Application of the rapid leaf A-Ci response (RACiR) technique: examples from evergreen broadleaved species.

Using steady-state photosynthesis-intercellular CO2 concentration (A-Ci) response curves to obtain the maximum rates of ribulose-1,5-bisphosphate carboxylase oxygenase carboxylation (Vcmax) and electron transport (Jmax) is time-consuming and labour-intensive. Instead, the rapid A-Ci response (RACiR) technique provides a potential, high-efficiency method. However, efficient parameter settings of RACiR technique for evergreen broadleaved species remain unclear. Here, we used Li-COR LI-6800 to obtain the optimum parameter settings of RACiR curves for evergreen broadleaved trees and shrubs. We set 11 groups of CO2 gradients ([CO2]), i.e. R1 (400-1500 ppm), R2 (400-200-800 ppm), R3 (420-20-620 ppm), R4 (420-20-820 ppm), R5 (420-20-1020 ppm), R6 (420-20-1220 ppm), R7 (420-20-1520 ppm), R8 (420-20-1820 ppm), R9 (450-50-650 ppm), R10 (650-50 ppm) and R11 (650-50-650 ppm), and then compared the differences between steady-state A-Ci and RACiR curves. We found that Vcmax and Jmax calculated by steady-state A-Ci and RACiR curves overall showed no significant differences across 11 [CO2] gradients (P > 0.05). For the studied evergreens, the efficiency and accuracy of R2, R3, R4, R9 and R10 were higher than the others. Hence, we recommend that the [CO2] gradients of R2, R3, R4, R9 and R10 could be applied preferentially for measurements when using the RACiR technique to obtain Vcmax and Jmax of evergreen broadleaved species.

Large differences in ammonia emission factors between greenhouse and open-field systems under different practices across Chinese vegetable cultivation.

Estimating ammonia (NH3) emission factors (EFs) for vegetable production can support assessment of potential atmospheric pollution risk and provide information for mitigating NH3 volatilization. The EFs in greenhouse and open-field systems under different fertilization, irrigation regimes, vegetable types and soil properties in both greenhouse and open-field vegetable production systems in China are poorly understood. An integrated analysis was performed, including 282 field measurements of NH3 volatilization from 54 field studies, to quantify ammonia EFs under different management practices and soil properties. The results showed that the mean ammonia EF across all measurements was 4.2 % (3.6 %-4.8 %). The EFs of greenhouse and open-field systems were 2.0 % (1.5 %-2.5 %) and 6.3 % (5.4 %-7.2 %), respectively. There was a power function relationship between nitrogen application rate and ammonia EF in greenhouses. No relationship was identified between nitrogen application rate and ammonia EF in the open-field system. The EFs of organic fertilizers were lower than those of both chemical fertilizers and the combination of chemical and organic fertilizers. EFs of leafy vegetables, cabbages, solanaceous vegetables and melons were 2.7 %, 2.9 %, 1.4 % and 1.4 % in the greenhouse system, and 5.2 %, 5.7 %, 7.6 % and 9.7 % in the open-field system, respectively. The EFs of the greenhouse production system increased with increasing soil organic matter. Boosted regression tree analysis showed that N application rate, pH and soil organic matter were the main driving factors of EFs in the greenhouse system. Vegetable type, pH and soil organic matter were the main driving factors in the open-field system. In this study, the EFs were evaluated and distinguished across greenhouse and open-field systems, and the results provided accurate EFs under different management practices and soil properties for vegetable production in both greenhouse and open-field systems.

Characteristics, formation, and sources of PM2.5 in 2020 in Suzhou, Yangtze River Delta, China.

