Chemosphere - Global Change Science最新文献

{"title":"Review of the IPCC methodology for estimating nitrous oxide emissions associated with agricultural leaching and runoff","authors":"Cynthia Nevison","doi":"10.1016/S1465-9972(00)00013-1","DOIUrl":"10.1016/S1465-9972(00)00013-1","url":null,"abstract":"<div><p><em>Context abstract</em>: The constraint imposed by the observed atmospheric N₂O increase suggests that the IPCC may overestimate the anthropogenic N₂<span>O source. The 1996 Revised IPCC methodology, which will be used by Parties to the Kyoto Protocol, predicts that N</span>₂<span>O accounts for 10% or more of national aggregate greenhouse gas emissions in many countries. This percentage contribution is comparable to or greater than the overall emissions reductions required by the Protocol. N</span>₂O emissions associated with agricultural leaching and runoff contribute a significant share of the IPCC N₂O source. The current methodology may significantly overestimate these emissions, with implications for the total IPCC anthropogenic N₂O source and for national greenhouse gas inventories.</p><p><em>Main abstract</em>: N₂O emissions associated with leaching and runoff play an important role in determining both the magnitude and the uncertainty of the agricultural N₂O source, as estimated by the 1996 revised IPCC methodology. According to the methodology, leaching/runoff emissions account for over 1/4 of the total agricultural N₂O source and nearly 1/2 of the range of uncertainty in the total source. Notably, the observed atmospheric N₂O increase of 3.9 Tg N/yr, which provides an important and well documented constraint on the anthropogenic N₂O source, is significantly lower than the IPCC total agricultural source of 6.3 Tg N/yr.</p><p>Several areas of uncertainty in the IPCC estimate of leaching and runoff-related N₂<span>O emissions are identified in this review. First, in the current methodology, a default-leaching fraction for fertilizer and animal waste of 30% is recommended for all countries, despite large variations within individual watersheds and agricultural systems. Second, the N</span>₂O emission factor associated with groundwater may be overestimated by an order of magnitude. Currently, groundwater accounts for 60% of leaching-related N₂O emissions, with the remainder assumed to occur from rivers and estuaries. Finally, leaching fractions and associated N₂O emission factors may not be defined in a conceptually consistent manner.</p></div>","PeriodicalId":100235,"journal":{"name":"Chemosphere - Global Change Science","volume":"2 3","pages":"Pages 493-500"},"PeriodicalIF":0.0,"publicationDate":"2000-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1465-9972(00)00013-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84489546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanisms of nitrous oxide production in the subtropical North Pacific based on determinations of the isotopic abundances of nitrous oxide and di-oxygen","authors":"Nathaniel E. Ostrom ,&nbsp;Mary E. Russ ,&nbsp;Brian Popp ,&nbsp;Terri M. Rust ,&nbsp;David M. Karl","doi":"10.1016/S1465-9972(00)00031-3","DOIUrl":"10.1016/S1465-9972(00)00031-3","url":null,"abstract":"<div><p>In this study, we compare stable isotopic compositions of di-oxygen (O₂) and nitrous oxide (N₂O) in two depth profiles at the well-characterized deep water station ALOHA (A Long-term Oligotrophic Habitat Assessment) in the subtropical North Pacific gyre to attain an understanding of the mechanisms of N₂O production. The δ¹⁸O of O₂ varied from values indicative of an atmospheric origin near the surface (<span><math><mtext>24.7‰</mtext></math></span>), to minimum values reflective of a predominance of photosynthesis over respiration between the surface and 200 m (as low as 22.2<span><math><mtext>‰</mtext></math></span>), to maximum values as high as <span><math><mtext>36.6‰</mtext></math></span> in association with the O₂ minimum near 800 m. A similar pattern of isotopic variation was evident in the δ¹⁸O of N₂O, however, values were enriched by approximately <span><math><mtext>20‰</mtext></math></span>. The similar pattern of variation in δ¹⁸O with depth is consistent with an origin of O in N₂O from dissolved O₂ via the nitrification of intermediate compounds NH₂OH or NO. Between the