Modeling impacts of farming management alternatives on CO2, CH4, and N2O emissions: A case study for water management of rice agriculture of China

Since the early 1980s, water management of rice paddies in China has changed substantially, with midseason drainage gradually replacing continuous flooding. This has provided an opportunity to estimate how a management alternative impacts greenhouse gas emissions at a large regional scale. We integrated a process-based model, DNDC, with a GIS database of paddy area, soil properties, and management factors. We simulated soil carbon sequestration (or net CO2 emission) and CH4 and N2O emissions from China\u27s rice paddies (30 million ha), based on 1990 climate and management conditions, with two water management scenarios: continuous flooding and midseason drainage. The results indicated that this change in water management has reduced aggregate CH4 emissions about 40%, or 5 Tg CH4 yr−1, roughly 5–10% of total global methane emissions from rice paddies. The mitigating effect of midseason drainage on CH4 flux was highly uneven across the country; the highest flux reductions (\u3e200 kg CH4-C ha−1 yr−1) were in Hainan, Sichuan, Hubei, and Guangdong provinces, with warmer weather and multiple-cropping rice systems. The smallest flux reductions (\u3c25 kg CH4-C ha−1 yr−1) occurred in Tianjin, Hebei, Ningxia, Liaoning, and Gansu Provinces, with relatively cool weather and single cropping systems. Shifting water management from continuous flooding to midseason drainage increased N2O emissions from Chinese rice paddies by 0.15 Tg N yr−1 (∼50% increase). This offset a large fraction of the greenhouse gas radiative forcing benefit gained by the decrease in CH4 emissions. Midseason drainage-induced N2O fluxes were high (\u3e8.0 kg N/ha) in Jilin, Liaoning, Heilongjiang, and Xinjiang provinces, where the paddy soils contained relatively high organic matter. Shifting water management from continuous flooding to midseason drainage reduced total net CO2emissions by 0.65 Tg CO2-C yr−1, which made a relatively small contribution to the net climate impact due to the low radiative potential of CO2. The change in water management had very different effects on net greenhouse gas mitigation when implemented across climatic zones, soil types, or cropping systems. Maximum CH4 reductions and minimum N2O increases were obtained when the mid-season draining was applied to rice paddies with warm weather, high soil clay content, and low soil organic matter content, for example, Sichuan, Hubei, Hunan, Guangdong, Guangxi, Anhui, and Jiangsu provinces, which have 60% of China\u27s rice paddies and produce 65% of China\u27s rice harvest

Reduced methane emissions from large-scale changes in water management of China’s rice paddies during 1980-2000

Decreased methane emissions from paddy rice may have contributed to the decline in the rate of increase of global atmospheric methane (CH4) concentration over the last 20 years. In China, midseason paddy drainage, which reduces growing season CH4 fluxes, was first implemented in the early 1980s, and has gradually replaced continuous flooding in much of the paddy area. We constructed a regional prediction for China\u27s rice paddy methane emissions using the DNDC biogeochemical model. Results of continuous flooding and midseason drainage simulations for all paddy fields in China were combined with regional scenarios for the timing of the transition from continuous flooding to predominantly mid-season drainage to generate estimates of total methane flux for 1980–2000. CH4 emissions from China\u27s paddy fields were reduced over that period by ∼5 Tg CH4 yr−1

Greenhouse gas emissions from croplands of China

China possesses cropland of 1.33 million km 2. Cultivation of the cropland not only altered the biogeochemical cycles of carbon (C) and nitrogen (N) in the agroecosystems but also affected global climate. The impacts of agroecosystems on global climate attribute to emissions of three greenhouse gases, namely carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O)

Early development of vocal interaction rules in a duetting songbird

This work was supported by the Maytag Endowment from the University of Miami, a Research Grant from the Animal Behavior Society, a Research Grant from the Organization for Tropical Studies and a Doctoral Dissertation Improvement Grant by the National Science Foundation awarded to K.D.R.-C., and funds from Pacific University and the M.J. Murdock Charitable Trust to C.N.T.Exchange of vocal signals is an important aspect of animal communication. Although birdsong is the premier model for understanding vocal development, the development of vocal interaction rules in birds and possible parallels to humans have been little studied. Many tropical songbirds engage in complex vocal interactions in the form of duets between mated pairs. In some species, duets show precise temporal coordination and follow rules (duet codes) governing which song type one bird uses to reply to each of the song types of its mate. We determined whether these duetting rules are acquired during early development in canebrake wrens. Results show that juveniles acquire a duet code by singing with a mated pair of adults and that juveniles gradually increase their fidelity to the code over time. Additionally, we found that juveniles exhibit poorer temporal coordination than adults and improve their coordination as time progresses. Human turn-taking, an analogous rule to temporal coordination, is learned during early development. We report that the ontogeny of vocal interaction rules in songbirds is analogous to that of human conversation rules.Publisher PDFPeer reviewe