Here we present seasonal chemical characteristics, formations, sources of PM2.5 in the year 2020 in Suzhou, Yangtze River Delta, China. Expectedly, organic matter (OM) found to be the most dominant component of PM2.5, with a year-average value of 10.3 ± 5.5 µg m-3, followed by NO3- (6.7 ± 6.5 µg m-3), SO42- (3.3 ± 2.5 µg m-3), NH4+ (3.2 ± 2.8 µg m-3), EC (1.1 ± 1.3 µg m-3), Cl- (0.57 ± 0.56 µg m-3), Ca2+ (0.55 ± 0.91 µg m-3), K+ (0.2 ± 1.0 µg m-3), Na+ (0.18 ± 0.45 µg m-3), and Mg2+ (0.09 ± 0.15 µg m-3). Seasonal variations of PM2.5 showed the highest average value in spring, followed by winter, fall, and summer. Meanwhile, the formation mechanisms of the major PM2.5 species (NO3-, SO42-, and OM) varied in seasons. Interestingly, NO2 may have the highest conversion rate to NO3- in spring, which might be linked with the nighttime chemistry due to the high relative humidity. Moreover, OM in summer was mainly produced by the daytime oxidation of volatile organic compounds, while local primary organic aerosols might play a significant role in other seasons. Source apportionment showed that the more-aged PM2.5 contributed significantly to the PM2.5 mass (42%), followed by the dust-related PM2.5 (38%) and the less-aged PM2.5 (21%). Potential contribution source function (PSCF) results indicated that aged PM2.5 were less affected by transportation than dust-related PM2.5.

Effects of Water and Fertilizer Management Practices on Methane Emissions from Paddy Soils: Synthesis and Perspective.

Water and fertilizer management practices are considered to have great influence on soil methane (CH4) emissions from paddy fields. However, few studies have conducted a quantitative analysis of the effects of these management practices. Here, we selected 156 observations of water management from 34 articles and 288 observations of fertilizer management from 37 articles and conducted a global meta-analysis of the effects of water and fertilizer management practices on soil CH4 emissions in paddy fields. In general, compared with traditional irrigation (long-term flooding irrigation), water-saving irrigation significantly decreased soil CH4 emissions but increased rice yield. Among the different practices, intermittent irrigation had the fewest reductions in CH4 emissions but the greatest increase in rice yield. In addition, fertilization management practices such as manure, mixed fertilizer (mixture), and straw significantly enhanced CH4 emissions. Rice yields were increased under fertilization with a mixture, traditional fertilizer, and controlled release fertilizer. Our results highlight that suitable agricultural water and fertilizer management practices are needed to effectively reduce CH4 emissions while maintaining rice yields. We also put forward some prospects for mitigating soil CH4 emissions from paddy fields in the context of global warming in the future.

Temperature responsiveness of soil carbon fractions, microbes, extracellular enzymes and CO2 emission: mitigating role of texture.

The interaction of warming and soil texture on responsiveness of the key soil processes i.e. organic carbon (C) fractions, soil microbes, extracellular enzymes and CO2 emissions remains largely unknown. Global warming raises the relevant question of how different soil processes will respond in near future, and what will be the likely regulatory role of texture? To bridge this gap, this work applied the laboratory incubation method to investigate the effects of temperature changes (10-50 °C) on dynamics of labile, recalcitrant and stable C fractions, soil microbes, microbial biomass, activities of extracellular enzymes and CO2 emissions in sandy and clayey textured soils. The role of texture (sandy and clayey) in the mitigation of temperature effect was also investigated. The results revealed that the temperature sensitivity of C fractions and extracellular enzymes was in the order recalcitrant C fractions > stable C fractions > labile C fractions and oxidative enzymes > hydrolytic enzymes. While temperature sensitivity of soil microbes and biomass was in the order bacteria > actinomycetes > fungi ≈ microbial biomass C (MBC) > microbial biomass N (MBN) > microbial biomass N (MBP). Conversely, the temperature effect and sensitivity of all key soil processes including CO2 emissions were significantly (P < 0.05) higher in sandy than clayey textured soil. Results confirmed that under the scenario of global warming and climate change, soils which are sandy in nature are more susceptible to temperature increase and prone to become the CO2-C sources. It was revealed that clayey texture played an important role in mitigating and easing off the undue temperature influence, hence, the sensitivity of key soil processes.

