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Zn(N2)4(CO2)2 is Cyanogen Chloride-derived structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four carbon dioxide molecules, eight nitrogen molecules, and two zinc molecules.
Ozone was photolyzed at 2537 A and 25 C in the presence of 42-115 torr of O2 and about 880 torr of N2 to test the relative importance of the two reactions: (1) O(1D) + N2 + M yields N2O + M, and (2) O(1D) + N2 yields O(3P) + N2. N2O was not found as a product. Thus from our detectability limit for N2O (0.3 micron), an upper limit to the efficiency of the first reaction relative to the second of 0.0000025 at 1000 torr total pressure was computed. This corresponds to k1/k2 smaller than 0.8 x 10 to the minus 25 power cu cm/particle.
Rates of nitrous oxide (N 2 O) production from agricultural soils are highly variable across space and time. Improving predictions of N 2 O emissions will require improving our understanding of the drivers of denitrification and the sources of variability in the rates of N 2 O production between soils and over time. While the amount of available carbon (C) is a known control on denitrification and N 2 O reduction, relatively little attention has been paid to the effect of the chemical identity of C substrates on rates of denitrification and N 2 O reduction. We investigated the effects of twelve different C-substrate additions on the production and reduction of N 2 O in five soils taken from two distinct agricultural locations in Michigan under multiple land uses. We provided additions of glucose, cellulose, N-acetyl-glucosamine, chitin, amino acids, protein, vanillyl alcohol, lignin, citrate, succinate, methanol, and water in laboratory denitrification potential assays to determine the effects of denitrifier C preference on denitrification rates. We found that amino acids, protein, and organic acids stimulated the greatest rates of denitrification potential across all land uses. Similarly, we found these same substrates caused the most N 2 O reduction, resulting in the lowest net concentrations of N 2 O. Soils from agricultural rotations without cover crops had overall lower rates of denitrifier activity, leading to less net N 2 O production compared to soils from other land uses. In general, C-utilization patterns were similar among all soils, and C-substrate identity had a much stronger effect than land use. Here, we demonstrate that the chemical identity of available C gives rise to wide variability in rates of denitrification and N 2 O reduction.
GdAu3C6(N2O)3 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. Gd3+ is bonded in a 9-coordinate geometry to six equivalent N3- and three equivalent O2- atoms. All Gd–N bond lengths are 2.48 Å. All Gd–O bond lengths are 2.42 Å. Au1- is bonded in a linear geometry to two equivalent C4+ atoms. Both Au–C bond lengths are 2.00 Å. C4+ is bonded in a distorted single-bond geometry to one Au1- and one N3- atom. The C–N bond length is 1.17 Å. N3- is bonded in a 2-coordinate geometry to one Gd3+ and one C4+ atom. O2- is bonded in a distorted single-bond geometry to one Gd3+ atom.
SnC6H22(N2O)4(CO(NH2)2)6(C2NH6S2O4)2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two dimethanesulfonamide molecules, six urea molecules, and one SnC6H22(N2O)4 cluster. In the SnC6H22(N2O)4 cluster, Sn is bonded in an octahedral geometry to two equivalent C and four O atoms. Both Sn–C bond lengths are 2.13 Å. There are two shorter (2.27 Å) and two longer (2.30 Å) Sn–O bond lengths. There are three inequivalent C sites. In the first C site, C is bonded in a trigonal planar geometry to two N and one O atom. Both C–N bond lengths are 1.35 Å. The C–O bond length is 1.29 Å. In the second C site, C is bonded in a distorted trigonal non-coplanar geometry to one Sn and three H atoms. There is one shorter (1.09 Å) and two longer (1.10 Å) C–H bond length. In the third C site, C is bonded in a trigonal planar geometry to two N and one O atom. There is one shorter (1.34 Å) and one longer (1.35 Å) C–N bond length. The C–O bond length is 1.29 Å. There are four inequivalent N sites. In the first N site, N is bonded in a trigonal planar geometry to one C and two H atoms. There is one shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. In the second N site, N is bonded in a trigonal planar geometry to one C and two H atoms. There is one shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. In the third N site, N is bonded in a trigonal planar geometry to one C and two H atoms. There is one shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. In the fourth N site, N is bonded in a trigonal planar geometry to one C and two H atoms. Both N–H bond lengths are 1.02 Å. There are ten inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to one C atom. In the second H site, H is bonded in a single-bond geometry to one N atom. In the third H site, H is bonded in a single-bond geometry to one N atom. In the fourth H site, H is bonded in a single-bond geometry to one N atom. In the fifth H site, H is bonded in a single-bond geometry to one N atom. In the sixth H site, H is bonded in a single-bond geometry to one N atom. In the seventh H site, H is bonded in a single-bond geometry to one N atom. In the eighth H site, H is bonded in a single-bond geometry to one N atom. In the ninth H site, H is bonded in a single-bond geometry to one N atom. In the tenth H site, H is bonded in a single-bond geometry to one C atom. There are two inequivalent O sites. In the first O site, O is bonded in a distorted single-bond geometry to one Sn and one C atom. In the second O site, O is bonded in a distorted bent 120 degrees geometry to one Sn and one C atom.
