factors of characterisation models in life cycle impact assessment (LCIA). The aim of this study is to show how European average
and country-dependent characterisation factors for acidifying and eutrophying emissions differ when using (a) acidifying and
eutrophying potentials alone, (b) depositions from an atmospheric dispersion model or (c) critical loads in conjunction with
those depositions. Furthermore, in the latter case, the contributions of emissions, an atmospheric transport model and critical
loads to changes in characterisation factors of NO2 are studied. In addition, the new characterisation factors based on the accumulated exceedance (AE) method are presented
using updated emissions, a new atmospheric transport model and the latest critical loads.
Materials and methods In this study, characterisation factors for acidifying and eutrophying emissions are calculated by three different methods.
In the ‘no fate’ (NF) methods, acidifying and eutrophying potentials alone are considered as characterisation factors. In
the ‘only above terrestrial environment’ (OT) approach, characterisation factors are based on the deposition of the acidifying
or eutrophying substances to terrestrial land surfaces. The third method is the so-called AE method in which critical loads
are used in conjunction with depositions. The results of the methods are compared both at the European and the country level
using weighted mean, weighted standard deviation, minimum and maximum values. To illustrate the sensitivity of the AE method,
changes in European emissions, employed atmospheric dispersion model and the critical loads database are conducted step-by-step,
and the differences between the results are analysed.
Results and discussion For European average characterisation factors, the three characterisation methods of acidification produce results in which
the contributions of NH3, NO2 and SO2 to the acidification indicator do not differ much within each method when 1 kg of each acidifying substance is emitted. However,
the NF methods cannot describe any spatial aspects of environmental problems. Both OT and AE methods show that the spatial
aspects play an important role in the characterisation factors. The AE method results in greater differentiations between
country-dependent characterisation factors than does the OT method. In addition, the results of the AE and OT methods differ
from each other for individual countries. A major shortcoming of the OT approach is that it does not consider the sensitivity
of the ecosystems onto which the pollutants are deposited, whereas the AE approach does. In the case of the AE method, a new
atmospheric dispersion model, new information on emissions and critical loads have a different influence on the characterisation
factors, depending on the country. The results of statistics show that the change in the atmospheric dispersion model has
a greatest influence on the results, since ecosystem-specific depositions are taken into account for the first time.
Conclusions and recommendations The simple NF methods can be used in a first approximation to assess the impacts of acidification and terrestrial eutrophication
in cases where we do not know where the emissions occur. The OT approach is a more advanced method compared with the NF method,
but its capability to describe spatial aspects is limited. The AE factors are truly impact-oriented characterisation factors
and the information used here represents the current best knowledge about the assessment practice of acidification and terrestrial
eutrophication in Europe. The key message of this study is that there is no shortcut to achieving advanced characterisation
of acidification and terrestrial eutrophication: an advanced methodology cannot develop without atmospheric dispersion models
and information on ecosystem sensitivity. 相似文献
19.
Mark A. J. Huijbregts Jyri Seppälä 《The International Journal of Life Cycle Assessment》2001,6(6):339-343
In life cycle impact assessment (LCIA), limited attention is generally given to a consistent inclusion of a fate analysis in the derivation of aquatic eutrophication potentials. This paper includes fate and potential effects in the calculation of aquatic eutrophication potentials of NH3 and NOx emitted to the ait, N and P emitted to water, and N and P emitted to soil. These characterisation factors were calculated for the Netherlands, West-Europe and the world, respectively. Implementation in current LCIA practice is further facilitated by calculating normalisation scores for the Netherlands in 1997, West-Europe in 1995 and the world in 1990. Although the results presented may be a step forward, significant improvements are still needed in the assessment of pollutants causing aquatic eutrophication. In particular, the fate factors representing transport of NOx and NH3, air emissions via soils to the aquatic environment should be improved. In addition, differences in the biological availability of nutrients and differences in the sensitivity of aquatic environments should be included in the calculation of effect factors for aquatic eutrophication. 相似文献
20.
Joshua M. Unghire Ariana E. Sutton‐Grier Neal E. Flanagan Curtis J. Richardson 《Restoration Ecology》2011,19(6):738-746
Hydric soil development of riparian wetlands is primarily influenced by the hydrologic connection between the floodplains and the stream channel. Often, the goal of riparian restoration is to revitalize this connectivity through a restructuring of the stream channel and the floodplain; however, the effects of this restructuring on the physical and spatial characteristics of soil properties are rarely considered. The objective of this study was to quantify the impacts of restoration efforts on the spatial characteristics of soil properties by means of a pre‐ and post‐restoration comparison. We determined that the spatial patterns of soil organic matter (SOM) and exchangeable phosphorus (Pex) appeared less variable in the years following restoration than in the years before restoration. Mean SOM significantly decreased after restoration, whereas mean Pex significantly increased. The spatial characteristics and mean concentrations of NO2–NO3 did not differ much between sampling dates. The loss of this spatial patterning in SOM and Pex and the decrease in SOM pools may represent negative impacts of restoration on important ecosystem characteristics. This study demonstrates that soil properties and spatial patterns can be negatively affected by restoration activities potentially hindering ecosystem development and function. 相似文献