[Tracing the sources of sedimentary organic matter in Nanyue small watershed based on 13C, 15N and C/N]. / 基于13C、15N和C/N识别南岳小流域沉积有机质的来源.

Losses of organic matter in agricultural watersheds result in eutrophication and land degra-dation, which not only threaten water quality and food security, but also lead to environmental problems such as the greenhouse gases emission. We used 13C, 15N and C/N as fingerprint markers to trace the sources of sedimentary organic matter at the outlet in the Nanyue small watershed. We analyzed the spatial distribution in watershed sedimentary organic matter and soils of typical land use types, including forest, paddy field, and vegetable fields. The Bayesian stable isotope mixing model was used to quantitatively estimate the contribution of different sources. The results showed that there was significant spatial variation of δ13C. The δ13C of sediment organic matter (-22.6‰±0.53‰) and forest soil (-23.13‰±1.71‰) was significantly higher than that of paddy soil (-25.24‰±1.4‰). The differences of δ15N among the sources were not significant, with sediment having the maximum (4.37±0.83)‰ and forest soil having the minimum (2.38±1.97)‰. Forest soil had the highest C/N of 16.66±7.18, while paddy soil had the lowest C/N of 11.95±0.92. The results of the Bayesian stable isotope mixture model showed that the contribution rates of forest land, paddy fields and vegetable fields to the organic matter deposited at the outlet in the watershed were 19.6%, 15.7%, and 64.7%, respectively. Paddy filed and vegetable field had a combined contribution rate of 80.4%. It was concluded that, soils of agricultural land were the main sources of organic matter deposited in the Nanyue small watershed, and that nutrient loss in the watershed would be effectively controlled by optimizing farmland management.

Air warming and CO2 enrichment cause more ammonia volatilization from rice paddies: An OTC field study.

Ammonia (NH3) volatilization in rice paddies may be affected by elevated atmospheric CO2 concentration ([CO2]) and temperature due to changes in plant and soil nitrogen (N) metabolism. At present, little is known about the individual and combined effects of CO2 enrichment and warming on NH3 volatilization under field conditions. An experiment was conducted in a rice paddy in Central China, after 4 years of warming and CO2 enrichment using open-top chamber (OTC) devices. Compared with ambient conditions, elevated [CO2] had no significant effects on NH3 volatilization, although increases in soil pH and urease activity were observed. The stimulation on plant N assimilation under CO2 enrichment might offset the possible enhancement on NH3 volatilization, as more soil N was absorbed by plant thus reducing NH3 loss potential. Elevated temperature increased NH3 volatilization significantly, which could be attributed to increased soil ammonium nitrogen (NH4+-N) concentration, pH, and urease activity. Combination of CO2 enrichment and warming caused the highest cumulative NH3 loss, which increased by 26.5% compared with ambient conditions, but the interaction was not significant. Higher plant N uptake, soil NH4+-N concentration, pH and urease activity were also observed with co-elevation of [CO2] and temperature, but the combined effects were variable and not synergistic. Our findings confirm that field warming and CO2 enrichment cause more NH3 volatilization in rice paddies, among which warming effects are dominant, and suggest that improved N management or field practices are required to reduce NH3 losses under future climate change.

[Responses of net assimilation rate to elevated atmospheric CO2and temperature at different growth stages in a double rice cropping system]. / 双季稻不同生育期净同化速率对大气CO2浓度和温度升高的响应.