depths of 350 and 500 m, however, the distinction in the isotopic composition of N₂O and O₂ was reduced to as little as <span><math><mtext>12‰</mtext></math></span>. This decrease in the difference between the δ¹⁸O of N₂O and that of O₂ with depth indicates either a reduction in the magnitude of isotopic discrimination during nitrification or a contribution of O in N₂O from water via the reduction of NO₂⁻. Two mechanisms of N₂O production via nitrification may, therefore, occur in the subtropical Pacific; release from the nitrification of NH₂OH or NO at most depths and reduction of NO₂⁻ between 350 and 500 m. In that, the carbon flux decreases markedly over a similar depth interval at this locale (Karl, D.M., Knauer, G.A., Martin, J.H., 1988. Downward flux of particulate organic matter in the ocean: A particle decomposition paradox. Nature 332, 438–441), this distinct mechanism of N₂O production between 350 and 500 m may be associated with the mineralization of organic matter from sinking particles. Low O₂ or anoxic micro-environments within particles within this depth interval may be maintained by lower ambient O₂ than at the surface and high rates of microbial activity supported by the mineralization of organic matter. Such conditions may facilitate an environment conducive to N₂O production via NO₂⁻ reduction.</p></div>","PeriodicalId":100235,"journal":{"name":"Chemosphere - Global Change Science","volume":"2 3","pages":"Pages 281-290"},"PeriodicalIF":0.0,"publicationDate":"2000-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1465-9972(00)00031-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75487842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Contribution of vehicle exhaust to the global N2O budget","authors":"K.H Becker ,&nbsp;J.C Lörzer ,&nbsp;R Kurtenbach ,&nbsp;P Wiesen ,&nbsp;T.E Jensen ,&nbsp;T.J Wallington","doi":"10.1016/S1465-9972(00)00017-9","DOIUrl":"10.1016/S1465-9972(00)00017-9","url":null,"abstract":"<div><p>Assessment of the impact of vehicle emissions on the global environment requires accurate data concerning nitrous oxide (N₂O) emissions. We report herein `real world' N<sub>2</sub>O emissions from road vehicles in a tunnel in Wuppertal, Germany, together with `laboratory' emission measurements conducted at the Ford Motor Company using a chassis dynamometer with a standard driving cycle for 26 different cars and trucks. Consistent results were obtained from both approaches suggesting that a good approximation of the average emission factor (g N₂O/g CO₂)=(4<!--> <!-->±<!--> <!-->2)<!--> <!-->×<!--> <!-->10⁻⁵. This corresponds to an emission rate of 11-5 mg N₂O/km for vehicles with fuel economies of 12-6 l/100 km (20–40 miles/US gallon). N₂O emissions from vehicles have a global warming impact, which is 1–2% of that of the CO₂ emissions from vehicles. We estimate an annual emission of (0.12±0.06) Tg yr⁻¹ of N₂O (0.08±0.04 Tg N yr⁻¹) from the global vehicle fleet which represents 1–4% of the atmospheric growth rate of this species. These results update and supercede our previous study of N₂O emissions from vehicles (Becker, K.H., Lörzer, J.C., Kurtenbach, R., Wiesen, P., Jensen, T., Wallington, T.J., 1999. Nitrous oxide (N₂O) emissions from vehicles. Environ. Sci. Technol., 33, 4134–4139).</p></div>","PeriodicalId":100235,"journal":{"name":"Chemosphere - Global Change Science","volume":"2 3","pages":"Pages 387-395"},"PeriodicalIF":0.0,"publicationDate":"2000-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1465-9972(00)00017-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73814475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influences of application of sewage sludge compost on N2O production in soils","authors":"Kazuyuki Inubushi ,&nbsp;Sneh Goyal ,&nbsp;Kazunori Sakamoto ,&nbsp;Yukie Wada ,&nbsp;Keisuke Yamakawa ,&nbsp;Tatsuya Arai","doi":"10.1016/S1465-9972(00)00026-X","DOIUrl":"10.1016/S1465-9972(00)00026-X","url":null,"abstract":"<div><p>Laboratory incubation was conducted to determine the controlling factors affecting the production of N₂O in soil taken from short- and long-term experimental sites continuously amended with SS in three types of soil samples. Soil types and sludge application rates significantly affected the production of N₂O from soil amended with sludge compost. The