Stratospheric volume mixing ratio profiles of carbon tetrafluoride, CF4, obtained with the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument during the ATLAS (Atmospheric Laboratory for Applications and Science) -3 mission of 1994 are reported. Overall the profiles are nearly constant over the altitude range 20 to 50 km, indicative of the very long lifetime of CF4 in the atmosphere. In comparison to the stratospheric values of CF4 inferred from the ATMOS/Spacelab 3 mission of 1985, the 1994 concentrations are consistent with an exponential increase of (1.6 +/- 0.6)% yr(exp -1). This increase is discussed with regard to previous results and likely sources of CF4 at the ground. Further, it is shown that simultaneous measurements of N2O and CF4 provide a means of constraining the lower limit of the atmospheric lifetime of CF4 at least 2,300 years, two sigma.
Heterodyne frequency measurements on the 01(1)1-00(0)0 band of N2O have been made with the use of a tunable-diode laser, CO laser transfer oscillator, and a CO2 laser frequency synthesizer. A beat frequency was measured between a CO laser and tunable-diode laser whose frequency was locked to the peak of N2O absorption features. The frequency of the CO laser was simultaneously determined by neasuring the beat frequency with respect to a reference synthesized from two CO2 lasers. New rovibrational constants are given for the 01(1)1 state of N2O, which are in excellent agreement with previous results, although the band center is 4 MHz higher than in the previous measurements. A table for the line frequencies and their absolute uncertainties is given for the N2O absorption lines in the wave-number region from 1830 to 1920 kaysers. Some additional frequency measurements near the lower-frequency end of the 02(0)0-00(0)0 band have also been made with respect to a C-12)(0-18)2 laser.
Interannual variability in flux rates of biogenic trace gases must be quantified in order to understand the differences between short-term trends and actual long-term change in biosphere-atmosphere interactions. We simulated interannual patterns (1983-1988) of global trace gas fluxes from soils using the NASA Ames model version of CASA (Carnegie-Ames-Stanford Approach) in a transient simulation mode. This ecosystem model has been recalibrated for simulations driven by satellite vegetation index data from the NOAA Advanced Very High Resolution Radiometer (AVHRR) over the mid-1980s. The predicted interannual pattern of soil heterotropic CO2 emissions indicates that relatively large increases in global carbon flux from soils occurred about three years following the strong El Nino Southern Oscillation (ENSO) event of 1983. Results for the years 1986 and 1987 showed an annual increment of +1 Pg (1015 g) C-CO2 emitted from soils, which tended to dampen the estimated global increase in net ecosystem production with about a two year lag period relative to plant carbon fixation. Zonal discrimination of model results implies that 80-90 percent of the yearly positive increments in soil CO2 emission during 1986-87 were attributable to soil organic matter decomposition in the low-latitudes (between 30 N and 30 S). Soils of the northern middle-latitude zone (between 30 N and 60 N) accounted for the residual of these annual increments. Total annual emissions of nitrogen trace gases (N2O and NO) from soils were estimated to vary from 2-4 percent over the time period modeled, a level of variability which is consistent with predicted interannual fluctuations in global soil CO2 fluxes. Interannual variability of precipitation in tropical and subtropical zones (30 N to 20 S appeared to drive the dynamic inverse relationship between higher annual emissions of NO versus emissions of N2O. Global mean emission rates from natural (heterotrophic) soil sources over the period modeled (1983-1988) were estimated at 57.1 Pg C-CO2yr-1, 9.8Tg (1012 g) N-NO yr-1, and 9.7 Tg N-N2O yr-1. Chemical fertilizer contributions to global soil N gas fluxes were estimated at between 1.3 to 7.3 Tg N-NO yr-1, and 1.2 to 4.0 Tg N-N2O yr-1.