Effects of elevated atmospheric CO2 concentration and temperature on rice dry matter accumulation vary in planting regions and cropping systems. It remains unclear how dry matter productivity responds to factorial combination of elevated CO2 and temperature in the double rice cropping system of China. Field experiments were conducted using open-top chambers (OTC) to simulate different scenarios of elevated CO2 and/or temperature for three rotations of double rice in Jingzhou, Hubei Province. Liangyou 287 and Xiangfengyou 9 were used as rice cultivar for early rice and late rice, respectively. There were five treatments: UC, paddy field without OTC covering; CK, OTC with the similar temperature and CO2 concentration to field environment; ET, OTC with 2 ℃ temperature elevation; EC, OTC with 60 µmol·mol-1 CO2 elevation; ETEC, OTC with simu-ltaneous 2 ℃ temperature elevation and 60 µmol·mol-1 CO2 elevation. We measured aboveground biomass, leaf area index (LAI) and net assimilation rate (NAR) of dry matter under different treatments. Our results showed that elevated CO2 and/or temperature had no significant effects on NAR from transplanting to jointing, increased NAR from jointing to heading, but decreased NAR from heading to maturity (except for EC treatment in early rice). Elevated CO2 and/or temperature promoted leaf area development at all growth stages, with ETEC showing the highest increase in LAI except at maturity. Warming and CO2 enrichment jointly promoted dry matter accumulation at heading, with ETEC increasing aboveground biomass by 10.3%-39.8% and 23.6%-34.4% compared with CK in early rice and late rice, respectively. At maturity of early rice, elevated temperature partly offset the positive effects of elevated CO2 on aboveground biomass, as shown by a reduction of 3.2%-14.1% under ETEC compared with EC. Contrarily at maturity of late rice, co-elevation of CO2 and temperature further increased aboveground biomass, showing a synergistic interaction. Results from regression analysis showed that warming and CO2 enrichment had positive effects on NAR at vegetative stages of double rice, while warming showed negative effects on NAR at reproductive stages. Considering the dissimilarities in growth characteristics, growing periods and ambient temperature, elevated CO2 and temperature might increase dry matter production in the Chinese double rice cropping system.

Diffusive flux of CH4 and N2O from agricultural river networks: Regression tree and importance analysis.

River networks in subtropical agricultural hilly region become an inconvenient greenhouse gas (GHG, methane and nitrous oxide) source because of the influence of human activities, which has caused large uncertainties for refinement of national GHG inventories and their global budget. Based on field monitoring experiments at high temporal resolution, we employed regression tree and importance analysis to identify quantitatively factors that influence the diffusive flux of GHGs to provide a scientific basis for reducing GHG emissions and controlling regional carbon and nitrogen losses. The results indicate that significant spatiotemporal variation of methane (CH4) nitrous oxide (N2O) diffusion occurs in all the four reaches (W1, W2, W3 and W4) of Tuojia river networks. Among them, W1 contributed lowest CH4 (22.55 µg C m-2 h-1) and N2O (5.00 µg N m-2 h-1) diffusive flux than the other three (P < 0.05), while W4 offered highest CH4 (166.15 µg C m-2 h-1) and N2O (30.47 µg N m-2 h-1) diffusive flux but with no statistically significant difference between W2 and W3 due to homogeneous extraneous nutrition loading into the two reaches. W4 also contributed largest cumulative flux of CH4 (14.55 kg C ha-1 yr-1) and N2O (2.69 kg N ha-1 yr-1) in Tuojia River networks (P < 0.05). Furthermore, the regression tree and importance analysis indicate that, in the anaerobic environment, dissolved oxygen saturation controlled the production and diffusion for both CH4 and N2O. The findings of this investigation highlighted that decision support tools provide an effective pathway to enhance the GHG mitigation technology research in agroecosystems and simultaneously shed light on the global campaign on refinement of national GHG inventories as well as regional nutrient management.

Air warming and CO2 enrichment increase N use efficiency and decrease N surplus in a Chinese double rice cropping system.