yellow soil, with low organic matter content, resulted in higher production of N₂O with sewage sludge application probably due to ammonium oxidation in the soil. While andosol soil, with high organic matter content and heavy metal (Zn), resulted in lower N₂O production when amended with SS. Uncultivated brown forest soil amended with sewage sludge plus sawdust compost (SSS) at the rate of 20 ton ha⁻¹ showed a peak of N₂O production, while no N₂O was observed in the same soil at 10 ton ha⁻¹ application rate. These results help us to explain that N₂O production from soil amended with SS is greatly affected by soil types, types and application rate of the composts. It should be considered carefully to reduce N₂O emission from the recycling of nutrient between soil/agriculture and urban/water treatments in future.</p></div>","PeriodicalId":100235,"journal":{"name":"Chemosphere - Global Change Science","volume":"2 3","pages":"Pages 329-334"},"PeriodicalIF":0.0,"publicationDate":"2000-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1465-9972(00)00026-X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84593633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The control of nitrous oxide emissions from agricultural and natural soils","authors":"U Skiba ,&nbsp;K.A Smith","doi":"10.1016/S1465-9972(00)00016-7","DOIUrl":"10.1016/S1465-9972(00)00016-7","url":null,"abstract":"<div><p>This paper provides a summary of our current understanding of the key drivers of N₂O emissions from soil in temperate and tropical, natural and agricultural ecosystems. These drivers are substrate supply, as N additions and mineralisation of organic N in soil, soil water content and temperature. They can exert synergistic or antagonistic influences on the emissions which can vary spatially and temporally. Such influences explain why emission rates often differ greatly from those based on current IPCC methodology. The latter only takes account of N inputs: direct emissions from agricultural soils are taken to be 1.25% of the N applied, while those from natural soils are taken to be 1% of the N deposited from the atmosphere, however, observed values range from 0.2% to 15%. Inadequate accounting for all sources affecting levels of soil mineral N (e.g. freeze–thaw cycles, ploughing, biomass burning, the first rainfall in wet seasons) and inter-annual differences in the size and timing of rainfall events in relation to land management practices are prime causes of the deviations.</p></div>","PeriodicalId":100235,"journal":{"name":"Chemosphere - Global Change Science","volume":"2 3","pages":"Pages 379-386"},"PeriodicalIF":0.0,"publicationDate":"2000-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1465-9972(00)00016-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85460683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The formation of the trace gases NO and N2O in soils by the coupled processes of nitrification and denitrification: results of kinetic 15N tracer investigations","authors":"R Russow,&nbsp;I Sich,&nbsp;H.-U Neue","doi":"10.1016/S1465-9972(00)00012-X","DOIUrl":"10.1016/S1465-9972(00)00012-X","url":null,"abstract":"<div><p>Biogenic production in soils, especially when fertilized with high levels of nitrogen, is one of the main sources of nitrous oxide (N₂O) and may be a significant source of nitric oxide (NO). NO and N₂O are formed by the microbial processes of nitrification and denitrification but in soils these processes are not fully understood in detail. The kinetic ¹⁵N isotope method, is very useful for investigating the mechanism of such complex N transformation processes in soils. We used this method with <span><math><msup><mi></mi><mn>15</mn></msup><mtext>NH</mtext><msub><mi></mi><mn>4</mn></msub><msup><mi></mi><mn>+</mn></msup></math></span>, <span><math><msup><mi></mi><mn>15</mn></msup><mtext>NO</mtext><msub><mi></mi><mn>2</mn></msub><msup><mi></mi><mn>−</mn></msup></math></span>, and <span><math><msup><mi></mi><mn>15</mn></msup><mtext>NO</mtext><msub><mi></mi><mn>3</mn></msub><msup><mi></mi><mn>−</mn></msup></math></span> as tracers to study the processes of NO and N₂O formation in black earth soil (Haplic Phaeozem). The experiments were conducted using a special analytical set-up in which the incubation vessels were directly