Expanding biofuel production is expected to accelerate the conversion of unmanaged marginal lands to meet biomass feedstock needs. Greenhouse gas production during conversion jeopardizes ensuing climate benefits, but most research to date has focused only on conversion to annual crops and only following tillage. Here we report the global warming impact of converting USDA Conservation Reserve Program (CRP) grasslands to three types of bioenergy crops using no-till (NT) versus conventional tillage (CT). In three CRP fields planted to continuous corn, switchgrass, or restored prairie we established replicated NT and CT plots. For the two years following an initial soybean year in all fields, we found that, on average, NT conversion reduced nitrous oxide (N2O) emissions by 50% and carbon dioxide (CO2) emissions by 20% compared to CT conversion. Differences were higher in year 1 than in year 2 in the continuous corn field, and in the two perennial systems the differences disappeared after year 1. In all fields net CO2 emissions (as measured by eddy covariance) were positive for the first two years following CT establishment, but following NT establishment net CO2 emissions were close to zero or negative, indicating net C sequestration. Overall, NT improved the global warming impact of biofuel crop establishment following CRP conversion by over 20-fold compared to CT (-6.01 Mg CO2e ha-1 yr-1 for NT vs. -0.25 Mg CO2e ha-1 yr-1 for CT, on average). We also found that IPCC estimates of N2O emissions (as measured by static chambers) greatly underestimated actual emissions for converted fields regardless of tillage. Policies should encourage adoption of NT for converting marginal grasslands to perennial bioenergy crops in order to reduce carbon debt and maximize climate benefits.
The terrestrial and marine nitrogen cycles are examined in an attempt to clarify how the atmospheric content of N2O is controlled. We review available data on the various reservoirs of fixed nitrogen, the transfer rates between the reservoirs, and estimate how the reservoir contents and transfer rates can change under man's influence. It is seen that sources, sinks and lifetime of atmospheric N2O are not understood well. Based on our limited knowledge of the stability of atmospheric N2O we conclude that future growth in the usage of industrial fixed nitrogen fertilizers could cause a 1% to 2% global ozone reduction in the next 50 years. However, centuries from now the ozone layer could be reduced by as much as 10% if soils are the major source of atmospheric N2O.
MgC4H4(N2O)2(B)2(CN)4 crystallizes in the tetragonal I-42d space group. The structure is zero-dimensional and consists of eight boron molecules, sixteen hydrogen cyanide molecules, and four MgC4H4(N2O)2 clusters. In each MgC4H4(N2O)2 cluster, Mg2+ is bonded in an octahedral geometry to four equivalent N3- and two equivalent O2- atoms. All Mg–N bond lengths are 2.18 Å. Both Mg–O bond lengths are 2.06 Å. C2+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.16 Å. N3- is bonded in a distorted linear geometry to one Mg2+ and one C2+ atom. H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. O2- is bonded in a distorted trigonal planar geometry to one Mg2+ and two equivalent H1+ atoms.
Zn(CN4)2(CO2)2 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional and consists of eight formic acid molecules and one Zn(CN4)2 framework. In the Zn(CN4)2 framework, Zn2+ is bonded in a tetrahedral geometry to four equivalent N+1.25- atoms. All Zn–N bond lengths are 2.03 Å. C4+ is bonded in a water-like geometry to two equivalent N+1.25- atoms. Both C–N bond lengths are 1.34 Å. There are two inequivalent N+1.25- sites. In the first N+1.25- site, N+1.25- is bonded in a 3-coordinate geometry to one Zn2+, one C4+, and one N+1.25- atom. The N–N bond length is 1.36 Å. In the second N+1.25- site, N+1.25- is bonded in a distorted water-like geometry to two N+1.25- atoms. The N–N bond length is 1.30 Å.