Effectiveness of N might be modified in rice cultivation under future climate change with elevated atmospheric CO2 concentration ([CO2]). At present, limited information is available to understand how plant N uptake and N use efficiency respond to elevated [CO2] and/or temperature in Chinese double rice cropping systems. A four-year field experiment was therefore conducted using open-top chambers with varying [CO2] (ambient, ambient +60 µmol mol-1) and varying temperature (ambient, ambient +2 °C) in Hubei Province, Central China. Compared with ambient conditions, elevated [CO2] increased plant N uptake and N use efficiency, as measured by fertilizer N recovery efficiency (NRE), N agronomic efficiency (NAE), N physiological efficiency (NPE) and apparent system N use efficiency (NUEsys), in both early rice and late rice. CO2 enrichment tended to decrease soil mineral N concentration since more N was assimilated by plants. Elevated temperature led to lower plant N uptake and decreased NRE and NAE in early rice, due to a reduction in grain yield induced by heat injury. In contrast, warming increased plant N uptake and N use efficiency in late rice as no heat stress existed. Warming tended to increase soil mineral N concentration in early rice but had negligible effects in late rice. When elevated [CO2] and temperature were combined, the positive effects of CO2 enrichment for N utilization were able to compensate for the negative effects of warming in early rice, while the interaction was synergetic in late rice. Hence, co-elevation of [CO2] and temperature led to higher N use efficiency (64.6% for NUEsys across four years) and decreased annual N surplus by 28.6-36.5 kg N ha-1 compared with ambient conditions. Our findings confirm that CO2 enrichment and air warming can improve N use efficiency at both crop level and system level in Chinese double rice cultivation.

Assessment of Indirect N2O Emission Factors from Agricultural River Networks Based on Long-Term Study at High Temporal Resolution.

Assessment of indirect emission factors (EF5r) of nitrous oxide (N2O) from agricultural river networks remains challenging, and results are uncertain due to limited data availability. This study compared two methods of assessing EF5r using data from long-term observations at high temporal resolution in a typical agricultural catchment in subtropical central China. The concentration method (method 1) and the Intergovernmental Panel on Climate Change (IPCC) 2006 method (method 2) were employed to evaluate the emission factor. EF5r estimated using method 1 (i.e., EF5r1) was 0.00077 ± 0.00025 (0.00038-0.00097). EF5r calculated using method 2 (i.e., EF5r2) was lower than EF5r1, with a mean value of 0.00004 (0.000015-0.00012). Both EF5r1 and EF5r2 were significantly lower than the IPCC 2006 default value of 0.0025, suggesting that N2O emissions from China and world river networks may be grossly overestimated. A complex N2O production pathway and diffusion mechanism were responsible for the transfer of N2O from the sediment to river water and then to the atmosphere. These findings provide essential data for refining national greenhouse gas inventories and contribute evidence for downward revision of indirect emission factors adopted by the IPCC.

Solitons in spin-orbit-coupled spin-2 spinor Bose-Einstein condensates.

We investigate the different types of matter-wave solitons in spin-orbit-coupled spin-2 spinor Bose-Einstein condensates. Using mean-field theory and adopting the multiscale perturbation method, the original five-component Gross-Pitaevskii spin-orbit-coupled spin-2 spinor Bose-Einstein condensate model can be reduced to a single effective nonlinear Schrödinger equation, which allows us to find analytical soliton solutions of this system. In this way, for different regimes of the spin-orbit coupling, Raman coupling, and interatomic interactions, we find approximate bright and dark soliton solutions. Particularly, the type of solitons depends on the dispersion properties of the system. When the lowest-energy band has a single-well structure, we find there only exist positive mass bright or dark solitons due to the dispersion coefficient of effective nonlinear Shrödinger equation always positive. However, when the lowest-energy band has a double-well structure, there will appear positive (negative) mass bright or dark solitons because the sign of the dispersion coefficient can be positive (negative) under different momentum. We employ direct numerical simulation of the original five-component Gross-Pitaevskii equations to confirm the analytical results.