connected to a gas chromatograph quadrupole mass spectrometer system. This system allows simultaneous determination of the concentration of N₂O, NO and N₂ along with their ¹⁵N abundance in the gas phase. The results of these investigations are discussed and combined in a diagram, termed the model of coupled nitrification and denitrification, illustrating the formation of NO and N₂O. Nitrification and denitrification proceed under both water-unsaturated (nearly aerobic) and water-saturated (nearly anaerobic) conditions. The two processes are linked by a “common” nitrate pool. In contrast the nitrite, an important intermediate of the two processes, evidently exists within two separate pools. NO is mainly produced by nitrification as a by-product of the oxidation of ammonium to nitrite or directly by nitrite decomposition. If NH₄⁺ contents are high under aerobic conditions NO emission can markedly exceed that of N₂O. Nitrous oxide is mainly formed by denitrification of nitrate. Therefore increasing water saturation promotes N₂O emission. NO could not be confirmed as a free precursor of N₂O formation via denitrification.</p></div>","PeriodicalId":100235,"journal":{"name":"Chemosphere - Global Change Science","volume":"2 3","pages":"Pages 359-366"},"PeriodicalIF":0.0,"publicationDate":"2000-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1465-9972(00)00012-X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78653505","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Special issue: Atmospheric Nitrous Oxide","authors":"M.A.K Khalil","doi":"10.1016/S1465-9972(00)00046-5","DOIUrl":"10.1016/S1465-9972(00)00046-5","url":null,"abstract":"","PeriodicalId":100235,"journal":{"name":"Chemosphere - Global Change Science","volume":"2 3","pages":"Page 233"},"PeriodicalIF":0.0,"publicationDate":"2000-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1465-9972(00)00046-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83584078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photo-induced isotopic fractionation of stratospheric N2O","authors":"Charles E Miller ,&nbsp;Yuk L Yung","doi":"10.1016/S1465-9972(00)00011-8","DOIUrl":"10.1016/S1465-9972(00)00011-8","url":null,"abstract":"<div><p><em>Context Abstract</em>: N₂O has been identified in the Kyoto Protocol as one of the six greenhouse gases for which anthropogenic emissions should be regulated, however, regulation procedures may not be implemented until a well-defined N₂O budget has been established. The measurement of N₂O isotopic fractionation provides a potential means for constraining the global budget since biological and anthropogenic sources have distinctly different isotopic signatures.</p><p><em>Main Abstract</em>: This paper shows that N₂O isotopic fractionation in the stratosphere may be understood within the limits of the standard photochemical models if mass-dependent photodissociation rates for the various N₂O isotopomers are incorporated. Thus, we conclude that there is no demonstrable reason to invoke a significant chemical source of N₂O in the middle atmosphere. This paper presents a general theory for isotopomer dependent photodissociation rates that accounts for the isotopic fractionation observed in stratospheric N₂O and how photodissociations appear to be both a source and a sink of N₂O in the middle atmosphere. Photo-induced isotopic fractionation effects (PHIFE), explain the distinct fractionation signatures found for ¹⁵N/¹⁴N and ¹⁸O/¹⁶O ratios in both laboratory and remote sensing measurements. Furthermore, PHIFE predicts substantially different isotopic fractionations in the stratosphere for the isotopomers ¹⁵N¹⁴N¹⁶O and ¹⁴N¹⁵N¹⁶O, which have identical molecular weights but different isotopic substitution sites. Modeling results based on this theory suggest that there is no demonstrable reason to invoke a significant chemical source of N₂O in the middle atmosphere and that N₂O multi-isotope correlations should prove a useful measure of stratospheric air parcel history.