Laboratory measurements of the line strengths of H2O and N2O in the 1900-kayser spectral region are reported which were made with moderate resolution using a modification of a Michelson interferometer. The N2O analysis includes measurements of the line strengths of the P and R branches and the integrated strength of the Q branch of the nu-1 + nu-2(1) band as well as the integrated strengths of the Q branches of the nu-1 + nu-2(2) - nu-2 and nu-1 + nu-2(0) - nu-2(1) bands. The H2O data cover the region from 1830 to 1980 kaysers; they include line-strength measurements of 61 lines of the nu-2 band, 10 lines of the nu-2 band of H2(O-18), two lines of the nu-2 band of H2(O-17), and three lines of the 'hot' band transition 2 nu-2 - nu-2. The estimated uncertainties in the measured line strengths range from 7% to 20% for H2O, 10% to 25% for H2(O-18) and H2(O-17), and 4% to 8% for N2O.
Distinguishing planetary formation and evolution pathways and understanding the origins of volatiles on planetary bodies requires determination of relative abundances and isotope ratios in the noble gases, and also of the isotope ratios in C, H, N, O and S at high precisions. Traditional planetary mass spectrometers uniquely provide excellent survey capability including the noble gas relative abundances and their isotope ratios. However, to distinguish planetary evolution models for the outer planets, stable isotope ratios in C and O require precisions of ∼10 or better, readily achievable with a tunable laser spectrometer (TLS). As demonstrated on the Mars Curiosity rover, and as planned for a now-selected NASA Venus mission, tunable laser spectrometers play a unique role synergistic with the capabilities of planetary mass spectrometers. The TLS technique of recording infrared absorption spectra at ultrahigh resolution (resolving power λ/δλ ∼ 5 million) provides unambiguous detection of a wide variety of gases such as H2O, H2O2, H2CO, HOCl, NO, NO2, HNO3, N2O, O3, CO, CO2, NH3, N2H4, PH3, H2S, SO2, OCS, HCl, HF, O2, HCN, and CH4, C2H2, C2H4, C2H6 at parts-per-billion levels. Through line-depth or line-area ratio comparisons of adjacent spectral lines, planetary TLS instruments can achieve isotope ratio measurements in C, H, N, O, and S molecules at precisions of ∼1–2, including for the triple isotope components of O and S. Expected performance of TLS instruments for Venus, Saturn, Enceladus and Uranus will be described as constrained by actual measurements reported at Mars on the Curiosity rover.
Climate stabilization remains elusive, with increased greenhouse gas concentrations already increasing global average surface temperatures 1.1°C above pre-industrial levels (World Meteorological Organization 2019). Carbon dioxide (CO2) emissions from fossil fuel use, deforestation, and other anthropogenic sources reached ~ 43 billion metric tonnes in 2019 (Friedlingstein et al 2019, Jackson et al 2019). Storms, floods, and other extreme weather events displaced a record 7 million people in the first half of 2019 (IDMC 2019). When global mean surface temperature four million years ago was 2°C–3°C warmer than today (a likely temperature increase before the end of the century), ice sheets in Greenland and West Antarctica melted and parts of East Antarctica’s ice retreated, causing sea levels to rise 10–20 m (World Meteorological Organization 2019). Methane (CH4) emissions have contributed almost one quarter of the cumulative radiative forcings for CO2, CH4, and N2O (nitrous oxide) combined since 1750 (Etminan et al 2016). Although methane is far less abundant in the atmosphere than CO2, it absorbs thermal infrared radiation much more efficiently and, in consequence, has a global warming potential (GWP) ~86 times stronger per unit mass than CO2 on a 20-year timescale and 28- times more powerful on a 100-year time scale (IPCC 2014). Global average methane concentrations in the atmosphere reached ~1875 parts per billion (ppb) at the end of 2019, more than two-and-a-half times preindustrial levels (Dlugokencky 2020). The largest methane sources include anthropogenic emissions from agriculture, waste, and the extraction and use of fossil fuels as well as natural emissions from wetlands, freshwater systems, and geological sources (Kirschke et al 2013, Saunois et al 2016a, Ganesan et al 2019). Here, we summarize new estimates of the global methane budget based on the analysis of Saunois et al (2020) for the year 2017, the last year of the new Global Methane Budget and the most recent year data are fully available. We compare these estimates to mean values for the reference ‘stabilization’ period of 2000–2006 when atmospheric CH4 concentrations were relatively stable. We present data for sources and sinks and provide insights for the geographical regions and economic sectors where emissions have changed the most over recent decades.