Adsorption performance and mechanisms of Pb(II), Cd(II), and Mn(II) removal by a ß-cyclodextrin derivative.

In this study, the novel adsorbent PVA-TA-ßCD was synthesized via thermal cross-linking between polyvinyl alcohol and ß-cyclodextrin. The characterization methods SEM-EDS, FTIR, and XPS were adopted to characterize the adsorbent. The effect of pH, contact time, initial concentrations, and temperature during the adsorption of Pb(II), Cd(II), and Mn(II) onto the PVA-TA-ßCD was also investigated. In a single-component system, the data fitted well to pseudo-second-order, and film diffusion and intra-particle diffusion both played important roles in the adsorption process. As for isotherm study, it showed a heterogeneous adsorption capacity of 199.11, 116.52, and 90.28 mg g-1 for the Pb(II), Cd(II), and Mn(II), respectively. Competition between the ions existed in a multi-component system; however, owing to the stronger affinity of the PVA-TA-ßCD for Pb(II) relative to Cd(II) and Mn(II), the Pb(II) adsorption onto the PVA-TA-ßCD was less affected by the addition of the other metals, which could be effectively explained by the hard and soft acid and base theory (HSAB). Furthermore, PVA-TA-ßCD showed good reusability throughout regeneration experiments.

Panax notoginseng saponins mitigate cisplatin induced nephrotoxicity by inducing mitophagy via HIF-1α.

We investigated the role of HIF-1α in the mitigation of cisplatin-induced nephrotoxicity by Panax notoginseng saponins (PNS) in a rat model. Serum creatinine (Scr), blood urea nitrogen (BUN) and urinary N-acetyl-ß-D-glucosaminidase (NAG) levels were all elevated in cisplatin treated rats. PNS reduced Scr, BUN and NAG levels in the presence or absence of the HIF-1α inhibitor 2-methoxyestradiol (2ME2). PNS also reduced the high tubular injury scores, which corresponded to renal tubular damage in cisplatin-treated rats and which were exacerbated by 2ME2. Renal tissues from PNS-treated rats showed increased HIF-1α mRNA and nuclear localized HIF-1α protein. Moreover, PNS treatment increased BNIP3 mRNA as well as LC3-II, BNIP3 and Beclin-1 proteins and the LC3-II/LC3-I ratio in rat renal tissues. This suggested that PNS treatment enhanced HIF-1α, which in turn increased autophagy. This was confirmed in transmission electron micrographs of renal tissues that showed autophagosomes in PNS-treated renal tissues. These findings demonstrate that PNS mitigates cisplatin-induced nephrotoxicity by enhancing mitophagy via a HIF-1α/BNIP3/Beclin-1 signaling pathway.

Carbon footprint of grain production in China.

Due to the increasing environmental impact of food production, carbon footprint as an indicator can guide farmland management. This study established a method and estimated the carbon footprint of grain production in China based on life cycle analysis (LCA). The results showed that grain production has a high carbon footprint in 2013, i.e., 4052 kg ce/ha or 0.48 kg ce/kg for maize, 5455 kg ce/ha or 0.75 kg ce/kg for wheat and 11881 kg ce/ha or 1.60 kg ce/kg for rice. These footprints are higher than that of other countries, such as the United States, Canada and India. The most important factors governing carbon emissions were the application of nitrogen fertiliser (8-49%), straw burning (0-70%), energy consumption by machinery (6-40%), energy consumption for irrigation (0-44%) and CH4 emissions from rice paddies (15-73%). The most important carbon sequestration factors included returning of crop straw (41-90%), chemical nitrogen fertiliser application (10-59%) and no-till farming practices (0-10%). Different factors dominated in different crop systems in different regions. To identity site-specific key factors and take countermeasures could significantly lower carbon footprint, e.g., ban straw burning in northeast and south China, stopping continuous flooding irrigation in wheat and rice production system.