</p></div>","PeriodicalId":100235,"journal":{"name":"Chemosphere - Global Change Science","volume":"2 3","pages":"Pages 255-266"},"PeriodicalIF":0.0,"publicationDate":"2000-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1465-9972(00)00011-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74919226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Testing hypotheses on global emissions of nitrous oxide using atmospheric models","authors":"A.F Bouwman ,&nbsp;J.A Taylor ,&nbsp;C Kroeze","doi":"10.1016/S1465-9972(00)00027-1","DOIUrl":"10.1016/S1465-9972(00)00027-1","url":null,"abstract":"<div><p><span>The nitrous oxide (N</span>₂<span>O) budget has been the least well constrained of the global trace gas budgets. For biogenic sources the uncertainty is caused by their extreme spatial and temporal heterogeneity. For the anthropogenic sources political, economic and cultural factors are major uncertainties associated with scaling-up. Zero-, one- and two-dimensional models are useful tools to explain historic time series of observations. Although no unique solutions are found for emissions, analysis of historic emission sources can provide an understanding of the total source strength and its increase in time, and the relative importance of sources. The impossibility to find unique solutions also occurs in forward and inverse simulations with three-dimensional models. Common problems of three-dimensional atmospheric models is that time-averaged emissions and wind fields are used for large grids, or the meteorology is taken from a specific year. This may cause discrepancies between model results and observations, which are often not representative of the temporal and spatial scale of the atmospheric model. Although the uncertainty of atmospheric concentrations is much smaller than that of emission estimates, there are other problems in forward and inverse three-dimensional modelling related to the atmospheric measurements. The observational network is scant, and at some stations the sampling frequency is low, often with temporal gaps in the observations. Finally, individual observations are of limited accuracy and precision, and observations from different networks are often not easily compared because of differences in measurement techniques and standards used. Expansion of the monitoring network with continental stations and isotopic characterization of emissions may help to better constrain the N</span>₂O budget using atmospheric models.</p></div>","PeriodicalId":100235,"journal":{"name":"Chemosphere - Global Change Science","volume":"2 3","pages":"Pages 475-492"},"PeriodicalIF":0.0,"publicationDate":"2000-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1465-9972(00)00027-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78727617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An approach to characterization of sources of urban airborne particles through heavy metal speciation","authors":"Antonio J. Fernández,&nbsp;Miguel Ternero,&nbsp;Francisco J. Barragán,&nbsp;Juan C. Jiménez","doi":"10.1016/S1465-9972(00)00002-7","DOIUrl":"10.1016/S1465-9972(00)00002-7","url":null,"abstract":"<div><p>Airborne particles, collected in an urban atmosphere, influenced by surrounding farm areas (Seville), were analyzed by speciation for ten heavy metals. The use of a sequential extraction procedure allowed the subdivision of the total content of each metal into four different fractions. Statistical multivariate analysis was performed on the fractions and the main sources of metal contamination were characterized. The results show that soil aerosols make the largest contribution to pollution with Fe and Al as the most abundant metals acting as markers for this source. In addition, the close correlation between Pb and Cu suggests that these are mainly pollutants generated by traffic. The other metals permitted identification of an industrial source but always in association with a soil source. From the percentage distribution of species, we found that Fe and Al are found in the carbonate or oxide fraction (40%) and in the residual metal fraction (40%). While Pb and Cu mainly appear as oxides and carbonates (50% and 40%, respectively), Cd prevails in soluble or exchangeable form (55%).</p></div>","PeriodicalId":100235,"journal":{"name":"Chemosphere - Global Change Science","volume":"2 2","pages":"Pages 123-136"},"PeriodicalIF":0.0,"publicationDate":"2000-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1465-9972(00)00002-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73465470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}