Group Vibrational Mode Assignments as a Broadly Applicable Tool for Characterizing Ionomer Membrane Structure as a Function of Degree of Hydration

Infrared spectra of Nafion, Aquivion, and the 3M membrane were acquired during total dehydration of fully hydrated samples. Fully hydrated exchange sites are in a sulfonate form with a C₃V local symmetry. The mechanical coupling of the exchange site to a side chain ether link gives rise to vibrational group modes that are classified as C₃V modes. These mode intensities diminish concertedly with dehydration. When totally dehydrated, the sulfonic acid form of the exchange site is mechanically coupled to an ether link with no local symmetry. This gives rise to C₁ group modes that emerge at the expense of C₃V modes during dehydration. Membrane IR spectra feature a total absence of C₃V modes when totally dehydrated, overlapping C₁ and C₃V modes when partially hydrated, and a total absence of C₁ modes when fully hydrated. DFT calculated normal mode analyses complemented with molecular dynamics simulations of Nafion with overall λ (λ_(Avg)) values of 1, 3, 10, 15 and 20 waters/exchange site, were sectioned into sub-cubes to enable the manual counting of the distribution of λ_(local) values that integrate to λ_(Avg) values. This work suggests that at any state of hydration, IR spectra are a consequence of a distribution of λ_(local) values. Bond distances and the threshold value of λ_(local), for exchange site dissociation, were determined by DFT modelling and used to correlate spectra to manually counted λ_(local) distributions

Laser diode ignition activities at Sandia National Laboratories

The topics are presented in viewgraph form and include the following: ignition subsystems, enhanced safety, optical ordnance power densities, optical ignition factors, low energy optical ordnance program, absorptance of 2-(5-cyanotetrazolato) pentaaminecobalt(III) perchlorate (CP) near 800 nm, power dependence of doped CP, system operational electrical requirements, dopant concentration effects for different CP particle sizes, ZR/KCLO4 optical ignition thresholds, and electrostatic discharge testing

Greenhouse gas emission consequences of large-scale changes in water management of China’s rice paddies during 1980-2000

In China, midseason paddy drainage, which reduces growing season methane fluxes and enhances growing season nitrous oxide fluxes, was first implemented in the early 1980s, and has gradually replaced continuous flooding in much of the paddy rice area. We constructed a prediction rice paddy methane and nitrous oxide emissions in China using the DNDC biogeochemical model. Results of continuous flooding and midseason drainage simulations for all paddy fields in China (about 30 million ha) were combined with regional scenarios for the timing of the transition from continuous flooding to predominantly mid-season drainage to generate estimates of total methane (CH4) and nitrous oxide (N2O) flux for 1980-2000. By shifting from continuous flooding to midseason drainage management, we estimate that total N2O emissions from the rice paddies in China increased by about 0.17 Tg N2O-N yr−1 due to the stimulated nitri- fication and denitrification, while CH4 emissions decreased by about 4.5 Tg CH4-C yr−1 due to increased soil aeration. Simulated net carbon loss in paddy soils was about 0.65 Tg C yr−1 due to elevated decomposition. On a 100-year time frame, CH4 has a global warming potential (GWP) 23 times that of CO2, and N2O has a GWP 296 times that of CO2. The total GWP impact (2000 vs. 1980) of shifting to predominantly mid-season paddy drainage was -0.138 Pg CO2-equiv yr−1 from methane, +0.077 Pg CO2-equiv yr−1 from nitrous oxide and +0.0024 Pg CO2 yr−1 from soil C loss, for a total GWP impact of -0.059 Pg CO2-equiv yr−1 . The results imply that more than half of the GWP benefit of decreased CH4 emissions was offset, primarily by increases in N2O emissions, and to a small degree by soil C loss

Returning to the Past to Rethink Socio-Political Antagonisms: Mapping Today’s Situation in Regards to Popular Insurrections

This article seeks to elaborate a map or cartogram based on a number of protests and social mobilizations that took place in different parts of the world -mainly in Latin America, but also in Europe and Asia. Beyond the data and figures available from various sources, which never speak for themselves, an interpretation is proposed here to reveal the meaning of these events. In other words, by displaying a map of these social movements, the authors propose not only the visualization of a collection of data, but also an illumination of these events in the light of history. From there, the authors offer hypothetical predictions. These predictions allow the authors to consider the lessons that, sometimes, seem to be forgotten or are not learned yet

Phylogenetic Analysis of West Nile Virus, Nuevo Leon State, Mexico

West Nile virus RNA was detected in brain tissue from a horse that died in June 2003 in Nuevo Leon State, Mexico. Nucleotide sequencing and phylogenetic analysis of the premembrane and envelope genes showed that the virus was most closely related to West Nile virus isolates collected in Texas in 2002