Long-term effect of biochar application on yield-scaled greenhouse gas emissions in a rice paddy cropping system: A four-year case study in south China.

To evaluate long-term effect of biochar application on yield-scaled greenhouse gas emissions (YSGE) in a paddy rice cropping system, a 4-year field experiment by static chamber - gas chromatograph method was conducted in South China. Principal component analysis and terminal restriction fragment length polymorphism (T-RFLP) and real-time qPCR was used to unravel the microbial mechanisms of biochar addition. Six treatments were included: control (CK), application of 5tha(-1) biochar (BC1), application of 10tha(-1) biochar (BC2), application of 10tha(-1) biochar (BC3), rice straw return at 2400kgha(-1)(RS) and inoculated rice straw return at 2400kgha(-1)(RI). The results indicated that biochar amendment significantly decreased methane (CH4) and gross greenhouse gas (GHG) emissions. This may primarily be ascribed to the stimulated biodiversity and abundance of methanotrophic microbes, increased soil pH and improved aeration by reducing bulk density after biochar incorporation. Compared with CK, RS and RI, 26.18%, 70.02%, 66.47% of CH4 flux and 26.14%, 70.16%, 66.46% of gross GHG emissions were reduced by biochar (mean of three biochar treatments), respectively. Furthermore, biochar significantly increased harvest index of double rice production (p<0.05). In comparison with CK, RS and RI, 29.14%, 68.04%, 62.28% of YSGE was reduced by biochar, respectively, and the highest biochar addition rate (20tha(-1)) contributed most to the mitigation of GHG emissions (36.24% decrease compared to CK) and improvement of rice yield (7.65% increase compared to CK). Results of our study suggested that long-term application of biochar should be the potential way to mitigate GHGs emissions and simultaneously improve rice productivity in the paddy rice system.

[Driving force analysis of land use change in the developed area based on Probit regression model: A case study of Nanjing City, China].

Based on the remote sensing image in 1996, 2002 and 2010, with the help of RS and GIS technology, and using the Probit regression model, this paper analyzed the characteristics of land use change in Nanjing City from 1996 to 2010, and the driving factors of land use change. The results showed that the cultivated land and woodland decreased, constructive land, garden plot and grassland continued to increase, and the comprehensive land use change rate was rising since 1996. The results of regression model for cultivated land and woodland change indicated that the change of cultivated land in the years 1996-2002 was mainly affected by the factors of "distance to the nearest rural settlement" and "farmers' population density". However, in the years 2002-2010 it was mainly affected by the factors of "change of per area GDP", "distance to the rural settlement" and "distance to the nearest road". The change of woodland in the years 1996-2002 was mainly affected by the factors of "the elevation" and "distance to the rural settlement". However, in the years 2002-2010 it was mainly affected by the factors of "change of per area GDP", "population density" and "distance to the nearest road". By comparison, the early driving factors of land use change were mainly natural factors, but in recent years, they were mainly social, economic and demographic factors.

[Modeling Study of A Typical Summer Ozone Pollution Event over Yangtze River Delta].

WRF/Chem model was used to analyze the temporal and spatial distribution characteristics and physical and chemical mechanism of a typical summer ozone pollution event over Yangtze River Delta (YRD). The result showed that the model was capable of reproducing the temporal and spatial distribution and evolution characteristics of the typical summer ozone pollution event over YRD. The YRD region was mainly affected by the subtropical high-pressure control, and the weather conditions of sunshine, high temperature and small wind were favorable for the formation of photochemical pollution on August 10-18, 2013. The results of simulation showed that the spatial and temporal distribution of O3 was obviously affected by the meteorological fields, geographic location, regional transport and chemical formation over YRD. The sensitivity experiment showed that the O3 concentration affected by maritime airstream was low in Shanghai, but the impact of Shanghai emissions on the spatial and temporal distribution of O3 concentration over YRD was significant; The main contribution of the high concentration of O3 in Nanjing surface was chemical generation ( alkene and aromatic) and the vertical transport from high-altitude O3, whereas the main contribution of the high concentration of O3 in Hangzhou and Suzhou was physics process. The influence of the 15:00 peak concentration of O3 over YRD was very obvious when O3 precursor was reduced at the maximum O3 formation rate (11-13 h).