MgC6H24(N2O)6(CO(NH2)2)4(Br)2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four hydrobromic acid molecules, eight urea molecules, and two MgC6H24(N2O)6 clusters. In each MgC6H24(N2O)6 cluster, Mg is bonded in an octahedral geometry to six O atoms. There are a spread of Mg–O bond distances ranging from 2.08–2.13 Å. There are three inequivalent C sites. In the first C site, C is bonded in a trigonal planar geometry to two N and one O atom. There is one shorter (1.36 Å) and one longer (1.37 Å) C–N bond length. The C–O bond length is 1.26 Å. In the second C site, C is bonded in a trigonal planar geometry to two N and one O atom. There is one shorter (1.35 Å) and one longer (1.36 Å) C–N bond length. The C–O bond length is 1.27 Å. In the third C site, C is bonded in a trigonal planar geometry to two N and one O atom. Both C–N bond lengths are 1.35 Å. The C–O bond length is 1.28 Å. There are six inequivalent N sites. In the first N site, N is bonded in a trigonal planar geometry to one C and two H atoms. Both N–H bond lengths are 1.02 Å. In the second N site, N is bonded in a distorted trigonal planar geometry to one C and two H atoms. There is one shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. In the third N site, N is bonded in a trigonal planar geometry to one C and two H atoms. Both N–H bond lengths are 1.02 Å. In the fourth N site, N is bonded in a trigonal planar geometry to one C and two H atoms. Both N–H bond lengths are 1.02 Å. In the fifth N site, N is bonded in a trigonal planar geometry to one C and two H atoms. There is one shorter (1.01 Å) and one longer (1.03 Å) N–H bond length. In the sixth N site, N is bonded in a trigonal planar geometry to one C and two H atoms. There is one shorter (1.01 Å) and one longer (1.02 Å) N–H bond length. There are twelve inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to one N atom. In the second H site, H is bonded in a single-bond geometry to one N atom. In the third H site, H is bonded in a single-bond geometry to one N atom. In the fourth H site, H is bonded in a single-bond geometry to one N atom. In the fifth H site, H is bonded in a single-bond geometry to one N atom. In the sixth H site, H is bonded in a single-bond geometry to one N atom. In the seventh H site, H is bonded in a single-bond geometry to one N atom. In the eighth H site, H is bonded in a single-bond geometry to one N atom. In the ninth H site, H is bonded in a single-bond geometry to one N atom. In the tenth H site, H is bonded in a single-bond geometry to one N atom. In the eleventh H site, H is bonded in a single-bond geometry to one N atom. In the twelfth H site, H is bonded in a single-bond geometry to one N atom. There are three inequivalent O sites. In the first O site, O is bonded in a distorted bent 120 degrees geometry to one Mg and one C atom. In the second O site, O is bonded in a distorted bent 120 degrees geometry to one Mg and one C atom. In the third O site, O is bonded in a bent 120 degrees geometry to one Mg and one C atom.
NiCoC4H4(N2O)2(H2O)4 crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four nickel molecules, sixteen water molecules, and four CoC4H4(N2O)2 clusters. In each CoC4H4(N2O)2 cluster, Co2+ is bonded in an octahedral geometry to four N3- and two equivalent O2- atoms. There are two shorter (2.09 Å) and two longer (2.11 Å) Co–N bond lengths. Both Co–O bond lengths are 2.15 Å. There are two inequivalent C2+ sites. In the first C2+ site, C2+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.17 Å. In the second C2+ site, C2+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.17 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a linear geometry to one Co2+ and one C2+ atom. In the second N3- site, N3- is bonded in a distorted linear geometry to one Co2+ and one C2+ atom. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. O2- is bonded in a distorted water-like geometry to one Co2+ and two H1+ atoms.
Concentrated samples of stratospheric air were obtained at pressure altitudes of 18.3 km and 21.3 km aboard U-2 aircraft, and at 28.3 km and 35.9 km aboard a balloon platform. The mixing ratios of CF2Cl2 and N2O are reported for locations in California, Oregon, Texas, and Quebec, Canada. The observed mixing ratios compare within a factor of 2 to those reported by other investigators and show a more rapid decrease with altitude than predicted by a two-dimensional model.