[Research on soil bacteria under the impact of sealed CO2 leakage by high-throughput sequencing technology].

Carbon dioxide Capture and Storage has provided a new option for mitigating global anthropogenic CO2 emission with its unique advantages. However, there is a risk of the sealed CO2 leakage, bringing a serious threat to the ecology system. It is widely known that soil microorganisms are closely related to soil health, while the study on the impact of sequestered CO2 leakage on soil microorganisms is quite deficient. In this study, the leakage scenarios of sealed CO2 were constructed and the 16S rRNA genes of soil bacteria were sequenced by Illumina high-throughput sequencing technology on Miseq platform, and related biological analysis was conducted to explore the changes of soil bacterial abundance, diversity and structure. There were 486,645 reads for 43,017 OTUs of 15 soil samples and the results of biological analysis showed that there were differences in the abundance, diversity and community structure of soil bacterial community under different CO, leakage scenarios while the abundance and diversity of the bacterial community declined with the amplification of CO2 leakage quantity and leakage time, and some bacteria species became the dominant bacteria species in the bacteria community, therefore the increase of Acidobacteria species would be a biological indicator for the impact of sealed CO2 leakage on soil ecology system.

[Observation for CH4 and N2O emissions under different rates of nitrogen and phosphate fertilization in double rice fields].

Two non-CO2 greenhouse gas emissions (methane and nitrous oxide) and related environmental factors were measured within rice growing season under five treatments including non-fertilization (CK), balanced fertilization (BF), decreased nitrogen and phosphate 1 (DNP1), decreased nitrogen and phosphate 2 (DNP2) and increased nitrogen and phosphate 1 (INP) in double rice fields of red clay soil in 2009, using the method of static chamber-gas chromatograph techniques. The results showed that the average CH4 emission fluxes for treatments of BF, DNP1, DNP2 and INP were 4.57, 5.42, 4.70 and 4.65 mg x (m2 x h)(-1) during early rice growing period, which increased by 39%, 49%, 41% and 40% compared with non-fertilizer treatment, respectively. The average CH4 emission fluxes in late rice growing season was higher than preseason's. Compared to CK, CH4 emission increased by 11%, 1%, 26% and - 4% in treatments of BF, DNP1, DNP2 and INP within late rice growing season. Applying nitrogen and phosphate enhanced CH4 emission in turning green period for early and late rice. No significant difference was observed between the CH4 emissions of five treatments during early and late rice growing season (p > 0.05). N2O emission was very little during mid-seasonal drainage period. In contrast, N2O emission peaks were observed in period of alternation of wetting and drying after mid-seasonal drainage in this experiment. N2O emission was, on average, equivalent to 0.18% of the nitrogen applied in double rice growing season. Statistically, air temperature, soil Eh and soil moisture (water-filled pore space, WFPS) at 0-10cm depth significantly affected the fluctuations of the seasonal CH4 flux, but no significant correlationship has been found between N2O flux and related environmental factors. CH4 was the dominated greenhouse gas in double rice fields which contributed approximately 90% for the integrated global warming potential of CH4 and N2O released during the rice growing season. Therefore, the mitigation options should focus on how to reduce CH4 emission in local area. The result indicates that BF is a recommended fertilization method for early rice production, and a optimum fertilization for late season can increase rates of nitrogen and phosphate fertilizers on the basis of BF treatment slightly by considering total global warming potential and grain yield. The rates of BF treatment were 150-90-90 kg x hm(-2) N-P2O5-K2O for early rice, and 180-90-135 kg x hm(-2) N-P2O5-K2O for late rice, respectively.